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Title: Conservation of marine birds of northern North America: - papers from the international symposium held at the Seattle Hyatt House
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Language: English
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WILDLIFE RESEARCH REPORTS
This series comprises reports of research relating to birds, mammals,
and other wildlife and their ecology, and specialized bibliographies
on these, issued for wildlife research and management specialists. The
Service distributes these reports to official agencies, to libraries,
and to researchers in fields related to the Service's work.
Library of Congress Cataloging in Publication Data
Conservation of marine birds of northern North America.
(Wildlife research report: 11)
Supt. of Docs. no.: I 49.47/4:11
1. Sea birds--North America--Congresses. 2. Sea birds--Northwest,
Pacific--Congresses. 3. Birds, Protection of--North
America--Congresses. 4. Birds, Protection of--Northwest,
Pacific--Congresses. 5. Birds--North America--Congresses. 6.
Birds--Northwest, Pacific--Congresses. I. Bartonek, James C. II.
Natural Resources Council of America. III. United States. Fish and
Wildlife Service. IV. Series.
QL681.C59 333.9'5 79-607005
Use of trade names does not imply U.S. Government endorsement of
commercial products.
CONSERVATION OF MARINE BIRDS OF NORTHERN NORTH AMERICA
[Illustration]
CONSERVATION OF MARINE BIRDS OF NORTHERN NORTH AMERICA
Papers from the International Symposium held at the Seattle Hyatt
House, Seattle, Washington, 13-15 May 1975
Edited by
James C. Bartonek and David N. Nettleship
Sponsored by
Natural Resources Council of America
National Audubon Society
National Wildlife Federation
U.S. Department of the Interior, Fish and Wildlife Service
UNITED STATES DEPARTMENT OF THE INTERIOR
FISH AND WILDLIFE SERVICE
Wildlife Research Report 11
Washington, D.C. • 1979
Dedicated to the Memory
of
Robert D. Bergman, Leonard A. Boughton, and J. Larry Haddock, Wildlife
Biologists of the Fish and Wildlife Service, and Robert Johnson, Pilot
of the Office of Aircraft Services, all of the U.S. Department of the
Interior, who perished in the Gulf of Alaska on 30 September 1974 while
conducting aerial surveys of marine birds,
and to
Einar Brun, Professor of Zoology in Tromsø University and a contributor
to these proceedings, who perished in the Vega Sea on 13 July 1976 when
returning from making aerial surveys of marine birds.
Contents
Page
Foreword, by Harvey K. Nelson vii
Introduction, by Lynn A. Greenwalt ix
Marine Environment of Birds 1
Long-term Climatic and Oceanographic Cycles Regulating Seabird
Distributions and Numbers, by M. T. Myres 3
Sea Ice as a Factor in Seabird Distribution and Ecology in the Beaufort,
Chukchi, and Bering Seas, by George J. Divoky 9
Status of Marine Bird Populations 19
Distribution and Status of Marine Birds Breeding Along the
Coasts of the Chukchi and Bering Seas, by James C. Bartonek and
Spencer G. Sealy 21
Breeding Distribution and Status of Marine Birds in the Aleutian
Islands, Alaska, by Palmer C. Sekora, G. Vernon Byrd, and Daniel
D. Gibson 33
The Historical Status of Nesting Seabirds of the Northern and Western
Gulf of Alaska, by LeRoy W. Sowl 47
Status and Distribution of Breeding Seabirds of Southeastern Alaska,
British Columbia, and Washington, by David A. Manuwal and
R. Wayne Campbell 73
The Biology and Ecology of Marine Birds in the North 93
Trophic Relations of Seabirds in the Northeastern Pacific Ocean
and Bering Sea, by David G. Ainley and Gerald A. Sanger 95
Population Dynamics in Northern Marine Birds, by William H. Drury 123
Time-energy Use and Life History Strategies of Northern Seabirds,
by Erica H. Dunn 141
Zoogeography and Taxonomic Relationships of Seabirds in
Northern North America, by M. D. F. Udvardy 167
Conflicts Between the Conservation of Marine Birds and Uses of
Other Resources 171
Social and Economic Values of Marine Birds, by David R. Cline,
Cynthia Wentworth, and Thomas W. Barry 173
Resource Development Along Coasts and on the Ocean Floor: Potential
Conflicts with Marine Bird Conservation, by Donald E. McKnight
and C. Eugene Knoder 183
Mortality to Marine Birds Through Commercial Fishing, by Warren B. King,
R. G. B. Brown, and Gerald A. Sanger 195
Interactions Among Marine Birds and Commercial Fish in the Eastern
Bering Sea, by Richard R. Straty and Richard E. Haight 201
Interrelations Between Seabirds and Introduced Animals,
by Robert D. Jones, Jr., and G. Vernon Byrd 221
Oil Vulnerability Index for Marine Oriented Birds, by James G. King
and Gerald A. Sanger 227
Programs and Authorities Related to Marine Bird Conservation 241
Programs and Authorities Related to Marine Bird Conservation in
Washington State, by Ralph W. Larson 243
Programs and Authorities of the Province of British Columbia
Related to Marine Bird Conservation, by W. T. Munro and R. Wayne
Campbell 247
Petroleum Industry's Role in Marine Bird Conservation, by Keith
G. Hay 251
Conservation of Marine Birds in Other Lands 259
Conservation of Marine Birds in New Zealand, by Gordon R. Williams 261
Marine Birds in the Danish Monarchy and Their Conservation,
by Finn Salomonsen 267
Present Status and Trends in Population of Seabirds in Norway,
by Einar Brun 289
Symposium Summary 303
Conservation of Marine Birds of Northern North America--a Summary,
by Ian C. T. Nisbet 305
Appendix. Papers and oral summaries presented at the symposium but which
do not appear in this publication 319
Foreword
The international symposium "Conservation of Marine Birds of Northern
North America" was convened because of a growing awareness that not
all was well with our marine birds. The symposium provided a forum
for scientists, governmental administrators, conservationists, and
laypeople to discuss the diverse topics and issues that we must all
understand if we are to act both responsively and responsibly to assure
that marine birds will not be lost through our neglect.
The symposium was cosponsored by the Natural Resources Council of
America, National Audubon Society, National Wildlife Federation,
and the U.S. Department of the Interior, Fish and Wildlife Service;
additional support was provided by the Canadian Wildlife Service,
the International Association of Game, Fish, and Conservation
Commissioners, the Pacific Seabird Group, the Sierra Club, the
Smithsonian Institution, the Wildlife Management Institute, and the
Wildlife Society.
Persons interested and knowledgeable in the many and varied
aspects of marine bird conservation were invited to participate
in this symposium. There were 139 registered and several score of
unregistered participants in attendance. Major topics treated were:
(1) socioeconomic considerations and conservation of marine birds; (2)
the marine environment of birds; (3) status of marine bird populations
on land and sea; (4) the biology and ecology of marine birds in the
North; (5) conflicts between the conservation of marine birds and
uses of other resources; (6) programs and authorities related to the
conservation of marine birds; and (7) conservation of marine birds in
other lands.
The objective of the symposium was to identify problems and the needed
information and programs necessary for the conservation of marine birds
of northern North America. For the purpose of this symposium the term
"northern North America" referred to the coasts of Washington, British
Columbia, Alaska, Yukon Territory, and Northwest Territories and the
adjacent North Pacific and Arctic Oceans. "Marine bird" was defined as
being any bird using marine or estuarine waters. Speakers were asked
to describe the status of information or the state of the art as it
pertained to their topic within the limitations set by the objective
of the symposium. Examples from other regions and of bird species
not found in the regions of concern were to be used for comparative
purposes when little pertinent information was known for regions or
species of concern. Speakers were asked to identify the gaps in the
knowledge and methodology that are most critical to their topic.
I believe that this symposium was particularly successful in that it
provided a timely forum for many scientists who were about to embark on
studies of marine birds in those areas of Alaska and California being
considered for outer continental shelf oil and gas exploration and
development. These published proceedings may be of lesser importance
from that standpoint because some data, particularly those on
populations, are out of date. However, I believe that the proceedings
will long be of importance to biologists and administrators alike in
charting their respective courses to ultimately assure conservation of
this valuable avian resource.
Many people from many organizations and agencies worked hard to put
together the symposium in the relatively short time of about 8 months.
Nathaniel P. Reed was the person primarily responsible for bringing
this symposium to fruition. The Steering Committee was composed of
Daniel A. Poole, John S. Gottschalk, David N. Nettleship, Amos S. Eno,
C. Eugene Knoder, Warren G. King, Louis Clapper, Robert Hughes, Fred G.
Evenden, James C. Bartonek, and me. James C. Bartonek, Warren G. King,
David N. Nettleship (Co-chairmen), C. Eugene Knoder, David A. Manuwal,
William H. Drury, and Spencer G. Sealy served on the Program Committee.
David A. Manuwal and Terence R. Wahl arranged trips for persons to
observe pelagic birds off the Washington coast and other birds on
Skagit Flats. C. Eugene Knoder handled financial matters. John A. Sayre
and Richard Bauer made arrangements for facilities and entertainment.
Elaine Rhode prepared the program and abstracts for printing. John
Pitcher kindly contributed the artwork used in this publication as well
as that used in the program and abstracts.
George Reiger made general introductions to the symposium; Spencer
G. Sealy, Daniel W. Anderson, and I served as Session Chairmen; and
James C. Bartonek served as General Chairman. Elvis J. Stahr was guest
speaker at the symposium banquet.
Most credit for the success of this symposium goes to the 52 persons
who as authors, coauthors, or summarizers of sessions presented
much meaningful information in their presentations, during recorded
discussions, and during many informal occasions. I wish to make special
recognition of Ian C. T. Nisbet for his skillful summary of the
symposium.
Editorial assistance in preparing the proceedings was provided by
Judith Brogan.
Harvey K. Nelson
_Chairman of Symposium and
Director of Wildlife Resources_
Introduction
Migratory birds make up a resource that is shared by many people
of many nations. Public awareness of marine birds--their manifold
values, ecological requirements, and problems--is prerequisite to
their protection. I am proud that the Fish and Wildlife Service can
further this needed awareness by publishing these proceedings of the
international symposium "Conservation of Marine Birds of Northern North
America."
Lynn A. Greenwalt, _Director
Fish and Wildlife Service_
MARINE ENVIRONMENT OF BIRDS
Long-term Climatic and Oceanographic Cycles Regulating Seabird
Distributions and Numbers
by
M. T. Myres
Department of Biology, University of Calgary
Calgary, Alberta, Canada T2N 1N4
Abstract
Seabird ornithologists have generally paid
little attention to the possible roles played
by long-term climatic cycles or air-ocean
interactions on population changes at
established colonies or on the processes of
colony establishment or extinction. Yet, a
rapidly expanding literature in the physical
sciences suggests that seabird numbers are not
naturally stable at particular colonies for any
great length of time. It is suggested that the
establishment of new colonies at one end of
the range may counter the decline of colonies
at the other end. Perhaps these changes in
small marginal colonies are important, and they
may be more indicative and significant (when
detected and explained) than are much larger
changes in numbers in bigger reproductive units
in the center of a species' range. Fluctuations
in seabird numbers must in future be first
considered as possible responses either to
short-term, or turnarounds in longer term,
natural climatic or oceanographic cycles, or to
trends ranging in length from a few years to at
least several decades.
During the last 30 years extensive literature in the fields of physical
and biological oceanography has accumulated that is not readily
accessible to the nonprofessional student of seabirds and not as
widely understood by career seabird ornithologists as it should be.
This literature in oceanography and marine fisheries is as extensive
in Russian and Japanese together as in the main languages of Western
Europe combined; this abundance compounds the problem of becoming
familiar with it if, as a student of seabirds, one's interest in the
literature is initially somewhat marginal. Nevertheless, to achieve the
best possible appreciation of the oceanographic influences affecting
seabirds, particularly in the north Pacific Ocean and its adjacent
embayment seas, it is necessary to make the effort.
Because of the rigor of carrying out their primary duties while at sea,
only a very few North American and European oceanographers or fishery
biologists have found time to interest themselves in seabirds and then,
with a few notable individual exceptions, only as an off-duty pastime.
The reason is not far to seek. It is far less important to examine the
ecology of organisms at the next highest level of the food chain to the
ones that are the primary concern than it is to examine the next lowest
level (the food of the fishes or, in the case of phytoplankton, the
physical and chemical environment in which the organisms grow best).
Seabirds are at the very top of the marine food chain, and they are not
wholly aquatic in any case since they mainly travel through the air
rather than the water and reproduce on land rather than in the sea.
Only with the relatively recent recognition that seabirds contribute to
the recycling of nutrients back into the ocean to an important degree,
have seabirds gained a new scientific constituency.
At about the same time, governments have begun to recognize that
seabirds are relatively easily examined indicators of the presence of
unseen chemical pollutants in coastal seas, perhaps primarily for the
very same reasons that they were previously so largely ignored; namely,
that they are at the top of the food chains (and so accumulate the
most-persistent and least-degradable pollutants) and that the on-land
failures in their reproductive biology are readily visible.
During the last 10 years, it has become evident that yet another
fundamental science is even more basic to the achievement of a balanced
and in-depth understanding of the influence of the environment
upon seabirds--the combined field of astrophysics, geophysics, and
climatology. New developments in this field (when they are not
published in _Nature_ or _Science_) appear in journals that are less
familiar to seabird ornithologists than those in which the fishery
biologists and biological oceanographers publish their findings.
Unfortunately, important advances in understanding the dynamics and
energy transport mechanisms of both the atmosphere and the water masses
of the oceans are not being picked up by students of seabirds because
of the natural lag in communication that occurs between disparate
disciplines. Only in the last few years have oceanographers and
climatologists been invited to address gatherings of ornithologists,
and the modesty with which they have sometimes done so has limited the
impact of their offerings.
At this symposium, it was left to a biologist with no pretentions in
either physics or mathematics to demonstrate the need for seabird
ornithologists to understand basic environmental processes well beyond
their usual range of interests. I did so with a series of slides taken
from this "other" literature, and I had intended to include in the
published version of this paper an extensive bibliography, subdivided
into category groupings, so that seabird ornithologists could make
their own selection of the points in the spectrum at which they most
needed information.
Unfortunately, limitations upon space in this volume, daily additions
to the exploding literature, and my own inability to keep up with
understanding this have forced me to omit any references and not to
attempt to expound detailed specific physical mechanisms.
Thus unencumbered here, I shall briefly outline instead what I perceive
to be some of the significance for seabird ornithology and conservation
of the rapidly expanding understanding of the oceans, the air-sea
interface, atmospheric dynamics, and influences upon the world's
climate of extraterrestrial events.
Small-scale or Short-term Influences
There is no need to dwell on the well-known events that could be
mentioned under this heading. Seabird ornithologists are familiar
with the fact that the atmosphere is the medium of seabirds both when
searching the ocean for feeding areas and when on migration, and also
a violent enemy, as when particular storms cause occasional "wrecks"
of seabirds inland from coastlines. As a refinement of the former,
Manikowski of Poland suggests that seabirds respond to the passage of
weather systems, so that their distribution over the open ocean may
be constantly changing. Whereas some species may attempt to avoid the
stormy conditions of low-pressure areas (cyclonic conditions), others
more highly specialized for exploiting the aerodynamic properties of
wind over a moving water surface may possibly, instead, try to avoid
large high-pressure regions (anticyclonic conditions with little or
no wind). My student, Juan Guzman, is attempting to determine whether
this may be so; if it is, it might be possible, for example, to predict
some things about the distribution patterns and population structure of
southern hemisphere shearwaters while they are visiting the oceans of
the northern hemisphere during the nonbreeding season.
In comparison with the "wrecks" brought about by storms, which are of
short duration and not usually very serious, seabird ornithologists are
also familiar with relatively brief and localized disasters caused by
changes in the ocean itself. The best-known example is a slight change
in the boundary of an ocean current (or other shift in the position of
a distinctive water mass) that results in the failure of food fishes to
appear as they normally would, close to breeding sites of conspicuous
colonial seabirds, such as the periodic shift in the El Niño off the
west coast of South America. A scarcely studied refinement of this
type of event would be the effects of less-pronounced oceanic changes
that might reduce the planktonic food supply of nocturnally active,
burrow-nesting seabirds. In such instances, the effects might also be a
breeding failure for only one or two seasons; in all probability such
events occur, but whether they are as likely to be detected by us is
problematical. However, the populations of most seabirds are probably
already adapted to survive short-term crises of this type because,
having long adult life spans, reproductive adults that fail to raise
young one year may mostly live to succeed in doing so in the next or
succeeding year, when the oceanic "anomaly" has disappeared. What
constitutes an "anomaly" will be considered again shortly.
A third critical condition for seabirds may be local or widespread,
temporary or final, or some combination of these. A single local spill,
or outfall, of a chemical pollutant will be short term if we can take
steps to alleviate the consequences or stem the flow. Alternately, we
may consider it to be long term if we take the view that it is one
additional act of violence resulting from the "progress" of Industrial
Man, and that it is never going to shift into reverse gear. We may
say that the effect on seabird populations of spills of oil products
or chemical pollutants in coastal waters of a region will be a "final
solution" for any that become wholly extinct before the oil wells go
dry or the industries fail. On the other hand, the effect will have
been merely a perturbation of the population if the species survives
and outlives these activities. Recent upturns in populations of
peregrine falcons _(Falco peregrinus)_ and pelicans _(Pelecanus sp.)_
in certain places where environmental controls have been enacted give
us hope that crises of several years' duration can be withstood by
at least those species that once were common in relation to their
respective food sources or available safe breeding habitats. The really
critical features to document are the means whereby abandoned breeding
sites are reoccupied and the time it takes.
It must never be forgotten that we know almost nothing about the
ecology of subadult or nonreproductive adult seabirds during the years
they are at sea unconfined by membership in a breeding unit and that
we know almost nothing about the activities of pelagic seabirds in the
nonbreeding season. These birds may be far from land and hard to study,
but what happens during those phases of their lives is basic to the
composition of the colony and condition of the birds when breeding.
A start would be to learn everything that is known and is being
discovered about the oceans by oceanographers and, thus forearmed, go
looking for the seabirds with certain questions clearly in mind.
Detecting the Effects of Long-term Cycles
A scientist's working life lasts only a few decades, and few studies of
seabirds by a single author or agency have been continued for longer
than 5-10 years on any one problem. Further, while we as individuals
may live to be equally active in a certain field of research 20 years
hence, our collective conscience and collective muscle consist of
several levels of government that tend to exhibit 4- or 5-year changes
of direction and priorities. Certainly, the civil service may live
on as an inertial recorder of collective experience. Certainly, too,
those who live under one form or another of dictatorship or, as in some
Canadian provinces, where conservative patterns of voting occur, may
experience a continuity of research and development and conservation
policies that exceed the 4- to 5-year turnaround pattern that is most
common. Yet, even these more continuous systems may come to an end
quite suddenly because of economic or political happenstance.
The point of this digression is to show that seabird ornithologists
must not rely on government programs to provide continuous data over
a long period of years--not, at least, in most countries. Monitoring
the biological circumstances of seabirds is not the same as recording
the temperature regularly by machine at a weather station, since this
activity is unlikely to be terminated unless the society collapses
altogether. We may know that in some countries the amateur naturalist
exists in such numbers that records of seabirds will continue to be
made whatever the circumstances. Nevertheless, planning of censuses
that will be repeated every 10 years is best assured if government
and career biologists combine with the amateur element, so that any
one of them can continue the work if any other element should be
incapacitated. At any one time, either the amateur or the government
or the university personnel may be the prime mover, and each of these
forms now exists in various countries.
What the scientific literature in the fields of the geophysical,
atmospheric, and oceanographic disciplines demonstrates is that natural
climatic oscillations probably range in length from the 11-year sunspot
cycle through several decades (or a human lifetime) to several hundred
years. So, when our children are the new trustees of seabird colonies
20 or 40 years hence, they must interpret their data using the full
range of physical as well as biological data that we can leave for
them. Indeed, the information is, I believe, already available over
a long enough period (since 1940 at least) to allow some speculative
interpretations of what may have been happening to our seabird
populations, whether or not we knew or had any evidence of it.
I have already suggested that extraterrestrial events, particularly
the 11-year sunspot cycle, are increasingly believed to influence the
atmosphere of this planet. The Chinese and Japanese have remarkably
precise records of the northern limits of certain agricultural crops
at particular times, the phenology of flowering, and the freezing of
lakes. These demonstrate long-term trends in overall climate in eastern
Asia that extend over hundreds of years. The climate of Japan is
influenced by the high-pressure area in winter over mainland East Asia.
There is evidence that severe ice conditions in the Bering Sea during
the early 1970's may have been due to an eastward shifting of this
high-pressure area. Again, the water mass of the Kuroshio Extension and
the West Wind Drift takes several years to travel across the Pacific
Ocean, and there is an established temperature variation that travels
like a slow wave with it. Off Japan, the Kuroshio Current periodically
develops meanders which slow the speed of the eastward flow. Cold and
warm "pools" of water approach the west coast of Canada and the western
United States from time to time.
Ocean currents are driven by the atmospheric motion above them, which
consists of several convective cells between the equator and each pole.
The outcome is zonal winds, such as the trade winds and the westerlies.
However, as the influence of the sun on the atmosphere is variable, the
input of heat and the extent of the major high-pressure areas vary,
as does the path of the jet stream. The recent droughts in northern
Africa and unusually heavy rains in Australia are both linked to a
southward shift of the Intertropical Convergence Zone in the atmosphere
and a "corrugation" of the wind circulation from a more normal zonal
(latitudinal) path. These shifts in the atmospheric circulation are
almost certainly transmitted also to the ocean currents and the marine
ecosystem, with the influence being felt for a long period of years.
One of the oceanic domains of the North Pacific is the transitional
domain, which lies east-west where the West Wind Drift impinges upon
the coasts of British Columbia and Washington State. It is precisely
in this sector that there was a well-documented "temperature anomaly"
in 1957-58. Since an anomaly implies something completely out of the
ordinary, I seriously question the appropriateness of the term for an
event that may or may not be recurrent (at the time it was a pronounced
variation from the oceanographic records accumulated up to that time,
but the period had not been a very long one). It is no coincidence that
the numbers of albatrosses recorded at Ocean Weather Station "Papa" was
higher during this warm-water "anomaly" than subsequently (indeed, an
18-year record of the seabirds recorded at "Papa" also exhibits other
interesting fluctuations from the base-line data in certain years).
Recent analyses of sediments from off the coast of California have
demonstrated long-term fluctuations in sardine populations extending
back at least 1,800 years, with increases lasting 20-150 years and
spaced 20-200 years apart. The number of anchovies declined steadily.
Yet until now, El Niño events have been treated as anomalies in
that region as well as off the coast of Peru. Just as we recognize
that different species of fish follow the warm water north on such
occasions, we must also recognize the rather distinct seabird species
assemblage that is trapped, as it were, in the Gulf of California.
Clearly, like the termination point of the West Wind Drift at about the
45-55° parallel, the coast of Baja California and southern California
State, from the 25-35° parallel where the California Current begins to
swing away from the coast to the west as the North Equatorial Current,
is another zone of instability.
I think that it is no accident that the southern limit of several
northern species of North Pacific seabirds ends in southeastern Alaska
or northern British Columbia, and that the northern limit of the
ranges of several other species occurs in Washington State or southern
British Columbia. Indeed, the west coast of Vancouver Island is not
rich in species, and several of those that exist are not present in
great numbers. This is a region of rather more variable conditions than
elsewhere, and species evidently find that it is difficult to colonize
and it quickly becomes unsuitable again. Since 1940, indeed, there has
been a parallel decline in the annual mean sea-surface temperature
at a number of coastal recording stations in British Columbia, and
this seems to have been a rebound from a less well-documented rise
in sea-surface temperatures during the 20 years before that, which
culminated in a peak around 1940. Salinity has likewise trended
downwards during the last 30 years. The seabird colony size data before
1960 are so nonquantitative that it is impossible to be sure what
changes in seabird populations and breeding sites may have taken place
in response to these physical changes.
The lesson is that we must now examine all future census and
distribution data with trends in sea-surface temperature and salinity
in mind as two of several likely factors influencing them. We must no
more ignore data outside our own field than a salmon ecologist might.
Conclusions
We know little of the accuracy of censuses of seabird numbers made
between 1850 and 1950. There has been a tendency to assume that
numbers of seabirds at long-established colonies have been relatively
unchanging, even though the expansion of some species into previously
unrecorded breeding sites in low numbers is well documented.
Contraction of breeding ranges, likewise, has most commonly been
attributed to the influence of man. Recent literature from the physical
sciences, on the contrary, suggests that seabird numbers at particular
colonies are most unlikely to have been stable for any great length
of time, at least at high or middle latitudes and particularly at
points where boundaries between currents impinge on continental coasts.
Indeed, some early estimates of colony sizes may not have been as much
in error as we may have assumed, neither when apparently too large nor
when apparently unlocated by previous visitors.
The halving of a large colony over a period of 20 to 50 years in
the middle of the range of a species and the establishment and
disappearance of smaller breeding groups at opposite extremes of the
range (both latitudinally and longitudinally), may equally reflect
natural long-term climatic or oceanographic changes and may naturally
be reversed at some time in the future, perhaps within half a century.
The implication for conservation of seabird colonies that are at the
contracting end of a species' range is that cultural rather than
biological criteria may be the best determinants.
Sea Ice as a Factor in Seabird Distribution and Ecology in the
Beaufort, Chukchi, and Bering Seas
by
George J. Divoky[1]
U.S. Fish and Wildlife Service
Fairbanks, Alaska
Abstract
Arctic sea ice has a variety of effects on
seabirds. Although the decrease in surface area
available for feeding and roosting is probably
the major restrictive effect, also important
are productivity of water covered by ice and
the reduced prey abundance in nearshore areas
due to ice scour. The most important benefit
that sea ice provides to seabirds is the
plankton bloom that occurs in the ice in the
spring. In the Beaufort and Chukchi seas this
bloom supports an under-ice fauna that is an
important food source for seabirds.
Sea ice is a major factor in the distribution and ecology of many of
the birds treated in this symposium. Sea ice is defined here as ice
formed by the freezing of seawater and includes both free floating pack
ice and the more stable shorefast ice. Since icebergs are composed of
ice of land origin, they are not discussed.
Before discussing the specific relationship of birds and sea ice in
the Beaufort, Chukchi, and Bering seas, I list the general effects
that arctic ice can have on seabirds. For purposes of discussion these
effects can be divided into negative effects, or disadvantages, and
positive effects, or advantages.
General Effects of Ice on Birds
_Negative Effects_
Sea Ice Decreases the Surface Area of Water
The decrease in the surface area of water is the simplest and most
immediate effect that sea ice has on birds. Ice acts as a barrier that
restricts the availability of food in the water. Surface feeders are
the most severely affected since, in general, ice cover of 50% reduces
the possible feeding area by half. The effect on diving species is not
as severe since, if open water is scattered throughout the ice, diving
species still have access to much of the prey in the water column and
benthos. When open water is scarce, however, diving species can become
concentrated in the available water, resulting in intense competition
for available prey. In certain situations the open water is used only
as a migratory pathway, but open water is necessary for birds that must
roost or feed.
Sea Ice Reduces Primary Productivity in the Water Column
Ice inhibits phytoplankton blooms in the water column, thus decreasing
the biological productivity of ice-covered waters. This inhibition
occurs in two ways:
• _By decreasing light penetration of the water column._--Much of the
sunlight reaching the ice is reflected by the ice and by snow on the
ice. The amount of light reaching the water depends on the angle of
the light, thickness of ice, and amount of snow cover. When the layer
of under-ice algae forms, it absorbs light and further reduces the
amount of light reaching the water (Bunt 1963). This reduction in light
reduces the depth of the euphotic zone.
• _By increasing the stability of the water column._--Increased
stability of the water column reduces the upwelling of nutrient-rich
waters into the euphotic zone. Ice stabilizes the water column
primarily by preventing wind-driven movement of surface waters and by
forming a layer of meltwater at the surface in the spring and summer
(Dunbar 1968).
Sea Ice Reduces Benthic and Intertidal Biota
Benthic flora and fauna can be reduced by the presence of ice in two
ways: In shallow water ice can freeze to the bottom for much of the
year and prevent the establishment of plant and animal populations;
and when ice floes are pushed together, they form underwater ice keels
that can scour the bottom when the ice moves. Both of these events not
only act directly to decrease benthic populations but also disturb the
sediment, making it less suitable for colonization. In areas with heavy
ice scour, sessile benthic populations can be greatly reduced, although
motile species may move into scoured areas during the ice-free period
in summer. In addition to preventing the establishment of sessile
benthic animal populations, ice scour also prevents the establishment
of beds of kelp and eelgrass _(Zostera marina)_, thus decreasing the
diversity and productivity of arctic inshore waters. Both kelp and
eelgrass beds are important feeding sites for birds in areas south of
the region affected by ice scour.
Sea Ice Allows Terrestrial Predators Access to Breeding Sites
The formation of ice between the mainland and offshore islands
allows the arctic fox _(Alopex lagopus)_ and other predators access
to the islands used by breeding birds. Foxes can become permanently
established on islands that have food sources during the period when
birds are absent from the island. Often, however, there is little to
attract foxes to the islands other than breeding birds. Because moats
form around many islands before the breeding birds arrive, foxes
are primarily a problem when moat formation is incomplete or when
the breakup of ice is late. Arctic foxes are found on the pack ice
throughout the summer and thus can visit islands that are separated
from the mainland by open water but are adjacent to the pack ice.
_Advantages_
Sea Ice Provides a Matrix and Substrate for an Ice-associated Plankton
Bloom and an Associated Under-ice Fauna
The first detailed studies on the blooms of diatoms that occur in the
lower levels of ice were done by Appollonio (1961). The importance
of this bloom in the energy budgets of arctic and subarctic seas has
only recently been realized (Alexander 1974; McRoy and Goering 1974).
In areas where ice is present throughout the year, the plankton bloom
supports a population of under-ice invertebrates. These populations
have been little studied but apparently consist primarily of copepods
and amphipods (Mohr and Geiger 1968). Feeding on the invertebrates
associated with the ice are two species of fish, polar cod _(Arctogadus
glacialis)_ and arctic cod _(Boreogadus saida)_. Andriashev (1968)
used the term cryopelagic to describe such fish, which are found in
the midwater zone but also are associated with ice during some part of
their life cycle.
The underside of multi-year ice has numerous ridges and pockets that
provide a heterogeneous environment for the under-ice fauna. This
environment is protected from disturbance from currents and wave action
by ice keels acting as barriers, which also provide shelter from
predators in the same manner as a coral reef. The overall effect of
the under-ice flora and fauna is to increase the diversity of surface
waters in arctic seas by creating an inverted benthic biota.
Sea Ice Provides Hauling Out Space for Marine Mammals
The mammals that inhabit the ice in the Chukchi and Bering seas and
their adaptations to the pack ice environment were discussed by Fay
(1974). Many of these species frequently haul out on the ice, where
they provide food in the form of feces, placentas, and carcasses.
Sea Ice Provides Roosting Sites
Ice provides a hard substrate that allows seabirds to leave the
water to roost. This allows such species as the _Larus_ gulls, which
typically roost on hard substrates, to occur in large numbers well
offshore.
Sea Ice Reduces Wind Chill
The unevenness of the upper surface of the ice reduces the speed of
winds directly over the ice, thus providing a microhabitat and reducing
the amount of wind chill for birds sitting on and next to the ice.
Sea Ice Decreases Wave Action
Ice floating on the water reduces the surface disturbance of the
water. Although swells pass through areas with much ice cover, waves
do not. In addition, surface waters on the lee side of ice floes and
cakes usually have little surface disturbance. Surface feeders may be
able to locate prey more easily because of these reductions in surface
disturbance.
Specific Effects of Ice on Birds in the Western Arctic
The retreat of the pack ice each spring and the formation of new ice
each fall greatly affect a large area of the Arctic Ocean off the coast
of Alaska and much of the Bering Sea. Specific ways in which birds
are affected by ice in the western Arctic are discussed on a seasonal
basis. All observations are my own, unless otherwise stated.
Winter
Chukchi and Beaufort Seas
From late November to mid-April, ice cover of the Chukchi and Beaufort
seas is almost complete. The only areas where birds can be expected
to winter in these seas are the chronic lead systems. Such lead
systems are found off Wainwright and Point Barrow and south of the
Point Hope-Cape Thompson area (Shapiro and Burns 1975). Only the black
guillemot _(Cepphus grylle)_ is known to regularly winter offshore
from Wainwright and Point Barrow (Gabrielson and Lincoln 1959; Nelson
1969). In the Point Hope-Cape Thompson area, glaucous gulls _(Larus
hyperboreus)_, the common murre _(Uria aalge)_, and the thick-billed
murre _(U. lomvia)_ occur throughout the winter (Swartz 1967). It is
likely that black guillemots are also found in this area.
The lack of chronic lead systems in the Beaufort Sea precludes the
presence of wintering seabirds. The one species that may be found
wintering in the Beaufort is the Ross' gull _(Rhodostethia rosea)_.
Ross' gull is believed to winter primarily in the Arctic Ocean (Bailey
1948). The number of sightings that have been obtained in both the
eastern and western Arctic indicate that the species may winter over
much of the Arctic Ocean. It may thus be expected to occur in both the
Chukchi and Beaufort seas during winter.
Ice cover--not prey abundance--plays the major role in severely
limiting bird numbers in the Arctic Ocean in winter. Prey is known
to be abundant in parts of the Arctic Ocean during the period of
ice cover. In the Chukchi Sea, Eskimos fishing through the ice can
catch 23 kg of arctic cod per person per day (D.C. Foote, unpublished
data). Eskimos jig for the fish at considerable depths, and the cod
do not appear to be as common directly below the ice as they are in
summer. The effects of new ice (which forms on the underside of the
ice during the winter) on the under-ice fauna are not known. The
abundance of amphipods in ice-covered waters in winter is demonstrated
by the experience of the Greeley Expedition in the eastern arctic.
They discovered that any scrap of food thrown into a lead was quickly
consumed by amphipods. Nets were made to catch the amphipods and the
availability of this food source played a major part in the survival of
the expedition (Schmitt 1965).
Aside from the food found in leads in the ice, the only food available
to birds in the Beaufort and Chukchi seas in winter is carrion and the
feces of mammals found on the pack ice. The presence of the arctic
foxes on the pack ice during the winter demonstrates the availability
of scavenging opportunities on the ice. Arctic foxes on the pack ice
live on feces and the remains of seals killed by polar bears _(Ursus
maritimus)_. Polar bear and seals are both common in the Beaufort and
Chukchi seas in winter, but no scavenging seabirds are found there in
the winter. It was thought that the ivory gull _(Pagaphila eburnea)_
was associated with marine mammals during the winter, but they are now
known to winter at the Bering Sea ice edge, where they feed on fish and
crustaceans (Divoky 1976). The only birds associated with polar bear
kills in the Chukchi Sea in March are ravens, _Corvus corax_ (T. J.
Ely, Jr., personal communication).
Bering Sea
Ice begins to cover the northern Bering Sea in November and reaches its
maximum by February, when it usually extends as far south as the edge
of the continental shelf, and covers nearly 75% of the surface of the
Bering Sea (Lisityn 1969). Coverage can vary greatly from year to year.
In certain years Bristol Bay may be completely covered and in others
ice is found only in the northern part of the Bay. Almost all ice in
the Bering Sea is first-year ice. This ice tends to be flat on the top
and underside and in general lacks the extensive keels and pressure
ridges found on multi-year ice.
The Bering Sea ice has a number of large-scale features of importance
to birds. The "front" is a zone of ice south of the consolidated pack
that is composed of small floes, ice pans, and brash ice. This zone is
prevented from forming large floes by the action of swells from the
open water to the south. The front continually changes in width. When
winds are from the south, it is compressed into a narrow band; when
winds are from the north, it is a broad zone composed of bands of ice
interspersed with open water.
Polynias (areas of open water) are found immediately south of the large
islands in the northern Bering Sea. They are formed by the southward
movement of ice caused by the prevailing winds. This movement causes
ice to be pushed away from the south side of islands, leaving areas
of open water. Large polynias are associated with St. Lawrence, St.
Matthew, and Nunivak islands and with the south side of the Seward
Peninsula (Shapiro and Burns 1975).
The most biologically active area of the Bering Sea in winter is
the ice front. Studies of primary productivity in April show that
production at the surface in the ice front is high (1.98 mg C/m³
per h). Surface waters directly under the pack ice have much lower
production (0.29 mg C/m³ per h), and that in the water south of the
ice is lower yet. At this time production within the ice is very high
(more than 5 mg C/m³ per h) (McRoy and Goering 1974). Because this
phytoplankton bloom is trapped in the ice, it is not available to
grazers. Thus, before the spring melt the ice front is the only area
where a large quantity of phytoplankton is available to higher levels
of the marine food chain.
The winter distribution of birds in the Bering Sea correlates well with
the findings on primary productivity. Densities south of the ice and
the continental shelf average less than 10 birds/km². At the ice front
during one cruise in March, densities exceeded 500 birds/km². Densities
at the ice front increase from south to north; they drop in the region
where the ice front grades into more consolidated pack ice, and are
less than 0.1 bird/km² in the consolidated pack.
The most numerous species at the ice front are common and thick-billed
murres, which constitute more than 90% of all birds seen. Irving et
al. (1970) were the first to report on the large number of murres at
the ice front. Feeding flocks of 25,000 individuals have been observed
at the front, in which densities were as high as 10,000 birds/km². No
other diving species is common at the ice front. The parakeet auklet
_(Cyclorhynchus psittaculus)_ is seen on most cruises, but only during
a small percentage of observation periods and always in low numbers.
Black guillemots are common north of the ice front and stragglers
are occasionally seen at the front. Pigeon guillemots _(Cepphus
columbus)_, least auklets _(Aethia pusilla)_, and crested auklets _(A.
cristatella)_ are irregular visitors to the front.
Surface feeding species commonly found at the ice front include
the northern fulmar _(Fulmarus glacialis)_ and five species of
gulls. The fulmar is common south of the ice and is found only in
the southern portion of the front. Three species of _Larus_ are
found at the ice front. The most common is the glaucous-winged gull
_(Larus glaucescens)_; the glaucous gull is less frequently seen. The
slaty-backed gull _(L. schistisagus)_, a species that breeds in Asia,
is most common west of St. Matthew Island (McRoy et al. 1971). The
black-legged kittiwake _(Rissa tridactyla)_ is common in open water
south of the ice but is also found throughout the entire width of
the front. The ivory gull is unique in that it is found only at the
ice front in winter. In addition to these species, the fork-tailed
storm-petrel _(Oceanodroma furcata)_ is a regular but uncommon visitor
to the ice front in winter. Densities of surface feeding species at the
ice front are low when compared to the high densities of murres, and do
not regularly exceed 10 birds/km².
The primary food consumed by birds at the ice front is pollock
_(Theragra chalcogramma)_. An amphipod _(Parathemisto libellula)_ and
the euphausiids are less important. Examination of the stomach contents
of birds and fish show that large feeding flocks are usually associated
with schools of pollock feeding on _P. libellula_ and euphausiids.
The habitat of the consolidated pack in the Bering Sea is markedly
different from that at the ice front. Whereas the front is
characterized by bands of ice interspersed with open water and ice
coverage rarely exceeding 4 oktas (4/8), the consolidated pack consists
primarily of large expanses of unbroken ice. Small leads are formed
by the shifting of the ice caused by currents and wind. Ice coverage
is usually 7 to 8 oktas. The southern part of the consolidated pack,
which grades into the ice front, has frequent leads. Most of the
species found at the ice front can be found in the southern part of the
consolidated pack, but murres are most common. Their numbers decrease,
however, in the more northerly pack, where leads are less frequent.
Black guillemots, in contrast, increase with increasing ice cover, and
reach their greatest abundance in the small leads constantly forming
and refreezing deep within the ice. Because they exploit this habitat,
they are dependent on the formation of lead systems. I have often seen
leads a quarter mile wide refrozen to the point where new ice covered
all but a small patch of open water; black guillemots were frequently
crowded into this open water. Before the lead closes completely
the guillemots must fly to an open lead. When winds are light and
temperatures low, lead systems fail to form as rapidly as usual, and
when they do they refreeze quickly, causing a loss of the preferred
habitat of wintering black guillemots. A severe winter in the White Sea
in 1965-66 decreased the amount of open water and caused an increased
black guillemot mortality (Bianchi and Karpovitsch 1969). On a windless
day in March I conducted bird observations in the Bering Sea ice where
no leads or open water were encountered. The only bird seen was a black
guillemot flying over the ice. In situations such as this, where black
guillemots are prospecting for open water, they may use the "water sky"
and steam fog associated with leads as visual aids. "Water sky" is the
reflection of the dark water in the clouds over the lead, and contrasts
sharply with the "ice sky." The presence of "water sky" allows birds to
detect open water from a distance of many miles.
Aside from birds found in and near island-associated polynias, only
murres and black guillemots are regularly found on the consolidated
pack ice in winter.
The polynia associated with islands in the consolidated pack provide
refuge(s) for seabirds. Fay and Cade (1959) found the polynias south of
St. Lawrence to be most important to oldsquaws _(Clangula hyemalis)_.
King eiders _(Somateria spectabilis)_, common eiders _(S. mollisima)_,
and oldsquaws are common in the St. Matthew Island polynias (McRoy et
al. 1971). Because these polynias are in shallow-water areas, they
provide feeding opportunities for benthic feeding species.
_Spring_
Chukchi and Beaufort Seas
In April and May a lead system develops from the Bering Strait north
to Cape Lisburne and then northeast to Point Barrow. The lead is a
flaw lead that occurs between the shorefast ice and the free-floating
pack. It is a major migration route for a number of species of birds,
primarily eiders. East of Point Barrow in the Beaufort Sea, no similar
well-defined large lead exists. Consequently, there is a greater chance
of bird mortality occurring in the Beaufort Sea than in the Chukchi
Sea because the early migrants are unable to find open water. In 1960,
10% of all the king eiders that migrate through the Beaufort Sea
died during a late freeze (Barry 1968). Additional records of eider
mortality due to late breakup or sudden freezes were presented by
Palmer (1976).
In late May, rivers that empty into the northern Chukchi and Beaufort
seas begin to flow. The shorefast ice is still present at this time
and the rivers flow over the ice. For large rivers, such as the
Colville and the Sagavanirktok, the area of ice covered by water is
considerable. Openings in the ice develop sometime after the river
runoff starts and the river water drains through the ice.
This river overflow plays an important role in the breeding biology of
certain island nesting species, since the overflow surrounds islands
and prevents arctic foxes from reaching the islands. The overflow also
allows birds to sit in the water near breeding sites. It is not known
whether river overflow contains prey items available to birds. After
the overflow drains through the ice, the shorefast ice that has been
covered with river overflow decomposes quickly, and patches of open
water occur early in areas just seaward of major river deltas. For this
reason the largest breeding colonies on barrier islands in the northern
Chukchi and Beaufort seas are all found near the mouths of large
rivers. Islands away from rivers become isolated from the pack ice by
moats, which are caused by the absorption of solar radiation by the
islands and the melting of the ice immediately adjacent to them. Moat
formation is not as predictable and uniform as river overflow.
Bering Sea
When the ice in the Bering Sea begins to melt in April, the edge of the
pack does not recede northward as is frequently thought. Rather, there
is a general decomposition of ice throughout the pack. The leads that
are constantly forming in the ice no longer freeze. As melt continues
and ice becomes rotten, leads form with increasing frequency. This
manner of ice decomposition is important to birds. The leads that
form deep in the pack ice provide feeding and roosting areas near the
large seabird colonies found north of the ice edge, and are used by
certain tundra-nesting ocean migrants such as eiders, red phalaropes
_(Phalaropus fulicarius)_, and jaegers (_Stercorarius_ spp.). If
ice decomposition is retarded by persistent low temperatures, the
initiation of breeding may be delayed at northern Bering Sea colonies
and for some tundra species.
At the time of decomposition the large standing stock of phytoplankton
present in the pack ice is released into the water. No information is
available on fish and invertebrate populations that are associated
with the decomposing ice. The quantity of organic carbon released
is considerable, although it is not known what fish or invertebrate
populations are supported by this plankton as soon as it is released.
For birds breeding in areas where ice is present in the initial stages
of breeding, the phytoplankton released by the disintegrating ice could
play an important part in the birds' energy budgets.
_Summer_
Chukchi and Beaufort Seas
In the northern Chukchi and Beaufort seas the nearshore marine
environment is dominated by sea ice in June and July. In June the
coastal areas are characterized by a snow-free tundra teeming with
nesting waterfowl and shorebirds next to an expanse of sea ice almost
completely devoid of bird life. In areas where river outflow does not
occur, the use of nearshore waters usually begins when a moat forms
along the shoreline. Amphipods and other invertebrates are found in
this moat, especially at stream mouths. Limited but regular use of the
moat occurs, primarily by loons (_Gavia_ spp.), oldsquaws, and arctic
terns _(Sterna paradisaea)_.
As the snow on top of the shorefast ice begins to melt, ponds form on
top of the ice. As melt proceeds, these melt ponds merge into long,
parallel channels and may cover well over 50% of the ice surface. Only
when thaw holes form and the melt ponds are connected to the water
under the ice is food present in the channels. Amphipods are then
seen swimming in these channels. Bird use of these channels is not
extensive.
It is usually late July before the nearshore ice begins its rapid
decomposition. Ice in the lagoons is the first to melt. Ice seaward of
the barrier islands decomposes more slowly because of the presence of
keels and pressure ridges. As the ice melts, the in-ice algal bloom is
released into the water. These algae are important because they provide
at least 25 to 30% of the productivity in coastal waters and allow the
biological growing season to begin before the open-water plankton bloom
occurs (Alexander 1974). In nearshore areas close to Barrow, large
populations of mysids and amphipods are associated with the decomposing
ice. At least in certain areas, these ice-associated zooplankton
populations are a major food source for nearshore migrants, especially
red phalaropes, arctic terns, and Sabine's gulls _(Xema sabini)_.
The effects of ice scour on the shoreline and the nearshore bottom of
the Chukchi and Beaufort seas is demonstrated by the absence of sessile
benthic fauna and flora. The effect this absence has on birds is seen
in the feeding habits of nearshore birds. Oldsquaws and eiders, which
frequently feed on molluscs, feed instead on motile benthos species
such as mysids, amphipods, and isopods. The emperor goose _(Philacte
canagica)_ is absent from the northern Chukchi and Beaufort seas,
apparently due to the absence of eelgrass beds. Ice scour is the major
cause of the absence of eelgrass in northern Alaska (C. P. McRoy,
personal communication).
The offshore ice in the Chukchi decomposes more rapidly than that in
the Beaufort, largely because Bering Sea water enters the Chukchi
through the Bering Strait (Coachman and Barnes 1961). By late July the
Chukchi is usually ice free as far north as Icy Cape. In the Beaufort,
however, ice decomposition occurs slowly through June and July, and
only in August does a definite strip of open water develop between
the shore and the edge of the pack ice. The amount of open water
varies greatly from year to year. In certain years the Beaufort is not
navigable due to the lack of open water.
Aerial censusing in June and July shows that bird densities on the
offshore ice are extremely low. In August and September, when shipboard
censusing can be conducted, densities on the pack ice in both seas are
about 10 birds/km². Unlike the Bering Sea, where densities south of
the ice are much less than on the ice, bird densities south of the ice
in the Beaufort and Chukchi seas are slightly higher in the open water
south of the ice, averaging about 20 birds/km². In the Chukchi the
principal species encountered on the ice are the black-legged kittiwake
and the thick-billed murre. In the Beaufort, red phalaropes, oldsquaws,
and glaucous gulls are the most common species.
Numerous arctic cod are associated with the underside of the summer
pack ice. Shipboard censusing in the ice is complicated when cod are
stranded on ice floes, as the ice shifts under the weight of the ship.
Gulls, arctic terns, and jaegers gather behind the ship to feed on
these fish; mixed flocks of more than 100 birds are common. In the
absence of a ship to provide the disturbance needed to make large
numbers of cod available, these birds are dependent on locating the
fish in the surface waters next to ice floes. Because cod frequently
swim over underwater ice shelves they are highly visible from above and
should be easily accessible to aerial feeders.
_Fall_
Chukchi and Beaufort Seas
By the time ice formation begins in late September or early October,
most seabirds have left the Arctic on their southward migration. The
principal exception is the oldsquaw, which does not begin its migration
until September. Some oldsquaws remain in nearshore waters until they
are driven out by the formation of new ice. In contrast to the spring
mortality, there are few records of extensive bird mortality in the
fall due to lack of open water. One instance was reported for 1975,
when nearshore waters froze early and flightless eiders were seen
sitting on the ice near Pt. Lay in the Chukchi Sea. The birds were in
a weakened condition, apparently due to their inability to obtain food
(W. J. Wiseman, personal communication).
In the offshore waters the species associated with the pack ice in
September are the same as those in August. In late September, however,
ivory and Ross' gulls become the most common species at the ice edge in
the Chukchi. Glaucous gulls and black guillemots are also associated
with the advancing ice edge (Watson and Divoky 1972). Except for the
Ross' gull, which apparently winters in the arctic basin, these species
remain with the ice as it advances into the Bering Sea.
Bering Sea
Little is known about bird distribution in the Bering Sea during ice
formation because cruises in rapidly forming ice are potentially
hazardous. It is not known if the large numbers of birds found at the
ice edge in March are present in December and January.
Discussion
The principal effect of the arctic pack ice is to lower biological
productivity and bird densities in the areas it covers. Unlike the
antarctic pack ice, which supports a large biomass of pagophilic
species, the number of pagophilic species supported by the arctic pack
ice is small. Only the ivory gull, Ross' gull, and black guillemot
have specific adaptations to the ice environment. The Ross' gull and
guillemot winter in the pack ice, and the ivory gull is associated with
ice throughout the year. The total biomass of these species is low.
Other species which are regularly associated with the arctic pack, such
as murres and black-legged kittiwakes, are also found in large numbers
away from the ice. In addition, these species are usually associated
with ice for limited periods during the year--murres primarily in
winter and spring and kittiwakes primarily in summer.
The difference in the antarctic and arctic pack ice systems is largely
due to the antarctic pack ice being surrounded by ocean, whereas
the arctic pack ice is, in general, surrounded by land. The high
productivity associated with the antarctic pack ice is due primarily
to the mixing that occurs at the edge of the pack ice. There is little
opportunity for mixing to occur next to the arctic pack ice, except
where it is next to large expanses of boreal waters. This occurs in the
Bering Sea in winter and spring, in the North Atlantic, and to a minor
extent in the Chukchi Sea in summer and fall (Dunbar 1968). The limited
geographic range and seasonal nature of high productivity at the arctic
pack ice edge has been a major factor in preventing a well-developed
pagophilic avifauna.
The importance of the in-ice algal bloom and its associated under-ice
fauna is not yet clear. It is probably most important in areas such
as the Beaufort Sea, where productivity in the water column is low.
Although considerable numbers of seabirds are regularly found in the
summer pack ice feeding on arctic cod and zooplankton associated
with the ice, bird densities south of the ice are usually greater
than those in the ice. The only species that appear to depend on the
ice-associated fauna for much of their food are the three pagophilic
species mentioned above.
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during a cruise in the ice-covered Bering Sea in March 1968.
Condor 72:110-112.
Lisityn, A. P. 1969. Recent sedimentation in the Bering Sea
(Transl. from Russian.) Israel Program for Scientific
Translations, Jerusalem. 614 pp.
McRoy, C. P., and S. R. Goering. 1974. The influence of ice on the
primary productivity of the Bering Sea. Pages 403-421 _in_ D. W.
Hood and E. J. Kelly, eds. Oceanography of the Bering Sea. Univ.
Alaska Inst. Mar. Sci. Occas. Publ. 2.
McRoy, C. P., S. W. Stoker, G. E. Hall, and E. Muktoyuk. 1971.
Winter observations of mammals and birds, St. Matthew Island.
Arctic 24:63-65.
Mohr, J. L., and S. R. Geiger. 1968. Arctic Basin faunal
precis-animals taken mainly from arctic drifting stations and
their significance for biogeography and water-mass recognition.
Pages 297-313 _in_ J. E. Sater, coordinator. Arctic drifting
stations. Arctic Institute of North America.
Nelson, R. K. 1969. Hunters of the northern ice. University of
Chicago Press, Chicago, Ill. 429 pp.
Palmer, R. S. 1976. Handbook of North American birds. Vol. 3. Yale
University Press, New Haven, Conn. 560 pp.
Schmitt, W. L. 1965. Crustaceans. University of Michigan Press, Ann
Arbor. 204 pp.
Shapiro, L. H., and J. J. Burns. 1975. Major late-winter features
of ice in northern Bering and Chukchi seas as determined from
satellite imagery. Univ. Alaska Geophys. Inst. Rep. 75-78.
Swartz, L. G. 1967. Distribution and movements of birds in the
Bering and Chukchi seas. Pacific Sci. 21:332-347.
Watson, G. E., and G. J. Divoky. 1972. Pelagic bird and mammal
observations in the eastern Chukchi Sea, early fall 1970. U.S.
Coast Guard Oceanogr. Rep. 50:111-172.
FOOTNOTES:
[1] Present address: Point Reyes Bird Observatory, 4990 State Route 1,
Stinson Beach, California 94970.
STATUS OF MARINE BIRD POPULATIONS
Distribution and Status of Marine Birds Breeding Along the Coasts of
the Chukchi and Bering Seas
by
James C. Bartonek[2]
U.S. Fish and Wildlife Service
Fairbanks, Alaska
and
Spencer G. Sealy
University of Manitoba
Winnipeg, Manitoba, Canada
Abstract
The Alaska coast fronting on the Chukchi
and Bering seas, exclusive of the Aleutian
Islands, supports seven complexes of marine
bird colonies numbering more than 1 million
birds each, nine colonies of 100,000 to almost
1 million birds, and many smaller colonies.
Colonies are found on most headlands and
islands and are dominated numerically by
alcids and kittiwakes (_Rissa_ sp.). Estuarine
habitats (mainly the lowlands of northern
Seward Peninsula, Yukon-Kuskokwim delta, and
the north side of the Alaska Peninsula) are
extremely important for breeding and migrating
marine waterfowl, shorebirds, gulls (_Larus_
sp.), and terns (_Sterna_ sp.). Information on
population size and distribution of breeding
marine birds within this area is extensive for
only a few of the more heavily hunted species
of waterfowl. Except for the intensive and
systematic censusing of a few colonies in this
region, population data on cliff-, burrow-, and
crevice-nesting birds are such that all but
gross changes in numbers may go unnoticed, and
if noticed they could not be measured.
Habitats for breeding marine birds are found along much of the 4,100-km
coastline of Alaska that fronts on the Chukchi and Bering seas.
Seasonal sea ice and an extensive outer continental shelf are dominant
features that contribute to the productivity of these marine waters,
which sustain populations of fishes, birds, and mammals that are of
considerable and diverse values to man (Kelley and Hood 1974).
Our purpose in this paper is to describe the distribution, abundance,
and relative status of some of the nearly 100 species of marine birds
breeding within this region and the information base from which
the descriptions are derived. Although the selection is admittedly
arbitrary, we discuss mainly the colonial nesting species because they
are generally in greater jeopardy from lost breeding habitat and from
catastrophes than are the species that are widely dispersed or solitary
in nesting. Because we believe matters affecting the conservation of
marine birds will be geographically oriented, we discuss the status
and distribution of breeding birds on that basis, rather than by
the more traditional taxonomic approach. We use the terms "colony"
and "colonies" somewhat loosely and interchangeably to include any
aggregation of birds of the same or different species nesting in
proximity to each other, even those on the same island or headland,
although populations may be miles apart and occupy different kinds of
habitats. The nature of this paper and the scale of our maps do not
allow for detailed resolution of each colony's location (for the most
part this information is not available), but rather facilitates a
general impression of status.
Most place-names used by us are shown in Fig. 1; the others may be
located by referring to Orth's (1967) gazetteer on Alaska.
Information Base
There is no adequate catalog of marine bird colonies and other avian
habitats for the Bering-Chukchi region or for Alaska as a whole.
King and Lensink (1971) described the waterfowl populations and
major lowland habitats of the State and listed only a few of the
many colonies of cliff-nesting birds. LeResche and Hinman (1973)
identified a few additional colonies, provided fragmentary information
on composition and abundance at some of these sites, and delineated
areas of wetland habitats on maps in their statewide atlas on wildlife.
General and occasionally site-specific information on the location,
but rarely on population size and composition, of colonies can be
gleaned from the 321 species accounts presented by Gabrielson and
Lincoln (1959) and from the general works by Bent (1919, 1921, 1922,
1923, 1925, 1927, 1929), Dement'ev and Gladkov (1951), Dement'ev et al.
(1951, 1952), Palmer (1962), Fisher (1952), Tuck (1960), and others.
The birds on the Asiatic side of these waters, which are not treated in
this paper, were described by Portenko (1973).
Information on the status of waterfowl in the region is generally more
detailed than that for most other groups of birds because waterfowl
have been the object of systematic surveys since the late 1940's as
part of the continent-wide effort to manage populations for sport
hunting. Because the emphasis of these surveys has been directed toward
the species of ducks important to hunters in the "lower 48" States,
data are not adequate to measure changes in populations for most sea
ducks and marine geese nesting in this region. These surveys have,
however, enabled biologists to delineate waterfowl habitats and make
reasonable estimates of populations for some of the more abundant and
conspicuous species (King and Lensink 1971; U.S. Fish and Wildlife
Service [FWS] 1973_c_; U.S. National Park Service [NPS] 1973).
_Chukchi Sea Coast_
A disproportionate percentage of ornithological investigations in
arctic Alaska have centered about Barrow, where ornithologists were
attracted because of the propensity of vagrant birds to collect
there and because of the above average facilities, conveniences,
and transportation afforded first by the whaling station, then by
the military, and later by a research laboratory. Recent petroleum
development near Prudhoe Bay has resulted in a somewhat commensal
eastward shift in ornithological studies.
Bailey (1948), Gabrielson and Lincoln (1959), and Pitelka (1974)
reviewed much of the published information on arctic avifauna,
including that of the Chukchi coast. Selkregg [1975] mapped various
avian habitats, ascribed either relative or absolute values for the
population size of certain groups of birds, and included a selected
bibliography that did not entirely duplicate those provided by the
other reviewers. Watson and Divoky (1975) described the avifauna of
Alaska's Beaufort Sea coast, which is much the same as that of the
Chukchi coast from Point Barrow south to Cape Lisburne (both coasts are
of low relief).
Intensive studies near Barrow have done much to characterize the
behavior, productivity, and ecological requirements of calidridine
sandpipers (Pitelka 1959; Pitelka et al. 1974; Holmes 1970, 1971)
and, to partly explain the cyclical relationships between jaegers
(_Stercorarius_ spp.) and their prey (e.g., Pitelka et al. 1955; Maher
1974). Quantitative estimates of certain bird populations at Cape
Thompson (Swartz 1966; Williamson et al. 1966), Little Diomede (Kenyon
and Brooks 1960), and on the coastal lowlands of the Seward Peninsula
(King and Lensink 1971; U.S. NPS 1973), and for black guillemots
_(Cepphus grylle)_ throughout the region (Divoky et al. 1974) are among
the best data on status of marine birds for any locality in Alaska.
Grinnell (1900_a_) described the birds he observed in the Kotzebue
Sound area.
[Illustration: Fig. 1. Place-names in the region of the Chukchi and
Bering seas.]
Cursory aerial surveys conducted by J. C. Bartonek, J. G. King, and
D. R. Cline (U.S. FWS 1973_a_; U.S. NPS 1973; this paper) in 1972 and
1973 provided information on the location and relative size of most, if
not all, colonies of cliff-nesting marine birds between Point Barrow
and the Bering Strait, including those at Cape Lisburne, at Motherhood
Point, Nine-mile Point, Cape Deceit, Towalevic Point, Sullivan Bluff,
all on the northern base of the Seward Peninsula, and at Fairway
Rock. The relative size of populations of most species was probably
underestimated because the burrow-and crevice-nesting species were
largely unseen.
_Bering Sea_
Aside from work by Gabrielson and Lincoln (1959) and the early but
understandably incomplete accounts by Nelson (1883, 1887) and Turner
(1886), no comprehensive description of the avifauna of the Alaskan
coast of the Bering Sea exists. Many studies adequately describe local
avifauna, and some of them are exemplary assessments of the status of
populations.
Most of the coastline suitable for cliff-nesting marine birds and most
of the smaller nearshore islands from the Bering Strait south to the
tip of the Alaska Peninsula were reconnoitered piecemeal from aircraft
between 1970 and 1973 by J. C. Bartonek, J. G. King, D. R. Cline, C. D.
Evans, and M. L. Plenert (U.S. FWS 1973_a_, 1973_b_; this paper). In
late June 1973 Bartonek, Cline, and Plenert made brief reconnaissances
on foot of King, Besboro, and Shaiak islands. Bartonek and J. G.
Divoky, traveling by boat and occasionally on foot, reconnoitered
colonies at Cape Seniavin, a portion of the Walrus Islands group,
Shaiak Island, and the coastline from Cape Peirce around Cape Newenham
to Security Cove (U.S. FWS 1973_a_, 1973_b_; this paper). Although
these cursory surveys (especially those from aircraft) tended to
identify nesting sites of cliff-nesting birds while missing sites used
by burrow-and crevice-nesting species, information was obtained on the
location and relative size of many previously unreported colonies.
The mainland and island colonies in Norton Sound have received little
notice in the published literature. Bailey (1943, 1948), although
working mainly at Little Diomede and in Arctic and Lopp lagoons on
the north side of the Seward Peninsula, mentioned the birds at Wales
Mountain and Tin City. Nelson (1883, 1887) traveled throughout the
region studying the avifauna and the anthropology of Eskimos. Grinnell
(1900_b_) at Nome, McGregor (1902) along the Koyuk River, Hersey (1917)
and Turner (1886) near St. Michael, and Cade (1952) at Sledge Island
provide fragmentary examples of the area's marine bird populations.
Colonies at King, Besboro, Egg, and Sledge islands, near York
Mountains, and at Bluff were described in proposals for new National
Wildlife Refuges (U.S. FWS 1973_a_).
Sealy et al. (1971) reviewed the literature and discussed the various
zoogeographic relationships among the avifauna of St. Lawrence Island.
Fay and Cade (1959) estimated numbers and biomass of all birds on St.
Lawrence Island but did not identify locations and sizes of particular
populations; consequently, replication of their estimates is precluded.
An exemplary study by Bédard (1969) identified the locations and
sizes of all populations of crested auklets _(Aethia cristatella)_,
least auklets _(A. pusilla)_, and parakeet auklets _(Cyclorrhynchus
psittacula)_ on the island. Sealy (1973) identified breeding sites of
horned puffins _(Fratercula corniculata)_ there and throughout the
species' range. Thompson (1967) listed the birds observed at Northeast
Cape and on nearby Punuk Islands.
Annotated accounts have been published on the breeding avifauna of St.
Matthew, Hall, and Pinnacle islands by Elliott (1882), Hanna (1917),
Bent (1919), and Gabrielson and Lincoln (1959). Klein (1959) presented
quantitative data on the birds he observed incidental to his study of
reindeer _(Rangifer tarandus)_.
The avifauna of the Yukon-Kuskokwim delta, which is rich both in
numbers and diversity, has been treated extensively in the literature.
Nelson (1883, 1887), Turner (1886), Conover (1926), Brandt (1943),
Gabrielson and Lincoln (1959), Williamson (1957), Kessel et al.
(1964), Harris (1966), Dau (1972), and Holmes and Black (1973) all
described the avifauna in the same general area of the delta, i.e.,
the eroding portion in the general vicinity of Hooper and Hazen bays.
The avifauna of the aggrading portion of the Yukon delta and of the
Kuskokwim's mouth have not been accorded similar attention. Populations
of waterfowl nesting on the delta and their wintering affinities were
described by King and Lensink (1971) and U.S. FWS (1973_c_).
Studies of particular species of marine birds on the delta (again, all
in the general vicinity of Hooper and Hazen bays) were reported by
Hansen and Nelson (1957) and Shepherd (1960) for black brant _(Branta
bernicla)_, by Headley (1967) and Eisenhauer and Kirkpatrick (1977) for
emperor geese _(Anser canagica)_, by Dau (1974) and Mickelson (1975)
for spectacled eiders _(Somateria fischeri)_, by Petersen (1976) for
red-throated loons _(Gavia stellata)_, and by Holmes (1970, 1971, 1972)
for dunlins _(Calidris alpina)_ and western sandpipers _(C. mauri)_.
Birds of Nunivak Island were reported by Swarth (1934), but the
importance of the island to marine birds was not put into proper
perspective until the Nunivak National Wildlife Refuge was evaluated
for designation as a wilderness area (U.S. FWS 1972).
The Pribilof Islands have served as a focal point for ornithological
investigations of the Bering Sea in much the same way that Barrow
has for the Arctic. The avifauna of the Pribilofs has been described
by Coues (1874), Elliott (1882), Palmer (1899), Hanna (1918), Preble
and McAtee (1923), Gabrielson and Lincoln (1959), Kenyon and Phillips
(1965), and a host of others that mainly added new species to the
record list. Although most of these ornithologists marveled at the
numbers of birds, information is lacking from which most changes in
populations can be noted. (An exception is the record of common and
thick-billed murres, _Uria aalge_ and _U. lomvia_, which formerly
nested in such abundance on Walrus Island that annually several tons of
eggs were gathered for consumption by residents of the islands [Palmer
1899], but were greatly reduced in numbers by the summer of 1973, when
J. C. Bartonek, J. G. King, G. J. Divoky, and D. T. Montgomery observed
only a few thousand murres on a small portion of the island. Most
of the suitable nesting sites, especially the flat areas often used
by common murres, were occupied by Steller's sea lions, _Eumetopias
jubata_, which, apparently because of reduced hunting pressure,
occupied the island and displaced the murres.)
For some unexplained reason the numerous and large marine bird colonies
along the north side of Bristol Bay appear to have been largely
overlooked until recent years (Bartonek and Gibson 1972). Gabrielson
and Lincoln (1959) summarized the few observations by Osgood (1904)
and Turner (1886) in this area, but obviously were unaware that, in
aggregate, these colonies rival those of the Pribilofs. Dick and Dick
(1971) made an exemplary study of marine birds and their numbers
at Cape Peirce and on nearby Shaiak Island. Murie (1959) provided
annotated remarks on marine birds of Amak Island, but not of nearby
Sealion Rocks.
Status and Distribution
Seven groups of colonies of cliff-, burrow-, and crevice-nesting birds
are found on the headlands and islands in the coastal region, each
numbering more than 1 million birds; nine colonies range downward to
100,000 birds; and a host of others range downward to 1,000 birds (Fig.
2). Un-estimated numbers of other marine birds nest on the lowlands
about Kotzebue Sound, the Yukon-Kuskokwim delta, and Bristol Bay, but
are not shown in Fig. 2. The occurrence at colonies of 20 of the nearly
100 species of marine birds is shown in Fig. 3; their relative numbers
at these sites are not shown because data are generally lacking.
[Illustration: Fig. 2. Relative numbers of marine birds at colonies in
different localities, without regard to species composition or breeding
status.]
[Illustration: Fig. 3. Location of known breeding populations of some
marine bird species without regard to size of population.]
[Illustration]
_Chukchi Sea_
The largest colonies of seabirds in the Chukchi Sea are those on Little
Diomede Island, Cape Lisburne, Cape Thompson, and Fairway Rock. Smaller
colonies are in Kotzebue Sound along the northern base of the Seward
Peninsula. These colonies are largely dominated by thick-billed and
common murres and black-legged kittiwakes _(Rissa tridactyla)_ and on
the islands in the Bering Strait also the crested, least, and parakeet
auklets. Horned puffins, tufted puffins _(Lunda cirrhata)_, pelagic
cormorants _(Phalacrocorax pelagicus)_, and glaucous gulls _(Larus
hyperboreus)_ make up the remaining majority. For the whole area there
are probably fewer than a hundred birds each of black guillemots and
pigeon guillemots _(Cepphus columba)_ occupying colonies. Dovekies
_(Alle alle)_ are occasionally sighted in this area, but only as
stragglers from their normal range.
Part of the mystery surrounding the nesting location of Kittlitz's
murrelet _(Brachyramphus brevirostris)_ was solved when Thompson et al.
(1966) discovered a downy chick in the Kukpuk River drainage nearly
45 km by river from salt water. Other nesting sites of the Kittlitz's
murrelets in this region were reported for Wales Mountain (Ford 1936;
Bailey 1943, 1948) and the Cold Bay area (Bailey 1973) (Fig. 3).
Only the colonies at Cape Thompson have been censused systematically
throughout a breeding season. During one of three years of varying
census efforts, Swartz (1966) estimated that about 400,000 birds of
nine species occupied the cliffs. Whereas the Cape Thompson colonies
received considerable attention because of Swartz's efforts, the
colonies that extend along nearly 35 km of headlands southward from,
but mainly at, Cape Lisburne have received little if any attention
by either early or recent ornithologists in the Arctic, even though
they support perhaps twice the number of birds. Also perplexing is why
Chamisso and Puffin islands with their several thousand nesting horned
puffins and lesser numbers of other seabirds were designated as the
Chamisso National Wildlife Refuge in the early 1900's when none of the
many larger and more species-diverse colonies in the area received
comparable recognition by and protection through refuge designation.
The lowlands on the north side of the Seward Peninsula produce
fall flights of sea ducks that average 49,200 oldsquaws _(Clangula
hyemalis)_, 51,000 eiders (mostly common eiders, _Somateria
mollissima_), and 26,700 scoters (mostly black scoters, _Melanitta
nigra_) (King and Lensink 1971). Small populations of black brant and
emperor geese breed in what outwardly appears to be excellent habitat,
and King and Lensink (1971) speculated that subsistence hunting by
local Eskimos is responsible for suppressing these populations.
_Bering Sea_
The largest concentration of nesting seabirds in the Bering Sea and
perhaps in the entire North Pacific is that on St. George Island.
Colonies that rank somewhere below that at St. George are along the
coast from Cape Newenham to Cape Peirce, in the Walrus Islands (Round,
High, Crooked, and Summit islands, The Twins, and Black Rock), at Cape
Mohican on Nunivak Island, St. Matthew Island, Southwest Cape of St.
Lawrence Island, and King Island.
The Pribilofs have the unique distinction of being the primary nesting
site of red-legged kittiwakes _(Rissa brevirostris)_. They are also
interesting from the zoogeographic standpoint in that they are the
northernmost stronghold of red-faced cormorants _(Phalacrocorax
urile)_; guillemots are conspicuous by their absence, and larid gulls
are conspicuously scarce nesters.
St. Matthew Island and associated Hall and Pinnacle islands, and all
but Walrus Island of the Pribilofs, are sites of nesting northern
fulmars _(Fulmarus glacialis)_. Nesting fork-tailed or Leach's
storm-petrels (_Oceanodroma furcata_ and _O. leucorhoa_) have been
found nowhere in this region, although both are commonly observed at
sea and both nest throughout the Aleutians.
Most colony sites identified in Fig. 2 are dominated by common or
thick-billed murres (or both) and black-legged kittiwakes. Glaucous
gulls (generally north of the Yukon-Kuskokwim delta), glaucous-winged
gulls _(Larus glaucescens)_ (generally to the south of the delta),
and pelagic cormorants occupy almost every rocky prominence along the
entire coast (most of these sites are not shown in Figs. 2 and 3).
Double-crested cormorants _(Phalacrocorax auritus)_ nest at a few
island and inland locations in the Bristol Bay area. The small auklets
are largely restricted to islands in the Bering Sea; the parakeet
auklet is the only one occasionally found in mainland colonies.
The marine birds of the Yukon-Kuskokwim delta lowlands, although
largely uncounted, in their aggregate probably exceed the numbers at
any individual site identified in Fig. 2. This is not particularly
surprising since the delta has nearly 70,000 km² of habitat (King and
Lensink 1971) in contrast to the generally small parcels of habitat
occupied at the sea-cliff and island sites.
King and Lensink (1971) estimated that fall flights of sea ducks
originating on the delta averaged 292,300 oldsquaws, 51,000 eiders
(mostly common and spectacled eiders with lesser numbers of Steller's
eiders, _Polysticta stelleri_), and 157,000 scoters (primarily black
scoters). They also estimated that half of the 150,000 black brant and
most of the 150,000 emperor geese in Alaska's fall flight originate
there. Although no counts have been made, we believe that the delta's
lowlands support easily more than half of Alaska's nesting dunlins,
black turnstones _(Arenaria melanocephala)_, rock sandpipers _(Calidris
ptilocnemis)_, western sandpipers, and substantial percentages of red
phalaropes _(Phalaropus fulicarius)_, northern phalaropes _(Lobipes
lobatus)_, and red-throated loons.
The north side of the Alaska Peninsula (including the wetlands,
uplands, and estuaries) is perhaps more important to marine birds as
a staging, feeding, and resting area than as a nesting habitat. The
importance of Izembek Lagoon to black brant and emperor geese during
fall and spring is a classic example. King and Lensink (1971) estimated
that the fall flight of sea ducks originating from the Peninsula
averages 53,400 oldsquaws, 1,700 eiders, and 74,400 scoters. Breeding
geese are scarce throughout the area.
Conclusions and Recommendations
Most of the major breeding habitats of marine birds in the Chukchi
and Bering seas are known, but imprecisely identified as to location
and size. With few exceptions, the populations of birds using these
habitats are described only by the subjective and ambiguous descriptors
of abundance such as "abundant, common, occasional, and rare," which
makes measurement of change impossible.
We recommend that first and foremost a catalog of habitats used by
birds be developed to aid resource administrators, developers, and
biologists (all of whom should be "conservationists") in identifying
critical habitats. We believe that such a catalog would preclude many
problems because birds and their habitats could be considered at the
planning stage rather than only at the operational stage. Such a
catalog would also be useful to students of ornithology who are seeking
locations suitable for particular studies.
Nowhere in this region have studies of marine birds been of sufficient
duration to enable changes in populations (from whatever cause) to
be characterized. Since some species of marine bird are known not to
breed before at least 3 or more years of age, meaningful information
on survival and recruitment in populations cannot be obtained by
studies of less than 10 years. We therefore recommend that long-term
studies be initiated at as many places as possible, but at least at
one site on the Yukon-Kuskokwim delta; at a mainland colony site that
has predominantly murres, kittiwakes, puffins, and cormorants; and
at an island site that also has small auklets. Although the nesting
distribution of the Kittlitz's murrelet remains an enigma, we regard it
less of a conservation issue and more of an ornithological challenge.
Consideration of logistics and support facilities must, of course, be
included in the site selection process. Most of the areas suggested for
these studies also merit recognition and protection by being designated
as a National Wildlife Refuge, a National Park or Monument, or a State
Game Sanctuary.
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FOOTNOTES:
[2] Present address: U.S. Fish and Wildlife Service, 500 NE Multnomah
Street, Portland, Oregon 97232.
Breeding Distribution and Status of Marine Birds in the Aleutian
Islands, Alaska
by
Palmer C. Sekora[3]
U.S. Fish and Wildlife Service
Kailua, Hawaii
G. Vernon Byrd[4]
U.S. Fish and Wildlife Service
Adak, Alaska
and
Daniel D. Gibson
_University of Alaska
Fairbanks, Alaska_
Abstract
Seabird population estimates are generally
lacking for the 1,800-km-long Aleutian Islands.
Only the locations of the larger colonies are
known, and for these there are only imprecise
estimates of colony sizes and often even of
species composition. Changes in the status of
several species and populations resulting from
geologic and marine actions and from human
intrusions are evident. Accounts are given for
25 species of marine birds breeding in these
islands.
The 1,800-km-long chain of islands known as the Aleutians provides
nesting habitat for various species of marine birds, including three
species of Procellariiformes and three of cormorants (_Phalacrocorax_
spp.), one species of gull _(Larus glaucescens)_, both kittiwake
species (_Rissa_ spp.), two species of terns (_Sterna_ spp.), and at
least 13 species of alcids.
Seabird population estimates of known accuracy are lacking for this
isolated area. Locations of larger colonies of breeding seabirds are
known, however, and sufficient data are available to place colonies
in broad size ranges. Published information on the breeding biology
of marine birds is also lacking from the Aleutians, but some studies
are under way. The distribution of nesting marine birds away from the
nesting cliffs is totally unknown.
Introduced predators, primarily arctic foxes _(Alopex lagopus)_, are
now found on nearly every island. Breeding marine bird populations
have suffered drastic reductions as a result. They have probably also
changed because of natural habitat modifications caused by earthquakes,
volcanic eruptions, tidal waves, and marine erosion.
The purpose of this paper is to summarize the known present
distribution and status of breeding marine birds in the Aleutian
Islands.
Description of the Aleutian Islands
The Aleutian Islands form an arc that separates the Bering Sea and
the north Pacific Ocean (Fig. 1). The island chain extends from the
tip of the Alaska Peninsula to within 483 km of the Commander Islands
of Siberia. The chain contains more than 200 islands--the peaks of a
submarine volcanic mountain range. Volcanic activity and earthquakes
occur regularly.
Weather is characterized by perpetual overcast, dense summer fog,
high-velocity winds, and mild temperatures with low annual and diurnal
variations. The sea is ice-free year-round except in extremely cold
winters, when the arctic ice pack may reach the extreme northern
islands.
The Aleutians are treeless except for a few introduced, stunted
spruces. Woody shrubs are restricted to the most northern islands on
each end of the Chain. Mosses, lichens, club mosses, and heaths are
common ground-cover plants, and taller grasses, sedges, and umbellifers
constitute the overstory. Hulten (1960) provided a list of terrestrial
plants found in the Aleutians. Amundsen and Clebsch (1971) discussed
terrestrial plant ecology at Amchitka, central Aleutians. The marine
plant communities around the islands are fairly diverse. Lebednik et
al. (1971) described marine algal communities at Amchitka.
The easternmost Aleutian island, Unimak, has a mammalian fauna like
that of the Alaska Peninsula, including brown bear _(Ursus arctos)_,
caribou _(Rangifer tarandus)_, wolf _(Canis lupus)_, and wolverine
_(Gulo gulo)_. West of Unimak, red foxes _(Vulpes fulva)_ occurred
historically as far as Umnak, and arctic foxes were apparently on Attu
when the Russians came in 1741 (Murie 1959). Except for man and dog, no
land mammals occurred between Umnak and Aggatu islands. Arctic foxes,
introduced before 1930 for fur farming, still roam almost every island.
Norway rats _(Rattus norvegicus)_ were introduced on many islands when
ships were wrecked or as a result of military activities during World
War II.
Sea otters _(Enhydra lutris)_ have repopulated most of the Aleutians
after being nearly extirpated by 1900. Rookeries of Steller's sea lion
_(Eumetopias jubata)_ are scattered throughout the Aleutians during
summer, and numerous harbor seals _(Phoca vitulina)_ haul out on
beaches and offshore rocks.
All five species of Pacific salmon (_Oncorhynchus_ spp.) occur near the
islands, and at least four of them (all but _O. tshawytscha_) spawn in
Aleutian streams. Dolly Varden _(Salvelinus malma)_ and three-spine
sticklebacks _(Gasterosteus aculeatus)_ are found nearly everywhere
there is fresh water. The marine environment provides habitat used by
at least 77 species of fish (Isakson et al. 1971). O'Clair and Chew
(1971) furnished a recent reference to littoral macrofauna at Amchitka.
About 200 species of birds have been recorded in the Aleutians
(Aleutian Islands National Wildlife Refuge, unpublished data). Many of
these are windblown stragglers from both North America and Asia; only
59 species breed on the islands. Although seabirds make up less than
half (26 species or 44%) of the breeding birds, they may compose more
than 90% of the breeding avian biomass.
Ornithological Investigations in the Aleutians
Published ornithological information from the Aleutian Islands is
relatively scarce. G. W. Steller, naturalist on Vitus Bering's 1741
expedition to Alaska, was the first person to record ornithological
information in the islands (Stejneger 1936). More than a century passed
before W. H. Dall (1873, 1874) published the next papers dealing with
birds in the Aleutians. In 1878, the U.S. Army Signal Corps sent L.
M. Turner to the Aleutians to set up weather stations at several
locations. Turner kept notes on birds at various locations in the
Aleutians and published two papers (1885, 1886) on his observations.
Turner's data (1886) provided the first report based on extended and
widespread observations in the area. E. W. Nelson, who replaced Turner,
also provided data on birds (Nelson 1887).
In 1906, A. C. Bent came to the Aleutians specifically to look for
birds, and he and Alexander Wetmore recorded birds throughout the
island chain (Bent 1912). A. H. Clark (1910) provided a valuable
record of his observations in the Near Islands. All these workers
recorded birds in several locations, but none provided data on more
than a very few seabird colonies.
[Illustration: =Fig. 1.= The Aleutian Islands.]
O. J. Murie, U.S. Biological Survey, made the most complete survey of
the Aleutians (Murie 1959). He specifically recorded seabird colonies,
spending parts of four summers in the area. Murie visited every
large Aleutian island and most small ones. He recorded nearly every
major colony of cliff-nesting or talus-nesting seabirds known in the
Aleutians, but seldom gave sizes of colonies, and separate colonies on
a particular island were often not differentiated.
World War II brought several ornithologists to the Aleutians. Cahn
(1947), Sutton and Wilson (1946), Taber (1946), and Wilson (1948)
provided accounts of birds observed at specific locations. After the
war, Fish and Wildlife Service personnel--including I. N. Gabrielson
(Gabrielson and Lincoln 1959), K. W. Kenyon (Kenyon 1961), and R. D.
Jones (Refuge Narrative Reports 1949-1970)--recorded observations of
breeding seabirds at several locations in the Aleutians. Investigations
associated with Atomic Energy Commission nuclear testing at Amchitka
Island provided the first ecological study of avifauna of an Aleutian
island (White et al. 1977). Byrd et al. (1974) provided a list of birds
at Adak.
In 1971, the Near Islands were surveyed by U.S. Fish and Wildlife
personnel in a Cape Cod dory. In 1972, the Aleutian Islands National
Wildlife Refuge obtained a vessel, the _Aleutian Tern_, which allowed
visits to all parts of the island chain. That year, nearly every large
island as far west as Buldir was visited, and seabird colonies were
mapped. Every island has been visited at least once since 1972.
Methods
In estimating the current status of seabirds in the Aleutians, all
available data were considered. Most of the information used, however,
is from surveys conducted by the U.S. Fish and Wildlife Service
(1970-75, unpublished data). Because these surveys only incidentally
included Unimak, Akun, Akutan, Unalaska, and Umnak islands, data for
these areas are almost totally lacking. Data for Bogoslof, Adak,
Amchitka, Buldir, Agattu, Nizki, Alaid, and Attu are most accurate
because fairly intensive investigations have been conducted there since
1970.
The available data are of unknown accuracy. The method used by most
investigators who have surveyed areas in the Aleutians for seabird
colonies has been to circle islands in a ship or small boat; when a
colony was encountered, they simply estimated the number of birds they
saw at the time. The accuracy of the estimates is affected by weather,
distance from the colony, density of birds, ability and experience
of the observer, and other variables. Estimates of kittiwakes and
cormorants should be the most accurate, since nests were actually
counted. Murres (_Uria_ spp.) are readily visible on the cliffs, but
the percentage of breeders on the cliffs at a particular time of day
during a particular part of the breeding season is not known. Auklet
numbers are perhaps hardest to estimate, since swirling "clouds" of
birds are encountered.
Even when the estimates of birds seen are assumed to be accurate, data
interpretation is complex. Lack of information on diurnal rhythms adds
difficulty to data interpretation. Counts of burrow-nesting birds
(e.g., puffins) have been inaccurately interpreted because of the
lack of understanding of their nesting ecology. Gulls (_Larus_ spp.),
terns, and jaegers (_Stercorarius_ spp.) are not well known since
shore parties have seldom investigated island interiors. Nocturnal
species (e.g., ancient murrelet, _Synthliboramphus antiquus_, and
storm-petrels, _Oceanodroma_ spp.) are perhaps the least known. Since
only crude estimates of colony sizes are available, broad limits are
used in this paper to describe known colonies.
Status and Distribution of Breeding Seabirds
Even from the sparse literature available, it is apparent that some
seabird populations are now drastically different from those in the
Aleutians around 1900. Changes in nesting habitat due to volcanic
eruptions, tidal waves, marine erosion, and earthquakes have occurred
for centuries, and colonial nesting bird populations have fluctuated
accordingly. In addition, native Aleuts used marine birds and their
eggs for food and their skins for clothing, but the Aleuts were so
diminished in numbers by 1900 that they have had little recent effect
on the bird populations.
From about 1900 to 1936, arctic foxes were introduced to most of the
Aleutians for fur farming. The foxes lived on birds in summer, and some
species (e.g., Aleutian Canada geese, _Branta canadensis leucopareia_)
were wiped out wherever foxes were introduced. Ground-nesting and some
burrow-nesting seabirds were also drastically reduced or extirpated on
many islands.
During World War II the thousands of troops in the Aleutians brought
dogs and cats to some of the islands as pets, and many of the animals
were set free when the men departed. The military also accidentally
introduced Norway rats to some of the islands. Their role in seabird
population reductions is unknown.
Figures 2-15 (pages 40-46) present data on the distribution of
populations of birds that have survived the foxes and other introduced
predators. An annotated list of seabirds breeding in the Aleutians
follows.
_Annotated List of Species_
Northern fulmar _(Fulmarus glacialis)_
Northern fulmars breed on only three islands: Buldir (200 pairs),
Gareloi (1,500 pairs), and Chagulak (more than 100,000 pairs). Fulmars
were apparently much more widespread formerly (Murie 1959; Turner
1886). Introduced foxes were probably involved in the decline.
Fork-tailed Storm-petrel and Leach's Storm-petrel (_Oceanodroma
furcata_ and _O. leucorhoa_)
The distribution of storm-petrels is poorly known due to their
nocturnal behavior near the nesting colonies. The presence of birds
has generally been noted by finding them aboard ships anchored near
islands after darkness. Population estimates are not available for
any colonies, so symbols used in Fig. 3 indicate probable numbers of
breeding birds. In few cases have active burrows or crevices been
discovered. Storm-petrels were formerly much more common. Murie (1959)
and John L. Trapp (personal communication) found large numbers of
storm-petrel remains in fox dens. Most present breeding colonies are
probably confined to offshore islets and fox-free islands.
Double-crested Cormorant, Pelagic Cormorant, and Red-faced Cormorant
(_Phalacrocorax auritus_, _P. pelagicus_, and _P. urile_)
Double-crested cormorants breed as far west as the Islands of Four
Mountains. The colonies vary in size from a few to 25 pairs. Pelagic
and red-faced cormorants nest from Amak to Attu on nearly every
island. Relative abundance of the two in mixed colonies varies between
areas as well as from year to year. Red-faced cormorants tend to
nest in colonies mixed with kittiwakes and murres, but pure colonies
also occur. Pelagic cormorants occupy isolated, small colonies, but
they also nest with kittiwakes and murres and are often found with
red-faced cormorants. By far the densest concentration of cormorants
occurs in the Near Islands, especially at Attu, where an estimated
77,000 birds were seen in 1970. In the Aleutians as a whole, red-faced
cormorants outnumber pelagic cormorants, and double-crested cormorants
make up only a very small percentage of the breeding population.
Parasitic Jaeger _(Stercorarius parasiticus)_
The distribution of jaegers is poorly known because investigators have
spent little time ashore on most islands. Murie (1959) found jaegers on
a number of islands, and most of the data in Fig. 5 are his. Population
estimates are available only for Amchitka (25 pairs; White et al. 1977)
and Buldir (30-40 pairs; G. V. Byrd, unpublished data).
Glaucous-winged Gull _(Larus glaucescens)_
Glaucous-winged gulls no longer nest on islands where foxes occur
except where islands in lakes are available. Most colonies are on
offshore rocks or islets and range in size from a few pairs to over 200
pairs, and occasionally more. They are found throughout the Aleutians,
but the largest known colonies are at Bogoslof (500 pairs) and Buldir
(250 pairs).
Black-legged Kittiwake and Red-legged Kittiwake (_Rissa tridactyla_ and
_R. brevirostris_)
Black-legged kittiwakes breed locally in every major island group,
usually mixed with murres and cormorants. The large colonies contain
over 25,000 birds, but colonies of less than 50 pairs also occur.
Red-legged kittiwakes breed only on Buldir and Bogoslof. They are
remnants of a previously more widespread population.
Arctic Tern and Aleutian Tern (_Sterna paradisaea_ and _S. aleutica_)
Terns breed locally in each island group. Both species occur at Attu,
Amchitka, Adak, and Umnak, but only arctic terns are found at Nizki.
Factors limiting distribution are unknown. Colonies vary in size from
less than 10 pairs to 100 pairs.
Common Murre and Thick-billed Murre (_Uria aalge_ and _U. lomvia_)
Like kittiwakes, murres are abundant locally. A pure colony of either
species is almost unknown, although one species often makes up more
than 90% of a colony. Common murres may have been reduced by foxes,
since they tend to use sites with less slope than those used by
thick-billed murres. At Bogoslof and the Baby islands, the birds use
inland, gently sloping areas because there are no foxes. The presence
of the lichen _(Caloplaca spp.)_, which according to Tuck (1960) is
indicative of bird roosts, on several extensive cliff areas suggests
that either murres or kittiwakes, or both, formerly used areas they do
not use now.
Pigeon Guillemot _(Cepphus columba)_
This species has been noted near almost every island that has been
visited. Nesting under beach boulders and driftwood, the birds only
occasionally are found in large concentrations (near Great Sitkin more
than 4,000 birds were seen in 1971). Murie et al. (1937) summed up
the distribution of pigeon guillemot accurately: "Each island has its
meager quota of these birds, nesting unobtrusively among the rocks but
never assembled in any really large groups." Estimates of populations
may be extremely inaccurate because the diurnal rhythm of the pigeon
guillemot is unknown.
Marbled Murrelet and Kittlitz's Murrelet (_Brachyramphus marmoratus_
and _B. brevirostris_)
Nests of neither species have been located in the Aleutians, but
nesting of both is suspected at Adak, Unalaska, and Unimak, where
specimens of Kittlitz's with brood patches or eggs in the oviduct have
been collected in nearshore waters. Courtship has been recorded in
marbled murrelets (Byrd et al. 1974).
Ancient Murrelet _(Synthliboramphus antiquus)_
The distribution of this species is very poorly known, since it is
nocturnal near nesting colonies. Murie (1959) wrote, "This is one of
the species that undoubtedly has greatly declined in recent years, as
a result of increase of the blue-fox industry." The leading of downy
young to sea by the adults is a very noisy process and foxes could
easily take large numbers. Also, these murrelets nest in fairly shallow
burrows which foxes could dig out easily. Birds were recorded near
islands in every group during surveys from 1972 to 1975, but workers
seldom went ashore to determine if they were nesting. In Fig. 12, the
only basis for designating most of the areas marked as colonies is the
presence of birds during breeding season (15 May-1 July).
Cassin's Auklet _(Ptychoramphus aleuticus)_
This is another species that was more common before the fox was
introduced. Cassin's auklet now seems to occur only locally, but these
nocturnal birds are probably often overlooked. They are known only from
Buldir, Umnak, and the vicinity of Oglodak.
Parakeet Auklet _(Cyclorrhynchus psittacula)_
This auklet, which nests under beach boulders, in burrows, and in rock
crevices, seems to use a greater variety of breeding sites than do
the other auklets. The largest known colony is at Chagulak, where an
estimated 10,000 were seen in 1972. Smaller colonies are found as far
west as Buldir.
Crested Auklet, Least Auklet, and Whiskered Auklet (_Aethia
cristatella_, _A. pusilla_, and _A. pygmaea_)
_Aethia_ nest primarily in rock crevices of talus slides. Such habitat
occurs locally in each major island group except the Near Islands.
Least auklets outnumber crested auklets in the Aleutians, and whiskered
auklets are far less common than either. Estimates of populations
are probably grossly inaccurate because of the difficulty both in
estimating the number of birds in the milling flocks observed and in
interpreting the estimates after they are obtained.
Horned Puffin and Tufted Puffin (_Fratercula corniculata_ and _Lunda
cirrhata_)
Horned puffins favor rock crevices in talus slides and cliff faces
for nesting, whereas tufted puffins are primarily burrow nesters.
The historical distribution of the two species was probably based on
availability of nesting sites, so tufted puffins were more widespread
and numerous. However, in areas where extensive talus slopes are
available, horned puffins reached high densities. Predation by
introduced foxes may have altered the distribution of tufted puffins,
which now nest primarily on fox-free islets just offshore from the
larger islands where foxes occur. The distribution of horned puffins
may not have been altered significantly, since they are relatively free
from fox predation in their rock crevices.
Recommendations
A complete survey of the Aleutian Islands has not been done. This
should be done, by methods that will provide accurate population
estimates. Life history information is needed on almost all species,
and data should be gathered on selected populations to determine
trends. Information on winter distribution should also be compiled. The
effects of introduced predators should be evaluated quantitatively, and
if control measures are needed, effective, humane methods should be
devised and implemented.
Acknowledgments
The authors are grateful to the following Fish and Wildlife Service
personnel who helped collect previously unpublished data used in this
paper: E. P. Bailey, C. S. Craighead, C. P. Dau, M. H. Dick, G. J.
Divoky, R. Martin, J. L. Trapp, G. W. Watson, and C. M. White. Most of
the data were collected from the deck of the Aleutian Islands National
Wildlife Refuge research vessel _Aleutian Tern_. Captain George Putney
is acknowledged for his peerless seamanship and constant encouragement;
he also contributed observations of birds.
The maps were adapted from a master supplied by Elaine Rhode, Public
Affairs Office, U.S. Fish and Wildlife Service, Anchorage; she also
suggested the use of squares to display data. C. M. White graciously
made his in-press manuscript available. W. B. Emison, R. J. Gordon,
and J. L. Trapp kindly made their field notes available, and Trapp
helped compile data. Most of the funds for the surveys in 1971-75 were
provided by the U.S. Fish and Wildlife Service.
References
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terrestrial ecosystem vegetation of Amchitka Island, Alaska.
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Bent, A. C. 1912. Notes on birds observed during a brief visit to
the Aleutian Islands and Bering Sea in 1911. Smithsonian Misc.
Coll. 56(2):1-29.
Byrd, G. V., D. D. Gibson, and D. L. Johnson. 1974. The birds of
Adak Island, Alaska. Condor 76:288-300.
Cahn, A. R. 1947. Notes on the birds of the Dutch Harbor area of
the Aleutian Islands. Condor 49:78-82.
Clark, A. H. 1910. The birds collected and observed during the
cruise of the United States Fisheries steamer "Albatross" in
the north Pacific Ocean and in the Bering, Okhotsk, Japan, and
Eastern seas from April to December 1906. Proc. U.S. Natl. Mus.
38:25-74.
Dall, W. H. 1873. Notes on the avifauna of the Aleutian Islands,
from Unalaska eastward. Proc. Calif. Acad. Sci. 5:25-35.
Dall, W. H. 1874. Notes on the avifauna of the Aleutian Islands,
especially those west of Unalaska. Proc. Calif. Acad. Sci.
5:270-281.
Gabrielson, I. N., and F. C. Lincoln. 1959. The birds of Alaska.
The Stackpole Co., Harrisburg, Penn., and Wildlife Management
Institute, Washington, D.C. 922 pp.
Hulten, E. 1960. Flora of the Aleutian Islands. J. Kramer,
Weinham/Bergstr., Sweden. 376 pp.
Isakson, J. S., C. A. Sinensted, and R. L. Burgner. 1971. Fish
communities and food chains in the Amchitka area. Bioscience
21:666-670.
Jones, R. D. 1949-1970. Annual refuge narrative reports, Aleutian
Islands N.W.R. Cold Bay, Alaska. (Unpublished administrative
report.)
Kenyon, K. W. 1961. Birds of Amchitka Island, Alaska. Auk
78:305-326.
Lebednik, P. A., F. C. Weinmann, and R. E. Norris. 1971. Spatial
and seasonal distributions of marine algal communities at
Amchitka Island, Alaska. Bioscience 21:656-660.
Murie, O. J. 1959. Fauna of the Aleutian Islands and Alaska
Peninsula. U.S. Fish Wildl. Serv., N. Am. Fauna 61. 364 pp.
Nelson, E. W. 1887. Report upon natural history collections made in
Alaska between the years 1877 and 1881. U.S. Army, Signal Serv.
Arct. Ser. Publ. 3. 337 pp.
O'Clair, C. E., and K. K. Chew. 1971. Transect studies of littoral
macrofauna, Amchitka Island, Alaska. Bioscience 21:661-664.
Stejneger, L. 1936. George Wilhelm Steller--the pioneer of Alaska
natural history. Harvard University Press, Cambridge, Mass. 623
pp.
Sutton, G. M., and R. S. Wilson. 1946. Notes on the winter birds of
Attu. Condor 48:83-91.
Taber, R. D. 1946. The winter birds of Adak, Alaska. Condor
48:272-277.
Tuck, L. M. 1960. The murres. Ottawa. Canadian Wildlife Series 1.
260 pp.
Turner, L. M. 1885. Notes on the birds of the Near Islands, Alaska.
Auk 2:154-159.
Turner, L. M. 1886. Contributions to the natural history of Alaska.
U.S. Army, Signal Serv. Arct. Ser. Publ. 2. 226 pp.
White, C. M., F. S. L. Williamson, and W. B. Emison. 1977.
Avifaunal investigations. Pages 227-260 _in_ M. L. Merritt and
R. G. Fuller, eds. Environments of Amchitka Island, Alaska. U.S.
Energy Research and Development Association, Oak Ridge, Tenn. 682
pp.
Wilson, R. S. 1948. The summer bird life of Attu. Condor 50:124-129.
[Illustration: Fig. 2. Breeding distribution of northern fulmar.]
[Illustration: Fig. 3. Breeding distribution of storm-petrels.]
[Illustration: Fig. 4. Breeding distribution of cormorants.]
[Illustration: Fig. 5. Breeding distribution of parasitic jaeger.]
[Illustration: Fig. 6. Breeding distribution of glaucous-winged gull.]
[Illustration: Fig. 7. Breeding distribution of kittiwakes.]
[Illustration: Fig. 8. Breeding distribution of terns.]
[Illustration: Fig. 9. Breeding distribution of murres.]
[Illustration: Fig. 10. Breeding distribution of pigeon guillemot.]
[Illustration: Fig. 11. Breeding distribution of marbled and Kittlitz's
murrelet.]
[Illustration: Fig. 12. Breeding distribution of ancient murrelet.]
[Illustration: Fig. 13. Breeding distribution of auklets.]
[Illustration: Fig. 14. Breeding distribution of horned puffin.]
[Illustration: Fig. 15. Breeding distribution of tufted puffin.]
FOOTNOTES:
[3] Present address: U.S. Fish and Wildlife Service, William L. Finley
National Wildlife Refuge, Route 2, Box 208, Corvallis, Oregon 97330.
[4] Present address: U.S. Fish and Wildlife Service, Kilauea, Hawaii.
The Historical Status of Nesting Seabirds of the Northern and Western
Gulf of Alaska
by
LeRoy W. Sowl
U.S. Fish and Wildlife Service
1011 East Tudor Road
Anchorage, Alaska 99507
Abstract
The history of ornithological field work in the
Gulf of Alaska dates back to 20 July 1741 and
Bering's discovery of Alaska. In spite of this
long history, the record is fragmentary and
often seemingly contradictory. The coming of
the tanker terminal at Valdez and the pending
development of oil and gas resources on the
outer continental shelf threaten massive change
for seabirds in the Gulf of Alaska. Often
overlooked, however, is the fact that man has
already effected a change in status for many
of these birds. In this paper I examine the
scanty, general record from the exploratory
period, roughly 1741 to 1935, and the somewhat
more comprehensive record of the reconnaissance
period, 1936-74, and attempt to develop a basis
for better understanding of the change in
seabird status that has already taken place.
This paper should be treated as a verbal model
which can be improved as our knowledge of
seabirds in the Gulf of Alaska is expanded.
From the perspective of history, 1970 should prove to have been
a momentous year for Alaska and its seabirds. Two events, the
construction of the Trans-Alaska Pipeline and the passage of the
National Environmental Policy Act (NEPA) merged head on in 1970 with
the decision that Section 2c of NEPA applied to the proposed pipeline.
The systematic appraisal of potential environmental impacts required
by Section 2c quickly exposed the inadequacy of the existing data base
in many areas. With respect to seabirds in the Gulf of Alaska, it was
apparent that there had never been any effort to develop a synthesis of
the information accumulated over 230 years. The data gaps which were
uncovered were appalling.
While the Trans-Alaska Pipeline impact statement had provided shock
therapy, it was not the only influential event on the horizon. Two
local disturbances had already preceded the pipeline. These were
Project Chariot at Cape Thompson and the Amchitka Island test program.
Now in quick succession the Wilderness Act and native land claims added
new urgency to the need for solid resource information. More recently,
the outer continental shelf minerals leasing program has made the quick
development of base-line information even more essential.
All of the new activity in Alaska's coastal waters has the potential
to affect seabirds in one way or another. We must remember, however,
that man's activities have been affecting seabirds for a long time. We
cannot accurately assess the effect of a tanker terminal at Valdez or
offshore oil activity without first developing some understanding of
the current status of seabirds in the context of the historical record.
Seabird work in Alaska can be divided roughly into three periods.
The first is the early historical or exploratory period; it extended
from Georg Steller's 1741 visit to Kayak Island to 1935. This was
literally a period of exploration and the collection of information
was dependent upon interest and opportunity. The second is the
reconnaissance period; during this period investigators were dispatched
to a particular area to gather general information for management
application. This period begins with Murie's extensive investigations
of the Alaska Peninsula and the Aleutian Islands; I see it extending
from 1936 to 1975. In 1975 the need for data became so acute that
it was necessary to enter the third period, one of intensive data
gathering. Knowing where the big seabird colonies were located and
knowing their general species composition was no longer adequate. The
current intensive data-gathering effort in the waters over oil and
gas leasing areas is a partial response to the recognition of this
inadequacy.
In this paper I draw some tentative conclusions relative to the status
of the 26 species of primary seabirds (Fisher and Lockley 1954)
breeding in, or which may have bred in, the northern and western Gulf
of Alaska area. This area extends from Cape Fairweather, 59°N 138°W,
westerly along the coast to Ikatan Bay, 55°N 163°W, at the end of the
Alaska Peninsula. These bird species tend to be colonial, but not
exclusively so. Two birds which are primary seabirds, the mew gull
_(Larus canus)_ and Bonaparte's gull _(L. philadelphia)_, have not been
included because they tend to be more riverine than marine in habit.
Several marine ducks have been excluded because they are secondary
seabirds.
Information from the early exploratory period is summarized under the
next section. The more detailed information from the reconnaissance
period is discussed in the species accounts.
Summary of the Historical Record
The history of ornithological field work in the Gulf of Alaska
goes back 235 years to 20 July 1741. On that day Bering's
surgeon/naturalist, Georg W. Steller, spent a scant 10 h ashore on
Kayak Island. He collected a single bird. This bird, later named for
Steller, reminded him of a plate of the blue jay by Make Catesby,
the colonial-era predecessor of Audubon, in Volume 1 of the _Natural
History of Carolina, Florida, and the Bahama Islands_ (Stejneger's
annotated translation of Steller's journal in Golder 1925). Collection
of the bird confirmed for Steller that the first Russian Expedition had
reached America.
Steller was an accomplished naturalist, but his overbearing and
superior manner had apparently sorely irritated Bering and his officers
long before the expedition reached Kayak Island. The seamen made little
effort to go ashore anywhere in Alaska and Steller was blocked from
doing so as well. In addition to Kayak Island, he was able to go ashore
only on Nagai Island, first with a water party on 30 August and again
the next day. He noted that "all sorts of waterbirds in abundance were
seen." These included two kinds of cormorants, auks, ducks, gulls,
divers, pigeon guillemots _(Cepphus columba)_, tufted puffins _(Lunda
cirrhata)_, and horned puffins _(Fratercula corniculata)_.
Stejneger's comment on the identity of the cormorants is interesting
because, based on his experience, he assumed them to be pelagic and
double-crested cormorants (_Phalacrocorax pelagicus_ and _P. auritus_).
He gave no thought to red-faced cormorants _(P. urile)_ which are now
common there.
Steller noted on 6 September off Bird Island in the Shumagin
Islands, that "when we were out to sea about half a mile we were
especially astonished at the untold numbers of seabirds which we
saw on the northern side of the island." These birds were listed as
cormorants, auks, horned puffins, fulmars _(Fulmarus glacialis)_,
pigeon guillemots, black oystercatchers _(Haematopus backmani)_,
and a pied diver which Stejneger assumed was an ancient murrelet
_(Synthliboramphus antiquus)_.
On 15 September when Bering's vessel, the _St. Peter_, was south of
Amukta Pass, Steller recorded observing "river gulls." The observation
is not as interesting as Stejneger's comment (Golder 1925) concerning
it. Stejneger stated that no true river gulls lived in the Aleutians
and these must, therefore, have been another small gull with red
feet. He thought they must have been the red-legged kittiwake _(Rissa
brevirostris)_, which "inhabits the Aleutian Islands from Bering Island
to Sannak."
Thirty-seven years after Bering's voyage, Captain James Cook sailed
into the Gulf of Alaska, arriving off Kayak Island on 11 May 1778.
Cook was not accompanied by an able naturalist. His surgeon, William
Anderson, did have some experience gained on earlier voyages in
preparing skins and taking notes, but he had contracted tuberculosis
and became so ill that even his notes ceased after 8 June, while the
expedition was in Cook Inlet.
Cook was under orders to keep a careful record of everything he saw.
One of the results was that he had birds collected even though he had
no naturalist to do the work. Several birds were collected in Prince
William Sound while Cook's vessels were at anchor in Port Etches.
These included two marbled murrelets (_Brachyramphus marmoratus_--type
specimens), a black oystercatcher, a surfbird _(Aphriza virgata)_, a
surf scoter _(Melanitta perspicillata)_, and a red-breasted merganser
(_Mergus serrator_--type specimen), along with several forest birds
(Stresemann 1949).
The watch journals of Cook and his officers provide some additional
information. Captain Charles Clerke (Beaglehole 1974) remarked in
his log on the passage out of Prince William Sound through Montague
Strait on 20 May that "it had almost become tautology to mention whales
and seals and innumerable sea fowl that so confoundingly kept their
distance."
Between the Trinity Islands and Chirikof Island on 18 June, Cook's men
collected a single tufted puffin. Later Cook passed close to the Semidi
Islands and the Shumagin Islands and directly through the Sandman
Reefs. Beaglehole's version of this part of the voyage makes no mention
of seabirds.
There is a gap of 87 years during which there is almost no hint of
published material bearing on the status of seabirds in the Gulf of
Alaska. In 1865 the Russo-American Telegraph Expedition touched this
area. Dall and Bannister (1869) provide us with a few scraps garnered
during that expedition, primarily by Bischoff. The glaucous-winged gull
_(Larus glaucescens)_ was described as the most common species from
California northward. Bischoff's collections at Kodiak indicate that
the horned and tufted puffins were collected with ease. He was able
also to collect an Aleutian tern (_Sterna aleutica_--type specimen)
along with an egg.
Dall (1873) noted in 1872 that the black-legged kittiwake _(Rissa
tridactyla)_ was common at Round Island and Delarof Harbor, Unga
Island, in the Shumagins. The inference is that it was more common at
these two places than elsewhere. The Arctic tern _(Sterna paradisaea)_
was abundant in the Shumagin Islands and particularly at Range Island
in Popoff Strait. Dall expressed the opinion that the horned puffin was
very abundant in the Shumagins and appeared to fill the niche of the
tufted puffin, which he did not see there. The only other bird which he
thought to be very common was the pigeon guillemot. He did not note the
common murre _(Uria aalge)_ at all.
In 1908 the second of three Alexander Expeditions conducted field work
in the Prince William Sound area. From Dixon (1908) and Grinnell (1910)
we can derive some basis for assessing status in a very general way.
The most common seabird noted was the marbled murrelet. Glaucous-winged
gulls and black-legged kittiwakes were common; the glaucous-winged
gull was the more common. Horned puffins were judged to be slightly
more common than tufted puffins by both authors. The northern end
of Montague Strait appears to have been the center of abundance for
puffins. Dixon noted that on 16 July 1908 there were swarms of puffins
in the channel along Green Island. Pigeon guillemots were common along
the rocky coasts. Parakeet auklets _(Cyclorrhyncus psittacula)_, common
murres, and ancient murrelets were noted only in very small numbers.
After the Alexander Expeditions there was another doldrum in which
little was done. During this lull in activity, a note by Townsend
(1913) appeared which compared the numbers of crested auklets _(Aethia
cristatella)_ at Yukon Harbor, Big Koniuji Island, to the least auklets
_(A. pusilla)_ of St. George Island, stating that the crested auklets
were more numerous. He sailed into the Yukon Harbor anchorage on the
evening of 1 August and observed that crested auklets "were present in
myriads. The surface of the water was covered with them, and the air
was filled with them."
The formal record available to researchers is very shallow for
this exploratory period. With a few exceptions it was compiled by
non-scientists, primarily explorers and egg and skin collectors.
Current Status
_Setting the Stage_
This paper should be viewed as a conceptual model. While I attempted
to be as objective as possible, subjectivity was unavoidable. Many
of the tentative conclusions are based on very little data. Each
improvement will make it a better management tool. Because of the space
limitations, it is not possible to go into a detailed tracking of my
reasoning for each species. In an attempt to overcome this handicap, I
am including some examples of the sorts of reasoning that went into the
process.
In 1973 I led a Fish and Wildlife Service (FWS) reconnaissance survey
team that was delineating seabird colonies along the Alaska Peninsula.
In the Shumagin Islands we entered or crossed Koniuji Strait twice
(on 11 and 12 June) without even suspecting the presence of a horned
puffin colony. A third passage through the strait (13 June) was not so
uneventful. The water and the air were filled with horned puffins. This
led to the discovery that the 430-m mountain on the southeastern corner
of Big Koniuji was also covered with horned puffins, clear to its top.
The minimum estimate of the birds that were visible was 140,000. Even
this number of birds would make this the largest horned puffin colony
ever discovered. David Spencer (personal communication) had noted
similar swarms of horned puffins in this strait in 1956 while flying
sea otter surveys in the area. In 1975 a field camp was established at
Yukon Harbor, with study of this colony as one of the prime objectives
of the investigators. As far as these investigators could tell no such
large colony existed there, even though the nesting habitat was still
there, unaltered. This sort of event, one of the banes and vagaries of
estimating seabird numbers, is not rare.
In 1973, when FWS personnel delineated the colony on the southwestern
end of Bird Island in the Shumagins, there were estimated to be 43,000
kittiwakes, 24,000 murres, and 6,000 cormorants present; no tufted
puffins were seen about the colony. The last time (in 1970) one of the
observers, Edgar Bailey, had visited the colony with Robert Jones,
there was an extremely large colony of tufted puffins which Jones (E.
Bailey, personal communication) estimated at more than 1 million birds.
We made a particular effort to visit Jude Island, between the Shumagin
Islands and the Pavlof Islands, because David Spencer (personal
communication) had reported once having seen the air over the island
filled with an extremely large number of tufted puffins. However, there
were no puffins at this colony either.
Let us examine the facts in context. On 8 June we had visited High
Island where we had attempted to collect puffin eggs for pesticide
analysis, but had been able to find only one egg. Also, there were
only 6,000 tufted puffins where George Putney, master/engineer of the
_Aleutian Tern_, had seen much larger numbers in 1972. These two facts
could easily be related to explain the current situation because it
was still early in the breeding season. The horned puffin observations
in Koniuji Strait (11-13 June) were in keeping with this conclusion
also--an indication that these birds had not yet settled down to a
full breeding effort. The erratic comings and goings of common puffins
_(Fratercula arctica)_ early in the season have been well documented
(Lockley 1962). It is an easy step to extend this reasoning to the
absence of birds at Bird Island on 11 June, even though fresh signs of
the characteristic evidence of tufted puffin occupancy were missing.
Jude Island provides a different clue, however. There were 3,000
pigeon guillemots, an unheard-of concentration, apparently occupying
abandoned tufted puffin burrows on 15 June. Also, on 7 June we had made
a very interesting observation that had no special significance at the
time: murres on Spitz Island were occupying little parapets created by
mashing down the mouths of puffin burrows which filled the slope above
the cliff portion of their colony.
After looking at all of the observations cited above, I conclude that
tufted puffins were greatly reduced in numbers on these sites in 1973
and that they had been absent from the burrows used by the murres and
pigeon guillemots for more than the current breeding season. What
causes these sorts of changes? I do not know.
One reason for year-to-year change may be local movements of colonies.
Black-legged kittiwakes nest at several places in lower Orca Inlet,
Prince William Sound. Counts made at these sites in 1972 and 1974
yielded almost identical totals but the numbers of birds varied
between individual sites. This may be an indication that all of these
sites are part of one large composite colony and that, at least in this
colony and for this species, the birds shift at will.
The best record of population flux involving two species has been
summarized by Peterson and Fisher (1955). In 1872 and 1873 the murres
observed on Walrus Island in the Pribilofs were almost entirely common
murres. In 1890 common and thick-billed murres _(Uria lomvia)_ were
evenly matched in number. By 1901 the colony was almost exclusively
dominated by thick-billed murres. In 1911 and 1914 the few thick-billed
murres present were almost lost among the then dominant common murres.
In 1940 thick-billed murres dominated again. When Peterson and
Fisher visited the island in 1953, the situation was again reversed
and common murres had almost completely replaced the thick-billed
murres. These changes are even more impressive because of the number
of birds involved, between 1 and 2 million in 1953. There are more
tenuous indications that somewhat the same thing may occur between
two other congener pairs, the pelagic and red-faced cormorants and
the black-legged and red-legged kittiwakes. The causative factor, or
factors, is not readily apparent. One possibility is long-term climatic
fluctuation.
Dement'ev and Gladkov (1966) provide an example of abrupt and massive
change. Before 1876, the pelagic cormorant abounded on the Commander
Islands. During the winter of 1876-77, the birds were decimated by an
unknown epizootic disease. By spring only a few individuals remained
alive. The record shows that by 1882 they were already becoming common
again. Red-faced cormorants were apparently not reduced in number
because Dement'ev and Gladkov (1966) state that they were common in
"the second half of the last century and the beginning of this." Did
they flourish only while the pelagic cormorants were reduced in number?
Bowles (1908) gives another indication of naturally induced population
impact. He noted large numbers of dead seabirds on Washington beaches
and the ocean "rather plentifully dotted with sick birds ..." He
examined some birds and found "many hundreds" of tapeworms in every
bird. His conclusion was that their intestines were so solidly packed
with tapeworms that starvation was "an absolute certainty."
Some apparent disruptions are long term. In the Gulf of Alaska there is
a hiatus in the distributions of a number of small seabirds that are
active around their colonies only at night. Repeatedly, the northern
Gulf of Alaska shows up as an area of reduced population, as a boundary
between subspecies, or as a limit to a range. This same area has a
noticeable lack of total darkness during a substantial portion of the
breeding season.
The nocturnal habit no doubt evolved because it was advantageous to
concentrate on the breeding grounds only under the cover of darkness,
when diurnal predators were at a great disadvantage. Cody (1973) states
that Cassin's auklet _(Ptychoramphus aleuticus)_, which is strictly
nocturnal around its colonies, avoids these colonies on brightly
moonlit nights. He sees this as an apparent response to gull predation.
At higher latitudes the small alcids have overcome this disadvantage by
swamping predators through their sheer numbers. In the Gulf of Alaska I
suspect that few of the small seabirds, except possibly the fork-tailed
storm-petrel _(Oceanodroma furcata)_, have ever achieved great enough
numbers to offset the impact of extended daylight.
Past disruptions of seabird populations are both natural and
man-induced; however, the documentary record is much too fragmentary to
allow us to fully appreciate what has occurred or what the long-term
effect has been. To give some perspective to the problems associated
with assessing change and attempting to understand it, some of the
indicators of natural and unnatural change and flux in seabird
populations are reviewed here.
The flux in bird numbers can be related to the time of day, season of
the year, and atmospheric conditions on a short-term basis. This sort
of flux or apparent flux can easily be explained. The underlying cause
of some of the longer term flux is not so easily arrived at. Murie
(1959), Gabrielson and Lincoln (1959), and Sowl and Bartonek (1974)
have noted some of the man-induced changes. These are also explored to
some extent in the species accounts as they are found to apply.
I sometimes refer to a colony size class when discussing the existing
data rather than to an actual population estimate. The size classes
used are defined as follows:
Class I--less than 100 birds
Class II--100-1,000
Class III--1,000-10,000
Class IV--10,000-100,000
Class V--100,000-1,000,000
Class VI--more than 1,000,000
The _Dictionary of Alaska Place Names_ (Orth 1967) is the reference for
those who wish to locate some of the less obvious sites. The _Coast
Pilot, No. 9_ (U.S. Department of Commerce 1964) is another useful
reference.
_Species Accounts_
Northern Fulmar _(Fulmarus glacialis)_
Petrels of a number of species can be found in the Gulf of Alaska, some
of them in great numbers. Only the northern fulmar breeds there.
The fulmar is common in the offshore waters of the northern Gulf of
Alaska throughout most of the year (Isleib and Kessel 1973). Most
authors, including Clark (1911), one of the earlier ones, who commented
on the distribution of fulmars farther out in the Gulf, have considered
them to be abundant. Nichols (1927) raised one of the few voices of
apparent dissent; he noted that in 1926 he encountered the largest
number of fulmars (about 800) on 11 July in Shelikof Strait after he
had left the Gulf. During the summer, fulmars are very common seaward
of Montague Island, particularly to the northeast of Patton Bay and in
the approaches to Montague Strait. Data derived from FWS surveys in
July and August 1972 showed an estimated 10,000 fulmars in a stretch of
waters 19 km wide along the east side of Montague Island (Isleib and
Kessel 1973).
Over the Portlock Banks and in Stevenson Entrance, fulmars sometimes
concentrate in very large numbers, either by themselves or in company
with sooty shearwaters _(Puffinus griseus)_. In August 1973, FWS
observers crossing Perenosa Bay saw large numbers of tube-nosed birds
moving northeastward across the Bay. Although these appeared to be
predominantly shearwaters, there were also many fulmars. There was a
general movement of birds through Shuyak Strait from Shelikof Strait
into the Gulf of Alaska. It was not determined whether the fulmars were
moving with the shearwaters or on a regular feeding flight. Fulmars are
often found close to Afognak Island in the area between Sea Lion Rocks
and Sea Otter Island. Gabrielson and Lincoln (1959) reported seeing
swarms of fulmars in Marmot Strait and around the small islands on the
north side of Afognak in early August. Murie (1959) noted fulmars in
Shelikof Strait and again around the Shumagin Islands. There is nothing
in this record to indicate any change in their distribution at sea
recently.
The Semidi Islands support the Gulf of Alaska's largest fulmar breeding
population, a Class V colony (U.S. Bureau of Sport Fisheries and
Wildlife 1973). Gabrielson and Lincoln (1959) considered it to be one
of the four largest colonies in Alaska.
Gabrielson (1940) was told by Captain Sellevold of the marine vessel
_Brown Bear_ that he thought the birds nested on Sea Otter Island in
Perenosa Bay. Gabrielson also learned that they probably nested on
Sea Lion Rock at the head of Marmot Strait. In August 1973 I observed
fulmars in close proximity to Sea Lion Rock. More recently, small
numbers of apparently breeding fulmars have been found in the Barren
Islands (L. W. Sowl, personal observation and Edgar Bailey, unpublished
FWS report, Anchorage, Alaska). Although no other colonies are known or
suspected, the evidence suggests the possible existence of some.
Peterson and Fisher (1955), on noting dark fulmars between St. Paul
and St. George when only the light morph was present on any of the
colonies in the Pribilofs, expressed no surprise. They offered the
opinion that a round trip of 960 km to one of the dark morph colonies
in the Aleutians just might be within the operating range of a fulmar
on a 4-day vacation from nest-tending duties. Using this as a general
yardstick, it appears that the rich foraging grounds over the Portlock
Banks might also be within the range of breeding fulmars from the
Semidis. The trip up Shelikof Strait and on to Portlock Bank by way of
Shuyak Strait is only slightly longer than the one from Chagulak to St.
Paul. The feeding grounds off Montague Island would require a 1,600-km
round trip from the colonies in the Semidi Islands. Birds from the
Barren Islands and any colonies around Shuyak Island could easily reach
the Montague Island grounds, but why would they cross the Portlock
Banks to do so?
Fulmar colonies may be found in the Chiswell Islands. It is also a
possibility that the existence of colonies on islands along the north
coast of Afognak Island will be verified and that others will be
found in the vicinity of Shuyak Island. Gabrielson and Lincoln (1959)
expressed the opinion that there is almost certainly a colony on Sutwik
Island. If there is one, however, I did not see it on one quick trip
around the island in 1973.
Gabrielson (1940) expressed surprise at the size of the Semidi Island
breeding colony. Gabrielson and Lincoln (1959) considered 1911 to be
the first time breeding fulmars were found in the Shumagins. They
apparently based this on two eggs collected there that year and
documented in a plate in Bent (1964). Other than Gabrielson's opinion,
there is nothing to indicate a major change in fulmar status during
this century. If there has been a change in status, it has probably
been in the direction of increasing populations.
Fork-tailed Storm-petrel _(Oceanodroma furcata)_
The fork-tailed storm-petrel probably breeds throughout the Gulf of
Alaska. It is abundant at sea during the summer in most offshore
waters. Murie (1959) described it as the dominant petrel in the Bering
Sea and the North Pacific.
In view of its wide distribution and apparent abundance very little is
known about the fork-tailed storm-petrel's breeding colonies. Friedmann
(1935) recorded specimens and eggs from Kodiak dating back to 1843.
Murie (1959) noted them as nesting on Sanak Island and stated that they
almost certainly nested in the Shumagins and on other islands along the
Alaska Peninsula. David Roseneau (Isleib and Kessel 1973) found this
storm-petrel "breeding by the 10,000's" on East Amatuli Island in the
Barren Islands in June 1965. This was subsequently verified in 1974 by
Edgar P. Bailey (unpublished report, FWS, Anchorage, Alaska).
On 2 July 1972, responding to a tip by James W. Brooks (personal
communication), M. E. Isleib and I anchored at Fish Island in the
Wooded Islands. We did not locate any storm-petrel burrows, but a
steady flow of storm-petrels passed over the boat throughout the
darkest part of the night. Surveys conducted at about that time
provided an estimate of 19,000 fork-tailed storm-petrels in Prince
William Sound, primarily in or close to Montague Strait, and in
coastal waters on the east side of the Sound's outer islands. In this
area Isleib (personal communication) has noted a general movement
of fork-tailed storm-petrels westward around Montague Island and
into Prince William Sound through Montague Strait each morning and a
corresponding countermovement each evening. I conclude that in 1972
there was a Class IV colony in the Wooded Islands, numbering between
19,000 and 38,000 birds. Additional colonies will be discovered in a
similar manner as more systematic searches are made.
No colonies were discovered during the 1973 reconnaissance survey of
the islands south of Alaska Peninsula. Working primarily inshore, FWS
investigators encountered very few storm-petrels during the day. On
the night of 14 June, the FWS vessel, _Aleutian Tern_, responded to
a Mayday call and was either in transit or participating in rescue
operations from 2245 to 0420 h on the morning of 15 June. During
this period numerous fork-tailed storm-petrels were encountered,
particularly off Cape Wedge on Nagai Island. After we anchored in Eagle
Harbor on Nagai, more storm-petrels were heard about the vessel.
At about this same date, National Marine Fisheries Service enforcement
officers flying fisheries patrols observed storm-petrels in abundance
south of the Shumagin Islands (James Branson, personal communication).
These observations support the belief that there are probably
substantial undiscovered colonies in the Shumagin Islands.
Fork-tailed storm-petrels are abundant summer residents in the northern
Gulf of Alaska and the estimate by Isleib and Kessel (1973) is that
populations using the waters off the North Gulf Coast probably number
in the millions. Certainly the same estimate is valid for the rest of
the Gulf area west of the Chugach Islands.
The status of these birds relative to their historical abundance
cannot be derived from the existing information. There is strong
suspicion that the introduction of fox on many of the islands in the
area during the early part of this century probably caused a reduction
in their numbers. Murie (1959) said that experience taught him that
wings left from fox kills or remains of storm-petrels in fox droppings
could be accepted as evidence of the presence of a colony. Gabrielson
and Lincoln (1959) reported that E. P. Walker visited the Wooded
Islands in 1922 searching for a storm-petrel colony that had been
reported to exist there in 1918. He could not find it even though he
searched diligently. This apparent disappearance was attributed to the
introduction of fox.
There is another factor to consider, however. The limited number of
specimens now available from the Gulf of Alaska indicates that separate
subspecies occupy the eastern and western Gulf of Alaska. The accepted
boundary is somewhere in the vicinity of Prince William Sound. This
is an indication that there has been a hiatus in this area of rather
long duration. I have speculated that this sort of break may be in
some way related to the length of day and a period during the summer
when there is little darkness to cover activities near the colony.
Thoresen (1964) and Cody (1973) have both reported that western gulls
_(Larus occidentalis)_ assemble in Cassin's auklet colonies on moonlit
nights to prey on arriving adults. It is likely that other nocturnal
species would provoke the same sort of hunting tactic. A light-related
predation factor implies that the predators rely on sight. Avian
predators are indicated.
Leach's Storm-petrel _(Oceanodroma leucorhoa)_
Even less well understood than the breeding distribution of the
fork-tailed storm-petrel is that of Leach's storm-petrel.
Bendire (1895) quotes notes from Chase Littlejohn, who found
Leach's storm-petrel to be an abundant breeder on unspecified small
islands near Sanak in 1894. It greatly outnumbered the fork-tailed
storm-petrel. On his visit in 1937 Murie (1959) learned that all of the
large colonies of seabirds that had once existed there were gone. He
attributed this to overfishing and associated perturbation and to the
introduction of fox. No systematic assessment of seabirds on Sanak has
been attempted since Littlejohn's time.
No Leach's storm-petrel colonies have been encountered during
reconnaissance surveys of the Gulf of Alaska. Small numbers have been
reported from time to time and while it is very much less abundant
than the fork-tailed storm-petrel, I expect that it will be found
in small numbers at various places in the Gulf of Alaska when it
becomes possible to make more thorough searches. It may occur in
remote areas like the smaller islands scattered throughout the Sandman
Reefs--possibly even in large numbers. On the basis of the Sanak
record, we must assume that this storm-petrel has been greatly reduced
in numbers, at least in the western portion of the Gulf.
Double-crested Cormorant _(Phalacrocorax auritus)_
The white-crested cormorant, the race of the double-crested cormorant
residing in the Gulf of Alaska, is principally an inhabitant of the
marine environment. This cormorant is a common, but apparently patchily
distributed, resident throughout the northern and western Gulf of
Alaska.
Gabrielson and Lincoln (1959) thought that it nested only from Kodiak
Island westward into the Aleutians. However, it probably breeds from
Yakutat Bay westward. Isleib and Kessel (1973) estimated the abundance
of the double-crested cormorant along the North Gulf Coast as several
thousands, about one-tenth as common as the pelagic cormorant. It is
the third most abundant of the four cormorant species nesting in the
area. It occurs as scattered inclusions in many colonies throughout
the area, and at least in the Shumagin Islands, even occurs in some
colonies by itself.
There are no data on which to base an estimate of any change in status.
It probably is not much affected by many of the naturally occurring
perturbations.
Brandt's Cormorant _(Phalacrocorax penicillatus)_
On 22 July 1972, 13 Brandt's cormorants (4 sitting on nests) were
found at Seal Rocks in Hinchinbrook Entrance, Prince William Sound
(Isleib and Kessel 1973). Two years later I positively identified two
individuals in breeding plumage among a mixed group of cormorants in
the Chiswell Islands west of Seward. Are these recent range extensions?
Possibly, but I propose an alternative explanation.
Palmer (1962) showed the distribution of this cormorant as breeding
north to Puget Sound and as a straggler north to Forrester Island,
Alaska. This viewpoint is shared by the American Ornithologists' Union
(1957), which regards the bird as casual as far north as Forrester
Island, where this species was collected by Willet (1918).
Let us look at the other record, the one that is not supported by
specimens. Bent (1964) thought of Brandt's cormorant as a breeding
resident of Forrester Island. Gabrielson and Lincoln (1959) admonished
bird observers to be on the lookout for this particular cormorant
in the vicinity of Ketchikan and Prince of Wales Island. Brandt's
cormorant also appears on the bird list for the Kodiak National
Wildlife Refuge as an accidental visitor.
Early observers like Bent were explorers. They carefully examined and
made notes on all the birds they saw because there was always a chance
of a new discovery. It is also very probable that Bent paid particular
attention to the cormorants when he was at a place like Forrester
Island. He would have undoubtedly been very interested in trying
to confirm the presence of the now extinct Palla's cormorant _(P.
perspiculatus)_, as he must have been aware of Schlegel's (1862-64)
list of the birds in the Dresden Museum since Willet (1914) had
recently referred to it. The staffs for the Kodiak and Aleutian Islands
National Wildlife refuges have included some very careful observers,
such as Frank Beals. These men would have noticed the difference if a
new bird such as Brandt's cormorant was seen, verified the sighting
visually, and then noted it in their field diaries. They would not
have bothered to develop the type of proof needed for an undisputable
record, but the bird would have appeared in the refuge bird list (as it
does).
The outside coasts of the Alexander Archipelago, Kenai Peninsula,
and the Islands of the Kodiak Archipelago impose some logistical
requirements which discourage all but the most determined birders. Not
many have been able to reach more than very limited segments of the
entire coast. Given the vast distances involved, few of the FWS vessels
passing through the area have had the time to thoroughly examine any
cormorant colonies or roosts bird by bird. Even for those who pause,
the ever present swells and the constant chop of the summer westerlies
make positive identification difficult.
It is possible that Brandt's cormorant has been in the area in small
numbers for a long time, either regularly or intermittently. It could
have escaped observation because of the conditions described above.
This species may be there as a relict, as a pioneer, or only because
surplus birds are being pushed into marginal habitat by population
pressures on their main range to the south.
Pelagic Cormorant _(Phalacrocorax pelagicus)_
The pelagic cormorant is the most abundant of the four cormorants
residing in the Gulf of Alaska. It is found throughout coastal Alaska
south of the Bering Strait and even in some colonies in the southern
Chukchi Sea.
Cormorants have a certain invisibility which is brought about by their
universal presence. This blindness appears to have affected everyone,
even the earliest observers.
The earliest accounts provide a composite picture of the distribution
and abundance of the pelagic cormorant which is very similar to that
encountered today. In southeastern Alaska, beginning at the eastern
edge of the area under discussion, the pelagic cormorant was pictured
as the sole resident cormorant. However, we know from Willet's
collection of a Brandt's cormorant at Forrester Island that this might
not be quite true. From Yakutat Bay westward into the Aleutians this
species coexisted with the double-crested cormorant. In the Western
Aleutians there is some disagreement, but in general it appears to have
been accepted that the red-faced cormorant occurred there along with
pelagic and possibly double-crested cormorants. In the Bering Sea this
species coexisted with the red-faced cormorant.
A number of recent authors (Gabrielson 1940, 1944; Murie 1959; and
others) have considered the pelagic cormorant to be the most widely
distributed and abundant of the four species found in Alaska. Since the
modern picture fits, in a general way at least, it would be easy to
conclude that the species enjoys an unchanged status. There is just a
faint suggestion that this may not be true.
Dement'ev and Gladkov (1966) refer to a great die-off of pelagic
cormorants referred to earlier, in the Commander Islands. Stejneger
(1885) enlarges on this disaster. It is true that Stejneger visited
these islands a relatively short time after the die-off, but he
reported that even though the pelagic cormorants were increasing,
"people having seen their former multitude think that there is no
comparison between the past and the present." Murie (1959) thought
that the pelagic cormorant, while numerous, was outnumbered by the
red-faced cormorant in the Aleutians. More recently there has been the
rapid eastward expansion of the red-faced cormorant. Although it is not
possible to determine what the real status of the pelagic cormorant is
relative to its past status, I conclude that during this century its
status relative to that of the red-faced cormorant has declined.
Red-faced Cormorant _(Phalacrocorax urile)_
The red-faced cormorant, in spite of superficial similarities to the
pelagic cormorant, just does not look the same to an experienced
observer. However, it would have been possible for inexperienced
observers in the days before modern optics to overlook the differences.
The problem was further compounded by the "invisibility" of the
ubiquitous cormorants referred to earlier. Apparent absences or blank
spots in their range may not have been real.
Dement'ev and Gladkov (1966), reporting on the Russian record, stated
that the red-faced cormorant was common in the Commander Islands during
the last part of the 19th century and into the early part of the 20th.
Older authors had also reported it from Kamchatka and the Kurile
Islands. Now, according to Dement'ev and Gladkov, it is an uncommon
breeder on Mednyi Island in the Commander Islands and occurs only as an
autumn visitor to some of the southern Kurile Islands.
Turner (1885) reported that the double-crested cormorant was abundant
in the Near Islands and that the pelagic cormorant was common, but
makes no reference to the red-faced cormorant. One specimen of the
latter in the Leningrad Academy of Science was taken at Attu on 16
September 1844 (Gabrielson and Lincoln 1959), which indicates that
they were probably present during the period reported on by Turner
and, therefore, relatively uncommon. Clark (1911) identified red-faced
cormorants only a few times and in the Aleutians only once, near
Agattu. Dall (1874) noted two red-faced cormorants collected at
Amchitka but he (Dall 1873) apparently did not see any east of Unalaska.
Nelson (1887) apparently found red-faced cormorants breeding on the
Siberian and Alaskan mainlands at either side of Bering Strait, but
Bailey (1948) searched for some sign of their presence and found
none. Nelson (1887) also reported the red-faced cormorant from St.
Matthew and St. Lawrence islands in the northern Bering Sea and from
St. Michael and Nelson Island on the Alaskan coast. Gabrielson and
Lincoln (1959) pointed out that it has not been found breeding north
of the Pribilofs since then. Friedmann (1934) provides support for
Nelson by reporting red-faced cormorant bones from archeological sites
on St. Lawrence. Gabrielson and Lincoln (1959) cited two red-faced
cormorants in the Leningrad Academy of Science which were collected in
the Pribilofs in 1843. Dall and Bannister (1869) reported them to be
plentiful on St. George Island. Baird (1869) also noted their presence
in the Pribilofs.
Bent (1964) makes no mention of seeing the red-faced cormorant in the
Aleutians. He gives their breeding range as the Bering Sea region, the
Pribilof Islands, and perhaps the western Aleutians, the Commander
Islands, and the coast of Siberia north of North Cape. The American
Ornithologists' Union (1931) gave their breeding range as the Pribilof
Islands, the Commander Islands, and Siberia north to North Cape.
Murie (1959) found a colony of between 4,000 and 5,000 red-faced
cormorants nesting on Amak Island in 1925. In 1936 he was surprised
to find that the red-faced cormorant was the most abundant breeding
cormorant in the Aleutian Islands. Pelagic cormorants still appeared
to be most numerous, but there were large numbers of nonbreeding birds.
In 1936 he located "a good sized colony" of red-faced cormorants at
Unga in the Shumagin Islands. He found about 300 birds starting their
nests on 16 May.
In August 1946 Gabrielson (Gabrielson and Lincoln 1959) visited the
colony at Delarof Harbor, Unga, where several thousand cormorants
were observed. From a number of small samples he estimated that the
red-faced cormorants outnumbered pelagic cormorants five to two.
In 1973 I observed about 2,000 cormorants, mostly red-faced, in
this colony. Gabrielson also located them at two other sites in the
Shumagins and at Aghiyuk Island in the Semidi Islands.
Howell (1948) noted only double-crested cormorants at Double Island,
Kodiak. Shortly after that the leaflet, _Birds of the Kodiak Island
National Wildlife Refuge_ (first issued in 1955), listed red-faced
cormorants as common summer residents. The red-faced cormorant was next
found at Katchemak Bay about 1963. Isleib (Isleib and Kessel 1973)
first noticed red-faced cormorants wintering in Prince William Sound
in 1969. In July 1972 Isleib and Sowl had found a colony containing
75 nests at Point Elrington at the western approach to Prince William
Sound. By 1974 Isleib and Haddock (unpublished data, FWS, Anchorage,
Alaska) found them east of the Copper River Delta at Wingham Island.
The relatively rapid expansion of the range and apparent population
size of the red-faced cormorant is remarkable. But has this been a
real expansion into vast stretches of new territory? The record in the
literature which I have summarized shows, I think, something else.
We can demonstrate a historical range for the red-faced cormorant
that extends on the Asiatic Coast from North Cape, Siberia, south to
the Kurile Islands, the entire Aleutian Arc including the Commander
Islands, all the Bering Sea islands north to Bering Strait, Norton
Sound, Nelson Island, and the islands south of the Alaska Peninsula at
least as far east as Kodiak Island. The recently occupied coast from
Cook Inlet to the Copper River may represent a real range extension.
The breeding range of this species at the present time does not include
parts of its historical range west of the Commander Islands or north of
the Pribilof Islands.
The fragmentary record appears to show a long-term perturbation in the
range and populations of the red-faced cormorant that covers at least
100 years. I believe that we are probably seeing a recovery of lost
range and a return to something resembling a former distribution and
abundance.
What caused the perturbation? I am not prepared to answer this
question, but there are two occurrences which I find suggestive.
It is interesting to note (Dement'ev and Gladkov 1966) that on the
Commander Islands the red-faced cormorant was most abundant during the
first 50-odd years after the pelagic cormorants had been wiped out
in the winter of 1876-77. Perhaps some clues are to be found in the
interactions between these similar species.
It does not appear that the introduction of fox could have been a
causative factor. The first observations of population expansion were
noted almost concurrently with the heyday of the fox-farming industry.
Because of its choice of nesting habitat (very steep cliffs), this
cormorant would not have been affected by predators except for the one
that went into a very rapid population decline at a time that would
fit--the Aleut.
Jochelson (1968) and Hrdlicka (1945) summarized references to Aleut
clothing in the diaries and reports of early Russian visitors to
the Aleutian Islands. Evidently Aleut women sometimes wore a long,
robe-like parka made of harbor seal _(Phoca vitulina)_ skins or, for
women of high rank, parkas made of sea otter _(Enhydra lutra)_. The men
in almost all reports were said to have worn bird-skin parkas; puffins
and guillemots appear to have been preferred, but cormorants were
sometimes used. It took about 40 puffin skins to fabricate a parka and
a man evidently needed from one to three of these garments each year.
Sea otter populations were drastically reduced by Russian hunters. Rats
were introduced to the Aleutians very early during the Russian period
and must have had a substantial impact on populations of tufted puffins
and guillemots. The introduction of fox would have had a further impact
on burrow-nesting birds. Turner (1885) noted that Aleuts in the Near
Islands kept the fox confined to Attu so that they could keep the fox
away from the birds on Agattu. This is evidence of an Aleut recognition
of serious competition. Could cormorants, particularly red-faced
cormorants, have been preferred sources of fiber? Were Aleuts forced to
rely more heavily on cormorant skins as puffin and guillemot numbers
were reduced by rats and fox and sea otters by men?
Whatever the cause and effect, the status of red-faced cormorants now
appears to be better in the Gulf of Alaska than for at least the last
100 years.
Glaucous-winged Gull _(Larus glaucescens)_
The glaucous-winged gull is apparently one of the more successful
seabirds breeding in the Gulf of Alaska. While it is outnumbered (both
locally and in total abundance) by the black-legged kittiwake, it is
generally the most commonly seen and most uniformly distributed gull
in the Gulf of Alaska. Murie (1959) called it the common breeding gull
about the Alaska Peninsula. Cahalane (1943, 1944) considered it to be
numerous to abundant around Kodiak and in the Shelikoff Strait area.
Gabrielson (1944) reported that it could be seen in small numbers
everywhere. Most recently, Isleib and Kessel (1973) reported it to be
an abundant resident in the north Gulf Coast area. My own experience
would confirm these observations.
This gull appears to use a wider variety of nesting sites than some
others (Gabrielson and Lincoln 1959). Except where man's activities
have created new food sources, there appears to be a close link
between the location of glaucous-winged gull colonies and those of
murres, kittiwakes, and cormorants. Swartz (1966) found that during
the breeding season glaucous-winged gulls at Cape Thompson derived
almost all of their food from murre eggs and chicks. I have noted
small numbers of these gulls nesting, usually on turf near the tops of
cliffs, in most colonies of favored prey species.
The glaucous-winged gull is the principal scavenger throughout much
of coastal south-central Alaska. This has sometimes resulted in the
development of large concentrations near canneries and, more recently,
near dumps.
Two glaucous-winged gull concentrations stand out in the northern
Gulf of Alaska. One of these is on Egg Island at the western end of
the Copper River Delta. Patten (1976) estimated that this colony
contained 10,000-12,000 gulls in 1975. At times it appears to spread
onto nearby Hinchinbrook Island. M. E. Isleib (personal communication)
has estimated its size as high as 25,000 gulls. The other large
concentration is on the Susitna Flats across Cook Inlet from Anchorage.
This colony, or colony cluster, may be larger than the one at Egg
Island. There are no other known colonies even approaching these in
size. Most colonies range between a few pairs and 2,000-3,000.
Glaucous-winged gulls do not appear to have had any great changes
in population that can be detected from the literature. There have
almost certainly been local fluctuations in the number of breeding
birds as food supplies, such as canneries and dumps, have appeared
or disappeared in an area. Long-term changes in salmon runs have
undoubtedly had an impact as well. One other change, the reduced
level of egging, has undoubtedly had an effect also. Along the Alaska
Peninsula and in the Shumagin Islands, cannery workers of Filipino
heritage and fishermen who have a strong Aleut heritage still harvest
gull eggs for food. However, this activity is much reduced from what it
must have been.
Herring Gull _(Larus argentatus)_
The herring gull is a resident of Upper Cook Inlet and is found up and
down the coast from Prince William Sound to the Alaska Peninsula. Not
too much was learned about it during the recent FWS reconnaissance.
Williamson and Peyton (1963) reported the interbreeding of herring
gulls and glaucous-winged gulls in this area. This interbreeding has
resulted in a situation in which assignment of these gulls to one group
or another in the field can be rather arbitrary. The result has most
often been that field observers tend to lump them with glaucous-winged
gulls unless their herring gull characteristics are obvious. Specimens
collected by Williamson and Peyton (1963) indicate that herring gulls
have the edge in numbers in Upper Cook Inlet.
Black-legged Kittiwake _(Rissa tridactyla)_
The black-legged kittiwake is the most abundant gull in the northern
and western Gulf of Alaska. Colonies of this species can be found
throughout the entire area, and range in size from a few pairs
(Class I) to more than 100,000 birds (Class V). They may be found in
essentially pure colonies, but are often found sharing colonies with
murres.
The center of abundance for breeding black-legged kittiwakes in the
Gulf of Alaska is in the Semidi Islands, where Palmer Sekora (U.S.
Bureau of Sport Fisheries and Wildlife 1973) estimated that there were
426,000 breeding kittiwakes in 1972. He located kittiwake colonies at
eight sites, ranging in size from 1,000 to 109,000 nesting birds. The
size of the average colonial site was 27,000 birds. Ten sites were
Class IV in size and one was a solid Class V.
The easternmost known colony in the northern Gulf of Alaska is at
Wingham Island. Up to 1973, 22 colonies had been located in Prince
William Sound. The largest of these contained only 5,636 nests in 1972
(Isleib and Kessel 1973). Class IV or larger colonies are found at
Cape Resurrection, the Barren Islands, Chisik Island, Boulder Bay and
Cape Chiniak on Kodiak Island, and at Delarof Harbor and the Haystacks
in the Shumagin Islands. It is interesting to note that Gabrielson
(1940) considered Whale Island to be one of the largest known kittiwake
colonies in Alaska. He stated that there were many thousands of pairs
extending over a mile or more of cliff. He saw a second site which he
did not visit but looked equally large. A photograph in an article
by East (1943) also indicated the presence of a large colony. C. J.
Lensink (personal communication) estimated that there were about
100,000 kittiwakes in the colony in 1956. When last visited by Vernon
Berns (personal communication), this colony contained only 3,000 birds.
It is also of interest that Gabrielson (1940, 1944) did not notice
either the kittiwakes or the murres now breeding on Nord Island in the
Barren Islands or the kittiwakes on East Amatuli Island.
Whale Island and possibly the colonies in the Barren Islands give
evidence of local population fluctuations, but for the most part I have
not found an indication of a major perturbation over the past 40 years.
Before 1936, the record is too fragmentary to allow an assessment.
One of the interesting aspects of kittiwake ecology in the Gulf of
Alaska is the common occurrence of breeding failure. David Snarski
(December 1943 Quarterly Progress Report, Alaska Cooperative Wildlife
Research Unit, University of Alaska) observed breeding failure on
colonies in the Tuxedni National Wildlife Refuge in 1970 and 1971 and
obtained circumstantial evidence of another failure in 1972. In 1973
all of the breeding cliffs were occupied and nesting was successful.
Whatever the cause of these periodic failures, they do not yet appear
to have had a permanent impact that we are able to measure.
Red-legged Kittiwake _(Rissa brevirostris)_
Red-legged kittiwakes are not now known to breed in the western Gulf
of Alaska. Turner (1886) stated that he saw a few at Sanak in 1878. We
also have Stejneger's (1885) statement, that "red-legged" kittiwakes
nest from Bering Island to Sanak. Friedmann (1937) reported two
humeri from Kodiak Island middens. During the summer of 1976, two
birds were observed off Kodiak Island by Irving M. Warner (personal
communication), and one at 158°W and 54°30'-54°20'N south and east of
the Shumagin Islands (Patrick J. Gould, personal communication).
Turner (1885) listed the red-legged kittiwake as abundant and breeding
in the Near Islands. Turner (1886) also stated that he had seen quite a
number about a cliff back of the village on Akutan Island in 1878. He
added that to the westward this kittiwake was more abundant than the
black-legged kittiwake. Murie (1959) expressed the opinion that Turner
had confused the short-billed gull with the "short-billed" kittiwake.
Clark (1911) also reported that he had seen the red-legged kittiwake
in small numbers near Unalaska and that they became progressively
more common west to the Near Islands. Nelson (1887) reported seeing
large numbers of red-legged kittiwakes at Unalaska. Murie (1959) and
Gabrielson (1940, 1944) did not see any red-legged kittiwakes in the
Aleutian Islands. The species has recently been discovered breeding at
Buldir and Bogoslof islands (G. Vernon Byrd, personal communication).
Is it possible that we have here another species which is exhibiting a
response to some unknown long-term perturbation? The suggestion that
such an event has occurred is faint, but it is there. Do we have in
the red-legged and black-legged kittiwakes an example of yet another
congener pair that has been affected by some perturbation in which one
was affected positively and the other negatively? Clark (1911) reported
small numbers of black-legged kittiwakes to go with large numbers of
red-legged kittiwakes in the Near Islands, which is the reverse of the
current situation.
Arctic Tern _(Sterna paradisaea)_
Gabrielson and Lincoln (1959) attribute to the Arctic tern the most
extensive range of any Alaskan water bird. It is found in suitable
habitat everywhere north of Tracy Arm in Southeastern Alaska. Murie
(1959) stated that he found it nesting at suitable sites everywhere he
went. Isleib and Kessel (1973) considered it to be an abundant breeder
in Prince William Sound and along the northern Gulf Coast.
The Arctic tern was observed in FWS aerial surveys in Prince William
Sound, and surveys in July and August 1972 provided an estimate of
45,000 terns in the Sound (Isleib and Kessel 1973). On the other hand,
tern colonies were located only rarely in the FWS colony surveys before
1975. This is, however, a reflection of the equipment and methods used
and not of the abundance of terns.
From the fragmentary data available, it is not possible to detect
changes in Arctic tern status at the present time. We have to assume
that the widespread introduction of fox had at least local impact.
Although this tern uses a wide variety of nesting sites, it tends to
nest on flat sites where access by mammalian predators is easy.
Aleutian Tern _(Sterna aleutica)_
No Aleutian tern colonies were discovered in the Gulf of Alaska
area during FWS colony surveys in the early 1970's. This is again a
reflection of the fact that surveys were not designed to locate tern
colonies. Aleutian terns were encountered at least twice, once during
late March 1972 in Hawkins Cutoff, Prince William Sound, and again when
two birds were noted offshore from the Katmai National Monument on 30
May 1973 (L. W. Sowl, personal observations).
The type specimen of the Aleutian tern and a single egg were collected
at Kodiak Island on 12 June 1868 by Bischoff (Coues 1874). Fisher
(Gabrielson and Lincoln 1959) collected four more eggs in 1882. The
bird was not found breeding there until Howell (1948) found a colony
of 50 pairs at Bell's Flats in 1944. Walker (1923) found them nesting
on the Situk River, Yakutat, in 1917 and shortly thereafter saw them
at the Alsek River Flats. He also reported that D. H. Stevenson of
the Bureau of Biological Survey had told him that they nested on the
Isanotski Islands at the end of the Alaska Peninsula. This latter
report was the only one from the Aleutian Island chain for many years.
Isleib and Kessel (1973) considered it an uncommon local breeder in
the northern Gulf of Alaska. Isleib estimated its population at a
few hundred pairs on the Copper River Delta in May 1973 and 300-500
birds in June 1970. He also reported that they appeared more or less
regularly near Controller Bay and off the Situk River.
In recent years Aleutian terns have been seen with increasing frequency
in many places in western Alaska and the Aleutian Islands. This is
probably partly due to the increasing level of field work. At Amchitka
Island the several colonies that have been found in recent years are
almost certainly exhibiting a response to the removal of fox from the
island.
Although there is no way of determining what the past status of the
Aleutian tern has been in the Gulf of Alaska area, it has been there in
small numbers since it was first discovered on Kodiak. It has probably
not been abundant at any time and may have suffered a long-term decline
brought about by the introduction of fox.
Common Murre _(Uria aalge)_
The common murre is resident in the northern and western Gulf of
Alaska from Pinnacle Rock, Kayak Island, westward. East of Cook Inlet
colonies are located at Wingham Island, the Martin Islands, Middleton
Island, Porpoise Rock in Hinchinbrook Entrance, Barwell Island/Cape
Resurrection, the Chiswell Islands, the Barren Islands, and Chisik
Island.
For some reason, the islands of the Kodiak-Afognak Archipelago do not
host any known major murre colonies. There is also a rather large gap
between the Chisik Island colony and the next major colony at Oil
Creek west of Puale Bay. Directly west of Oil Creek is another colony
at Cape Unalishagvak. Both of these latter colonies are Class V and
they are the first colonies of this size to be encountered in the Gulf
of Alaska. West of these colonies the next large colony is at Atkulik
Island. To the south, midway between the last-named colonies, lies the
major composite murre colony in the Semidi Islands. These sites make
up the only Class VI colony in the Gulf of Alaska. Westward, the next
major colony, a Class V, is at Spitz Island south of Mitrofania Island.
In the Shumagin Islands one Class V colony is at Karpa Island, and
lesser colonies with large murre components are found at the Haystacks,
Castle Rock, and Bird Island. Only minor murre colonies are found
between the Shumagin Islands and the end of the Alaska Peninsula.
Gabrielson and Lincoln (1959) were aware only of the colonies at Cape
Resurrection (which Gabrielson considered to be large), at the Chiswell
Islands, and at Chisik Island for the area from Cook Inlet east.
Gabrielson visited the Barren Islands on 13 June 1940 and apparently
did not notice the present murre colonies, both Class IV, at East
Amutuli (an island which he visited) and Nord Island.
Gabrielson (Gabrielson and Lincoln 1959) found a few small colonies
at Kodiak, mostly on small offshore islands. Gabrielson found common
murres to be abundant in the Semidi Islands and stated that there were
no notable colonies in the Shumagins, although on his return to the
Shumagins in 1949 he did find a fairly large colony at the Haystacks.
That size description would fit the colony that is there now. He
obviously did not see the other colonies. Rausch (1958) reported murres
from Middleton Island.
There is quite a difference between the distribution of murres as we
know it today and the way Gabrielson and Lincoln pictured it. Why does
this difference exist? There are two possible answers: either the
number of colonies has increased, or the coverage of colony locations
has improved. The latter case, at least, is established. I must confess
to being puzzled by the way Gabrielson was able to move about close to
what are now known to be sizeable colonies without seeing them, those
in the Barren Islands and the Shumagin Islands in particular. Perhaps
this represents the vague outlines of yet another population change.
The center of abundance for murre distribution in the Gulf of Alaska
today is from Paule Bay west to eastern Shumagin Islands. The Semidi
Islands are the heartland of this area of maximum abundance. We have no
definitive data on species composition of these colonies. Common murres
undoubtedly dominate in most of the colonies; the only ones where we
know of a sizeable thick-billed murre component are in the Shumagin
Islands.
Thick-billed Murre _(Uria lomvia)_
Thick-billed murre population information cannot be separated from that
of the common murre on the basis of existing data. A direct assessment
of present-day status is not possible. After reviewing what we know
about their distribution, I suggest a way to examine the question
indirectly.
The thick-billed murre is found in colonies with the common murre from
Middleton Island westward; Rausch (1958) noted about 400 murres at
Middleton Island and observed that the thick-billed murre outnumbered
the common murre by several times. Isleib and Sowl (FWS, unpublished
data) saw a thick-billed murre mixed with common murres at Porpoise
Rock in July 1972. Isleib and Kessel (1973) expressed the opinion that
small numbers of thick-billed murres will be found in most common murre
colonies in the northern Gulf of Alaska when it is possible to survey
these colonies in detail. Karpa Island had a significant component
of thick-billed murres in June 1973, and they constituted 40% of the
colony at the Haystacks (L. W. Sowl, unpublished data).
Bent (1963) reported that many thick-billed murre eggs have been
taken by collectors at Round Island in the Shumagin Islands. Dall and
Bannister (1869) reported a thick-billed murre that was taken at
Kodiak in 1867.
The Gulf of Alaska is at the periphery of the breeding range of the
thick-billed murre. While it probably occurs in mixed colonies with the
common murre throughout this area, the thick-billed murre is much less
abundant. Occasionally in the Gulf of Alaska, a colony will be occupied
predominantly by the thick-billed murre. Gabrielson and Lincoln (1959)
noted that the thick-billed murre outnumbered the common murre in many
colonies in the Aleutians and that it became progressively more common
at higher latitudes.
We have almost no data relative to the species composition of murre
colonies in the Gulf of Alaska. Until we do it will not be possible to
fully understand the population status of the thick-billed murre. It
appears that changes in the species composition of murre colonies in
the Bering Sea may be an indicator of perturbation. The data for the
Gulf of Alaska are still too fragmentary to provide any indication of
whether or not the same indicator would work there. Close monitoring of
the Shumagin Islands colonies over a number of years might produce the
answer.
Earlier in this paper I noted the dramatic changes in species
composition of murre colonies on Walrus Island. Gabrielson and Lincoln
(1959) also commented on this well-documented and anything but static
situation. Investigators who visited this island during 1976 reported
seeing no murres on the island and only small numbers on offshore
rocks. James Bartonek (personal communication) said that this situation
has prevailed for several years.
There is an indication that a similar population fluctuation and
change in species composition of murre colonies have also occurred on
St. Matthew Island. Bent (1963) found mostly common murres and few
thick-billed murres at St. Matthew. Hanna (1916) saw only thick-billed
murres. Later, Gabrielson (1941) found this to be true in 1940.
Dramatic fluctuation in murre populations may be common and, at least
in some cases, the two species may be affected differently. Perhaps
this phenomenon has potential for providing us with an indicator of
some natural perturbations.
Peterson and Fisher (1955) expressed the opinion that thick-billed
murres arrived at the nesting ledges later than the common murre and
had to take the sites that were left. Tuck (1960) reported data from
the western Atlantic showing that thick-billed murres arrive later than
common murres. On the other hand, Belopol'skii (1961) reported data
showing that the two species arrive on breeding colonies in East Murman
simultaneously. At Cape Thompson, Swartz (1966) found that thick-billed
murres arrived about a week before common murres. The date of arrival,
while perhaps a contributing factor, is probably not decisive.
Interspecific competition of another sort is indicated.
In mixed murre colonies where there are large numbers of common murres,
this species occupies the choice nesting sites. Thick-billed murres are
usually left with the narrower ledges while the common murres occupy
the longer, broader ledges (Belopol'skii 1961). The broader ledges have
lower chick and egg mortality (Spring 1971). Spring also noted that
thick-billed murres are excluded from the centers of mixed colonies.
Johnson (1938) found that this contributes to higher losses of eggs to
predators and to the loss of other social benefits of occupying the
colony center (Johnson 1941).
Kozlova (1961) said that during the occupation of a colony there is
a sharp competitive struggle between the two species. In the end
thick-billed murres are pushed out to the periphery of the colonies
or left with narrow ledges or other equally unfavorable sites. Spring
(1971) studied the functional anatomy of both species and concluded
that the common murre is more successful in these encounters because it
has a more upright gait and greater agility than the thick-billed murre.
It follows that in a portion of their respective ranges, where the
two species overlap and where there is an equal chance that either
common murres or thick-billed murres will dominate a given colony,
the common murre dominates. I conclude from this that where there are
dramatic changes in species composition of murre colonies, such as at
Walrus Island, it is probably because the common murre has been greatly
reduced in numbers at the colony.
Spring (1971) concluded that the common murre is well adapted to
pursuit and capture of pelagic fishes and that the thick-billed murre
is better adapted for deep diving and the capture of benthic fishes
and pelagic and benthic invertebrates. Having greater latitude for
food selection, the thick-billed murre would have a greater tolerance
for ecological perturbations affecting the available food supply. The
common murre has an advantage when pelagic fishes are available but
cannot switch to the other foods as readily as can the thick-billed
murre. The low density of pelagic fishes in high arctic areas probably
also accounts for the greater success of the thick-billed murre at
higher latitudes relative to common murres.
Belopol'skii (1961) presented data from East Murman which indicates
that the common murre restricts its diet almost entirely to a small
number of fish species. Swartz (1966) found strong indications that
there were significant differences in the food preferences of the
two species of murres. Thick-billed murres made much greater use of
invertebrates. Bédard (1976) asserted that it is well known that the
common murre is quite partial to zooplankton. So again the issue is not
clear-cut.
The situation is, of course, much more complex than I have portrayed
it. Nonetheless, I think that it offers potential for use as a tool in
assessing population change and perturbations in the food supply which
should be studied quite closely.
Pigeon Guillemot _(Cepphus columba)_
Gabrielson and Lincoln (1959) noted that the pigeon guillemot was one
of the most regularly observed birds in Alaskan waters. It is found
everywhere throughout the northern and western Gulf of Alaska area,
with only a few understandable and relatively small blanks, such as in
the silty waters of Upper Cook Inlet. Because it obviously lacks the
breeding murres' need for close contact with its nearest neighbors, it
is able to exploit the available nesting habitat to the fullest. It
seems that literally every bit of suitable nesting habitat is normally
occupied.
Because of the dispersed way in which it breeds and because it does
much of its feeding in the onshore zone (which is hazardous for boats)
the pigeon guillemot is an almost impossible species to inventory by
standard methods.
There is no evidence that the pigeon guillemot has been greatly
affected by any major perturbation. Because of its choice of nesting
habitat, it is probably subject to the attack of only one egg predator,
the rat. Because of its loose social structure and the way it selects
nesting sites, eggs and young do not sustain loss from panic flights.
Its dispersed distribution should insure that man-made impacts such as
oil spills will have limited impact.
The population levels of the pigeon guillemot are probably relatively
very stable. The widespread introduction of the rat to most of its
nesting range undoubtedly had impact, but this impact has gone
undocumented. It would be interesting to follow the response of
guillemot populations on islands where rats had been totally removed,
if that ever becomes more than a dream.
Marbeled Murrelet _(Brachyramphus marmoratus)_
The marbled murrelet apparently breeds throughout most of the northern
and western Gulf of Alaska. This apparently is a necessary condition
because to date, at least in this part of Alaska, we can only guess
where and under what conditions this murrelet breeds.
In some relatively sheltered waters like Prince William Sound, where
marbled murrelets were estimated to number about 250,000 in 1972
(Isleib and Kessel 1973), they are the most abundant seabirds. We know
from Dixon (1908) and Grinnell (1910) that this has been so in Prince
William Sound since the beginning of the century. We know also that
the type specimens came from there as well (Stresemann 1949), which is
not necessarily an indication of abundance but is suggestive of their
abundance relative to species not collected.
Gabrielson (Gabrielson and Lincoln 1959) found marbled murrelets common
near Yakutat, in Prince William Sound, in Resurrection Bay, and at
Kodiak, and reported seeing them at the Chiswell Islands and at Chignik
and Pavlof Bay on the Alaska Peninsula. Cahalane (1943, 1944) found
them to be common in Kupreanof Strait, and along the Alaska Peninsula
north of Katmai Bay. Murie (1959) found them all along the Alaska
Peninsula. My own field notes from 1973 indicate that the only place
where they were common along the Alaska Peninsula was at Wide Bay.
We can sample marbled murrelet numbers by using standard transect
methodology; however, I have some very serious reservations about our
ability to convert these data into a population estimate. This is not
an unusual assessment for Alaskan seabirds in general, but I think it
is particularly apropos to this species.
We are still able only to guess at where the marbled murrelet nests and
we have not a clue as to what sort of nesting strategy they pursue. I
am not prepared to accept, on the basis of one North American record
(Binford et al. 1975), that tree nesting is its habit throughout its
range. What has been proved is that the marbled murrelet nests in trees
and not, as these authors would have us believe, that it does not nest
on the ground. It has become rather fashionable to ignore the Chichagof
Island record (a ground nest), but it has not been discredited. The
color of the Chichagof egg differs from that of the Big Basin egg, but
does agree with the one taken from an oviduct by Cantwell (Gabrielson
and Lincoln 1959). My own experience leads me to believe that tree
nesting, if it occurs, is not the common habit of marbled murrelets
nesting in the Prince William Sound region.
After many hours of observing marbled murrelets over a period of
several years, I am intrigued by a number of things. These birds, as
often as not, appear to be clustered in "pairs" as they feed. This
occurs even at what should be the height of the breeding season. On
several occasions I have noted a very pronounced evening flight of
these birds from gathering areas on the water up into the surrounding
mountains at sunset. This has moved me to wonder if their nesting
strategy includes incubating at night but less than full-time
attendance on days when the eggs can be warmed by the sun. We know that
periodic egg-neglect is an aspect of storm-petrel behavior (Pefaur
1974). Is this behavior also possible on a more regular basis in an
alcid? If so, it would certainly help explain why nests are hard to
find.
It is apparent that more needs to be known about the population
dynamics and life history of the marbled murrelet before we can make a
proper estimate of its abundance. In spite of the fragmentary record,
I conclude that the marbled murrelet probably enjoys the same relative
abundance and distribution that it did at the beginning of the century.
Kittlitz's Murrelet _(Brachyramphus brevirostris)_
The Kittlitz's murrelet is not as abundant as the marbled murrelet,
but locally it is sometimes found in large numbers. FWS surveys
conducted during July-August 1972 provide an estimate of 57,000
murrelets of this species in Prince William Sound. Almost a fifth of
these were concentrated in Unakwik Inlet above Unakwik Reef. Even more
interesting, about 2,500 of these birds were concentrated in one loose
flock.
In addition to Unakwik Inlet, Kittlitz's murrelets concentrate in
College Fjord in Prince William Sound and in the waters fronting the
Bering-Malaspina ice-fields (Isleib and Kessel 1973). Common as they
are in these waters, this species is supposed to be even more abundant
at Glacier Bay. The common feature of these waters is the amount of ice
that can be found below their tributary glaciers.
The Kittlitz's murrelet is apparently distributed from LeConte Bay,
east of Petersburg, Alaska, north to Point Barrow and west across the
Aleutians to Attu, where Murie collected a pair (Gabrielson and Lincoln
1959). I once flushed a murrelet from an area of tread and riser
topography near the top of the highest point on Kiska Island in heavy
cloud cover, and although I could not see this bird well, I thought it
to be of this species. From the range description in Gabrielson and
Lincoln (1959) and Udvardy's (1963) range map, it is apparent that
the distribution of this species is rather patchy, but I suspect that
for the more mountainous part of its range this is more apparent than
accurate. The record is too fragmentary to allow an assessment of any
change in status during the historical period.
Ancient Murrelet _(Synthliboramphus antiquus)_
Chase Littlejohn (Bendire 1895) spent the spring and summer of 1894
collecting eggs on islands south of the Alaska Peninsula. He has left
us a detailed record of what he saw but not where he saw it. Bent
(1963) stated flatly that the site of his collecting was Sanak Island
and this has common acceptance. Several things in his account point
to a site which was a small island with several peers close by, but
this could not have been Sanak. It could have been an island in the
Sanak Island group or it could equally well have been somewhere in the
Sandman Reefs. Unfortunately, because of this the record is clouded.
There has never been anything approaching a survey of the southern half
of the Sandman Reefs. We do not know what breeding colonies are there.
At any rate, Littlejohn told of the large numbers of Leach's
storm-petrels, fork-tailed storm-petrels, auklets (of which only
Cassin's is specifically identified), and ancient murrelets which
occupied a large number of small islands. He could not calculate the
number of breeding murrelets on his small island, the size of which I
interpret to have been of the same order of magnitude as two others
which he estimated were about 2 acres. He does say that the murrelets
must have numbered several thousand and could, if left alone by the
Aleuts, have quickly grown too numerous for the island to accommodate.
Murie (1959) made a brief visit to Sanak in 1937 and learned that
there were no longer any large colonies of seabirds. He attributes
this to exploitation of the fisheries and to the fox-farming industry.
Littlejohn told of the repeated visits of Aleuts to his small islands,
where they took hundreds of birds each time and all of the eggs they
could find. This kind of activity could not help but disrupt the
breeding on these islands.
Littlejohn's description of the ancient murrelet's nest leaves little
doubt that the birds could be reached by fox or rats with ease. The
birds showed no particular care in selecting a nest site and often
worked their way back no more than about a meter into the dead
vegetative cover from preceding years, where they scratched out a
shallow nest.
There are few records of the ancient murrelet from the northern and
western Gulf of Alaska. Friedmann (1935) reported the collection of
a series of eggs in 1884 on Kodiak Island. Chase Littlejohn (Bendire
1895) collected eggs from somewhere in the Sanak Group in 1894. In 1908
Dixon (Grinnell 1910) saw a bird in Port Nellie Juan. Several were seen
by Jaques (1930) near Belkofski in May 1928. Gabrielson collected one
bird at Cordova in September 1941 and another at the Chiswell Islands
in July 1945 (Gabrielson and Lincoln 1959). He saw numerous flocks in
the Gulf of Alaska on 30 July of an unnamed year. In 1943, he would
have been near Cape Spencer on that date. In 1945 he would have been
near the Chiswell Islands. In either case, he was probably somewhere in
Blying Sound.
The ancient murrelet is relatively uncommon but regularly observed
in the inshore waters along the outer coasts of the islands fronting
Prince William Sound. FWS surveys in July-August 1972 provided an
estimate of almost 1,000 birds, mostly in nonbreeding plumage, along
the outer coast of Prince William Sound (Isleib and Kessel 1973). Small
numbers were found feeding close to the Wooded Islands on 24 July (my
personal observation). Rausch (1958) saw a few off Middleton Island in
1956. Isleib (Isleib and Kessel 1973) saw 400-500 widely distributed
at the mouth of Yakutat Bay in July and August 1968. The only large
numbers of ancient murrelets encountered on the FWS survey of the
Alaskan Peninsula in 1973 were in the Shumagin Islands. They were very
common in East Nagai Strait on 9 June and more than half of the 1,300
seabirds per square nautical mile encountered between Little Koniuji
and Chernabura Islands on 11 June were ancient murrelets. At Nagai
Island an estimated 5,000 ancient murrelets were observed in the west
bay at Pirate Shake, and later (on 19 June) several were observed in
the vicinity of Midun Island (FWS, Anchorage, Alaska, unpublished data).
On the basis of the observations recounted above, I have to conclude
that ancient murrelets are fairly regularly, if patchily, distributed
throughout the northern and western Gulf of Alaska. I do not believe
that the void in their range shown for the northern Gulf of Alaska
by Udvardy (1963) is correct. Several colonies are there, awaiting
discovery.
Ancient murrelets are not abundant in the Gulf of Alaska but they are
certainly more numerous than we have been able to prove. It is not
possible to tell from the existing data whether they were once more
abundant than they are now. I suspect, on the basis of the Sanak Island
experience, that we can conclude that this species has been reduced in
number by various of man's activities.
Cassin's Auklet _(Ptychoramphus aleuticus)_
Cassin's auklet is a very uncommon bird in the northern Gulf of Alaska.
In the western Gulf it is more common, particularly from the Shumagins
west.
This auklet apparently once bred in great numbers on islands in or near
the Sanak Group where Chase Littlejohn (Bendire 1895) found them to be
twice as numerous as the ancient murrelets. Murie (1959) did not find
them there.
Littlejohn began encountering Cassin's auklets at sea some 290 km
southeast of Unga, Shumagin Islands. Murie (1959) encountered them near
the Shumagins in May 1937. During the FWS 1973 reconnaissance survey of
the Alaska Peninsula, these auklets were not encountered (or at least
not identified) until we reached the vicinity of Unga Strait where we
saw a few in mixed flocks with other murrelets and auklets. They were
most numerous in East Nagai Strait. We encountered them only twice in a
situation which indicated they might be breeding--on Hall and Herendeen
islands on the north end of Little Koniuji Island.
Murie (1959) considered Cassin's auklet to be no longer common west of
Kodiak. In Gabrielson's many voyages through the northern and western
Gulf of Alaska he encountered them only twice, once off Cape Spencer
and once in the Chiswell Islands.
Thoresen (1964) commented that throughout the northern part of its
range the Cassin's auklet has become gradually less frequent. Although
there are no data to dispute this, I believe, as do Isleib and Kessel
(1973), that they are more numerous than observations would indicate,
and I would apply this to the entire area. There are certainly colonies
remaining in the Shumagin Islands, and quite probably along the south
coast of the Kenai Peninsula. When it is possible to fully explore the
Sandman Reefs there is a good probability that they will be found there.
We can only guess at the reasons for their decline. Bendire (1895) and
Murie (1959) have described some contributing factors.
Parakeet Auklet _(Cyclorrhyncus psittacula)_
Gabrielson and Lincoln (1959) described the parakeet auklet as the
least colonial of any of the Alaskan auklets. They also considered the
Aleutian Islands to be its principal nesting grounds. There are old
records of breeding parakeet auklets from Kodiak (Friedmann 1935) and
Little Koniuji (Bean 1882). Grinnell (1910) reported two that were seen
on Green Island, Prince William Sound, and several more that were seen
near Knight Island.
Murie (1959) did not see any parakeet auklets near Kodiak and Afognak
islands which he considered to be the eastern part of their range. He
did not think they were abundant anywhere along the Alaska Peninsula.
He found a few near Sutwik Island in May 1936 and then noted that they
were fairly common near the Shumagins in May 1937.
Gabrielson found this species to be quite numerous on the north side of
Chowiet Island in the Semidi Islands in 1945 (Gabrielson and Lincoln
1959). He also saw numerous individuals in Marmot Strait and saw one in
the Chiswell Islands during the same year. David Roseneau (Isleib and
Kessel 1973) found hundreds close to East Amatuli Island in the Barren
Islands in 1965.
During FWS colony surveys, parakeet auklets have been found in close
proximity to six seabird colonies in Prince William Sound. During the
July-August 1972 surveys, they were estimated to number about 3,000 in
the Sound. They have also been found closely associated with Chisik
Island (David Snarski, personal communication), the Chiswell Islands,
Nord and Sud islands in the Barrens, Sea Otter Island, and Central
and Long islands along the Alaska Peninsula. They were most numerous
in the Shumagin Islands, where they were found near Castle Rock, Hall
(9,000), Herendeen (3,000), Atkins (more than 5,000), and Little
Koniuju islands. They were again encountered south and west of Cold Bay
at High, Fawn, Let, Amagat, Umga, and Patton islands. Many of these
islands are in the north half of the Sandman Reefs, the only portion
where any attempt has been made to survey seabird colonies.
The parakeet auklet may not be abundant anywhere in the Gulf of Alaska
but, based on the numbers of places it has been seen in recent years,
its population appears to be well dispersed and probably doing very
well. This auklet is most abundant from the Shumagin Islands westward.
It is almost certainly more numerous than has been thought. Its habits
are secretive enough so that it could easily escape notice.
Because the parakeet auklet nests predominantly under boulders, it
probably was not much affected by fox. Rats would certainly have
reduced its numbers wherever these were introduced into its breeding
habitat. We have no data to tell us whether there may have been
population fluctuations in the past, but there undoubtedly were at
least minor ones locally after rats were introduced.
Crested Auklet _(Aethia pygmaea)_
Udvardy (1963) shows the breeding range of the crested auklet as
extending from southern Kodiak Island westward. Within the northern and
western Gulf of Alaska, it is certainly most abundant in the eastern
Shumagin Islands.
Isleib saw this auklet in Prince William Sound 3 times during the
winter of 1972-73. These are the only records he was aware of for that
area (Isleib and Kessel 1973). David Roseneau (Isleib and Kessel 1973)
saw several in Amatuli Cove, Barren Islands, in June 1965. I observed
one in the vicinity of Cape Spencer in August 1973.
Friedmann (1935) listed the crested auklet as a breeding bird at
Kodiak, but considered it to be much more abundant as a wintering bird.
Townsend (1913) has provided us with a vivid description of the myriads
of crested auklets he encountered at Yukon Harbor, Little Koniuji
Island. Gabrielson and Lincoln (1959) noted large numbers of crested
auklet around Simeonof and Bird islands in the Shumagin Islands in 1946
and stated that the Yukon Harbor colony was still thriving.
Crested auklets were not encountered on the 1973 FWS reconnaissance
survey until we reached the Shumagin Islands. They were abundant
only at the southeastern end of Little Koniuji, where we encountered
perhaps 10,000 in Yukon Harbor and more than 50,000 in a small cove
directly south of Yukon Harbor on the opposite side of the island. As
numerous as they were, they did not match Townsend's myriads or even
come close to his assessment that they "were here more numerous than
the 'choochkies' at St. George." St. George Island in the Pribilofs is
famous for its least auklets which, in the past, have been estimated to
number as high as 36 million (Peterson and Fisher 1955). The numbers
there today do not even approach this level and we have no way of
knowing how abundant they were when Townsend visited the Pribilofs,
but I think it is safe to say that they probably numbered in the
millions. There are probably more crested auklets than we observed on
Little Koniuji, but there is certainly no longer anything approaching
millions of birds. Properly pronounced, Koniuji is the Aleut name for
the crested auklet, so we can assume that the original inhabitants were
impressed by its numbers.
During the 1973 FWS survey we did not see crested auklets at either
Simeonof or Bird islands. On the overgrazed and cattle-trampled
Simeonof it does not seem possible that any could still exist.
I suspect that a cattleman's greed has been the undoing of any crested
auklets that may have nested on Simeonof Island. This would not account
for the loss of any colonies that may have been on Bird Island, but
the decaying fox-trapper's cabin on that island undoubtedly tells
the story. Churnabura, with its feral cattle, presents much the same
problem as Simeonof. As for Little Koniuji, have horned puffins been
partly responsible for the decrease in crested auklets? The puffin
colony at the south end of Little Koniuji must be exactly where
Townsend's millions of crested auklets once nested.
Least Auklet _(Aethia pusilla)_
No least auklets were encountered in FWS surveys in the Gulf of Alaska
in the early 1970's. Udvardy (1963) shows their breeding range as
starting well west in the Aleutians. Gabrielson and Lincoln (1959) give
the eastern limit of their breeding range as the Shumagin Islands. Bent
(1963) listed their breeding range as extending east to Kodiak Island,
and Friedmann (1935) knew of only a few specimens taken in the winter
from Kodiak. Perhaps least auklets nested somewhere in the western Gulf
of Alaska, and they may still, but at the moment we have no evidence to
prove that they do.
Rhinoceros Auklet _(Cerorhinca monocerata)_
Udvardy (1963) would have us believe that the rhinoceros auklet did not
nest between southeastern Alaska and the southern Kurile Islands. Bent
(1963_b_), on the other hand, lists their breeding range as extending
from Washington to Agattu. Clark (1910) noted this species in small
numbers at Atka and Agattu. Because of the lack of proof, Udvardy
probably had no options. I believe that Bent was probably closer to
describing their original range. I base this assumption on recent
observations and on the additional fragments of information reported by
Gabrielson and Lincoln (1959). Murie (1959) failed to find this species
anywhere in the Aleutians, but his primary reason for being there, the
fox-farming industry, may have had a lot to do with his not being able
to find any.
The FWS surveys in Prince William Sound in July-August 1972 located
small numbers of rhinoceros auklets in breeding plumage at the Wooded
Islands and at Stoney Island and Channel Island in Montague Strait.
These birds gave every impression of being local breeders. David
Roseneau (Isleib and Kessel 1973) encountered two at the Barren Islands
in June 1965. Isleib and Kessel (1973) list a few other records from
this area.
My own experience leads me to believe that there is a large colony
somewhere on Afognak Island, probably on or near Tonki Cape. On 30 May
1973 I noted a lone bird north of Afognak Island. Later, on 8 and 9
August, I saw several in the same area. On 13 August in Marmot Strait I
observed a number of rhinoceros auklets, either singly or in groups of
up to 12. Some of these had small fish in their beaks. As they flushed,
they all flew off toward Tonki Cape. This observation was made just at
last light, and I believe that there were many others about that could
not be seen in the dying light. We did not encounter this species along
the Alaska Peninsula during the FWS survey in 1973 until we reached
the end. There I had one quick glimpse of what I was certain was a
rhinoceros auklet at Amagat Island.
Horned Puffin _(Fratercula corniculata)_
The horned puffin is one of the most abundant breeding birds in the
Gulf of Alaska. There are only a few really large colonies but these
birds breed just about anywhere there is a cliff (even a low one) with
suitable fractures and crevices. During the Alaska Peninsula surveys
in 1973, I estimated that the frequency with which these birds were
seen on the water was about half that of the tufted puffin. They have
been recorded in so many places that there is nothing to be gained by a
reiteration of the record in the literature.
The horned puffins reach their greatest density in the Gulf of Alaska
west of Kodiak Island. Murie (1959) estimated that the colony at Amagat
Island, Morzhovi Bay, contained 15,000 birds, one of the largest he had
seen. It contained at least 50,000 in 1973. Even at that, it was no
match for the colony on Little Koniuji Island with its minimum 140,000
horned puffins. Other colonies with large horned puffin components
were at High Island (40,000), Castle Rock (20,000), Mitrofani Island
(35,000), and Sosbee Bay (15,000).
Earlier in this paper, I commented at length on the great and often
rapid fluctuations in populations of tufted puffins. The same
phenomenon affects horned puffins. In 1975 there were relatively small
numbers of horned puffins at Little Koniuji where they had flourished
2 years earlier (James Bartonek, personal communication). Because they
are apparently subject to erratically oscillating populations, it is
hard to tell how they have fared over the years.
Tufted Puffin _(Lunda cirrhata)_
The tufted puffin, as previously indicated, is also a bird with
widely fluctuating populations. Until we develop an understanding of
their population dynamics and can understand the underlying cause of
these fluctuations it will not be possible to assess trends in their
populations or understand the implications of such trends.
Tufted puffins are abundant throughout the Gulf of Alaska. Small
colonies can be located almost anywhere. Along the Alaska Peninsula
there are a number of colonies with an estimated breeding population
in 1973 of more than 15,000 birds. These are: Ashiiak Island (20,000),
Central Island (90,000), the Brother Islands (45,000), The Haystacks
(19,000), Castle Rock (85,000), Bird Island (none, but may contain
500,000-1,000,000 at times), Peninsula Islands (35,000), the Twins
(18,000), Amagat Island (40,000), and Umga Island (22,000). These
colonies correspond to the area where colonies were listed for the
horned puffin.
Tufted puffin populations respond readily to some undetermined
short-term perturbations. This is clearly demonstrated by their rapid
population fluctuations. Because of their numbers and because of the
apparent rapidity with which their numbers rebound, it is not so
apparent that they have been affected by long-term perturbations, as so
many other seabirds apparently have.
There is much unused or underused nesting habitat suitable for this
species. In some cases there are very strong clues pointing to why this
habitat is vacant. On many islands along the Alaska Peninsula, which
have very good-looking tufted puffin nesting habitat and no puffins,
there are visible signs of the presence of fox--either fox trails or
abandoned trappers' cabins. I also suspect that the brown bear _(Ursa
arctos)_ is another possible contributing factor to population declines
of burrow nesters along this coast. I have seen brown bears swimming
from island to island on foraging expeditions. George J. Divoky
(personal communication) has found brown bears visiting Ugaiushak
Island, which is 13 km from shore. There are other islands between
Ugaiushak and the mainland but the shortest route from shore would
require one swim of 7 km. The motivation must be strong.
Tufted puffins may shift from colony to colony. This could be an
explanation for apparent local population fluctuation, but if so, I
am puzzled by the apparent tenacity with which puffins cling to some
sites. Their constant occupancy of sites where the vegetative mat is
breakaway tundra (Amundsen 1972) or is underlain by sand results in the
destruction of these sites. Tufted puffins often cling to them in spite
of the fact that they have been reduced to "slums."
My conclusion is that in spite of their large numbers it appears that
tufted puffin populations in the Gulf of Alaska probably have been
reduced to a level below that of their undisturbed state.
Conclusions
Seabird numbers in the Gulf of Alaska are not static. Generally, they
are probably much less abundant than they were when Bering made his
voyage of discovery. There are, nonetheless, considerable numbers of
seabirds breeding along the coasts of these waters. Some species show
signs of recovery from past insults by man. With enlightened management
there is still time to preserve the vast natural heritage that they
represent and, in many cases, to improve their status.
In attempting to address a complicated subject in short space and a
relatively narrow frame of reference, I have certainly erred a number
of times. I would like to see the wealth of new data that will be
derived from current work applied to this concept. An understanding
of past population fluctuations and the underlying perturbations that
they reflect is essential for managers faced with the problem of making
good decisions on measures to mitigate the potential adverse impact of
development.
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Status and Distribution of Breeding Seabirds of Southeastern Alaska,
British Columbia, and Washington
by
David A. Manuwal
College of Forest Resources
University of Washington
Seattle, Washington 98195
and
R. Wayne Campbell
Provincial Museum
Victoria, British Columbia, Canada
Abstract
Current breeding seabird population estimates,
nest-site preferences, and population changes
are reviewed for southeastern Alaska,
British Columbia, and Washington. There are
19 species of seabirds and a minimum of
216,566 pairs breeding in British Columbia
and Washington. There are limited data on
breeding populations for southeastern Alaska.
Species diversity ranges from 17 species in
Alaska to 15 species in British Columbia and
14 species in Washington. Eighty percent of
all British Columbia seabirds breed on the
east coast of Queen Charlotte Islands and
the northwest coast of Vancouver Island.
The three most numerous species in British
Columbia are the fork-tailed storm-petrel,
_Oceanodroma furcata_ (31.3%); Cassin's
auklet, _Ptychoramphus aleuticus_ (24.6%); and
ancient murrelet, _Synthliboramphus antiquus_
(12.5%). In Washington, 74% (43,274 pairs) of
the seabird population resides on the Olympic
coast; the remaining 26% are in the San Juan
Island area. About 54% of this population
consists of the common murre _(Uria aalge)_ and
rhinoceros auklet _(Cerorhinca monocerata)_.
The rhinoceros auklet and glaucous-winged gull
_(Larus glaucescens)_ make up 97% of the total
seabird population of the San Juan Islands.
About 68% of all seabirds on the northeastern
Pacific coast are nocturnal, burrow or rock
crevice-nesting species. Currently available
population data are inadequate to determine
significant changes in population density for
most species. Suggested topics for future
research are presented.
The purpose of this paper is to discuss the known distribution,
habitat, abundance, and status of breeding seabirds of the Alexander
Archipelago in southeastern Alaska, the Province of British Columbia,
Canada, and the State of Washington.
Even though several studies of the breeding biology of several
seabird species in this area have been published, there have been few
published surveys of known breeding colonies. In British Columbia the
most extensive work has been done by the British Columbia Provincial
Museum and the University of British Columbia (Drent and Guiguet 1961).
Gabrielson and Lincoln (1959) summarized the available literature
on Alaskan birds up to about 1958. Since then, no extensive surveys
have been conducted in southeastern Alaska. The U.S. Department of
the Interior (1972), in its environmental impact statement for the
Trans-Alaska Pipeline, presented additional information on the seabirds
of other parts of Alaska. In Washington, there are no published
comprehensive surveys except those of Kenyon and Scheffer (1961) and
unpublished surveys by the U.S. Fish and Wildlife Service and the
University of Washington.
Table 1. _Taxonomic distribution of marine birds breeding
along the Pacific Coast of Washington, British Columbia, and
southeastern Alaska._
------------------------------------------------------------------------
Regions
---------------------------------------
British Southeastern Total
Family Common name Washington Columbia Alaska forms
------------------------------------------------------------------------
Hydrobatidae Storm-petrels 2 2 2 2
Phalacrocoracidae Cormorants 3 3 1 3
Haematopodidae Oystercatchers 1 1 1 1
Laridae Gulls and terns 2 2 3 4
Alcidae Auks, murres, puffins 6 7 9 9
Total 14 15 16 19
------------------------------------------------------------------------
Taxonomic Distribution of Marine Birds
There are 19 species of seabirds that breed along the Pacific coast
of southeastern Alaska, British Columbia, and Washington (Table 1).
Southeastern Alaska has the largest number (17) of species. Errors
in species identification are most likely with the Larus gulls,
particularly in southeastern Alaska where the herring gull _(L.
argentatus)_ and glaucous-winged gull _(L. glaucescens)_ breed in mixed
colonies (Patten and Weisbrod 1974). A similar situation exists in
Washington where the western _(L. occidentalis)_ and glaucous-winged
gulls intergrade (Scott 1971). Brandt's _(Phalacrocorax penicillatus)_
and double-crested cormorants _(P. auritus)_ are often difficult to
identify from the air. This would be a problem in Washington and the
southwest coast of Vancouver Island, where the two species are locally
sympatric.
Southeastern Alaska
The area under consideration is the 400-km-long Alexander Archipelago
(Fig. 1). This complex pattern of islands, bays, and inlets is
characterized by extremely high precipitation and typical cool marine
temperatures. Average annual precipitation in the Sitka area is 245.4
cm (1931-60), and the average annual temperature is 6.3°C (U.S. Weather
Bureau 1974). As a consequence of this cool, humid environment, most
of the islands are densely covered with conifers, chiefly Sitka spruce
_(Picea sitkensis)_ and hemlock _(Tsuga heterophylla)_, and an almost
impenetrable shrub cover composed of salmonberry _(Rubus spectabilis)_,
elderberry _(Sambucus callicaipa)_, devil's club _(Echinopanax
horridus)_, and three species of _Vaccinium_ (Heath 1915).
[Illustration: Fig. 1. Map of southeastern Alaska showing major seabird
breeding colonies: 1--North Marble Island; 2--Forrester Island.]
There are 16 species of marine birds breeding in the Alexander
Archipelago. The major seabird breeding colonies are located at Glacier
Bay and at St. Lazaria, Hazy, and Forrester islands (Fig. 1; Table
2). Published surveys of these colonies are available only for St.
Lazaria (Willett 1912) and Forrester islands (Heath 1915; Willett
1915). Several authors have reported on seabirds from surrounding areas
(Grinnell 1897, 1898, 1909; Swarth 1911, 1922, 1936; Patten 1974).
There have been no surveys of seabirds of southeastern Alaska since
before the 1940's (J. G. King, Jr., personal communication). However,
since census data are available for only two colonies, we discuss them
in more detail.
Table 2. _Population estimates of seabirds breeding on St.
Lazaria and Forrester islands, southeastern Alaska_ (data from
Willett 1912 and 1915).
St. Lazaria Island Forrester Island
----------------------------------------------------------------------
Number Percent Number Percent
Bird species of pairs of total of pairs of total
----------------------------------------------------------------------
Fork-tailed storm-petrel 2,000 8.0 10,000 6.0
Leach's storm-petrel 20,000 80.0 50,000 30.0
Pelagic cormorant 150 0.6 150 0.0
Black oystercatcher 4 0.0 50 0.0
Glaucous-winged gull 300 1.2 8,000 4.8
Herring gull 220 0.0
Common murre 300 1.2 20,000 12.0
Pigeon guillemot 150 0.6 300 0.0
Ancient murrelet 20,000 12.0
Cassin's auklet 2,000 1.2
Rhinoceros auklet 75 0.0 20,000 12.0
Horned puffin 12 0.0 1,100 0.7
Tufted puffin 2,000 8.0 35,000 21.0
Total 24,991 166,820
The studies by Willett (1912, 1915) and Heath (1915) provide some
base-line information on species composition and abundance with which
future studies on St. Lazaria and Forrester islands can be compared
(Table 2). The somewhat greater species diversity on Forrester Island
is primarily due to its greater size and more suitable soil type for
ancient murrelets _(Synthliboramphus antiquus)_ and Cassin's auklets
_(Ptychoramphus aleutica)_, species that are absent on St. Lazaria.
Storm-petrels (_Oceanodroma_ spp.) are the most numerous species on
both islands, but there are proportionately more storm-petrels (88%)
on St. Lazaria than on Forrester (36%). On the other hand, there are
many large, burrowing alcids on Forrester Island. Nearly a third of the
birds on Forrester are rhinoceros auklets _(Cerorhinca monocerata)_,
tufted puffins _(Lunda cirrhata)_, and horned puffins _(Fratercula
corniculata)_.
The species composition of seabirds breeding on other islands is
similar to that found on Forrester and St. Lazaria islands but less
abundant. In Glacier Bay, for example, the only population data
available are those provided by Patten (1974) for North Marble
Island: pelagic cormorants, _Phalacrocorax pelagicus_ (30 pairs);
black oystercatchers, _Haematopus bachmani_ (8); herring gulls (7);
glaucous-winged gulls (500); common murres, _Uria aalge_ (18); pigeon
guillemots, _Cepphus columba_ (60); horned puffins (4); and tufted
puffins (30).
At the present time, it is impossible to draw any conclusions about
changes in population density and distribution for most of the seabirds
breeding in southeastern Alaska. Adequate data are available only for
St. Lazaria and Forrester islands where Willet and Heath provided the
only early extensive census data for this part of Alaska.
British Columbia
The rugged British Columbia coastline is characterized by 930 km of
islands and inlets (Figs. 2, 3). With the exception of the inner
southern portion, this coast is mostly uninhabited. The physical
characteristics of the offshore islands are similar to those found off
the Washington coast. Descriptions of some of these islands and the
15 species of breeding seabirds on them have been given by Drent and
Guiguet (1961), Guiguet (1971), and Summers (1974).
A detailed analysis of British Columbia seabirds is not presented here
since a more thorough analysis is in preparation by R. W. Campbell
and R. H. Drent (manuscript). Instead, we present seabird population
estimates available for the Province up to the summer of 1975; Tables 3
and 4 summarize these estimates for the five major portions of coastal
British Columbia. The coast of British Columbia contains a myriad of
small islands where there may be small numbers of breeding seabirds.
Many of these have not been censused and are too numerous to include in
Tables 3 and 4.
[Illustration: Fig. 2. Map of northern British Columbia showing sites
of major seabird breeding colonies: 1--Skedans Island; 2--Limestone
Island; 3--Agglomerate Island; 4--Bischoff Island; 5--Ramsey Island;
6--Alder Island; 7--Rankins Island.]
[Illustration: Fig. 3. Map of southern British Columbia showing sites
of major seabird breeding colonies: 1--Triangle Island; 2--Cleland
Island.]
More than half of the breeding seabirds in British Columbia are found
on the east coast of the Queen Charlotte Islands, and the fork-tailed
storm-petrel _(Oceanodroma furcata)_ comprises more than half of
that total. However, new unpublished data (K. Vermeer) for Triangle
Island and the northwest coast of Vancouver Island indicate that
the population figures in Table 3 for this area are underestimates.
Nevertheless, these two regions have nearly 80% of all the breeding
seabirds in the Province. This results from the very large populations
of the rhinoceros auklet and tufted puffin on Triangle Island and the
fork-tailed storm-petrel, ancient murrelet, and Cassin's auklet on
various islands on the east coast of the Queen Charlotte Islands (Table
3).
Continuing surveys of breeding seabirds are being conducted by
personnel of the British Columbia Provincial Museum and the Canadian
Wildlife Service.
Washington State
_General Environment_
For this report, we have distinguished two major geographical areas in
Washington where breeding seabirds are found--the western coast of the
Olympic Peninsula and the San Juan Islands, including the Strait of
Juan de Fuca.
On the Olympic Peninsula, seabirds breed on the offshore rocks,
islands, and precipitous cliffs from Copalis Beach to Cape Flattery
(Fig. 4). The offshore rocks and islands throughout this area (except
Tatoosh Island) are now included in the Washington Islands National
Wildlife Refuge. Most of the larger rocks and islands have dense
stands of salmonberry, salal, and grasses, and a few support stands of
stunted conifers (Fig. 5); most are inaccessible to man. The adjacent
coast is dominated by the Olympic rain forest where the mean annual
precipitation is about 337.1 cm (U.S. Weather Bureau 1956, 1965_a_,
1965_b_).
Because the San Juan Islands lie northeast of the Olympic Peninsula and
east of Vancouver Island (Fig. 6) they are in a rain shadow; however,
because of highly variable topography and aspect, most islands have a
diverse assemblage of plant communities (Franklin and Dyrness 1973).
Exposed south-facing slopes are occupied by grassland vegetation and
frequently by scattered trees, usually _Pseudotsuga menziesii_ and
_Arbutus menziesii_. Most of the seabird colonies are located on rather
small exposed islands with short, grassy, shrubby vegetation. In
general, these islands are not suitable for burrowing species.
Table 3. _Species composition, population estimates, and
distribution of seabirds in British Columbia._[5][6] (+ =
Present.)
Southwest Northwest West coast
Straits of coast of coast of of Queen
Georgia and Vancouver Vancouver Charlotte
Bird species Juan de Fuca Island Island Island
Fork-tailed storm-petrel + + 1,050
Leach's storm-petrel 10,000 + 1,800
Double-crested cormorant 1,058 0 0 0
Brandt's cormorant 370 0 0
Pelagic cormorant 2,174 336 3,350 1,456
Glaucous-winged gull 10,123 6,870 600 412
Common murre 16 3,000 0
Pigeon guillemot 1,029 204 250 358
Ancient murrelet 0 0 200
Cassin's auklet + 50,000 +
Rhinoceros auklet 1,200 + 10,000
Tufted puffin 1 154 20,000 190
Total 14,385 19,150 77,200 15,466
East coast Prince Rupert
of Queen to Queen Percent
Charlotte Charlotte Total of
Bird species Island Island birds total
Fork-tailed storm-petrel 97,100 + 98,160 31.3
Leach's storm-petrel 180 750 12,730 4.1
Double-crested cormorant 0 0 2,116 >1.0
Brandt's cormorant 0 0 370 >1.0
Pelagic cormorant 496 12 9,998 3.2
Glaucous-winged gull 866 540 29,534 9.4
Common murre 0 0 3,016 1.0
Pigeon guillemot 1,458 1,650 5,978 1.9
Ancient murrelet 42,150 4 42,354 13.5
Cassin's auklet 26,500 450 76,950 4.6
Rhinoceros auklet 300 200 11,700 3.7
Tufted puffin 0 42 20,388 6.5
Total 169,050 3,648 313,294 81.2
Table 4. _Breeding seabird population estimates for British
Columbia_[7][8]
---------------------------------------------------------------------------
Population Percent
Geographic location estimate of total
---------------------------------------------------------------------------
Straits of Georgia and Juan de Fuca 14,385 9.2
Southwest Coast of Vancouver Island 9,575 6.1
Northwest Coast of Vancouver Island 38,600 24.6
West Coast of Queen Charlotte Island 7,733 4.9
East Coast of Queen Charlotte Island 84,530 54.0
Prince Rupert to Queen Charlotte Strait 1,824 1.2
Total 156,647 100.0
[Illustration: Fig. 4. Map of the Olympic Peninsula of Washington State
showing sites of major seabird breeding colonies: 1--Protection Island;
2--Carroll Island; 3--Destruction Island.]
In the Strait of Juan de Fuca, the two most important sites are Smith
and Protection islands. Both are composed of glacial deposits and
heavy sod that has developed under dense grassy vegetation (Fig. 7).
Consequently, these two islands support most of the burrowing seabirds
in the region. Unfortunately, both islands have historically been
subjected to much human disturbance (Richardson 1961; Manuwal 1974).
The existing information on seabird colonies in both the coastal and
San Juan Island areas has been largely derived from aerial surveys by
the U.S. Fish and Wildlife Service. These surveys are inherently biased
toward surface-nesting species such as gulls and cormorants. Population
estimates for guillemots, auklets, storm-petrels, and puffins are
less accurate. Some additional information obtained by direct island
visitation has been provided by Kenyon and Scheffer (1961), Richardson
(1961), Thoresen and Galusha (1971), G. Eddy (unpublished data), and D.
A. Manuwal (unpublished data). Although other accounts of Washington
seabirds are available, the references listed above are specifically
oriented toward population assessment.
_Olympic Peninsula_
Despite the large number of offshore rocks, islets, and islands
along the Pacific coast of Washington, significant seabird colonies
are present only on about 30 islands. Since Table 5 summarizes the
population estimates for 12 species of seabirds breeding on 24 major
sites, it represents only the majority and not the total number of
breeding seabirds on the Pacific coast of Washington. About 74% of the
entire Washington seabird population resides on the coastal rocks and
islands.
Major colony sites with more than 2,500 breeding pairs are Grenville
Arch, Willoughby Rock, Destruction Island, Cake Rock, Carroll Island,
and Bodelteh Island. More intensive censusing, especially of nocturnal
burrowing species will undoubtedly raise the population estimates for
these and other islands off the coast. About 54% of the total coastal
population is composed of the common murre and rhinoceros auklet.
[Illustration: Fig. 5. Photograph of Destruction Island off the coast
of Washington.]
[Illustration: Fig. 6. Map of the San Juan Archipelago showing sites
of major seabird breeding colonies: 1--Viti Rocks; 2--Colville Island;
3--Smith Island.]
_San Juan Islands_
There are about 86 actual or potential seabird colony sites in this
area; 25 (30%) are now considered important. Eleven islands are under
Federal protection as National Wildlife Refuges. Part of Protection
Island is owned by the Washington State Game Department to protect the
largest rhinoceros auklet colony in the State. Most colony sites are
on small islands with poorly developed soil which prevents burrowing
species from using them. Consequently, the dominant species are surface
nesters (such as gulls and cormorants) and rock-crevice nesters (like
the pigeon guillemot). In all, about 31,000 seabirds of 7 species breed
in the San Juan Island area. Breeding seabird population estimates for
49 of the 86 nesting sites are given in Table 6. Even though this does
not represent all the colonies, it covers the most important islands
and those islands where there appears to be potential for seabird
breeding.
[Illustration: Fig. 7. Photograph of Smith Island in the Strait of
Juan de Fuca, Washington. The glacial deposits are evident from the
composition of the cliff faces.]
Table 5. _Estimated breeding seabird populations of the outer
coast of Washington_.[9] (Unpublished data from U.S. Fish and
Wildlife Service and University of Washington)
-----------------------------------------------------------------------
Species
-----------------------------------------------------------------------
Storm-petrels Cormorants
-----------------------------------------------------------------------
Fork- Uniden- Double-
Breeding site tailed Leach's tified crested Brandt's Pelagic
-----------------------------------------------------------------------
Copalis Rock -- -- 15 -- -- --
Point Grenville -- -- -- 60 30 80
Grenville Arch -- -- -- 30 20 --
Flat Rock -- -- 30 -- -- --
Split Rock -- -- -- 100 -- --
Willoughby Rock -- -- -- 80 40 15
South Rock -- -- -- -- -- 40
Abbey Islet -- -- -- -- -- 30
Destruction Island -- -- -- -- -- --
Middle Rock -- -- -- -- -- 25
North Rock -- -- -- -- -- --
Alexander Island -- -- -- -- -- 50
Rounded Island -- -- -- -- -- 25
Giant's Graveyard -- -- -- -- -- 10
Quillayute Needles -- -- -- 50 50 50
James Island -- 30 -- -- -- 40
Cake Rock -- 500 -- -- -- 150
Sealion Rock -- -- -- 70 -- 30
Carroll Island -- 3,100 -- -- -- 100
Ball Rock -- -- -- -- -- 50
White Rock -- -- -- -- -- 100
Ozette Island -- -- -- -- -- --
Bodelteh Island 1,900 -- -- -- -- 100
Tatoosh Island -- 25 -- -- -- 100
Total 1,900 3,655 45 390 140 995
-----------------------------------------------------------------------
-----------------------------------------------------------------
Species
-----------------------------------------------------------------
Gulls
-----------------------------------------------------------------
Black Glaucous-
oyster- winged Common Pigeon
Breeding site catcher Western western murre guillemot
-----------------------------------------------------------------
Copalis Rock -- 30 -- -- --
Point Grenville -- 165 40 1,100 --
Grenville Arch 1 60 -- 3,000 4
Flat Rock -- -- 60 300 --
Split Rock 1 150 -- 2,100 4
Willoughby Rock -- 150 -- 3,000 --
South Rock -- -- 50 -- --
Abbey Islet 3 -- 50 -- --
Destruction Island 12 350 -- -- 25
Middle Rock -- -- 25 -- 50
North Rock -- -- 25 -- --
Alexander Island 5 -- 225 -- --
Rounded Island -- 25 -- -- 1
Giant's Graveyard -- -- -- 150 --
Quillayute Needles -- -- 150 900 --
James Island -- -- 150 750 40
Cake Rock -- -- 600 300 12
Sealion Rock -- -- 250 -- --
Carroll Island 3 -- 550 -- --
Ball Rock 7 -- 150 -- --
White Rock -- -- 75 250 --
Ozette Island 1 -- 15 -- --
Bodelteh Island 2 -- 300 -- 5
Tatoosh Island -- -- 1,500+ 100 20
Total 35 930 4,215 11,950 161
-----------------------------------------------------------------
-------------------------------------------------------
Species
-------------------------------------------------------
Auklets
-------------------------------------------------------
Tufted
Breeding site Cassin's Rhinoceros puffin Total
-------------------------------------------------------
Copalis Rock -- -- -- 45
Point Grenville -- -- -- 1,475
Grenville Arch -- -- 3 3,118
Flat Rock -- -- -- 390
Split Rock -- -- -- 2,355
Willoughby Rock -- -- 25 3,310
South Rock -- -- -- 90
Abbey Islet -- -- 10 93
Destruction Island -- 10,940 350 11,677
Middle Rock -- -- -- 100
North Rock -- -- -- 25
Alexander Island -- -- 1,550 1,830
Rounded Island -- -- -- 51
Giant's Graveyard 50 150 -- 360
Quillayute Needles -- -- 350 1,550
James Island -- -- 20 1,030
Cake Rock -- 50 1,000 2,612
Sealion Rock -- -- 5 355
Carroll Island 25 250 2,400 6,428
Ball Rock -- -- 750 957
White Rock -- -- 100 525
Ozette Island -- -- -- 16
Bodelteh Island -- -- 750 3,057
Tatoosh Island 25? 25? 30 1,825
Total 100 11,415 7,343 43,274
-------------------------------------------------------
Table 6. _Breeding seabird population estimates for the San Juan
Islands and Strait of Juan de Fuca, Washington, 1973-75_.[10]
A: Double-crested
B: Pelagic
C: Black oystercatcher
D: Glaucous-winged gull
E: Pigeon guillemot
F: Rhinoceros auklet
G: Tufted puffin
------------------------------------------------------------------
Species
------------------------------------------------------------------
Cormorants
----------
Breeding site A B C D E F G Total
------------------------------------------------------------------
Bare Island -- 50 1 120 + -- 2 173
Barren Island -- -- -- -- -- -- -- 0
Battleship Island -- -- -- -- -- -- -- 0
Bird Rocks 30 -- + 320 -- -- -- 350
Cactus Island -- -- 1 -- -- -- -- 1
Castle Island -- -- -- -- 30 -- -- 30
Colville Island -- 40 1 1,000 -- -- -- 1,041
Danger Island -- -- -- 125 7 -- -- 132
Decatur Island -- -- -- -- -- -- -- 0
Eliza Island -- -- -- 3 1 -- -- 4
Eliza Rock -- -- -- 1 -- -- -- 1
Flat Top Island -- -- -- -- + -- -- +
Flower Island -- 17 -- 90 -- -- -- 107
Goose Island -- -- -- 60 -- -- -- 60
Gull Rock -- -- + 125 7 -- -- 132
Gull Reef -- -- -- -- -- -- -- 0
Hall Island -- -- 1 275 -- -- -- 276
Harbor Rock -- -- -- -- -- -- -- 0
Iceberg Island -- -- -- -- -- -- -- 0
Johns Island -- -- 1 -- -- -- -- 1
Long Island -- -- 8 80 -- -- -- 88
Low Island -- -- 1 75 17 -- -- 93
Lummi Rocks -- -- -- 4 -- -- -- 4
Matia Island -- -- -- -- + -- -- +
Mummy Rocks -- -- -- 55 -- -- -- 55
Minor Island -- -- -- 100 -- -- -- 100
O'Neal Island -- -- -- -- -- -- -- 0
Patos Island -- -- -- 20 + -- -- 20
North Peapod Island -- -- 1 220 2 -- -- 223
South Peapod Island -- -- 1 75 2 -- -- 78
Pearl Island -- -- -- -- -- -- -- 0
Pointer Island -- -- -- 58 2 -- -- 60
Protection Island 3 110 3 1,500 30 9,200 35 10,881
Puffin Island -- -- 1 350 15 -- -- 366
Ripple Island -- -- -- -- -- -- -- 0
Sentinel Island -- -- -- -- 10 -- -- 10
Sentinel Rock -- -- 1 -- -- -- -- 1
Skip Jack Island -- -- -- 75 20 -- -- 95
Smith Island -- 20 6 10 30 600 -- 666
Speiden Island -- -- -- -- -- -- -- 0
South Sister Island 2 11 1 131 -- -- -- 145
Middle Sister Island -- -- 1 22 -- -- -- 23
North Sister Island -- -- 2 412 3 -- -- 417
Viti Rocks 29 80 1 387 1 -- -- 498
Waldron Island -- -- -- -- 2 -- -- 2
Williamson Rocks -- 67 1 346 2 -- -- 416
Whale Island -- -- 1 70 -- -- -- 71
White Rock -- -- + 125 13 -- -- 138
Yellow Island -- -- -- -- -- -- -- 0
Total per species 64 395 34 6,234 194 9,800 37 16,758
Percent of total
population 0.4 2.3 0.2 37.2 1.2 58.5 0.2 100.0
------------------------------------------------------------------
The major colony sites with more than 250 breeding pairs are located
at Protection and Smith islands, Bird Rocks, Colville Island, Hall
Island, North and South Peapod rocks, Puffin Island, North Sisters,
Viti Rocks, and Williamson Rocks (Fig. 6). Glaucous-winged gulls are
the predominant species on all these islands except Protection and
Smith islands, where there are large colonies of rhinoceros auklets.
Rhinoceros auklets (65%) and glaucous-winged gulls (32%) make up 97% of
the total San Juan Islands seabird population.
Nest-site Preferences
Food supply and availability of nest sites are two critically important
factors influencing the distribution and abundance of seabirds. Whereas
information on general diet composition is known for most seabird
species, we know little about the availability of favored seabird prey.
The dynamics of seabird food chains is reviewed elsewhere in these
proceedings.
The nest-site preferences for seabirds of the northeast Pacific Ocean
are given in Table 7, and Table 8 indicates the proportion of seabirds
that belong to specific nest-site categories. These preferences, in
conjunction with knowledge of the physical characteristics of seabird
habitat, permit a partial explanation of the present distribution and
abundance of seabirds. For example, if we compare the San Juan Island
habitats with those of the Washington coast, it is apparent that
there are more cliff-nesting species on the coast. This reflects the
physical characteristics of the two habitats. There are few cliffs in
the San Juan Islands, and those that exist are very unstable. Colony
sites in the San Juan Islands are typically on low, flat islands.
Glaucous-winged gulls are the most abundant nesting species there.
Coastal islands, on the other hand, are either covered by dense
vegetation or are large monolithic chunks of rock with few available
flat areas. Population estimates for the Washington coast are heavily
biased toward surface nesters, since most of the data have been
gathered by aerial surveys. Consequently, the burrow and rock crevice
categories are underestimated. The aerial survey is appropriate for
only about 43% of the birds nesting on the Washington coast.
Table 7. _Nest-site preference for seabirds breeding from Cape
Fairweather, Alaska, to the Columbia River, Washington._
Nest-site type Bird species
Burrow-rock crevice
Diurnal Pigeon guillemot
Horned puffin
Tufted puffin
Nocturnal Fork-tailed storm-petrel
Leach's storm-petrel
Kittlitz's murrelet
Ancient murrelet
Cassin's auklet
Rhinoceros auklet
Open nests
Flat or slope Double-crested cormorant
Brandt's cormorant
Glaucous-winged gull
Herring gull
Western gull
Black oystercatcher
Cliff face Pelagic cormorant
Common murre
Black-legged kittiwake
Tree branch Marbled murrelet
Northern and southern British Columbia provide another good example of
habitat availability as revealed through seabird population estimates.
The population data are more comprehensive and have largely been
gathered by island visitations. The islands in the northern portion
are heavily vegetated and many have well-developed soil into which
storm-petrels, auklets, and murrelets can burrow. Indeed, 96% of the
seabird population consists of nocturnal, burrow-nesting species. In
southern British Columbia, however, there are more open-nest species,
particularly glaucous-winged gulls and cormorants.
Overall, 68% of the breeding seabirds found along the northeastern
Pacific coast are nocturnal and nest in burrows or rock crevices (Table
8). The most conspicuous nesting birds such as gulls, cormorants, and
murres, comprise only 22% of the total population. Consequently, our
current estimates of breeding seabirds still underestimate the more
secretive, nocturnal, burrow-nesting species.
Table 8. _Proportional nest-site preferences of Pacific coast
seabirds.[11]_
Estimated number of pairs
British Columbia Total
San Juan Washington
Site Northern Southern Islands coast Population
Burrow-rock crevice
Diurnal 1,849 11,334 231 7,504 20,918
Nocturnal 90,347 30,600 9,800 17,070 147,817
Open nests
Flat or slope 909 15,101 6,298 5,755 28,063
Cliff face 982 5,525 395 12,945 19,847
Total 94,087 62,560 16,724 43,274 216,645
Percent of population
British Columbia Total
San Juan Washington
Site Northern Southern Islands coast Percent
Burrow-rock crevice
Diurnal 2.0 18.1 1.4 17.3 9.7
Nocturnal 96.0 48.9 58.6 39.4 68.1
Open nests
Flat or slope 1.0 24.2 37.6 13.3 13.0
Cliff face 1.0 8.8 2.4 30.0 9.2
Population Changes
The available data are inadequate to detect changes in population
distribution and density for most species (Table 9). In Washington,
for instance, limited unsubstantiated information suggests an overall
decline of the double-crested cormorant and tufted puffin in the
San Juan Island area. Likewise, there seems to be an increase in
glaucous-winged gulls there. In British Columbia, Drent and Guiguet
(1961) were able to detect changes in some species. For example, they
noted increases in the double-crested cormorant, pelagic cormorant,
and glaucous-winged gull. No change was observed in the tufted puffin.
Since then, the Brandt's cormorant has established a colony in Barkley
Sound (Guiguet 1971). The data in southeastern Alaska are inadequate
for all species except, perhaps, the Cassin's auklet which Gabrielson
and Lincoln (1959) reported to be declining throughout Alaska. In
short, no definitive statements can now be made concerning changes in
seabird population numbers.
Species Accounts
Fork-tailed Storm-petrel _(Oceanodroma furcata)_
Storm-petrels are especially difficult to census because they are
nocturnal, and the burrows and rock crevices where they breed are
often difficult to locate, especially in mixed-species colonies.
The census data are inadequate to determine whether there have been
changes in population density and distribution. Indeed, the biology of
this species is perhaps the least known of the North Pacific colonial
seabirds. In southeastern Alaska, this species is outnumbered by at
least 5 to 1 by the Leach's storm-petrel _(Oceanodroma leucorhoa)_. The
reasons for this are poorly understood. There is some evidence that the
numbers of breeding fork-tailed storm-petrels on Forrester Island may
fluctuate drastically from one year to the next (Gabrielson and Lincoln
1959).
Leach's Storm-petrel _(Oceanodroma leucorhoa)_
Of the two subspecies of this petrel (_O. l. leucorhoa_ and _O. l.
beali_), only _O. l. beali_ is found in southeastern Alaska. The
_leucorhoa_ subspecies is more northerly in distribution. Where
both fork-tailed and Leach's storm-petrels are sympatric, Leach's
predominates; however, this relationship becomes more unpredictable in
British Columbia and Washington. This species is undoubtedly widespread
in the forested islands of the Alexander Archipelago.
Double-crested Cormorant _(Phalacrocorax auritus)_
The double-crested cormorant apparently does not breed in southeastern
Alaska since Willett (1912), Gabrielson and Lincoln (1959), and S.
Patten (personal communication) do not report breeding colonies
for the area. The largest populations occur in southern British
Columbia principally in the Gulf Islands, where 71% of all breeding
double-crested cormorants are found (Table 10). According to Jewett
et al. (1953), this species was less common in Puget Sound than
was Brandt's cormorant, but is certainly not the case today (D. A.
Manuwal, unpublished data). The only common cormorants in the San Juan
Islands are the pelagic and double-crested species. The double-crested
cormorant seems to have declined in numbers on both coastal and inland
waters. On the basis of his observations, R. W. Campbell believes that
this species is increasing in British Columbia.
Table 9. _Distribution and status of marine birds breeding
along the Pacific coast of Washington, British Columbia, and
southeastern Alaska._ (X = known to breed in the region;? = data
insufficient; + = evidence indicates an overall increase in size
of population; - = evidence indicates an overall decrease in size
of population; 0 = no population change.)
-----------------------------------------------------------------------------
British
Washington Columbia
---------------- ---------------
Family and species Common name Presence Status Presence Status
-----------------------------------------------------------------------------
Hydrobatidae
_Oceanodroma furcata_ Fork-tailed X ? X ?
storm-petrel
_O. leucorhoa_ Leach's storm-petrel X ? X -
Phalacrocoracidae
_Phalacrocorax auritus_ Double-crested X - X -
cormorant
_P. penicillatus_ Brandt's cormorant X ? X 0
_P. pelagicus_ Pelagic cormorant X ? X +
Haematopodidae
_Haematopus bachmani_ Black oystercatcher X ? X +
Laridae
_Larus glaucescens_ Glaucous-winged gull X + X +
_L. occidentalis_ Western gull X ? X ?
_L. argentatus_ Herring gull
_Rissa tridactyla_ Black-legged
kittiwake
Alcidae
_Uria aalge_ Common murre X ? X -
_Cepphus columba_ Pigeon guillemot X ? X +
_Brachyramphus
marmoratus_ Marbled murrelet X ? X ?
_B. brevirostris_ Kittlitz's murrelet
_Synthliboramphus
antiquus_ Ancient murrelet X ?
_Ptychoramphus aleuticus_ Cassin's auklet X ? X ?
_Cerorhinca monocerata_ Rhinoceros auklet X ? X +
_Fratercula corniculata_ Horned puffin
_Lunda cirrhata_ Tufted puffin X - X 0
Total species 14 15
-----------------------------------------------------------------------------
---------------------------------------------------------------------
Southeastern
Alaska
----------------
Family and species Common name Presence Status
---------------------------------------------------------------------
Hydrobatidae
_Oceanodroma furcata_ Fork-tailed X ?
storm-petrel
_O. leucorhoa_ Leach's storm-petrel X ?
Phalacrocoracidae
_Phalacrocorax auritus_ Double-crested
cormorant
_P. penicillatus_ Brandt's cormorant ?
_P. pelagicus_ Pelagic cormorant X ?
Haematopodidae
_Haematopus bachmani_ Black oystercatcher X ?
Laridae
_Larus glaucescens_ Glaucous-winged gull X ?
_L. occidentalis_ Western gull
_L. argentatus_ Herring gull X ?
_Rissa tridactyla_ Black-legged X ?
kittiwake
Alcidae
_Uria aalge_ Common murre X ?
_Cepphus columba_ Pigeon guillemot X ?
_Brachyramphus
marmoratus_ Marbled murrelet X ?
_B. brevirostris_ Kittlitz's murrelet X ?
_Synthliboramphus
antiquus_ Ancient murrelet X ?
_Ptychoramphus aleuticus_ Cassin's auklet X -
_Cerorhinca monocerata_ Rhinoceros auklet X ?
_Fratercula corniculata_ Horned puffin X ?
_Lunda cirrhata_ Tufted puffin X ?
Total species 16
---------------------------------------------------------------------
Brandt's Cormorant _(Phalacrocorax penicillatus)_
Brandt's cormorant is the least abundant of the three cormorant species
that nest in the study area. Washington is at the northernmost edge
of the breeding distribution of this species. Only one more northerly
colony exists, on Sartine Island off Vancouver Island (Vermeer et
al. 1976). Brandt's cormorant comprises about 85% of the cormorant
population in Oregon (U.S. Fish and Wildlife Service, unpublished
data). However, in Washington it is only about 9% and in British
Columbia 3% of the total cormorant population.
Table 10. _Estimated seabird populations breeding
from Cape Fairweather, Alaska, to the Columbia River,
Washington._[12][13][14] (? = present in unknown
numbers; - = inadequate data.)
-----------------------------------------------------------------------------
Northern Southern San Juan Washington Total all
British British Islands coast regions
Columbia Columbia
Bird species Population Population Population Population Population
-----------------------------------------------------------------------------
Fork-tailed
storm-petrel 49,080 ? 0 1,900 50,980
Leach's
storm-petrel 1,365 5,000 0 3,655 10,020
Double-crested
cormorant 0 1,058 64 390 1,512
Brandt's cormorant 0 185 0 140 325
Pelagic cormorant 982 4,017 395 995 6,389
Glaucous-winged gull 909 13,858 6,234 4,215 25,216
Western gull 0 ? 0 930 930
Common murre 0 1,508 0 11,950 13,458
Pigeon guillemot 1,733 1,256 194 161 3,345
Ancient murrelet 21,177 0 0 0 21,177
Cassin's auklet 13,475 25,000 0 100 38,575
Rhinoceros auklet 5,250 6,000 9,800 11,415 27,065
Horned puffin 0 0 0 0 0
Tufted puffin 116 10,078 37 7,343 17,574
Total 94,087 67,960 16,724 43,194 216,566
--------------------------------------------------------------------------
-----------------------------------------------------------------------------
Northern Southern San Juan Washington Total all
British British Islands coast regions
Columbia Columbia
Bird species Percent Percent Percent Percent Percent
-----------------------------------------------------------------------------
Fork-tailed
storm-petrel 52.2 - - 4.4 23.5
Leach's
storm-petrel 1.5 8.0 - 8.5 4.6
Double-crested
cormorant - 1.7 >0.1 >0.1 >0.1
Brandt's cormorant - >0.1 - >0.1 >0.1
Pelagic cormorant 1.0 6.4 2.4 2.3 3.0
Glaucous-winged gull 1.0 22.2 37.3 9.8 11.6
Western gull - - - 2.2 >0.1
Common murre - 2.4 - 27.7 6.2
Pigeon guillemot 1.8 2.0 1.2 >0.1 1.5
Ancient murrelet 22.5 - - - 9.8
Cassin's auklet 14.3 40.0 - >0.1 17.8
Rhinoceros auklet 5.6 >0.1 58.6 26.4 12.5
Horned puffin - - - - -
Tufted puffin >0.1 16.1 >0.1 17.0 8.1
---------------------------------------------------------------------------
Comparing information in Jewett et al. (1953) with the current
situation, it is apparent that there has been a drastic change in the
distribution and probably in the numbers of this species in Washington.
Today, there are no Brandt's cormorant colonies in the San Juan Islands
or Strait of Juan de Fuca. Yet Jewett et al. (1953) reported colonies
at Bellingham Bay and on Lopez and Matia islands. We have observed
juvenile Brandt's cormorants in the San Juan Islands during the summer.
This species may be particularly susceptible to human disturbance,
since all three areas listed above are heavily used in the summer for
recreation.
Pelagic Cormorant _(Phalacrocorax pelagicus)_
The distribution of breeding colonies of the pelagic cormorant is
strongly determined by the availability of the steep cliffs on which it
constructs its nest. This is the only common cormorant in southeastern
Alaska. Throughout its extensive range, this species is generally found
breeding in small numbers. Nothing is known about fluctuations in its
numbers in Alaska.
This species is common in both British Columbia and Washington; nesting
sites are of the same type as those in Alaska except in the San Juan
Islands, where 200-300 birds nest on cliff faces composed of glacial
deposits. Here, there is frequent nest loss due to slippage off the
cliff face; this loss is especially severe on Smith and Protection
islands. There do not appear to be any changes in the distribution
of pelagic cormorants, but an accurate assessment of abundance is
impossible from the data currently available.
Glaucous-winged Gull _(Larus glaucescens)_
The glaucous-winged gull is the characteristic gull of southeastern
Alaska and British Columbia. In Washington, it is the dominant gull
in the San Juan Island area but interbreeds with the western gull on
the Washington outer coast from Tatoosh to Copalis Beach (Scott 1971).
In Alaska, it is widely distributed and locally abundant on Forrester
Island, St. Lazaria, and throughout Glacier Bay (S. Patten, personal
communication). The biology of this species has been extensively
studied in the southern part of its range, especially by Vermeer (1963)
and James-Veitch and Booth (1954). The only study of the breeding
biology of this species in southeastern Alaska is by Patten (1974) for
Glacier Bay. Glaucous-winged gulls are apparently increasing in British
Columbia (R. W. Campbell, unpublished data) and in Washington (T. R.
Wahl, personal communication). This increase is undoubtedly a result
of the proximity of breeding colonies to garbage dumps and commercial
fishing fleets in both Canada and the United States. Little is known
about changes in populations of gulls in southeastern Alaska.
Western Gull _(Larus occidentalis)_
The western gull is the common breeding gull of the Washington outer
coast; however, there is increased interbreeding with glaucous-winged
gulls northward from Destruction Island to Tatoosh Island. The
percentage of glaucous-winged gulls steadily increases until Vancouver
Island and the Strait of Juan de Fuca, where western gulls are rare.
Population estimates of gulls on the outer coast of Washington are
derived primarily from aerial flights. This makes identification of
gulls difficult, and in view of the amount of interbreeding, it is
probably impossible to classify many of the breeding gulls as to
species. Western gulls appear to be increasing in the Grays Harbor area
(G. D. Alcorn, personal communication).
Herring Gull _(Larus argentatus)_
The herring gull is typically found in inland Alaska but can be found
uncommonly along the coast of southeastern Alaska, where it often forms
mixed colonies with glaucous-winged gulls. These two species apparently
hybridize where they are sympatric (Williamson and Peyton 1963; Patten
and Weisbrod 1974; Patten 1974).
Black-legged Kittiwake _(Rissa tridactyla)_
The black-legged kittiwake is found only in the northern portions of
southeastern Alaska. It apparently is a common breeding bird in Glacier
Bay National Monument (S. M. Patten, Jr., personal communication). No
population estimates are available for this species other than that it
is locally abundant.
Common Murre _(Uria aalge)_
Common murres are common in southeastern Alaska and the coast of
Washington but breed only in small numbers in British Columbia and are
absent in the San Juan Islands. Since this species usually prefers
cliffs or the tops of inaccessible rocks, they are probably limited
by island topography in British Columbia, and are most certainly so
limited in the San Juan and Gulf Island groups.
In Alaska, common murres breed in unknown numbers in Glacier Bay and in
large numbers on St. Lazaria, Forrester, and the Hazy islands. No data
on population changes are available for any of the three regions.
Pigeon Guillemot _(Cepphus columba)_
The pigeon guillemot is common throughout the region from Cape
Fairweather to Washington. Even though it is not truly colonial, it
may be locally abundant where there are suitable nest sites. Since
these nest sites are usually difficult to find, population estimates
are seldom accurate, usually being conservative. It is evident that
guillemots appear to be small in number when compared with other
seabirds nesting at major colony sites in the north Pacific region
(Table 10). This disparity may be exaggerated by the difficulty of
censusing guillemots.
Marbled Murrelet _(Brachyramphus marmoratus)_
Since the marbled murrelet has been found to nest in coniferous forests
(Binford et al. 1975), traditional census techniques are unsuitable.
This species is common in southeastern Alaska (Gabrielson and Lincoln
1959), in British Columbia (Drent and Guiguet 1961), and in Washington
(Jewett et al. 1953).
Kittlitz's Murrelet _(Brachyramphus brevirostris)_
The difficulties in assessing breeding populations of Kittlitz's
murrelet are the same as those for the marbled murrelet. This species
nests on the ground at high elevation near the coast (Bailey 1973).
The largest concentrations are in the vicinity of Glacier Bay National
Monument (Gabrielson and Lincoln 1959). They are not found breeding in
Washington or British Columbia.
Ancient Murrelet _(Synthliboramphus antiquus)_
Ancient murrelets appear to be locally common throughout southeastern
Alaska. Their presence is probably strongly dependent upon a suitable
soil in which to excavate burrows. The only available population
estimates are those by Willett (1915) for Forrester Island (Table 1).
Censusing this species is especially difficult because its burrows are
easily confused with those of Cassin's auklet. There are no studies of
this species in southeastern Alaska; however, it has been well studied
in the Queen Charlotte Islands to the south by Sealy (1975).
Cassin's Auklet _(Ptychoramphus aleuticus)_
A synthesis of literature and unpublished observations led Gabrielson
and Lincoln (1959) to conclude that Cassin's auklet has greatly
decreased in numbers and is not abundant anywhere in Alaska. They
also concluded that the colony on Forrester Island (Table 1) was the
only well-documented colony in southeastern Alaska. Fishermen in the
southeastern Alaska area occasionally see this species (M. E. Isleib,
personal communication), but it is apparently still uncommon though
more widespread than just Forrester Island. The nocturnal habits
and burrowing in dense vegetation makes censusing this species very
difficult. Nothing is known about the ecology of this species in Alaska.
Rhinoceros Auklet _(Cerorhinca monocerata)_
Rhinoceros auklets seem to be found breeding only on islands where
there is a well-developed soil in which to excavate their extensive
burrows. From the limited evidence available, it appears that the
largest rhinoceros auklet populations probably are to be found in
southeastern Alaska. Willett (1912) found a very large population on
Forrester Island (Table 2), and the species has been found in the
summer in the Barren Islands east of Kodiak Island (E. P. Bailey,
personal communication). More intensive surveys of the Alexander
Archipelago will probably reveal other populations of this species.
This species is less common in British Columbia than either Alaska or
Washington. A possible reason for this is lack of suitable nesting
areas. In Washington, the two largest colonies are at Protection Island
in the Strait of Juan de Fuca and Destruction Island on the outer
coast. Smaller numbers exist on other coastal islands and on Smith
Island in the Strait of Juan de Fuca. The Smith Island colony is an
interesting one since it appears that early human disturbance in the
late 19th or early 20th century eliminated the species from the island.
In their discussion of Smith Island, Jewett et al. (1953) made no
mention of auklets, only of puffins and guillemots. Couch (1929) did
not record the species in 1925. The colony now numbers about 600 pairs.
Horned Puffin _(Fratercula corniculata)_
Although the horned puffin is one of the most abundant seabirds in
other parts of Alaska, it is much less abundant in the southeastern
portion. In addition to the information discussed by Sealy (1973),
it now appears that this species may breed as far south as Triangle
Island, British Columbia (K. Vermeer, personal communication; D. A.
Manuwal, personal observation). Here, as on Forrester Island, it is
greatly outnumbered by the tufted puffin. No data are available on the
breeding or status of this species in the study area.
Tufted Puffin _(Lunda cirrhata)_
The tufted puffin is found breeding on scattered islands throughout the
region. The largest known colonies are on Forrester Island, Alaska,
Triangle Island, British Columbia, and Carroll Island, Washington. It
is notably absent from most of the gulf and San Juan Islands. Even
though puffins have apparently never been numerous in the San Juan
Islands, their population has noticeably declined during the past
35 years. For example, Jewett et al. (1953) reported a colony of 50
pairs on Bare Island in 1937, but in 1973 only 2 pairs were counted
(D. A. Manuwal, unpublished data). Likewise, in 1915 there were more
than 250 pairs on Smith Island, but by 1916 there were only 75 pairs
(Jewett et al. 1953). The decline is attributed to rapid erosion of the
glacial-deposit cliffs. There are no puffins on Smith Island today,
and the largest colony in the Puget Sound area is the 35 pairs on
Protection Island (D. A. Manuwal, unpublished data).
Discussion
The total minimum estimate of the breeding seabird populations of
British Columbia and Washington is 216,500 pairs (Table 10). No
comprehensive estimates are available for breeding seabirds of
southeastern Alaska. It is likely, however, that the number of breeding
seabirds in the Alexander Archipelago may be equal to (or exceed)
the populations of both British Columbia and Washington. Data are
desperately needed from that area. Of the total seabird population in
the study area (Table 10) 43% reside in northern British Columbia. The
Washington State population represents 28% of the total. Fork-tailed
storm-petrels comprise almost 25% of all the breeding seabirds in the
area under consideration. The Cassin's auklet is the next most numerous
species (18% of the total).
It is apparent that current data are, for the most part, inadequate
for assessing anything but catastrophic changes in seabird breeding
colonies. This inadequacy is due to inadequate censusing because of
excessive reliance upon aerial surveys; in the past, this has often
been a result of insufficient funding.
Of the several threats facing seabird populations, none may be as
important as oil pollution. A general review of this subject is
presented elsewhere by Vermeer and Vermeer (1975). It is apparent
from this review that the most vulnerable species are those that dive
beneath the sea surface, including all the alcids and cormorants
breeding along the coast that are discussed in this paper. This
group makes up almost 60% of all the breeding seabirds in this area.
Unfortunately, our knowledge of several of these species is scanty and
our current census techniques are unsuitable for most of these birds.
Studies of the changes in seabird numbers have been made in other
oceans. For example, in Great Britain (Bourne 1972_a_, 1972_b_; Harris
1970), eastern Canada (Nettleship 1973), and the Atlantic coast of the
United States (Kadlec and Drury 1968), two major trends seem apparent.
First, there is an overall decline in alcid and tern numbers. The
decline in auks may be due to their extreme vulnerability to oil
pollution (Bourne 1972_a_, 1972_b_; Vermeer and Vermeer 1975). The
Atlantic puffin, however, may be suffering the additional effects of
gull cleptoparasitism (Nettleship 1972). Secondly, there seems to
be an increase in gull populations on both sides of the Atlantic,
particularly the herring gull and black-legged kittiwake.
Compared with the Atlantic coast of North America and northern Europe,
the data base for seabird populations of the Pacific coast is poor.
The fragmentary evidence now available indicates that there may be
small population increases in the western and glaucous-winged gulls
and range extensions of the Brandt's and double-crested cormorants and
of the rhinoceros auklet (Scott et al. 1974). Whether these changes
represent actual population increases or displacements remains unclear.
The remote locations of most of the large Pacific seabird colonies
may provide unofficial protection from human interference. Intensive
surveys are needed to establish base-line inventories in these areas.
As a consequence of this first comprehensive review of the status of
breeding marine birds of the northeast Pacific coast of North America,
we recommend the following future research topics as necessary for the
conservation of this great international resource.
• Seabird colony census techniques should
be refined since almost 68% of the seabirds
in this area are nocturnal and nest in burrows.
The present reliance on aerial censusing,
although economical, is inadequate to
census most breeding seabird populations;
more on-site surveys are needed. For surface-nesting
species and diurnal, burrowing
species, studies on species specific activity
cycles are needed so that census data
can be corrected for birds not observed at
the colony. For nocturnal, burrowing
species seasonal burrow occupancy rates
must be determined so that burrow counts
can be corrected for inactive burrows.
• Comprehensive surveys should be made
every 3-5 years.
• In 1980 a coordinated breeding bird survey
of the entire Pacific coasts of Mexico,
Canada, and the United States should be
conducted.
• Specific islands where key populations
exist should be carefully monitored for
subtle changes in population density or
species composition.
• Increased study of the breeding biology of
seabirds should be carried out so that base-line
reproductive characteristics can be
determined.
• Detailed studies of the effects of human
disturbance should be made, especially for
species that breed near large coastal cities
or marine recreation areas.
References
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75:457.
Binford, L., B. Elliott, and S. Singer. 1975. Discovery of a
nest and the downy young of the marbled murrelet. Wilson Bull.
87:303-319.
Bourne, W. 1972_a_. The decline of auks in Great Britain. Biol.
Conserv. 4:144-146.
Bourne, W. 1972_b_. Threats to seabirds. Int. Counc. Bird Preserv.
Bull. XI:200-218.
Couch, L. 1929. Introduced European rabbits in the San Juan
Islands, Washington. J. Mammal. 10:334-336.
Drent, R. H., and C. Guiguet. 1961. A catalogue of British Columbia
seabird colonies. Occas. Pap. B. C. Prov. Mus. 12. 173 pp.
Franklin, J., and C. Dyrness. 1973. Natural vegetation of Oregon
and Washington. U.S. For. Serv. Gen. Tech. Rep. PNW-8. 417 pp.
Gabrielson, I., and F. Lincoln. 1959. The birds of Alaska. The
Stackpole Company, Harrisburg, Penn., and Wildlife Management
Institute, Washington, D.C. 922 pp.
Grinnell, J. 1897. Petrels of Sitka, Alaska. Nidologist 4:76-78.
Grinnell, J. 1898. Summer birds of Sitka, Alaska. Auk 15:122-131.
Grinnell, J. 1909. Birds and mammals of the 1907 Alexander
Expedition to southeastern Alaska. Univ. Calif. Publ. Zool.
5:171-264.
Guiguet, C. 1971. A list of seabird nesting sites in Barkley Sound,
British Columbia. Syesis 4:253-259.
Harris, M. P. 1970. Rates and causes of increases of some British
gull populations. Bird Study 17:325-335.
Heath, H. 1915. Birds observed on Forrester Island, Alaska during
the summer of 1913. Condor 17:20-41.
James-Veitch, E., and E. Booth. 1954. Behavior and life history of
the glaucous-winged gull. Walla Walla Coll., Publ. Biol. 12.
Jewett, S., W. Taylor, W. Shaw, and J. Aldrich. 1953. Birds of
Washington State. Univ. of Washington Press, Seattle. 767 pp.
Kadlec, J., and W. Drury. 1968. Structure of the New England
herring gull population. Ecology 49:644-676.
Kenyon, K., and V. Scheffer. 1961. Wildlife surveys along the
northwest coast of Washington. Murrelet 42:29-37.
Manuwal, D. A. 1974. Conservation notes (Protection Island). Pac.
Seabird Group Bull. 1.
Nettleship, D. 1972. Breeding success of the common puffin
(_Fratercula arctica_ L.) on different habitats at Great Island,
Newfoundland. Ecol. Monogr. 42:239-268.
Nettleship, D. 1973. Tenth census of seabirds in the sanctuaries
of the north shore of the Gulf of St. Lawrence. Can. Field-Nat.
87:395-402.
Patten, S. 1974. Breeding ecology of the glaucous-winged gull
_(Larus glaucescens)_ in Glacier Bay, Alaska. M.S. Thesis. Univ.
of Washington, Seattle. 78 pp.
Patten, S., and A. R. Weisbrod. 1974. Sympatry and interbreeding of
herring and glaucous-winged gulls in southeastern Alaska. Condor
76:343.
Richardson, F. 1961. Breeding biology of the rhinoceros auklet on
Protection Island, Washington. Condor 63:456-473.
Scott, J. M. 1971. Interbreeding of the glaucous-winged gull and
western gull in the Pacific Northwest. Calif. Birds 2:129-133.
Scott, M., W. Hoffman, D. Ainley, and C. Zeillemaker. 1974. Range
expansion and activity patterns in rhinoceros auklets. West.
Birds 5:13-20.
Sealy, S. 1973. Breeding biology of the horned puffin on St.
Lawrence Island, Bering Sea, with zoogeographical notes on the
north Pacific puffins Pac. Sci. 27:99-199.
Sealy, S. 1975. Feeding ecology of the ancient and marbled
murrelets near Langara Island, British Columbia. Can. J. Zool.
53:418-433.
Summers, K. 1974. Seabirds breeding along the east coast of Moresby
Island, Queen Charlotte Islands, British Columbia. Syesis 7:1-12.
Swarth, H. 1911. Birds and mammals of the 1909 Alexander Alaska
Expedition. Univ. Calif. Publ. Zool. 7:9-172.
Swarth, H. 1922. Birds and mammals of the Stikine River Region of
northern British Columbia and southeastern Alaska. Univ. Calif.
Publ. Zool. 24:194-314.
Swarth, H. 1936. Origins of the fauna of the Sitkan District.
Alaska. Proc. Calif. Acad. Sci. Ser. 4, 15:59-78.
Thoresen, A., and J. Galusha. 1971. A nesting population study of
some islands in the Puget Sound area. Murrelet 52:20-23.
U.S. Department of the Interior, Interagency Task Force. 1972.
Environmental setting between Port Valdez, Alaska, and west coast
ports. Final Environmental Impact Statement, Vol. 3.
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States--supplement for 1931 through 1952, Washington.
Climatography of the United States 11-39. 79 pp.
U.S. Weather Bureau, Environmental Data Service. 1965_a_. Climatic
summary of the United States--supplement for 1951 through 1960,
Oregon. Climatography of the United States 86-31. 96 pp.
U.S. Weather Bureau, Environmental Data Service. 1965_b_. Climatic
summary of the United States--supplement for 1951 through 1960,
Washington. Climatography of the United States 86-39. 92 pp.
U.S. Weather Bureau, Environmental Data Service. 1974.
Climatological Data, Alaska Annual Summary 1974, 60:13.
Vermeer, K. 1963. The breeding ecology of the glaucous winged gull
_(Larus glaucescens)_ on Mandarte Island. B.C. Occas. Pap. B.C.
Prov. Mus. 13. 104 pp.
Vermeer, K., D. A. Manuwal, and D. S. Bingham. 1976. Seabirds
and pinnipeds of Sartine Island, Scott Island group, British
Columbia. Murrelet 57(1):14-16.
Vermeer, K., and R. Vermeer. 1975. Oil threat to birds on the
Canadian west coast. Can. Field-Nat. 89:278-298.
Willett, G. 1912. Report of George Willett, Agent and Warden
stationed on St. Lazaria Bird Reservation, Alaska. Bird-lore
14:419-426.
Willett, G. 1915. Summer birds of Forrester Island, Alaska. Condor
19:15-17.
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glaucous-winged and herring gulls in the Cook Inlet region,
Alaska. Condor 65:24-28.
FOOTNOTES:
[5] Data are minimum estimates of pairs and do not include breeding
sites with less than 100 birds.
[6] Does not include the black oystercatcher, marbled murrelet, and
western gull.
[7] Estimates only for colonies of 100 or more birds.
[8] Estimates are in number of pairs.
[9] Estimates are number of pairs.
[10] Estimates are numbers of pairs.
[11] Data for southeastern Alaska were inadequate to enable estimates
of breeding pairs.
[12] Population estimates are minimum and represent numbers of pairs.
[13] Does not include the following species for which population
estimates are lacking: black oystercatcher, herring gull, black-legged
kittiwake, marbled murrelet, Kittlitz's murrelet.
[14] Data for southeastern Alaska were inadequate to enable estimates
of breeding pairs.
THE BIOLOGY AND ECOLOGY OF MARINE BIRDS IN THE NORTH
Trophic Relations of Seabirds in the Northeastern Pacific Ocean and
Bering Sea
by
David G. Ainley
Point Reyes Bird Observatory
Stinson Beach, California 94970
and
Gerald A. Sanger[15]
National Marine Fisheries Service
Marine Mammal Division
Seattle, Washington
Abstract
Literature on the diets of seabirds is reviewed
for 70 species found in five subarctic
oceanographic regions of the northeastern
North Pacific Ocean and Bering Sea. Species
inhabiting estuaries and sheltered bays are
not included. The diets of cormorants, marine
ducks, alcids, and marine raptors are best
known; less information is available for loons,
grebes, petrels, and gulls. Enough is known,
however, to broadly characterize the diet of
each species. Less than 7% of all species feed
on one type of prey, about 60% feed on two or
three types, and the rest feed on four or more
types. Only 12% of all species feed on eight
or more types of prey. Most seabirds (77%)
feed as secondary and tertiary carnivores.
Where overlap in diet exists, seabirds
partition resources through use of different
feeding methods, selection of different-sized
prey, and zonation of habitat. Species that
have specialized diets are probably more
susceptible than others to local environmental
catastrophes. Species whose feeding methods are
highly adapted for exploitation of resources
in polar and subpolar habitats are not adapted
for coping with oil pollution. Competition
between birds and man for marine resources can
sometimes benefit seabirds and at other times
harm them. More research is needed on seabird
feeding relations so that the ecological roles
played by marine birds can be defined and
placed in perspective. Such work should be
conducted at the community level, year-round,
and should be so conducted as to facilitate
comparison with biological oceanographic data.
The ecology, morphology, and much of the behavior of a seabird species
are definable in terms of the food resources it exploits year-round and
the spatial and temporal relations between food and breeding sites.
This general point unifies such important reports as those by Kuroda
(1954), Bédard (1969_a_), Ashmole and Ashmole (1967), Ashmole (1971),
Spring (1971), and Sealy (1972). More concretely, information on
trophic relations of seabirds is useful in several ways. In conjunction
with biological oceanographic data, it can provide insight into
geographic location, marine habitat, depth, time of day, and general
method of food capture by seabirds. Collected over several years, it
can provide a basis for understanding annual differences in seabird
breeding phenology and success. Finally, supplemented with data on how
much seabirds eat and excrete, it is necessary for an understanding
of the energetic and ecological roles played by the birds in the
functioning of marine ecosystems.
Several studies that describe trophic relations within seabird
communities have helped to define the principals of community
organization pertaining to the exploitation of available food resources
and have given clues to food-chain pathways. Trophic relations
have been described for breeding communities in the Barents Sea
(Uspenski 1958; Belopol'skii 1961), in the tropical Pacific Ocean
(Ashmole and Ashmole 1967; Ashmole 1968), in the North Sea (Pearson
1968), and in the Chukchi Sea (Swartz 1966). The last-named study
pertained most directly to the geographic region discussed in this
paper, but several other studies have provided sound information on
segments of communities in the northeastern North Pacific and Bering
Sea. These include the work on three species of auklets (_Aethia_,
_Cyclorrhynchus_) in the Bering Sea (Bédard 1969_a_); investigations
on cormorants and other fish predators in British Columbia by Munro
(1941), Munro and Clemens (1931), and Robertson (1974); studies of
murres in Bristol Bay by Ogi and Tsujita (1973); observations on
several species near the Pribilof Islands by Preble and McAtee (1923);
work on diving species off Oregon by Scott (1973); and studies of
murrelets by Sealy (1975).
A review of available reports reveals three obvious gaps in the
emphasis placed in seabird food studies. First, few studies have ever
considered in detail the trophic relations of seabird communities
during the winter or nonbreeding season. Partial exceptions are the
works by Cottam (1939) and others on marine diving ducks, species that
are seabirds only during the winter, and by several researchers (Munro
and Clemens 1931; Munro 1941; Robertson 1974) on seabirds in British
Columbia. Divoky (1976) studied diets of pack-ice gulls during the
nonbreeding season, but those species are not included in the present
analysis because they rarely are found south of the Bering Strait.
Second, no study has considered the trophic relationships of an entire
seabird community, i.e., not just breeding species but also nonbreeding
species. In the rather broad communities considered here, 50-70% or
more of the birds breed in another part of the world. To say that these
nonbreeding species have no significant impact on resource exploitation
or on organization and evolution among breeding members would be naive.
Finally, few investigators have attempted to fit birds into an entire
ecosystem, including lower trophic level origins as well as fish,
marine mammals, and man.
The reasons for these gaps in study emphasis are readily apparent:
the inconvenience of marine research during the winter when weather
is stormy, the need for costly study platforms (boats), and the
difficulties in organizing the specialized community of biologists
required for such tasks. A less obvious but important reason is that
oceanographers and fishery biologists have overlooked seabirds as
important members of marine ecosystems.
Diets of Seabirds in Western North America
Relatively good information exists for most pelecaniformes of
the region. A notable exception is the brown pelican _(Pelecanus
occidentalis)_, an endangered species. This is unfortunate because
dietary information is important for understanding the species'
ecology. Observations in eastern North America (Palmer 1962) and Peru
(Murphy 1936) indicated that their diet consisted of fish that occur
at the surface. The larger cormorants are piscivorous, particularly
on schooling fishes that occur at moderate to great depths (Table 1).
The smaller cormorants feed more heavily on benthic fish and decapod
crustaceans. Cormorants apparently feed only during daylight and
then only for short periods because their wettable plumage loses its
buoyancy. Thus they remain relatively close (50 km) to nesting and
loafing areas.
Table 1. _Food of cormorants in different localities_ (x = major
prey, o = minor prey and * = incidental prey species)
-----------------------------------------------------------------------
Key:
A_Amphipod
B: Isopod
C: Decapod
D: _Clupea_
E: _Engraulis_
F: Salmonid
G: Argentinid
H: _Porichthys_
I: _Otophidium_
J: _Boreogadus_
K: _Microgadus_
L: _Gasterosteus_
M: _Sebastes_
N: Hexagrammid
O: Cottid
P: Agonid
Q: Embiotocid
R: _Chromis_
S: _Oxyjulis_
T: Stichacid
U: Pholid
V: Gobiid
W: _Ammodytes_
X: Pleuronectid
Y: Bothid
CRUSTACEAN
Location Diet A B C D E F G H I J K L M
-----------------------------------------------------------------------
Double-crested cormorant
_(Phalacrocorax auritus)_[16]
Alaska Peninsula (Palmer 1962) o o o x x x
SE Alaska (Bailey 1927) x
Mandarte Island (Robertson 1974) * * * * *
Vancouver Island (Munro and
Clemens 1931) x
Oregon (Palmer 1962) x * * x
Farallon Island (PRBO,
unpublished data) * *
Brandt's cormorant _(P.
penicillatus)_[17]
Vancouver Island (Robertson,
unpublished data) x
Vancouver Island (Munro and
Clemens 1931) x
Washington (Jewett et al. 1953)
Yaquina Head (Scott 1973) x o o
Farallon Island (PRBO,
unpublished data) * o * * x x x
San Diego (Hubbs
et al. 1970) *
Pelagic cormorant
_(P. pelagicus)_[18]
Cape Thompson (Swartz 1966) x x
Pribilof Island (Preble
and McAtee 1923) x
Alaska (Palmer 1962) x x x
SE Alaska (Heath 1915) x x
Mandarte Island (Robertson 1974) x
Vancouver Island
(Munro and Clemens 1921) x x x
Washington (Jewett et al. 1953) x x
Netarts, Oregon (Gabrielson and
Jewett 1940) * * x
Yaquina Head (Scott 1973) o o
Farallon Island (PRBO,
unpublished data) x x
Red-faced cormorant _(P. urile)_
Pribilof Islands (Preble and
McAtee 1923) x
-----------------------------------------------------------------------
-----------------------------------------------------------------------
CRUSTACEAN FISH
Location Diet N O P Q R S T U V W X Y
-----------------------------------------------------------------------
Double-crested cormorant
_(Phalacrocorax auritus)_[16]
Alaska Peninsula (Palmer 1962) o x
SE Alaska (Bailey 1927)
Mandarte Island (Robertson 1974) * o x x
Vancouver Island (Munro and Clemens 1931)
Oregon (Palmer 1962) * x * *
Farallon Island (PRBO, unpublished data) * x * * *
Brandt's cormorant _(P. penicillatus)_[17]
Vancouver Island (Robertson,
unpublished data) o x
Vancouver Island (Munro and Clemens 1931)
Washington (Jewett et al. 1953) x
Yaquina Head (Scott 1973) * o o o
Farallon Island (PRBO, unpublished data) * o * * *
San Diego (Hubbs et al. 1970) * o o * x
Pelagic cormorant _(P. pelagicus)_[18]
Cape Thompson (Swartz 1966) x x
Pribilof Island (Preble and McAtee 1923) x x
Alaska (Palmer 1962) x x x x x x
SE Alaska (Heath 1915) x
Mandarte Island (Robertson 1974) * * x x
Vancouver Island (Munro and Clemens 1921) x x x
Washington (Jewett et al. 1953) x x
Netarts, Oregon (Gabrielson and Jewett 1940) x
Yaquina Head (Scott 1973) x
Farallon Island (PRBO, unpublished data) x x
Red-faced cormorant _(P. urile)_
Pribilof Islands (Preble and McAtee 1923) x x x x x
-------------------------------------------------------------------------------
Table 2. _Food of marine ducks and geese (x = major prey, o =
minor prey, and * = incidental prey species_).[a]
Key:
A: Amphipods
B: Decapods
C: Barnacles
D: Mussels
E: Rock clams
F: Razor clams
G: Oysters, Scallops
H: Littorinids
I: Chitons
------------------------------------------------------------------------
|PLANTS
| |CRUSTACEANS
| | |MOLLUSCS
| | | |ECHINODERMS
Diet[19] | | | | |FISH
Location | |A|B|C|D|E|F|G|H|I| | |FISH EGGS
------------------------------------------------------------------------
=Geese= x
(_Branta_ spp.)
=Emperor goose= x
_(Philacte canagica)_
=Oldsquaw= o * * * * * * * o
_(Clangula hyemalis)_
=Harlequin duck= * x x o * * o o * *
_(Histrionicus histrionicus)_
=Steller's eider= o x * * * * o * * * *
_(Polysticta stelleri)_
=Common eider= * * x * o * o o * o *
_(Somateria mollissima)_
=King eider= * * o * x * o o * x *
_(S. spectabilis)_
=Spectacled eider= x * x o * * * *
_(S. fischeri)_
=White-winged scoter= * * * * o x * x o * * o o
_(Melanitta deglandi)_
=Surf scoter= o * * * x * * x o * * * o
_(M. perspicillata)_
=Black scoter= o * * o x * * x * * * *
_(M. nigra)_
=Red-breasted merganser= x
_(Mergus serrator)_
------------------------------------------------------------------------
Information on diets of marine ducks (Table 2) is more nearly complete
than for most other seabirds. These birds fall into four groups
with some overlap: species feeding on plants (_Branta, Philacte_,
_Anas_-type, and _Somateria fischeri_); those feeding on benthic
crustaceans (_Clangula hyemalis_, _Histrionicus histrionicus_,
_Polysticta stelleri_, _S. mollissima_); those feeding on benthic
molluscs (_Somateria_ spp. and _Melanitta_ spp.); and those feeding
on fish (_Mergus serrator_, _Clangula hyemalis_, and _Melanitta
deglandi_). A study by Perthon (1968), one of the few on a seabird's
diet during most of a year, showed a seasonal change in diet for _S.
mollissima_ in Norway. In general, waterfowl seem to specialize in
their diets much more than other seabirds and, for that reason, are
perhaps more restricted in their distributions. Some marine ducks
are known to dive to considerable depths (reviewed by Kooyman 1974),
but usually they occur in shallow waters where plants and sessile
invertebrates are readily available.
The summer diet of the pigeon guillemot _(Cepphus columba)_ is the best
known among seabirds in the region being considered here (Table 3).
Only in the extreme southern part of its range (i.e., the California
Channel Islands) is there no information available on its diet. The
species feeds on organisms, mostly fish, from rocky habitat and
apparently can dive to considerable depths (Follett and Ainley 1976).
Because so much is known about guillemot diets during summer, a study
of the winter diet would be valuable.
The diets of other alcids are known well enough to at least
characterize them broadly. The larger species, murres, tufted and
horned puffins (_Lunda cirrhata_, _Fratercula corniculata_), and the
rhinoceros auklet _(Cerorhinca monocerata)_, feed heavily on fish,
mainly species that school in midwater (Table 4). To a great degree,
these birds are opportunistic, feeding rather heavily at times on
cephalopods and crustaceans, particularly nektonic forms. Morphological
differences between the two murre species suggest that thick-billed
murres _(Uria lomvia)_ feed on benthic organisms much more than do
common murres _(U. aalge)_, and that the latter species is more
piscivorous (Spring 1971); however, field data on diets are barely
adequate to confirm this. Ogi and Tsujita (1973) analyzed the stomach
contents of murres drowned in salmon gill nets but did not separate the
two species. For the present paper we considered them to be mostly _U.
aalge_, since this species predominates in the region of the food study
(Bartonek and Gibson 1972). Adult murres sometimes eat different items
than they feed to their chicks (Spring 1971; Scott 1973). The smaller
alcids, ancient and marbled murrelets--_Synthliboramphus antiquus_ and
_Brachyramphus marmoratus_--(Table 5) and auklets (Table 6), feed on
macrozooplankton: crustaceans, and fish and squid larvae. Little is
known about the food or feeding ecology of Kittlitz's murrelet _(B.
brevirostris)_. Its diet is probably similar to that of the other
murrelets, especially the marbled murrelet, its allopatric congener,
but the diets of the other murrelets differ somewhat (Bédard 1969_b_;
Sealy 1975). The Kittlitz's murrelet's shorter bill suggests that it
feeds more on invertebrates. Alcids feed in deep or shallow water,
depending on food distribution. Some alcid species can be found at
great distances from land, particularly in winter (Hamilton 1958; Scott
et al. 1971).
Information on the diets of other seabirds in the region is fragmentary
and sometimes rather anecdotal. A little is known about the feeding
habits of loons (_Gavia_ spp.) and grebes (_Podiceps_ spp. and
_Aechmophorus occidentalis_), especially off British Columbia (Table
7). The larger of these birds feed mainly on inshore fish, but as
species become progressively smaller, there is a tendency toward eating
crustaceans. Work by Madsen (1957) in Denmark, indicated that loons and
grebes tend to take prey near or on the bottom. Much more information
is available on these birds' diets at their freshwater breeding sites
but this provides only partial insight into what they might eat in
marine habitats.
Information is especially poor for albatrosses and petrels (order
Procellariiformes) (Table 8). Yet, based on sheer numbers alone,
members of this diverse group are easily among the most ecologically
dominant of the region (Sanger 1972; Ainley 1977). The Laysan
albatross _(Diomedea immutabilis)_ seems to be a squid specialist; the
black-footed albatross _(D. nigripes)_, northern fulmar _(Fulmarus
glacialis)_, scaled petrel _(Pterodroma inexpectata)_, and the
fork-tailed and Leach's storm-petrels (_Oceanodroma furcata_ and _O.
leucorhoa_) appear to be large, medium, small, and tiny versions,
respectively, of surface-feeding generalists that eat whatever
they can find, including live and dead fish, squid, coelenterates,
crustaceans, and other organisms. The shearwaters (_Puffinus_ spp.)
feed to an unknown degree on schooling fish, squid, and crustaceans
that occur near the surface. For these very abundant shearwaters,
that, unfortunately, is close to the extent of our knowledge both for
the North Pacific, where they winter, and the South Pacific, where
they breed. Most petrels remain in oceanic habitats, but shearwaters,
particularly the sooty shearwater _(Puffinus griseus)_, and sometimes
fulmars feed close to, if not within, the inshore neritic habitat. A
much better understanding of the diets of this group is sorely needed.
Table 3. _Food of the pigeon guillemot_ (Cepphus columba) _in
different localities (x = major prey, o = minor prey, and * =
incidental prey species)_.
Key:
A: Amphipod
B: Isopod
C: Decapod
D: Petromyzontid
E: Chimaerid
F: Clupeid
G: Osmerid
H: Gadid
I: Gasterosteid
J: Scorpaenid
K: Cottid
L: Agonid
M: Embiotocid
N: Bathymasterid
O: Clinid
P: Cryptacanthodid
Q: Cebidichthyid
R: Stichaeid
S: Pholid
T: Ammondytid
U: Bothid
V: Pleuronectid
----------------------------------------------------------------------------
|CRUSTACEAN
| |OCTOPUS
Diet | | |FISH
Location |A|B|C| |D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T|U|V
----------------------------------------------------------------------------
Cape Thompson o o
(Swartz 1966)
Pribilof Island o o o
(Preble and McAttee 1923)
Mandarte Island o o * o x o o * o * o o o o o o
(Drent 1965; Koelink 1972)
Vancouver Island o o o
(Munro and Clemens 1931)
Olympic Peninsula o o o o
(Thoresen and Booth 1958)
Yaquina Head o o o o o
(Scott 1973)
Farallon Island o o * x x * o o o o
(Follett and Ainley 1976)
----------------------------------------------------------------------------
Knowledge on the food of gulls, shorebirds, and related species is
surprisingly scanty in view of all that is known about their breeding
biology and social behavior. Little is known about the marine food of
phalaropes, but by inference from their association with storm-petrels,
plankton-feeding whales, and convergence lines (Martin and Myers
1969), their tiny size, and their method of feeding (picking at
minuscule items on the water surface), one can guess that they feed
on zooplankton and detritus. Skuas _(Catharacta skua)_ and jaegers
(_Stercorarius_ spp.) apparently eat what they can find at the surface,
as well as whatever they can steal from gulls and terns. Almost all the
literature on their feeding (Bent 1946) dwells on accounts of their
stealing from other birds. That spectacular behavior would seem to be
so energetically costly, though, that it is probably less important
than we have been led to believe. Rather surprisingly, the question
of what foods the gulls and terns eat in the eastern North Pacific
is difficult to answer from the literature (Tables 9 and 10). Some
information exists for five of the larger larids at isolated places,
but little is known about food elsewhere in their respective ranges,
and the diets of the seven smaller gulls and the terns are practically
unknown. Studies on gull diets in the Atlantic region (e.g., Spaans
1971; Harris 1965) provide information on what to expect from the same
species in the Pacific, but that information must be considered only in
general terms because, the birds being somewhat opportunistic, their
diets differ greatly from one locality to another (Ingolfsson 1967). A
few observations are available for arctic terns _(Sterna paradisaea)_
in Alaska, but little information exists for other terns (Table 10).
Bent (1921) noted that Aleutian terns _(S. aleutica)_ sometimes
associate with arctic terns during feeding.
Finally, we must include raptors, particularly the peregrine _(Falco
peregrinus)_ and bald eagle _(Haliaeetus leucocephalus)_, because they
are important predators on the smaller seabirds (White et al. 1971,
1973). Peregrines have, in fact, been observed feeding on storm-petrels
far at sea (Craddock and Carlson 1970).
Trophic Relations Within Seabird Communities
We have compared and summarized in general terms the food partitioning
by species in five rather broad oceanographic regions and their
subdivisions in the northeastern North Pacific and Bering Sea, based
on the specific details on diets presented in Tables 1 through 10.
The five broad regions, defined oceanographically by Dodimead et al.
(1963) and Favorite et al. (1976) and modified by Sanger (1972), are
shown in Fig. 1. The five oceanographic regions (domains) were divided
further into inshore neritic, offshore neritic, and oceanic habitats
(Sanger and King, this volume). We did not include estuarine habitats
or sheltered bays in the analysis.
[Illustration: Fig. 1. Schematic oceanographic domains of the subarctic
Pacific regions (defined by Dodimead et al. (1963) and Favorite et al.
(1976) and modified by Sanger (1972).)]
Table 4. _Food of murres and puffins in different
localities (x = major prey, o = minor prey, and * = incidental
prey species)._
KEY:
CRUSTACEAN
A - Euphausiid
B - Amphipod
C - Isopod
D - Decapod
E - POLYCHAETE
F - CEPHALOPOD
CRUSTACEAN POLYCHAETE CEPHALOPOD
LOCATION A B C D E F
--------
=Common murre= _(Uria aalge)_[20]
Cape Thompson o o o o o
(Swartz 1966)
Pribilof Islands x o o
(Preble and McAtee 1923)
E. Bering Sea x o
(Ogi and Tsujita 1973)
Forrester Island o o
(Heath 1915)
Vancouver Island o o
(Robertson, unpublished
data)
Olympic Peninsula
(Cody 1973)
Yaquina Head x o
(Scott 1973)
Farallon Islands x o
(PRBO, unpublished data)
=Thick-billed murre=
_(U. lomvia)_[21]
Cape Thompson o o o
(Swartz 1966)
Pribilof Islands x x
(Preble and McAtee 1923)
Hooker Island x o
(Demme 1934, _in_
Dement'ev et al. 1968)
NE Canada x o o o
(Tuck and Squires 1937)
=Tufted puffin=
_(Lunda cirrhata)_[22]
Cape Thompson *
(Swartz 1966)
Forrester Island
(Heath 1915)
Langara Island
(Sealy 1973_a_)
Washington
(Jewett et al. 1953)
Olympic Peninsula
(Cody 1973)
Farallon Island
(PRBO, unpublished data) x
=Horned puffin=
_(Fratercula corniculata)_
Cape Thompson o
(Swartz 1966)
Alaska
(Bent 1946)
Forrester Island
(Heath 1915)
=Rhinoceros auklet=
_(Cerorhinca monocerata)_
NW Pacific (Kozlova 1961; x
Komaki 1967)
Forrester Island
(Heath 1915)
Langara Island
(Sealy 1973_a_)
Destruction Island
(Richardson 1961)
Olympic Peninsula
(Cody 1973)
So. California (Linton x
1908; Grinnell 1899)
---------------------------------------------------------------
KEY:
FISH
G - Clupea
H - Sardinops
I - Engraulis
J - Salmo
K - Onchorhynchus
L - Hypomesus
M - Thaleichthys
N - Mallotus
O - Boreogadus
P - Microgadus
Q - Theragra
R - Lycodes
S - Gasterosteus
T - Sebaste
U - Triglops
V - Myoxocephalus
W - Cottid
X - Cymatogaster
Y - Embiotocid
Z - Chirolophis
AA - Stichaeid
BB - Ammodytes
CC - Pleuronectid
DD - Liparid
FISH A B C D
LOCATION G H I J K L M N O P Q R S T U V W X Y Z A B C D
--------
=Common murre= _(Uria aalge)_[20]
Cape Thompson x o o o x
(Swartz 1966)
Pribilof Islands o
(Preble and McAtee 1923)
E. Bering Sea x x x
(Ogi and Tsujita 1973)
Forrester Island x
(Heath 1915)
Vancouver Island x o
(Robertson, unpublished
data) x x o o
Olympic Peninsula
(Cody 1973) x x o x o o o
Yaquina Head
(Scott 1973) x o o * x o o
Farallon Islands
(PRBO, unpublished data)
=Thick-billed murre=
_(U. lomvia)_[21] x o o o o o x o
Cape Thompson
(Swartz 1966)
Pribilof Islands
(Preble and McAtee 1923)
Hooker Island
(Demme 1934, _in_
Dement'ev et al. 1968) o x * x * o x o o o
NE Canada
(Tuck and Squires 1937)
=Tufted puffin= x
_(Lunda cirrhata)_[22] *
Cape Thompson
(Swartz 1966) x
Forrester Island
(Heath 1915) x
Langara Island x
(Sealy 1973_a_) x x x x
Washington o
(Jewett et al. 1953) x o x
Olympic Peninsula x
(Cody 1973) x o
Farallon Island
(PRBO, unpublished data)
=Horned puffin= x o
_(Fratercula corniculata)_ o x
Cape Thompson
(Swartz 1966)
Alaska
(Bent 1946) x
Forrester Island
(Heath 1915)
=Rhinoceros auklet=
_(Cerorhinca monocerata)_ x o x x
NW Pacific (Kozlova 1961;
Komaki 1967) x
Forrester Island
(Heath 1915) x
Langara Island
(Sealy 1973_a_) o x
Destruction Island o
(Richardson 1961) x x o
Olympic Peninsula
(Cody 1973) x
So. California (Linton
1908; Grinnell 1899)
-----------------------------------------------------------------------------
Table 5. _Food of ancient and marbled murrelets (x = major prey,
o = minor prey, and * = incidental prey species)._
Column Headings:
CRUSTACEAN
A - Euphausiid
B - Thysanoessa
C - Euphausia
D - Mysid
E - Acanthomysis
F - Amphipod
G - Gammarid
H - Carid shrimp
I - Decapod
J - Larvae
CRUSTACEAN
Location DIET A B C D E F G H I J
------------------------------------------------------------------------------
=Ancient murrelet= _(Synthliboramphus antiquus)_[23]
Commander Islands (Dement'ev et al. 1968) x x
Amchitka Island (White et al. 1971, 1973) x x x x
Langara Island (Sealy 1975) x x x * * *
=Marbled murrelet= _(Brachyramphus marmoratus)_[24]
SE Alaska (Grinnell 1897)
Langara Island (Sealy 1975) x x *
Vancouver Island (Munro and Clemens 1931) x
Olympic Peninsula (Cody 1973)
Column Headings:
SQUID
K - Larvae
FISH
L - Engraulis
M - Osmerid
N - Scorpaenid
O - Cymatogaster
P - Stichaeid
Q - Ammodytes
R - Larvae
SQUID FISH
Location DIET K L M N O P Q R
-----------------------------------------------------------------------------
=Ancient murrelet= _(Synthliboramphus antiquus)_[23]
Commander Islands (Dement'ev et al. 1968)
Amchitka Island (White et al. 1971, 1973) x
Langara Island (Sealy 1975) o o x
=Marbled murrelet= _(Brachyramphus marmoratus)_[24]
SE Alaska (Grinnell 1897) o
Langara Island (Sealy 1975) * * * x *
Vancouver Island (Munro and Clemens 1931) x x
Olympic Peninsula (Cody 1973) x x
Table 6. _Diets of auklets in different localities (x = major
prey, o = minor prey, and * = incidental prey species)._
Table Headings
CRUSTACEAN
A - Euphausiid
B - Thysanoessa
C - Mysid
D - Stylomysis
E - Amphipod
F - Parathemisto
G - Phronema
H - Gammarid
I - Copepod
J - Calanus
K - Carid shrimp
L - POLYCHAETE
SQUID
M - Larvae
FISH
N - Cottid
O - Larvae
Location Diet A B C D E F G H I J K L M N O
=Cassin's auklet=
_(Ptychoramphus aleuticus)_
Forrester Island (Heath 1915) x x x
Olympic Peninsula (Cody 1973) x x
Farallon Islands (Manuwal 1974) x x x x x o x
=Parakeet auklet=
_(Cyclorrhynchus psittaculus)_
Chukhotsk Peninsula (Portenko 1934,
_in_ Dement'ev et al. 1968) x x x x x
Aleutian Islands (Bent 1946) x
St. Lawrence Island (Bédard 1969_a_) x x o x x o o * o o o
=Crested auklet=
_(Aethia cristatella)_[25]
W. Bering Sea (Portenko 1934,
_in_ Dement'ev et al. 1968) x x
Commander Islands (Stejneger 1885) x
Amchitka (White et al. 1973) x x x x x
St. Lawrence Island. (Bédard 1969_a_) x x x o o x x *
Pribilof Islands (Preble and McAtee 1923) x x
=Least auklet= _(A. pusilla)_
Commander Islands (Stejneger 1885) x
Aleutian Islands (Bent 1946) x
St. Lawrence Island (Bédard 1969_a_) o o * o o o x x x
=Whiskered auklet= _(A. pygmaea)_
Commander Islands (Stejneger 1885) x x *
Table 7. _Diets of loons and grebes in different localities (x =
major prey, o = minor prey, and * = incidental prey species)._
Table Headings:
CRUSTACEANS
A - Euphausid
B - Amphipod
C - Mysid
D - Decapod
E - POLYCHAETE
FISH
F - Anguilla
G - Clapea
H - Sardinops
I - Salmo
J - Thaleichthys
K - Atherinops
Location A B C D E F G H I J K
=Common loon= _(Gavia immer)_
Alaska (Palmer 1962) * * o o
Vancouver Island (Munro and Clemens 1931) x
Denmark (Madsen 1957) *
=Yellow-billed loon= _(G. adamsii)_[26]
Alaska (Cottam and Knappen 1939) * *
Alaska (Bailey 1922)
=Arctic loon= _(G. arctica)_[27]
Vancouver Island (Palmer 1962) x
Vancouver Island (Robertson, unpublished data) x
California (Palmer 1962)
Denmark (Madsen 1957) * o
=Red-throated loon= _(G. stellata)_[28]
Oregon (Palmer 1962)
No. Atlantic (Palmer 1962)
Denmark (Madsen 1957) * o
=Western grebe= _(Aechmophorus occidentalis)_
Vancouver Island (Munro 1941) o * x
Vancouver Island (Robertson, unpublished data) x
Puget Sound (Phillips and Carter 1957) x
Washington (Chatwin 1956) * x
California (Palmer 1962) o * x x
=Red-necked grebe= _(Podiceps grisegena)_
Pribilof Islands (Preble and McAtee 1923) o
Vancouver Island (Wetmore 1924)
Vancouver Island (Munro 1941) x o
E. No. America (Wetmore 1924) o * o
=Horned grebe= _(P. auritus)_[29]
Pribilof Islands (Preble and McAtee 1923) x o
W. No. America (Wetmore 1924) x x *
Vancouver Island (Munro 1941) x x
Denmark (Madsen 1957) o o o
=Eared grebe= _(P. nigricollis)_[30]
W. No. America (Wetmore 1924) * x *
Vancouver Island (Munro 1941) x x o
Denmark (Madsen 1957) x *
Table Headings:
FISH
L - Zoarchid
M - Gadid
N - Fundulus
O - Gasterosteus
P - Sebastes
Q - Cattid
R - Cymatogaster
S - Stichaeid
T - Ammodytes
U - Gobiid
Location L M N O P Q R S T U
=Common loon= _(Gavia immer)_
Alaska (Palmer 1962) o o o
Vancouver Island (Munro and Clemens 1931)
Denmark (Madsen 1957) o x * o
=Yellow-billed loon= _(G. adamsii)_[26]
Alaska (Cottam and Knappen 1939) o x
Alaska (Bailey 1922) x
=Arctic loon= _(G. arctica)_[27]
Vancouver Island (Palmer 1962)
Vancouver Island (Robertson, unpublished data)
California (Palmer 1962) x
Denmark (Madsen 1957) * x x * x *
=Red-throated loon= _(G. stellata)_[28]
Oregon (Palmer 1962) x
No. Atlantic (Palmer 1962) x x o
Denmark (Madsen 1957) * x o * * o
=Western grebe= _(Aechmophorus occidentalis)_
Vancouver Island (Munro 1941) x
Vancouver Island (Robertson, unpublished data) x
Puget Sound (Phillips and Carter 1957) * o o o
Washington (Chatwin 1956)
California (Palmer 1962) x *
=Red-necked grebe= _(Podiceps grisegena)_
Pribilof Islands (Preble and McAtee 1923)
Vancouver Island (Wetmore 1924) x
Vancouver Island (Munro 1941) x
E. No. America (Wetmore 1924) o x
=Horned grebe= _(P. auritus)_[29]
Pribilof Islands (Preble and McAtee 1923)
W. No. America (Wetmore 1924) o o
Vancouver Island (Munro 1941) o o *
Denmark (Madsen 1957) o
=Eared grebe= _(P. nigricollis)_[30]
W. No. America (Wetmore 1924) o
Vancouver Island (Munro 1941)
Denmark (Madsen 1957) o
Table 8. _Diets of albatrosses and petrels in different
localities (x = major prey, o = minor prey, and * = incidental prey
species)._
Key:
CRUSTACEAN
A: Euphausiid
B: Amphipod
C: Copepod
D: Decapod
E: Larvae
F: Barnacle
FISH
G: "Fish"
H: _Engraulis_
I: Myctophid
J: _Sebastes_
K: _Ammodytes_
L: Carrion, fish offal
M: Fish eggs
-----------------------------------------------------------------------------
|CRUSTACEAN
| |COELENTERATE
| | |ECHINODERM
| | | |CEPHALOPOD
Location Diet |A|B|C|D|E|F| | | |
---------------------------------------------------------------------
=Black-footed albatross= _(Diomedea nigripes)_
No. Pacific (Palmer 1962) x
Aleutian Islands (Cottam and Knappen 1939) o x o
California (Miller 1936, 1940) o o x
=Laysan albatross= _(D. immutabilis)_
No. Pacific (Palmer 1962; Bartsch 1922;
Fisher 1904) x
=Northern fulmar= _(Fulmarus glacialis)_
Pribilof Islands (Preble and McAtee 1923) o x
Alaska (Gabrielson and Lincoln 1959) x x
Oregon (Gabrielson and Jewett 1940) x
No. Atlantic (Hartley and Fisher 1936;
Einarsson 1945; Fisher 1952) x
=Flesh-footed shearwater= _(Puffinus carneipes)_
Australia (Oliver 1955; Serventy et al. 1971) x x
=Pink-footed shearwater= _(P. creatopus)_
California (Murphy 1936; Ainley,
personal observation) x
E. Pacific (Cottam and Knappen 1939) x
=Buller's shearwater= _(P. bulleri)_
SW Pacific (Falla 1934; Serventy et al. 1971) x x
Peru (Murphy 1936) x
=Sooty shearwater= _(P. griseus)_
Aleutian Islands (Sanger, personal
observation) x x
British Columbia (Martin 1942; Sealy 1973_a_) x
Oregon (Gabrielson and Jewett 1940) x
California (Ainley, personal observation) x
Peru (Murphy 1936) x x
SW Pacific (Oliver 1955; Serventy et al. 1971) x x
=Short-tailed shearwater= _(P. tenuirostris)_
Bristol Bay (Bartonek, personal communication) x
Alaska (Cottam and Knappen 1939) x x x
No. Pacific (Palmer 1962; Kuroda 1955) x x
Australia (Serventy et al. 1971) x x
Bass Strait (Sheard 1953) x
=Mottled petrel= _(Pterodroma inexpectata)_
Pacific Ocean (Imber 1973)
E. No. Pacific (Kuroda 1955)
=Fork-tailed storm-petrel=_(Oceanodroma furcata)_
Pribilof Islands (Preble and McAtee 1923)
SE Alaska (Heath 1915) x
British Columbia (Martin 1942)
California (Ainley, personal observation)
=Leach's storm-petrel= _(O. leucorhoa)_
SE Alaska (Heath 1915) x
California (PRBO, unpublished data) x x x
So. California (Palmer 1962) x
No. Atlantic[31] (Palmer 1962) x x x
---------------------------------------------------------------------
----------------------------------------------------------------
|FISH
Location Diet|G|H|I|J|K|L|M
----------------------------------------------------------------
=Black-footed albatross= _(Diomedea nigripes)_
No. Pacific (Palmer 1962) x x
Aleutian Islands (Cottam and Knappen 1939) x x
California (Miller 1936, 1940) x x x
=Laysan albatross= _(D. immutabilis)_
No. Pacific (Palmer 1962; Bartsch 1922;
Fisher 1904)
=Northern fulmar= _(Fulmarus glacialis)_
Pribilof Islands (Preble and McAtee 1923)
Alaska (Gabrielson and Lincoln 1959) x
Oregon (Gabrielson and Jewett 1940)
No. Atlantic (Hartley and Fisher 1936;
Einarsson 1945; Fisher 1952) x
=Flesh-footed shearwater= _(Puffinus carneipes)_
Australia (Oliver 1955; Serventy et al. 1971) x
=Pink-footed shearwater= _(P. creatopus)_
California (Murphy 1936; Ainley,
personal observation) x
E. Pacific (Cottam and Knappen 1939) x
=Buller's shearwater= _(P. bulleri)_
SW Pacific (Falla 1934; Serventy et al. 1971) x
Peru (Murphy 1936)
=Sooty shearwater= _(P. griseus)_
Aleutian Islands (Sanger, personal
observation) x
British Columbia (Martin 1942; Sealy 1973_a_) x x
Oregon (Gabrielson and Jewett 1940)
California (Ainley, personal observation) x
Peru (Murphy 1936) x
SW Pacific (Oliver 1955; Serventy et al. 1971) x
=Short-tailed shearwater= _(P. tenuirostris)_
Bristol Bay (Bartonek, personal communication)
Alaska (Cottam and Knappen 1939) o
No. Pacific (Palmer 1962; Kuroda 1955) x
Australia (Serventy et al. 1971) x
Bass Strait (Sheard 1953)
=Mottled petrel= _(Pterodroma inexpectata)_
Pacific Ocean (Imber 1973) x
E. No. Pacific (Kuroda 1955) x
=Fork-tailed storm-petrel= _(Oceanodroma furcata)_
Pribilof Islands (Preble and McAtee 1923) x
SE Alaska (Heath 1915)
British Columbia (Martin 1942) x
California (Ainley, personal observation) x
=Leach's storm-petrel= _(O. leucorhoa)_
SE Alaska (Heath 1915)
California (PRBO, unpublished data) x x
So. California (Palmer 1962) x
No. Atlantic[31] (Palmer 1962) x x
----------------------------------------------------------------
Table 9. _Diets of gulls in different localities (x = major prey,
o = minor prey, and * = incidental prey species)._
Key:
CRUSTACEAN
A: Euphausiid
B: Barnacle
C: Decapod
MOLLUSC
D: Shell fish
E: Cephalopod
FISH
F: "Fish"
G: _Clupea_
H: _Engraulis_
I: _Osmerus_
J: _Porichihys_
K: _Otaphidium_
L: _Mallotus_
M: _Borrogadus_
N: _Microgadus_
O: _Gadus_
P: _Lycodes_
Q: _Sebastes_
R: _Myxocephalus_
S: _Genyonemus_
T: Embiotocid
U: _Ammodytes_
BIRD
V: Eggs
X: Chicks
Y: Adults
|CRUSTACEAN
| |POLYCHAETE
| | |MOLLUSC
| | | |ECHINODERM
| | | | |COELENTERATE
| | | | | |FISH
Diet | | | | | |
Location |A|B|C| |D|E| | |F|G|H|I|
---------------------------------------------------------------------------
=Glaucous gull= _(Larus hyperboreus)_
St. Lawrence Island (Fay and Cade 1959)
Chukchi Sea (Swartz 1966) x x x
Pribilof Islands (Preble and McAtee 1923) x x x x
Vancouver Island (Munro and Clemens 1931) x
=Glaucous-winged gull= _(L. glaucescens)_[32]
Pribilof Islands (Preble and McAtee 1923) x x x
Alaska (Bent 1921)
No. Pacific (Sanger 1973) x * *
Mandarte Island (Ward 1973) x x x
Vancouver Island (Munro and Clemens 1931; x x
Robertson, unpublished data)
=Western gull= _(L. occidentalis)_[33]
Farallon Islands (PRBO, unpublished data) x x o * x * * x
=Herring gull= _(L. argentatus)_
No. Atlantic (Zelikman 1961) x
E. No. America (Bent 1946; Ainley, x x x x x
personal observation)
Vancouver Island (Munro and Clemens 1931) x x
=Mew gull= _(L. canus)_
Alaska (Bent 1921) x
Vancouver Island (Munro and Clemens 1931) x x
=Heermann's gull= _(L. heermanni)_
California (Bent 1921) x x x
=Bonaparte's gull= _(L. philadelphia)_
E. No. America (Bent 1921) x x x
=Black-legged kittiwake= _(Rissa tridactyla)_[34]
Chukchi Sea (Swartz 1966) o * o
Pribilof Islands (Preble and McAtee 1923) o x
Alaska (Bent 1921) x
Cook Inlet[35] (Snarski, personal o o o
communication)
No. Atlantic (Hartley and Fisher x
1936; Zelikman 1961)
=Red-legged kittiwake= _(R. breuirostris)_
Pribilof Islands (Preble and McAtee 1923) x x x
=Sabine's gull= _(Xenia sabini)_
Pt. Barrow (Banner 1954) x
---------------------------------------------------------------------------
Location Diet |J|K|L|M|N|O|P|Q|R|S|T|U|
-----------------------------------------------------------------------------
=Glaucous gull= _(Larus hyperboreus)_
St. Lawrence Island (Fay and Cade 1959)
Chukchi Sea (Swartz 1966) x x
Pribilof Islands (Preble and McAtee 1923)
Vancouver Island (Munro and Clemens 1931)
=Glaucous-winged gull= _(L. glaucescens)_[32]
Pribilof Islands (Preble and McAtee 1923)
Alaska (Bent 1921)
No. Pacific (Sanger 1973)
Mandarte Island (Ward 1973) x
Vancouver Island (Munro and Clemens 1931;
Robertson, unpublished data)
=Western gull= _(L. occidentalis)_[33]
Farallon Islands (PRBO, unpublished data) x o o o x o o
=Herring gull= _(L. argentatus)_
No. Atlantic (Zelikman 1961)
E. No. America (Bent 1946; Ainley,
personal observation)
Vancouver Island (Munro and Clemens 1931)
=Mew gull= _(L. canus)_
Alaska (Bent 1921) x
Vancouver Island (Munro and Clemens 1931)
=Heermann's gull= _(L. heermanni)_
California (Bent 1921)
=Bonaparte's gull= _(L. philadelphia)_
E. No. America (Bent 1921)
=Black-legged kittiwake= _(Rissa tridactyla)_[34]
Chukchi Sea (Swartz 1966) o x o o x
Pribilof Islands (Preble and McAtee 1923)
Alaska (Bent 1921)
Cook Inlet[35] (Snarski, personal x o x
communication)
No. Atlantic (Hartley and Fisher
1936; Zelikman 1961)
=Red-legged kittiwake= _(R. breuirostris)_
Pribilof Islands (Preble and McAtee 1923)
=Sabine's gull= _(Xenia sabini)_
Pt. Barrow (Banner 1954)
-----------------------------------------------------------------------------
Diet |CARRION-OFFAL
| |BIRD
| | |FISH EGGS
Location | |V|X|Y|
----------------------------------------------------------------------
=Glaucous gull= _(Larus hyperboreus)_
St. Lawrence Island (Fay and Cade 1959) x x x
Chukchi Sea (Swartz 1966) x x
Pribilof Islands (Preble and McAtee 1923) x
Vancouver Island (Munro and Clemens 1931) x
=Glaucous-winged gull= _(L. glaucescens)_[32]
Pribilof Islands (Preble and McAtee 1923) x x x x
Alaska (Bent 1921) x
No. Pacific (Sanger 1973)
Mandarte Island (Ward 1973) x
Vancouver Island (Munro and Clemens 1931; x
Robertson, unpublished data)
=Western gull= _(L. occidentalis)_[33]
Farallon Islands (PRBO, unpublished data) x o o o
=Herring gull= _(L. argentatus)_
No. Atlantic (Zelikman 1961)
E. No. America (Bent 1946; Ainley, x * o x
personal observation)
Vancouver Island (Munro and Clemens 1931) x
=Mew gull= _(L. canus)_
Alaska (Bent 1921) x x
Vancouver Island (Munro and Clemens 1931) x
=Heermann's gull= _(L. heermanni)_
California (Bent 1921) x
=Bonaparte's gull= _(L. philadelphia)_
E. No. America (Bent 1921)
=Black-legged kittiwake= _(Rissa tridactyla)_[34]
Chukchi Sea (Swartz 1966)
Pribilof Islands (Preble and McAtee 1923) o
Alaska (Bent 1921) o
Cook Inlet[35] (Snarski, personal
communication)
No. Atlantic (Hartley and Fisher
1936; Zelikman 1961)
=Red-legged kittiwake= _(R. breuirostris)_
Pribilof Islands (Preble and McAtee 1923)
=Sabine's gull= _(Xenia sabini)_
Pt. Barrow (Banner 1954)
----------------------------------------------------------------------
=Table 10=. _Diets of terns in different localities (x = major prey
species)._
------------------------------------------------------------------------
CRUSTACEAN FISH
------------------------------------------------------------------------
|"Crustacean"|_Mallotus_
| |Euphausiid| |Cottid
Diet | | |Amphipod| | |_Ammodytes_
Location | | | | | | larvae
------------------------------------------------------------------------
=Arctic tern= _(Sterna paradisaea)_
Pribilof Islands (Preble and McAtee 1923) x x
Alaska (Bent 1921) x x x
No. Atlantic (Hartley and Fisher 1936) x
=Common tern= _(S. hirundo)_
E. No. America (Bent 1921) x x
------------------------------------------------------------------------
The oceanic habitat includes waters of the photic zone overlying the
deep ocean and continental slopes beyond the continental or insular
shelves. The Bering Sea and central subarctic domains are largely made
up of oceanic habitat. The other three domains include both inshore and
offshore neritic as well as some oceanic habitat. The boundary between
the inshore and offshore neritic has yet to be defined in terms of bird
life, but it lies at that line beyond which the bottom is too deep for
a diving bird to exploit. A depth contour thus defines the boundary. In
the antarctic South Pacific, emperor penguins _(Aptenodytes fosteri)_
dive to depths of 275 m, but so far as is known, no comparable bird
exists in the North Pacific. Some marine ducks and loons reportedly
dive to 50-60 m (Kooyman 1974). The inshore-offshore neritic boundary
for seabirds may lie near the 70-m depth contour.
Food resource partitioning by seabirds in the five oceanographic
domains are shown in Tables 11-15. Within each domain, the common
and usual members of the seabird community are listed, and the major
and minor categories in each of their diets are shown (on the basis
of available literature, Tables 1-10). The categories are grouped
further, and rather tenuously, according to the trophic level at which
a bird is presumably feeding: I = herbivore, II = secondary carnivore,
III = tertiary carnivore, IV = final carnivore, and Sc = scavengers
(carnivorous) feeding at many levels. Birds at level I feed on large
algae and seed plants and are not directly part of the same food webs
involving other species. These food webs originate with phytoplankton
(Fig. 2). So far as is known, no bird feeds on phytoplankton and few,
if any, feed on microzooplankton; hence birds do not generally feed as
primary carnivores. An exception at times might be the least auklet
_(Aethia pusilla)_ when it feeds on small copepods (see Bédard 1969_b_).
The above groupings are "tenuous" because prey in each category may
represent more than one trophic level, and a single prey species could
occur at one level one day or place and at another level the next day
or place, depending upon what it happened to be eating. This is shown
in Fig. 2, where the parakeet auklet _(Cyclorrhynchus psittaculus)_
can occur in the food web at different levels, depending both on
the prey it is eating and on what its prey is eating. Even without
this complication, many seabirds feed at more than one level in the
food web. For instance, murres eating euphausiids would be feeding
at a different level than murres feeding on larger fish. It might be
"safer" to regard prey organisms in level II as macrozooplankton, prey
organisms in level III as micronekton, and prey organisms (seabirds
themselves) in level IV as macronekton (after Sverdrup et al. 1942).
[Illustration: Fig. 2. Schematic food web of the parakeet auklet in the
eastern Bering Sea (based on Bédard 1969_a_ and Dunbar 1946). Arrow
sizes indicate relative importance of prey and Roman numerals refer to
prey sizes (see text).]
Table 11. _Use of food resources by seabirds in the Bering Sea
coastal domain._ Information is from Tables 1-10. (Trophic level
I = plants, II = secondary carnivore, III = tertiary carnivore,
IV = upper level carnivore [on birds only in this table], Sc =
scavenger on carrion, offal, or detritus [II-IV]; x = major food
in diet, o = minor food, * = incidental food, ? = probable food.)
-----------------------------------------------------------------------------
Habitat, bird trophic levels (I-IV. Sc), and food categories
-----------------------------------------------------------------------------
Oceanic and offshore neritic Inshore neritic Inshore neritic
-----------------------------------------------------------------------------
Key:
II II III
A. Crustacean J. Crustacean, midwater R. Fish, midwater
B. Polychaete K. Crustacean, benthic S. Fish, benthic
C. Coelenterate L. Coelenterate T. Cephalopod
D. Fish/squid eggs & larvae M. Echinoderm IV. U. Birds
III N. Mollusc Sc. V. Carrion/offal/
E. Fish Q. Fish/squid eggs & larvae detritus
F. Cephalopod
IV G. Birds
Sc H. Carrion/offal/detritus
I I. Plant
Seabirds | A B C D| E F G H I| J K L |M N Q |R S T |U V |
----------------------------------------------------------------------------|
_Gavia adamsii_ * o x
_G. arctica_ o x
_Podiceps grisegena_ o o x
_Diomedea nigripes_ x o o o x x x
_Fulmarus glacialis_ x o x o x x x
_Puffinus griseus_ x x x o o
_P. tenuirostris_ x o x o o
_Oceanodroma furcata_ x o o x x x x
_Phalacrocorax auritus_ o x o
_P. pelagicus_ x x
_P. urile_ x x
_Branta bernicla_ x
_Philacte canagica_ x
_Clangula hyemalis_ o x o o
_Histrionicus histrionicus_ o x o
_Polysticta stelleri_ o x o o
_Samateria mollissima_ x o x
_S. spectabilis_ o o o x
_S. fischeri_ x x
_Melanitta deglandi_ x o
_M. nigra_ o o x
_Haliaeetus leucocephalus_ x x x
_Falco peregrinus_ x
_Phalaropus fulicarius_ x x o x x
_Lobipes lobatus_ x x o x x
_Stercorarius_ spp. o x x ? x x x x
_Larus hyperboreus_ o o o o o o o o o o x x x
_L. glaucescens_ o o o o o o o o o o x x x
_L. argentatus_ o o o o o o o o o o x o x
_L. canus_ x o o o x x
_Rissa tridactyla_ x x x o
_Xema sabini_ x x o o
_Sterna paradisaea_ x x o o
_Uria aalge_ x o x x o o x o
_U. lomvia_ x o x x o x o x
_Lunda cirrhata_ ? x x
_Fratercula corniculata_ * x x
_Cepphus columba_ o x o
_Synthliboramphus antiquus_ x x o
_Brachyramphus brevirostris_ x o
_Cyclorrhynchus psittaculus_ x o * *
_Aethia cristatella_ x x
_A. pusilla_ x o
-----------------------------------------------------------------------------
Table 12. _Use of food resources by seabirds in the oceanic
and offshore neritic habitats, Bering Sea domain._ Information
is from Tables 1-10. (Trophic level I = plants, II = secondary
carnivore, III = tertiary carnivore, IV = upper level carnivore;
Sc = scavenger on carrion, offal, or detritus [II-IV]; x = major
food in diet, o = minor food, * = incidental food, ? = probable
food.)
Bird trophic levels and food categories
II III IV Sc
---------------------------------------------------------------------------
Fish/Squid eggs & Larvae | Fish
Coelenterate | | | Cephalopod
Polychaete | | | | | Birds
Crustacean | | | | | | | Carrion/offal
Seabirds | | | | | | | | | /detritus
---------------------------------------------------------------------------
_Diomedea nigripes_ x o o o x x x
_D. immutabilis_ x
_Fulmarus glacialis_ x o x o x x x
_Puffinus griseus_ x x x
_P. tenuirostris_ x o x
_Pterodroma inexpectata_ x x
_Oceanodroma furcata_ x o o x x x x
_Phalaropus fulicarius_ x x o
_Lobipes lobatus_ x x o
_Stercorarius_ spp. o x x ? x
_Larus hyperboreus_ x o o o x x ? x
_L. glaucescens_ x o o o x x ? x
_Rissa tridactyla_ x x x o
_R. brevirostris_ x x x o
_Xema sabini_ x x o o
_Sterna paradisaea_ x x o o
_Uria aalge_ x o x x
_U. lomvia_ x o x x
_Lunda cirrhata_ ? x x
_Fratercula corniculata_ * x x
_Synthliboramphus antiquus_ x x
_Cyclorrhynchus psittaculus_ x o * *
_Aethia cristatella_ x x
_A. pusilla_ x o
_A. pygmaea_ x
-----------------------------------------------------------------------------
Information contained in Tables 11-15 can be summarized to show
characteristics of seabird trophic relations. One such characteristic
is the range of diet breadth or diet complexity (Table 16). Few species
(about 6%) feed on only one type of prey and might, therefore, be
referred to as "specialists." Included are eared grebe _(Podiceps
caspicus)_, Laysan albatross, brown pelican, emperor goose _(Philacte
canagica)_, black brant _(Bernicia bernicla)_, peregrine falcon, and
whiskered auklet _(Aethia pygmaea)_. Consideration of these species
as specialists may require revision when more data become available.
Except for the albatross and auklet, these species are members of
the inshore neritic cohort. Food specialization does not seem to be
characteristic of oceanic birds in particular or of most seabirds in
general.
Table 13. _Use of food resources by seabirds in the Alaska Stream
domain._ Information is from Tables 1-10. (Trophic level I =
plants, II = secondary carnivore, III = tertiary carnivore, IV
= upper level carnivore, Sc = scavenger on carrion, offal, or
detritus [II-IV]; x = major food in diet, o = minor food, * =
incidental food, ? = probable food.)
----------------------------------------------------------------------------
Habitat, bird trophic levels (I-IV. Sc), and food categories
Key:
Oceanic and offshore neritic
II
A: Crustacean
B: Polychaete
C: Coelenterate
D: Fish/squid eggs & larvae
III
E: Fish
F: Cephalopod
IV
G: Birds
Sc
H: Carrion/offal/detritus
I
I: Plant
Inshore neritic
II
J: Crustacean, midwater
K: Crustacean, benthic
L: Coelenterate
M: Echinoderm IV:
N: Mollusc Sc:
Q: Fish/squid eggs & larvae
III
R: Fish, midwater
S: Fish, benthic
T: Cephalopod
IV
U: Birds
Sc
V: Carrion/offal/detritus
Seabirds A B C D E F G H I J K L M N Q R S T U V
----------------------------------------------------------------------------
_Gavia immer_ * x x
_G. adamsii_ * o x
_G. stellata_ * o x
_Podiceps grisegena_ o x o
_Diomedea nigripes_ x o o o x x x
_Fulmarus glacialis_ x o x o x x x
_Puffinus griseus_ x x x o
_P. tenuirostris_ x o x o
_Pterodroma inexpectata_ x x
_Oceanodroma furcata_ x o o x x x x
_Phalacrocorax auritus_ o x o
_P. pelagicus_ x x
_P. urile_ x x
_Philacte canagica_ x
_Clangula hyemalis_ o x o
_Histrionicus histrionicus_ x x o
_Polysticta stelleri_ o x o o
_Somateria mollissima_ x o x
_S. spectabilis_ o o x
_S. fischeri_ x x
_Melanitta deglandi_ x o
_M. perspicillata_ o x o
_M. nigra_ o o x
_Mergus serrator_ o x x
_Haliaeetus leucocephalus_ x x x
_Falco peregrinus_ x
_Phalaropus fulicarius_ x x o x x
_Lobipes lobatus_ x x o x x
_Stercorarius_ spp. o x x ? x x x x
_Larus hyperboreus_ o o o o o o o o o o x x x
_L. glaucescens_ o o o o o o o o o o x x x
_L. argentatus_ o o o o o o o o o o x o x
_L. canus_ x o o o x x
_Rissa tridactyla_ x x x o
_R. brevirostris_ x x x o
_Sterna paradisaea_ x x o o x o
_S. aleutica_ x o
_Uria aalge_ x o x x o o x o
_U. lomvia_ x o x x o x o x
_Lunda cirrhata_ ? x x
_Fratercula corniculata_ * x x
_Cepphus columba_ o x o
_Brachyramphus marmoratus_ x o x
_B. brevirostris_ x o
_Synthliboramphus antiquus_ x x x
_Cyclorrhynchus psittaculus_ x o * *
_Aethia cristatella_ x x
_A. pusilla_ x o
_A. pygmaea_ x
Table 14. _Use of food resources by seabirds in the oceanic
habitat, central subarctic domain._ Information is from Tables
1-10. (Trophic level I = plants, II = secondary carnivore, III =
tertiary carnivore, IV = upper level carnivore, Sc = scavenger on
carrion, offal, or detritus [II-IV]; x = major food in diet, o =
minor food, * = incidental food, ? = probable food.)
--------------------------------------------------------------------
Bird trophic levels and food categories
---------------------------------------
II III IV Sc
-------------- ------- --- ------------
|Crustacean
| |Polychaete
| | |Coelenterate
| | | |Fish/squid eggs & larvae
| | | | |Fish
| | | | | |Cephalopod
| | | | | | |Birds
Seabirds | | | | | | | |Carrion/offal/
| | | | | | | | detritus
--------------------------------------------------------------------
_Diomedea nigripes_ x o o o x x x
_D. immutabilis_ x
_Fulmarus glacialis_ x o x o x x x
_Puffinus carneipes_ o x x
_P. griseus_ x x x
_P. tenuirostris_ x o x
_Pterodroma inexpectata_ x x
_Oceanodroma furcata_ x o o o x x x
_O. leucorhoa_ x o o o x x x
_Phalaropus fulicarius_ x x o
_Lobipes lobatus_ x x o
_Stercorarius_ spp. o x x ? x
_Larus hyperboreus_ x o o o x x ? x
_L. glaucescens_ x o o o x x ? x
_L. argentatus_ x o o o x x x
_Rissa tridactyla_ x x x o
_Xema sabini_ x x o o
_Sterna paradisaea_ x x o o
_Uria aalge_ x * x x
_U. lomvia_ x * x x
_Lunda cirrhata_ o x x
_Fratercula corniculata_ * x x
_Cerorhinca monocerata_ x x
_Synthliboramphus antiquus_ x x
_Cyclorrhynchus psittaculus_ x o * *
_Ptychoramphus aleuticus_ x o
--------------------------------------------------------------------
Most species (roughly 53% in any community) include two or three
prey categories in their diets--usually midwater schooling fish,
squid, and crustaceans. These birds include the most numerous in the
communities--the shearwaters and some alcids--which feed largely on
three prey types, and also include some of the less abundant birds, the
marine ducks, which feed mostly on two prey categories.
The remaining seabirds are more general in their feeding. Many have
large populations, but are not as abundant as shearwaters or most
alcids. The true "generalists" are the species that feed on as many
as eight or more types of prey, and relatively few (12%) such species
exist in each avian community. These birds, the scavengers, include
black-footed albatross, fulmar, storm-petrels, and large gulls. The
petrels are the scavengers of the oceanic habitat and the gulls are
their counterparts in the neritic habitat (but see Sanger 1973).
Another comparison is shown in Table 17, where the species in each
community are categorized according to the number feeding at each
trophic level. If a species feeds at more than one level, it is
tallied once in each level. Most seabirds (66-77%) feed at the second
and third levels as secondary and tertiary carnivores. Few feed as
terminal carnivores, and relatively few are scavengers. Actually, most
scavenging occurs at levels II and III, so about 90% of the seabirds
in each community feed at levels II and III. Communities including
an inshore neritic feeding element are the only ones that include
herbivores, and even then, few of these species exist in significant
numbers in the marine environment (discounting estuaries and sheltered
bays).
Table 15. _Use of food resources by seabirds in the North
American coastal domain._ Information is from Tables 1-10.
(Trophic level I = plants, II = secondary carnivore,
III = tertiary carnivore, IV = upper level carnivore,
Sc = scavenger on carrion, offal, or detritus [II-IV]; x = major
food in diet, o = minor food, * = incidental food, ? = probable
food.)
-----------------------------------------------------------------
Habitat, bird trophic levels (I-IV, Sc), and food categories
-----------------------------------------------------------------
Key:
Oceanic and offshore neritic
II
A: Crustacean
B: Polychaete
C: Coelenterate
D: Fish-squid eggs & larvae
III
E: Fish
F: Cephalopod
IV
G: Birds
Sc
H: Carrion/offal/detritus
I
I: Plant
Inshore neritic
II
J: Crustacean, midwater
K: Crustacean, benthic
L: Coelenterate
M: Echinoderm
N: Mollusc
O: Fish/squid eggs & larvae
III
P: Fish, midwater
Q: Fish, benthic
R: Cephalopod
IV
S: Birds
Sc
T: Carrion/offal/detritus
Seabirds A B C D E F G H I J K L M N O P Q R S T
---------------------------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
_Gavia immer_ * x x
_G. adamsii_ * o x
_G. arctica_ o x
_G. stellata_ o x
_Podiceps grisegena_ o x o
_P. nigricollis_ x o
_P. auritus_ x x o
_Aechmophorus occidentalis_ o x x
_Diomedea nigripes_ x o o o x x x
_Fulmarus glacialis_ x o x o x x x
_Puffinus creatopus_ o x x
_P. carneipes_ o x x
_P. bulleri_ x x x
_P. griseus_ x x x o o o
_P. tenuirostris_ x o x o o o
_Oceanodroma furcata_ x o o o x x x
_Pelecanus occidentalis_ x
_Phalacrocorax auritus_ o x o
_P. penicillatus_ o x
_P. pelagicus_ x x
_Branta bernicla_ x
_Clangula hyemalis_ o x o o
_Histrionicus histrionicus_ o x o
_Melanitta deglandi_ x o o
_M. perspicillata_ o x o
_M. nigra_ * o o x
_Mergus serrator_ * x x
_Haliaeetus leucocephalus_ x x x
_Falco peregrinus_ x
_Phalaropus fulicarius_ x x o x x o
_Lobipes lobatus_ x x o x x o
_Stercorarius_ spp. o x x ? x x x o x
_Larus hyperboreus_ o o o o ? o o o o o o x x x
_L. glaucescens_ o o o o ? o o o o o x x x x
_L. occidentalis_ x x x x o x o o o * * x x o x
_L. argentatus_ o o o o o x o o o o o x o x
_L. heermanni_ x x x
_L. canus_ x o o o x x x
_L. philadelphia_ x x o
_Rissa tridactyla_ x x x o
_Xema sabini_ x x o o
_Sterna paradisaea_ x x o o
_S. hirundo_ o x
_Uria aalge_ x o x x o x o
_U. lomvia_ x o x x o x o x
_Lunda cirrhata_ ? x x
_Fratercula corniculata_ * x x
_Cerorhinca monocerata_ x x
_Cepphus columba_ o x o
_Brachyramphus marmoratus_ x o x
_B. brevirostris_ x o
_Synthliboramphus antiquus_ x x o
_Ptychoramphus aleuticus_ x x
---------------------------+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Table 16. _Number of seabirds of different oceanographic regions
having different numbers of categories of food in their diets._
----------------------------------------------------------------------------
Number of categories in the diets[36]
------------------------------------
Oceanographic region (domain) 1 2 3 4 5-7 7 8+
----------------------------------------------------------------------------
Bering Sea coastal 3 11 9 6 5 4 5
Bering Sea 2 6 5 7 0 5 0
Alaskan Stream 3 14 14 5 4 4 5
Central Subarctic 1 6 8 4 0 7 0
North American Coastal 3 14 17 6 3 4 6
Total 12 51 53 28 12 24 16
Percent total species (196) 6 26 27 14 6 12 8
----------------------------------------------------------------------------
It is readily apparent from the foregoing comparisons that much overlap
exists in the prey eaten by seabirds within each community. The
question whether real competition ever exists is academic. Competition
perhaps exists only rarely because seabirds partition resources through
use of different feeding methods, selection of different-sized prey,
and habitat zonation. Table 18 lists feeding methods (after Ashmole
1971 and Ainley 1977) and the body size and bill length of each species
considered in this review. Bill length is usually related directly to
body size (Ashmole 1968; Bédard 1969_b_), but note, for instance, that
the longer species of the two kittiwakes has the shorter bill. Body
weight would be a better measure of relative size than body size, but
few reliable weight data are available for seabirds.
The use of different feeding methods by species in each community
grossly assigns birds to feeding at different depths. Thus, whereas
shearwaters, puffins, and small gulls (_Xema_ sp., _Rissa_ spp.)
overlap almost entirely in prey categories and even prey species, the
gulls can capture these organisms only at the surface; the shearwaters
capture them at shallow depths; and the puffins capture them at much
deeper depths. Direct field observations of this phenomenon are few but
Gould (1971) and Sealy (1973_a_) compared the diets of birds feeding
in mixed-species flocks. An example of how even finer divergence in
feeding methods helps to partition food resources has been provided by
Spring (1971) in his comparison of the two murres. Both species feed
by diving to great depths, but the thick-billed murre is able to hover
over the bottom and thereby is better able to capture benthic organisms.
Table 17. _Number of species feeding at different trophic levels
within seabird communities and habitats of the northeastern North
Pacific Ocean and Bering Sea._ A single species can be represented
in more than one level. (Trophic level I = vegetarian,
II = secondary carnivore, III = tertiary carnivore, IV = upper
level carnivore, Sc = scavenger [II-IV].)
------------------------------------------------------------------------------
Oceanic/offshore neritic Inshore neritic
------------------------- ----------------------------
Domain II III IV Sc I II III IV Sc
------------------------------------------------------------------------------
Bering Sea Coastal 11 17 1? 10 6 23 18 6 6
Bering Sea 22 21 3? 11 -- -- -- -- --
Alaska Stream 21 19 1? 12 5 28 21 6 6
Central Subarctic 23 22 3? 12 -- -- -- -- --
North American Coastal 25 24 3? 11 3 28 35 7 10
Total 102 103 11? 56 14 79 74 19 22
Proportion 0.38 0.39 0.02[37]0.21 0.07 0.38 0.28 0.09 0.10
------------------------------------------------------------------------------
Table 18. _Size relationships and feeding methods of major
species in the eastern North Pacific and Bering Sea._ (D = dive,
SS = surface seize, PP = pursuit plunge, Di = dip, P = plunge,
T = tip, x = eats seabirds, A = piracy, SP = shallow plunge.)
--------------------------------------------------------------------
Body length[a] Bill length[b] Feeding[c]
Species (cm) (mm) method
--------------------------------------------------------------------
_Gavia adamsii_ 63.5 90-91 D
_G. immer_ 61.0 80-82 D
_G. arctica_ 45.7 51-52 D
_G. stellata_ 43.5 51-52 D
_Podiceps grisegena_ 33.0 48-50 D
_P. nigricollis_ 22.9 24-26 D
_P. auritus_ 24.1 23-24 D
_Aechmophorus occidentalis_ 45.7 65-76 D
_Diomedea nigripes_ 71.1 141-144 SS
_D. immutabilis_ 71.1 102-112 SS
_Fulmarus glacialis_ 45.7 36-37 SS
_Puffinus carneipes_ 45.7 41-46 PP
_P. creatopus_ 45.7 41-46 PP
_P. bulleri_ 38.1 38-45 PP
_P. griseus_ 40.3 41-42 PP
_P. tenuirostris_ 38.1 31-32 PP
_Oceanodroma furcata_ 19.0 15 Di,SS
_O. leucorhoa_ 19.0 16 Di,SS
_Pterodroma inexpectata_ 29.2 26-27 SS
_Phalacrocorax auritus_ 68.6 55-57 D
_P. penicillatus_ 73.7 66-71 D
_P. urile_ 71.1 54-55 D
_P. pelagicus_ 55.9 47-50 D
_Pelecanus occidentalis_ 104.0 294-319 P
_Branta_ spp. _(bernicla)_ 43.5 33-36 T
_Philacte canagica_ 45.7 37-42 T
_Anas_ spp. 40.0 32-35 T
_Clangula hyemalis_ 38.1 25-27 D
_Histrionicus histrionicus_ 30.5 25-28 D
_Polysticta stelleri_ 30.5 37-43 D
_Somateria mollisima_ 43.5 45-55 D
_S. spectabilis_ 40.3 31-33 D
_S. fischeri_ 38.1 22-26 D
_Melanitta deglandi_ 35.6 41-44 D
_M. perspicillata_ 40.3 ca. 40 D
_M. nigra_ 35.6 42-47 D
_Mergus serrator_ 40.3 45-54 D
_Haliaeetus leucocephalus_ 80.0 52-54 X
_Falco peregrinus_ 37.5 21-25 X
_Phalaropus fulicarius_ 16.5 22 SS
_Lobipes lobatus_ 15.2 22 SS
_Stercorarius pomarinus_ 43.5 40 SS,A
_S. parasiticus_ 40.3 32 SS,A
_S. longicaudus_ 38.1 29 SS,A
_Larus hyperboreus_ 61.0 55-60 SS
_L. glaucescens_ 55.9 54-58 SS
_L. occidentalis_ 53.0 54-57 SS,Di
_L. argentatus_ 50.8 48-54 SS,Di
_L. californicus_ 43.5 45-50 SS,Di
_L. heermanni_ 38.1 42-46 SS,Di
_L. canus_ 35.6 34-36 SS,Di
_L. philadelphia_ 27.9 30-31 Di
_Rissa tridactyla_ 34.2 39-40 Di
_R. brevirostris_ 38.1 29-30 Di
_Xema sabini_ 27.9 26-27 Di
_Sterna paradisaea_ 38.1 31-33 Di,SP
_S. hirundo/forsteri_ 35.6 36-39 Di,SP
_S. aleutica_ 33.0 33 Di,SP
_Uria aalge_ 35.6 43-47 D
_U. lomvia_ 35.6 39-42 D
_Lunda cirrhata_ 31.8 57-60 D
_Fratercula corniculata_ 29.2 49-51 D
_Cerorhinca monocerata_ 29.2 34-35 D
_Cepphus columba_ 26.7 32-33 D
_Brachyramphus marmoratus_ 20.3 15 D
_B. brevirostris_ 19.0 10 D
_Synthliboramphus antiquus_ 20.3 13 D
_Ptychoramphus aleuticus_ 17.8 19 D
_Aethia pygmaea_ 16.5 8-9 D
_A. pusilla_ 13.3 8 D
_A. cristatella_ 17.8 11 D
_Cyclorrhynchus psittaculus_ 18.4 15 D
--------------------------------------------------------------------
The scavengers (generalists) offer a good example of how a range of
bird and bill sizes is usually represented among species having similar
diets and feeding methods. The progression of oceanic scavenger sizes
is graded rather evenly from the black-footed albatross down to the
northern fulmar, to the scaled petrel, to the storm-petrel. All these
species capture prey that occur only at or near the water surface.
Recently Sanger (1973) reported appreciable numbers of glaucous-winged
gulls _(Larus glaucescens)_ and herring gulls _(L. argentatus)_,
noted neritic scavengers, out in the oceanic realm of the petrel.
He presented limited data that suggested an overlap between the
diet of these gulls and that of black-footed albatrosses, as noted
by Miller (1940). It would not be surprising if these gulls were as
much generalists in the oceanic habitat as they are in the neritic.
Interestingly, their bill and body sizes fall between those of the
albatross and the fulmar, thus in theory enabling them to invade the
oceanic habitat without great competition. It is likely that their
invasion occurred during historical times and is related to their habit
of following fishing boats from shore out to sea (Sanger 1973). If so,
the gulls might be assuming from other species part of a previously
uncontested resource.
Another interesting group of species that shows close similarities
in diet consists of the piscivorous loons, grebes, and mergansers.
All these birds, including seven or eight species, apparently feed on
fish occurring on or near the bottom in the inshore neritic habitat.
Again, however, an even progression in size exists: yellow-billed
loon _(Gavia adamsii)_, common loon _(G. immer)_, arctic loon
_(G. arctica)_, red-throated loon _(G. stellata)_, western grebe
_(Aechmophorus occidentalis)_, red-necked grebe _(Podiceps grisegena)_,
and common merganser _(Mergus merganser)_. Most likely then, they
select different-sized fish. Another example of this phenomenon is
provided by the eight neritic gulls, which are largely scavengers and
show a remarkably even progression in bill and body size. Finally, as
shown clearly by Bédard (1969_a_, 1969_b_) and Harris (1970), alcids of
different sizes select different-sized prey, often of the same species.
A final important way in which seabirds partition available resources
is by inhabiting different zones. Zonation is especially evident during
the breeding season when species common to the same breeding site
sort themselves out according to the distances they range for food.
This phenomenon was discussed by Murphy (1936), Shuntov (1974), Sealy
(1972), Cody (1973), and Scott (1973).
Trophic Relations and Seabird Conservation
The species that appear to have specialized food habits (if further
research confirms that indeed they do) are probably very sensitive
to vagaries in food availability or are, at least, much more
sensitive than other species. Some specialists which also have very
restricted distributions would, therefore, be susceptible to localized
catastrophes occurring where specialists are concentrated around the
food resource. This is proved in the case of the scoters, which are
both specialized and rather restricted to nearshore beds of molluscs
and have fallen victim to local oil slicks (Smail et al. 1972). An
example of another potentially critical situation is that of the black
brant, which at certain times of the year concentrate their entire
population around eelgrass beds in Bristol Bay, Alaska, where much
offshore oil drilling may soon occur.
Birds adapted to feed by diving, with the exception of cormorants,
spend most of their time in the water. These species are therefore
most susceptible to oiling (Smail et al. 1972), but pursuit plungers
(the shearwaters) are also highly susceptible (Point Reyes Bird
Observatory, unpublished data). A characteristic of polar and subpolar
seabird communities is the high percentage of birds that feed by
diving and pursuit plunging. These birds are mostly absent from
tropical and subtropical communities because feeding by these methods
is not adaptive there (Ainley 1977). Hence, oil pollution has all the
potential of rendering maladaptive the principal feeding methods of
many polar seabirds.
Another way in which seabird feeding relates to conservation problems
concerns competition between birds and man for commercially valuable
fishes. A related problem is the mass mortality of seabirds due to
man's fishing gear. An acute situation is the drowning of seabirds
caught in salmon gill nets (Bartonek et al. 1974; Pacific Seabird Group
1975; Ripley 1975; King et al., this volume). Immediate action is
definitely required.
Further, competition between birds and man for the same resource has
the potential for disastrous effects on bird populations if humans
out-compete the birds and overfish the resource. A classic example,
reviewed by Idyll (1973), is the possible collapse of the Peruvian
anchovy _(Engraulis ringens)_ fishery; if overfishing and an El Niño
should coincide, the Peruvian seabird populations could collapse as
well. The California fisheries and apparently the double-crested
cormorants that nest on the Farallon Islands have both suffered
from the demise of the Pacific sardine _(Sardinops caerulea)_ in
the California current (Ainley and Lewis 1974). In regulating fish
harvests, fishery organizations should include in their calculations
the harvest by creatures other than man (Schaefer 1970), rather than
evading the issue by referring to a vague "natural mortality."
* * * * *
Finally, fishing by humans can benefit seabirds by removing fish (or
whales) that compete with birds for food (Laws 1977). A potential
example is that of northern California, where salmon and seabirds both
feed heavily on juvenile rockfishes (Fitch and Lavenberg 1971; Point
Reyes Bird Observatory, unpublished data). Harvest of salmon should
theoretically leave more rockfish available for birds to eat. This sort
of situation has not yet been fully documented and definitely warrants
further study, especially in such areas as the Bering Sea, where some
fish stocks have become depressed due to overfishing (Gulland 1970).
Recommendations for Further Research
Many people realize intuitively that seabirds are important members
of marine ecosystems. Although the supporting evidence is not now
available, it will be needed if seabirds are to be protected. Emotion
alone will not justify the protection of seabirds in an age when the
human race moves steadily toward global famine. The job at hand is, in
part, to sell seabirds, not just to the public, government officials,
executives of oil companies, or fish-packing concerns, but also to
marine biologists and oceanographers, for the scientists have the best
means to study organisms at sea. We must move away from the concept
that seabirds are merely yo-yos of various sizes, shapes, and colors
on strings of various lengths that venture forth to sea from the land,
grab a quick lunch, and then return to the safety of terra firma.
Seabirds are marine organisms and deserve at least as much research
attention as that currently given marine mammals.
The information now available on seabird diets is largely presented in
terms of the number and volume of various prey species taken. Whereas
these data provide the relative importance of prey, fishery data on
prey stocks are usually measured in terms of biomass. Thus, it is
difficult to relate seabird data to the immense wealth of information
on biological oceanography. If we are to recognize the importance of
seabirds in the nutrient and energy cycling of marine ecosystems,
rather than considering them merely as "yo-yo predators," we must
relate them to the total marine community.
The goal of marine ornithologists should be to refine and broaden
considerably in detail such studies as those by Sanger (1972), Shuntov
(1974), and Laws (1977), who attempted to assess the relations
between seabird populations and stocks of other marine organisms for
the northern North Pacific, the world oceans, and the Antarctic,
respectively. The trophic roles played by seabirds must be studied in
detail at the community level year-round before those analyses can
be properly refined. Another exemplary work is that done by Brownell
(1974), who studied trophic relations of higher vertebrates off
Uruguay, including dolphins, pinnipeds, seabirds, and some large fish.
In a review study, Sanger (1974) considered the food-chain relations
of similar vertebrates in the Bering Sea. These sorts of studies will
serve to bring the role of seabirds into perspective with other upper
trophic level feeders.
Acknowledgments
We much appreciate the opportunity to participate in the symposium at
which this paper was presented. The encouragement and help given by
J. C. Bartonek was indispensable. D. G. Ainley's participation in the
symposium was supported by the Point Reyes Bird Observatory. This is
contribution No. 124 of the Point Reyes Bird Observatory.
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FOOTNOTES:
[15] Present address: U.S. Fish and Wildlife Service, Office of
Biological Services, 1011 East Tudor Road, Anchorage, Alaska 99503.
[16] Other incidental prey were squid and atherinid fishes, both at the
Farallon Islands.
[17] Other incidental prey were squid and such fishes as atherinids,
_Zaniolepis_, _Genyonemus_ and _Peprilus_ at the Farallones, and
atherinids, _Trachurus_ and _Heterostichus_ at San Diego.
[18] Other incidental prey were polychaetes at Netarts and the Farallon
Islands.
[19] Principal sources: Bent 1925; Cleaver and Franett 1945; Cottam
1939; Cottam and Knappen 1939; Kortright 1942; Mabbot 1920; McGilvrey
1967; Munro and Clemens 1939; Roberts and Huntington 1959.
[20] Other incidental items were the fish _Cololabis_ and _Peprilus_ at
the Farallon Islands.
[21] Other incidental items were myctophid fish in northeastern Canada.
[22] Other incidental items included the lamprey _(Lampetra)_ at the
Farallon Islands.
[23] Bent (1946) listed "fish" as prey.
[24] Grinnell (1897) listed "fish" as the major dietary component.
[25] Bédard (1969_a_) also listed "fish" as an incidental item.
[26] Other incidental prey were copepods and isopods.
[27] Other incidental prey were pholids in Denmark.
[28] Other incidental prey were copepods and cephalopods in North
Atlantic areas.
[29] Other incidental prey were isopods in western North America and
fish eggs near Vancouver Island.
[30] Other incidental prey were fish eggs in Denmark.
[31] Offal from wounded whales and seals, and bits of food, primarily
crustaceans and fish, from feeding whales are important scavenger foods
(Bent 1922).
[32] Other incidental prey were isopods in the North Pacific.
[33] Other incidental prey were the fish _Merluccius_ at the Farallon
Islands.
[34] Other incidental prey were isopods near the Pribilofs and in the
Chukchi Sea, and amphipods in the latter area; Bent (1921) considered
"crustaceans" to be major prey.
[35] Study conducted during period of breeding failure.
[36] These are the "food categories" of Tables 11-15. Items included in
diets are not included here.
[37] Proportion based on the arbitrary assumption that half (5) of the
11 species in question catch and eat birds at sea.
[38] Information on body sizes (length) is from Robbins et al. (1966).
[39] Information on bill lengths is from Palmer (1962), Dement'ev et
al. (1968), and Friedmann (1950).
[40] Feeding methods are from Ashmole (1971) as adapted by Ainley
(unpubl. manuscr.).
Population Dynamics in Northern Marine Birds
by
William H. Drury
College of the Atlantic
Bar Harbor, Maine 04609
Abstract
It seems only reasonable to assume that
populations of marine birds fluctuate even
when not disturbed by man; such fluctuations
would result both from the secondary effects
of species adaptive tactics and from changes
in the marine environment. I briefly review
some human activities and some other natural
processes that have resulted in changes in
numbers and distribution of seabirds and
present a short discussion of theoretical
models which emphasizes that conclusions drawn
or predictions made from models of the dynamics
of populations depend upon the assumptions
about stability that were used in preparing
the models. I then review those special
characteristics of seabirds which are directly
relevant to planning programs intended to
protect seabirds or encourage their increase
and identify several goals for improving our
understanding of the population dynamics and
biology of marine birds. My general conclusion
is that enough is already known to undertake
effective conservation programs, and that time
is pressing.
Seabirds have been categorized as renewable resources in only a few
places, although their symbolic value has been recognized for centuries
(for example, the medieval poem "The Seafarer" and the designs on Saint
Cuthbert's tunic). With the exception of the Russians (Belopol'skii
1961; Uspenski 1956), the Australians (Serventy 1967), and the
Icelanders, industrialized peoples have not considered seabirds to be
salable and therefore worth managing. Yet during many centuries the
seabirds of the northern seas were a major food for coastal and island
villages (Bent 1919, 1921, 1922; Fisher and Lockley 1954).
Some biological principles that affect the dynamics of seabird
populations are identified in this paper. I believe these principles
must form the basis of plans to maintain and increase seabird numbers.
I describe some observations of population changes, review briefly
the conflicting theoretical frameworks for population dynamics, and
identify some of the biological characteristics of marine birds that
affect the way in which population changes occur. The terms "seabirds"
and "marine birds" are used interchangeably for those bird species
which depend upon salt water for some part of their annual cycle (c.f.,
the Pacific Seabird Group).
Population Fluctuations
Broadly stated, the populations of northern seabirds have shown marked
short-and long-term fluctuations. Most authors have assumed that all
such fluctuations reflect human disturbance of the natural system,
because of the obvious effects of human predation during the last 200
years.
_Human Impact_
In the centuries before people traveled extensively between islands,
seabirds were taken in ways that we judge must have allowed the
survival of the colonies (e.g., those at the Faroes or Saint Kilda,
those in Iceland and Greenland, or those in the Aleutian Islands and
the Bering Strait). We presume either that the populations of island
peoples were regulated by shortage of resources other than seabirds
or that those who overcropped and eliminated the seabirds suffered the
consequences.
Negative Effects
When a sea-going, commodity-oriented way of life evolved, seabirds were
killed in huge numbers for such uses as the plumage trade, fish bait,
or rendering into oil (Tuck 1960; Fisher and Lockley 1954). Even the
elimination of several colonies--e.g., Funk Island, Newfoundland (Tuck
1960); Seal Island, Eastern Egg Rock, Maine (Norton 1921); Muskeget,
Massachusetts (Forbush 1929)--may have had little effect on the rate
of cropping because those who killed off one source could probably
seek out another. As the colonial seabirds became scarce they became
more valuable, which stimulated more intensive pursuit of the remnants
(Dutcher 1901, 1904).
In some places where seabird colonies did not supply a croppable
economic resource, the islands were used for alternative crops with
at least temporary commodity value (e.g., foxes were introduced in
the Aleutian Islands; Bent 1919). Large herbivores were introduced to
supply meat for island residents (e.g., Saint Matthew Island; Klein
1959), as well as pigs, cattle, sheep, goats, and rabbits on islands
in the North Atlantic and southern oceans (many authors). Increases in
many seabird populations over the last 75 years have been generally
associated with relief from predation by humans such as the fowlers,
eggers, and plume hunters of the 19th century. Such relief may have
been partly responsible for the increase of North Atlantic gannets,
_Sula bassana_, and common murres or guillemots, _Uria aalge_ (Fisher
and Vevers 1943, 1944; Cramp et al. 1974). On a smaller scale, several
population increases along the coast of New England have been recorded
following the enactment of protective legislation (Dutcher 1901, 1904;
Norton 1921, 1924; Palmer 1949; Drury 1973).
Coulson (1974) argued that in addition to relief from predation, the
explosion of the population of kittiwakes _(Rissa tridactyla)_ in this
century resulted from access to previously un-occupiable breeding
sites. Nesting cliffs and buildings suitable for kittiwake nesting are
abundant and now protected from egging or fowling.
Positive Effects
There can be little doubt that human activities have also had marked
positive effects in some cases. For example, Fisher (1952) suggested
that the North Atlantic fulmar _(Fulmarus glacialis)_ was provided
food first by whaling, then by commercial fishing, and that this food
allowed the species to increase steadily over the last 3 centuries.
The worldwide increase of gulls (_Larus argentatus_, _L. fuscus_, _L.
dominicanus_, _L. ridibundus_, _L. novae-hollandii_) has been credited
to availability of food from wasteful human garbage disposal (Murray
and Carrick 1964; Fordham 1968, 1970; Harris 1964; Harris and Plumb
1965; Kadlec and Drury 1968; Brown 1967; Mills 1973; Vermeer 1963).
It is hard to dismiss the evidence pointing to the impact of human
activities on seabird populations during the last 3 centuries. Yet
it would be misleading to assume that without man's interference
seabird populations would have remained stable. Success in designing
programs of protection and population enhancement must allow for the
realities--that seabird populations fluctuate inherently, and that
secular changes occur regularly in their environment.
_Impact of Natural Events_
Some population changes appear to result from sudden impacts; other
changes are gradual.
Sudden Disasters
Gromme (1927) reported windrows of dead murres in the Unimak Pass and
Alaska Peninsula; die-offs of murres in winter storms in the Atlantic
and Arctic Oceans were reported by Tuck (1960) and Dement'ev et al.
(1968).
Recently some mass mortalities have been associated with specific
causes. Bailey and Davenport (1972) reported that starvation caused
the die-off of common murres in the southern Bering Sea--Bristol Bay
area. Foul weather, which apparently inhibited feeding between 19
and 23 April 1970, culminated in an intense storm. Similarly in late
winter 1969 bad weather in the Irish Sea, combined with strains of
molt and perhaps contamination with industrial chemicals, seems to
have contributed to mass mortality of the same species (called common
guillemot in Britain; Holdgate 1971). The seabird victims of this
event had metabolized their body fat and as a result, polychlorinated
biphenyls (PCB) and other industrial chemicals passed into livers,
kidneys, and brains. Again, a storm at the end of a period of stress
seems to have been more than the birds could tolerate.
A further example of a die-off of waterfowl apparently brought on by
starvation was given by Barry (1968), who estimated that about 100,000
king eiders _(Somateria spectabilis)_ died when they arrived before the
ice broke up in the Beaufort Sea in spring 1964.
Diseases have produced massive die-offs in marine birds. Fowl
cholera caused high mortality in nesting common eiders _(Somateria
mollissima)_ in the Gulf of St. Lawrence in Quebec (Reed and Cousineau
1967) and in Penobscot Bay, Maine, in the early 1960's (H. Mendall,
personal communication). Poisoning from a "red tide" (a bloom of the
dinoflagellate _Gonyaulax tamerensis_) caused a die-off of black ducks
_(Anas rubripes)_ and herring gulls on the coast of New England in
1972. Similarly a die-off of shags _(Phalacrocorax aristotelis)_ on the
east coast of England was caused by a "red tide" (Coulson et al. 1968).
During a period of 1 week 90% of the shag nests on the Farne Islands in
Northumberland were deserted and about 80% of the breeding population
died.
Gradual Declines
When the new volcanic island of Bogoslov emerged in the western
Aleutians, Preble and McAtee (1923) reported that it was colonized by
large numbers of pigeon guillemots _(Cepphus columba)_, but in the
following decades the guillemots have steadily decreased (G. J. Divoky,
personal communication). As a further example, the nesting population
of Atlantic puffins _(Fratercula arctica)_ in the Atlantic has declined
over the past several years, especially those nesting on the Outer
Hebrides (Flegg 1972; Harris 1976).
It is difficult to find seabird species whose nesting grounds have
not been affected by humans but whose numbers have been censused. The
best illustrations of secular changes in relatively constant habitats
are probably those available in the British Trust for Ornithology's
breeding censuses of songbirds. Songbirds are short-lived and their
populations change on relatively short time scales. The northwestern
European landscape has remained relatively constant for the last 75
years, yet there are observable decade-long trends--for example, of
willow warblers _(Phylloscopus trochilus)_ and dunnock _(Prunella
modularis)_. There are detailed data on population changes in great
tits _(Parus major)_ through the work of Kluyver (1951), Lack (1964),
and Perrins (1965).
Effects Reflecting Environmental Change
Nelson (1966) argued that the increase of gannets in the North Atlantic
during this century has been related to increasing temperatures rather
than (as usually ascribed) to increased food from fish damaged or
escaped during commercial fishing.
Ainley and Lewis (1974) described a particularly interesting example
of the effects of environmental change on seabird populations. The
events begin with the decrease of seabirds on the Farallon Islands off
California as a result of human depredations. Even after fowling was
made illegal, the populations of murres, double-crested cormorants
_(Phalacrocorax auritus)_, and especially of tufted puffins _(Lunda
cirrhata)_ and pigeon guillemots continued to decline as a result
of oil pollution. During the last 3 decades the smaller species
of seabirds nesting on the Farallons, such as rhinoceros auklets
_(Cerorhinca monocerata)_, have increased rapidly and the authors
suggest that their increase was abetted by an increase in the small
prey fish, northern anchovy _(Engraulis mordax)_. One of course
expects predators to be affected by changes in the abundance of their
prey. During this same period, larger species of seabirds such as
double-crested cormorants and tufted puffins have failed to recover
their numbers, and the authors speculate that this failure is related
to a decrease of the larger prey fish, Pacific sardine _(Sardinops
caerulea)_.
A widely publicized impact of environmental fluctuation upon
seabird populations is that of the northeast wind, El Niño, off the
Peruvian coast. This wind pushes the upwelling Humboldt Current
water offshore and causes mass mortality in the Peruvian anchovies
_(Engraulis ringens)_ and, as a consequence, a die-off among the
millions of seabirds such as Peruvian guanay cormorants _(Phalacrocorax
bougainvillii)_ and Peruvian boobies or piquero _(Sula variegata)_
which feed upon them (Murphy 1936).
Theoretical Considerations
Can useful generalizations be drawn from these observations on
population changes? Can a model be constructed of the forces which
drive population changes or of population-habitat interactions which
keep populations from extinction? Some conflicting theories and
assumptions of population dynamics are examined and discussed below.
_The Assumption of Population Stability and of Closely Attuned
Density-dependent Mortality_
During the 5 decades before 1970, it was widely accepted that most
animal populations were generally stable and saturated before the
arrival of the white man. Although a few field biologists vigorously
dissented, "establishment" ecologists regarded fluctuations as a
departure from the norm, and as such, a hazard to the population.
Many theorists of both evolution and ecology argued that adaptations
were required to damp fluctuations or the fluctuations would become
"random walks" and the population would rapidly become extinct. As a
consequence, relatively all theoretical models included stability as a
central assumption.
• The basic element of this theoretical complex has been the
Lotka-Volterra formula for a logistic curve of population growth and
stabilization. According to this formula it has been reasoned that
by establishing the inherent rate of increase of a population (i.e.,
its average natality relative to mortality, or _r_) and by measuring
the carrying capacity of the environment (which is the density of
the population at saturation, or _K_), one can predict the maximally
productive population size, and maximum rate of production of new
individuals (or maximum sustained yield). These assumptions have
supplied the theoretical framework for virtually all game management
and many fisheries practices.
Once stability was assumed, a mechanism for maintaining stability was
necessary. This mechanism was found in an interaction between the
population and the environment, called density-dependent mortality
(Nicholson 1933). The impact of this feedback has been assumed to cause
the point of inflection of the "sigmoid curve" and to regulate the
density "at equilibrium."
Populations growing in relatively isolated or closed systems have been
observed to follow a sigmoid curve toward a steady state. We have data
on the growth of several Massachusetts gull colonies which show this
type of short-period rapid increase followed by a long sequence of
shallow oscillations (Drury and Nisbet 1972). But usually observations
have been terminated at about the time the population passed through
the point of inflection.
• Lack (1954) accepted the principles formulated by Lotka-Volterra
and hence viewed Nicholson's (1933) density-dependence as logically
necessary. Lack (1948, 1954) argued that reproductive effort (clutch
size or litter size times the number of broods) must be as large as
the parents can successfully raise to independence because these
biological characteristics are directly subject to natural selection.
He argued that because reproductive potential is excessive (Darwin
1859), mortality must be density-dependent if a population is to avoid
fluctuations. The only adequately density-dependent regulating process
he accepted was the population's response to its food supply (Lack
1954). In fact, for many years Lack rejected Kluyver and Tinbergen's
(1953) hypothesis that territory could act as a control on population
size in birds because, he argued, territories were compressible and
therefore allowed wide fluctuations. To his credit, however, Lack
eventually acknowledged this mistake.
The first defect in the concept of "carrying capacity" is the idea that
populations have "mechanisms" or "institutions" (Wynne-Edwards 1959)
by which the population is kept stable at the carrying capacity in a
stable habitat.
The second defect in the concept of carrying capacity is that it
presupposes a stable environment. During the early decades of the 20th
century most climatologists believed that a departure from the norms
of a regional climate set processes in motion which would return the
climate to normal. During the last decades, however, climatologists and
oceanographers have shown clearly that environments are continuously in
flux.
_An Attack on Density-dependent Mortality_
Some theorists rejected the concept of carrying capacity as soon as it
was formulated. Andrewartha and Birch (1954) predicted fluctuations
would be undamped by inherent population mechanisms but rather would
be controlled by external forces indifferent to the density. Their
supporting data were drawn from field studies of insects in arid
climates. Some of their ideas are directly relevant to seabirds; for
example, their assertion that in many cases limits to carrying capacity
of the habitat are not set in a way responsive to the density of the
population. The number of occupiable ledges on a seabird cliff are
fixed and when they are full no more birds can breed there regardless
of the amount of food available. For another example, some biological
processes act in a way that reinforces fluctuations. Predation can
act in this way in the relatively closed system of a seabird colony;
i.e., the smaller the prey population the larger the percentage taken
by the predators. The importance of predation as a selecting factor is
shown by the adaptations marine birds and waterfowl make to avoid it.
The fact that large colonies of seafowl are usually concentrated on
isolated, predator-free islands is one obvious case (Lack 1966).
Although their ideas are useful in understanding changes in many
species, primarily insect populations, the generality of Andrewartha
and Birch's (1954) hypothesis is weakened because it conflicts with
detailed studies of seabirds which show that in many cases local food
resources do limit breeding success. Ashmole (1963) showed this for
tropical terns, and Hunt (1972) for some colonies of herring gulls
on the New England coast. Nettleship (1972), studying the effects of
herring gulls on Atlantic puffins, showed that the effect of harassment
and stealing food from the parents was to reduce the amount of food
brought to the young and thus reproductive success. In those parts
of the colony where gulls were numerous or where the puffins were at
a disadvantage in escaping from gulls (i.e., flat rather than steep
slopes) the reproductive success of puffins was significantly lower
than in areas away from the gulls.
The literal application of Andrewartha and Birch's general ideas also
conflicts with observations on subtle adaptations some waterfowl have
made to counter predation.
Barry (1967) described the density-avoiding adaptations of
arctic-nesting geese to evade predation--specifically by foxes. Black
brant _(Branta nigricans)_ nest on low coastal or delta islands seeking
to escape by remoteness. Snow geese _(Chen caerulescens)_ are colonial
on large, flat areas, seeking protection in numbers. White-fronted
geese _(Anser albifrons)_ are solitary nesters on inland swamps,
seeking to be "over-dispersed" among scrub willow.
Common eiders, black scoters _(Melanitta nigra)_, tufted ducks _(Aythya
fuligula)_, and other ducks select gull colonies as nesting habitat.
Although there is little doubt that the ducks choose gull colonies for
nesting, there is some doubt as to the reasons. Finnish biologists
(summarized by Bergman 1957; Hildén 1965) have concluded generally that
gulls protect the duck nests from predation by hooded crows _(Corvus
corone)_.
_The Assumption that Fluctuations Are Generally Present_
Recently theorists have built models based on assumptions that
fluctuations are a general characteristic of population dynamics,
such as Gilpin's (1975) model describing multi-phased oscillations.
He took account of the fact that fluctuations (and models) become
more complex as more species and nonlinear effects are included. May
and Leonard (1975) emphasized that the effect of nonlinearities is
to make it impossible to speak even in principle of the equilibrium
point of a community. They pointed out that even though the model is
deterministic (i.e., assumes that the system will come to equilibrium)
the oscillations are so complex that they may appear to be random, and
it may be a very long time before the system returns to a position
near its starting point. "On the other hand a truly random ecological
system could always be fitted by a suitably ingenious limit cycle. This
suggests that ecological analysis which does not consider component
processes must be viewed with great suspicion" (Gilpin 1975). May
and Leonard (1975) and Gilpin are both making a familiar point--that
neither the logic nor the interactions described in a formula will
describe biological reality unless the assumptions are correct. They
are also making a different point--that an ingenious mathematician can
create a formula to describe almost any operation (whether its workings
are systematic or random), and the formula may seem to work.
Gilpin's moral is that one cannot learn very much that is helpful by
studying fluctuations as such. One must study the factors controlling
populations. This is a very old idea.
It would appear that defining carrying capacity and inherent rate of
increase will not be very instructive in managing seabird populations
other than in speculating upon what might be ideal upper limits.
It can also encourage the musty sophistry that when a population
increases beyond this abstract carrying capacity it "needs" to be
hunted to prevent overcropping resources and damage to itself through a
population decline. But we will not have the time to carry out detailed
studies of life histories seeking for critical population-habitat
interactions over several fluctuations for each species involved in a
disaster before designing programs to help seabird populations to build
up their numbers.
General Characteristics of Marine Birds and Waterfowl
Because general theory does not seem to work and because detailed
studies take too much time, I conclude that it is necessary to identify
certain general principles upon which to base applied programs. These
categories of knowledge include: (1) how vulnerable certain categories
of seabirds, waterfowl, and shorebirds are to specific types of
disasters, (2) how quickly their numbers build up after they have been
reduced, and (3) at what stages we can help them best (i.e., at the
breeding grounds, at the winter gathering grounds, or on migration). I
believe that we already know enough to design effective programs and to
begin work. To this end some characteristics of seabirds are identified
which determine the population structures and ways in which their
numbers respond to changes in the environment.
_Habitat_
Although the shallow oceans, islands, and seashores are among the
most permanent features of the earth in general, the details of
their numbers and distribution change rapidly. Sandy shores are
obviously being reworked even in the short span of a single lifetime.
Distribution of islands and the sediment load, extent, and strengths of
currents vary constantly in space and change with time.
The food that seabirds use is patchy and subject to both short-and
long-term fluctuations in numbers and shifts in geography. Suitable
breeding habitat is scattered, and in many places where oceanic
conditions provide a good food supply there are no nesting sites.
Consequently, seabirds aggregate in colonies, often dense, and the
colonies are clumped for geographical as well as biological reasons.
Lack (1966) discussed some general features of how the breeding
adaptations of seabirds are adjusted to the distances the birds
must go to find food. The species which feed close to the nest
characteristically establish isolated territories or nest in small
groups, and they accept many different kinds of nesting substrate.
Their clutch sizes are large, individuals move nesting sites readily,
and their young grow rapidly compared to the species which feed far at
sea. Species which feed far at sea aggregate in large colonies. These
species are often rigid in their requirements for suitable nesting
sites, their clutches are usually limited to one egg per season,
their young grow slowly, and there seems to be strong attachment to
traditional colony sites.
_Breeding_
Ashmole (1963) suggested that the clutch size of some oceanic birds is
small and colonies occupy only part of the available habitat because
food resources within efficient commuting distance of the breeding site
are limited. We can see this effect in the usual failure of common
terns to raise a third chick, even in the colonies that are surrounded
by favorable habitat (Nisbet 1973). Herring gulls whose colonies are
close to sources of human refuse raise more young than do those whose
colonies are at some distance (Drury 1963; Kadlec and Drury 1968; Hunt
1972).
Ashmole (1963) suggested that during the course of the breeding
season the birds exhaust the available food supply. The validity
of this suggestion is reflected in the long distances some species
(petrels, boobies, murres, dovekies) go for food to feed their young.
One would therefore expect that early nesting pairs would be more
successful, and this seems to be the case in herring gulls (Nisbet and
Drury 1972), kittiwakes (Coulson 1966), and red-billed gulls, _Larus
novaehollandiae_ (Mills 1973).
If food is in short supply and parents have to seek over a wide area
for food so that they can bring back only a little food at long time
intervals, one would expect these birds to have a small clutch and
their young to grow slowly, as is the case. One would also expect
seabird colonies situated near oceanic currents to be larger and more
successful because food is continuously renewed. Conversely, one would
expect colonies next to still waters to be smaller and less successful.
The small clutch size of seabirds means that when a population has
been reduced, it will grow slowly toward its former abundance. The
growth rates of seabird populations on the New England coast since
their release from human predation reflects this. Species such as black
guillemots with only two eggs per clutch and herring gulls with three
eggs per clutch have increased more slowly than have the populations of
common eiders or double-crested cormorants both with three to six eggs
per clutch (Drury 1973).
If the species that nest in colonies show a high degree of site
tenacity, they are not likely to reestablish a colony after it has
been eliminated. An exception to this is the food subsidy provided
by man, which seems to have been important in creating a nonbreeding
population of herring gulls large enough to form a "critical mass" for
the formation of a new gullery.
_Age Structure_
Because the main element of population size--the number of breeding
adults--is limited by the number of breeding colonies and the food
available to those colonies, one assumes that the total numbers of
seabirds is much less than could be supported by the larger areas
of productive oceans. Hence one suspects that there is lessened
competition for food outside the breeding season and that lack of
competition for food is a major reason for seabirds being long-lived,
often to extremes little suspected until recently. Mortalities of
10-12% per year are common, and some as low as 4% (wandering albatross,
_Diomedea exulans_; Tickell 1968) have been recorded.
In contrast, songbirds with large clutches, such as the titmice studied
by Kluyver (1951), produce a large number of young with whom they and
other adults must compete for food during the winter period of food
shortage. Because the titmice are permanent residents, they occupy all
of the available habitat throughout the year. Hence titmice suffer
intense intraspecific competition, which shortens the survival of
adults. Kluyver's experiments (1966) with nest boxes used by a closed
population of great tits on Vlieland, The Netherlands, showed that by
artificially reducing clutch size the survival of adults was increased.
Similar competition for the few territories available on marshes and
consequent shortened life expectancy, can be expected in waterfowl with
large broods. The effect should be less marked for geese with smaller
clutches that nest in less confined habitats.
The long life span of seabirds means that a population will have a
large component of older age categories; this characteristic has
several implications:
• It means that the population can survive years of reproductive
failure without the observable immediate effects that would be
manifest in titmice, grouse, or rabbits. Near failure of reproduction
during a breeding season among arctic seabirds at Bear Island was
reported by Bertram et al. (1934). Many similar observations have been
made since then: Pitelka et al. (1955) reported such a case among skuas
and gulls at Point Barrow, Drury (1961) for greater snow geese _(Chen
cerulescens atlantica)_ at Bylot Island, Jones (1970) for black brant
gathering at Isambek Lagoon on the Alaska Peninsula, and D. A. Snarski
(personal communication) for kittiwakes at Cook Inlet. Reproductive
failure can sometimes be chronic, as observed by Nisbet (1972) for
terns at Cape Cod, Massachusetts, or by Drury (1963) and Hunt (1972)
for herring gulls on the outer islands on the coast of Maine.
When reproductive failure becomes chronic as observed on peregrine
falcons _(Falco peregrinus)_ by Hickey (1969) and in ospreys _(Pandion
haliaetus)_ by Ames and Mersereau (1964), the population of adults may
hold on for a number of years without evident decline. Damage to the
structure of the whole population may be serious before any numerical
results are evident.
• Although there may not be intensive competition for food in the
habitat away from breeding colonies, there is intense competition for
food and breeding sites at and around the colonies. Hence age and
previous experience in seabirds assume importance in establishing
territory and in breeding success. Associated with this is the tendency
for immature birds to delay breeding until they are several years old
and for the immatures to remain on feeding grounds at some distance
from the colonies. In some cases young birds may "hang around" breeding
colonies and even feed some of the young. When young birds do first
breed they usually lay smaller clutches and raise fewer young than do
older birds. The importance of age and experience upon breeding success
has been well documented for kittiwakes (Coulson 1966) and red-billed
gulls (Mills 1973).
The fundamental biological importance of this delayed maturity seems
to be emphasized by the persistence for several years of immature
plumages, so clearly identifiable that even a human observer can
recognize the age of an individual. One assumes such an evident feature
must have adaptive significance.
_Wintering Grounds_
When colonial nesting seabirds leave their breeding islands for their
wintering grounds, their identification with that island is lost as far
as population effects are concerned, because birds from many colonies
mingle on the wintering grounds. Major mortality takes place on the
wintering grounds and must therefore act on the species population
as a whole rather than differentially on individuals associated with
especially dense colonies. Such a direct relation between colony
density and mortality would be necessary for density-dependent
mortality to regulate the number of birds on a breeding colony.
Conversely, one cannot expect that all colonies will decrease equally
because mortality should be equally distributed if all the population
gathers on a common wintering ground. Thus density-dependence acts only
in a very general way upon the sum of animals considered as an abstract
entity--the population.
In fact, on the wintering grounds, as shown by a graph of numbers of
gulls reported on Christmas Counts on Cape Cod, Massachusetts (Kadlec
and Drury 1968), herring gulls are very responsive to local conditions
and move several tens of miles to gather at favorable feeding sites.
An aerial survey of the gulls on the East Coast of the United States
(Kadlec and Drury 1968) showed that more than half of the gulls were
gathered near major food sources in large metropolitan districts.
Most of the remainder were gathered near small fishing ports. Very
few were scattered along the shoreline in what one assumes is the
traditional gull habitat. Later analyses of the relation between the
distribution of banding recoveries of birds in their first winter and
the distribution of immatures as found on this winter census (Drury and
Nisbet 1972) suggested that proportionately more first-year gulls died
in those areas where the birds were sparsely distributed than died in
the crowded metropolitan areas.
These results suggest both that there is not a direct feedback
between reproductive rate and mortality, and that mortality may even
be inversely density-dependent on wintering grounds. This last runs
counter to traditional ecological ideas that density causes a change
in mortality rate. The idea that individuals gather where "living is
easy" and mortalities are low is consistent with the theory of natural
selection. One would not expect the food of the gulls to be evenly
distributed, and one would expect individuals to move away from areas
where food is scarce and mortality is high.
_Differences in Breeding Success Between Colonies_
Breeding success has been shown to vary among individual pairs of
gulls (Drost et al. 1961). Certain groups of individuals nesting in
patches within a single colony have greater breeding success than do
others (Coulson 1968; Drury and Nisbet, in preparation). Differences
in breeding success also occur between colonies (Frazer-Darling
1938; Kadlec and Drury 1968; Drury and Nisbet 1972). Some colonies
reproduce consistently better than others--for example, the gull
colonies close to fishing ports and metropolitan areas. Other colonies
produce consistently fewer young, such as the colonies on the outer
islands in the Gulf of Maine (Drury 1963; Kadlec and Drury 1968; Hunt
1972). The populations of successful colonies grow while the numbers
of unsuccessful colonies decline, even during a period of general
population increase (Kadlec and Drury 1968).
The difference between success and failure, growth and decline,
appears to lie in the food available. Colonies increase where breeding
success is high and decrease where breeding success is low. One
important reason seems to be that adult gulls may move to a more
productive colony even after they have nested with another colony
(Drury and Nisbet 1972; Kadlec 1971). Such adaptations can be viewed
as adjustments by which individuals meet the requirements of an
environment in which the availability of food and other necessities is
patchy and shifting.
_Dispersal_
In general terms, the willingness of some individuals to disperse while
the majority of individuals remain loyal to a colony can be considered
a major mechanism of population maintenance. If conditions deteriorate
seriously at one place so that the local populations decline or
disappear, dispersal from other centers can be expected to repopulate
the area as soon as local conditions again become suitable. This
subject has been treated in more detail by Drury and Nisbet (1972) and
Drury (1974_b_).
Occupation of new, or return to former, nesting sites has been recorded
in detail for fulmars _(Fulmaris glacialis)_ by Fisher (1952) and for
herring gulls by Kadlec and Drury (1968). Dispersal is also known for
waterfowl. Hansen and Nelson (1957) reported that of some 8,000 brant
banded in midsummer on the Yukon delta 8 were recovered in northern
Siberia and 28 in northern Alaska and arctic Canada. They suspected
that pairing on the wintering grounds was responsible for the change in
breeding areas, a change that would not be expected among other North
American species of geese. Similarly, wide dispersal seems to occur
in pintails _(Anas acuta)_, mallards _(Anas platyrhynchos)_, and wood
ducks _(Aix sponsa)_.
The general tendency for some individuals to disperse and the frequency
of "extra limital" breeding attempts is especially well established in
the Bering Sea region, in part at least because vagrants from Siberia
or North America are readily identified as such. In the Aleutian
Islands, Emison et al. (1971) and Byrd et al. (1974) have enumerated
the nesting vagrants. For the Pribilof Islands, Kenyon and Phillips
(1965), Sladen (1966), and Thompson and DeLong (1969) have recorded the
repeated appearance of birds of Siberian distribution, and Fay and Cade
(1959) and Sealy et al. (1971) did the same for St. Lawrence Island.
One can conclude that a few individuals are constantly trying to
settle in new geographical areas. As climatic and habitat conditions
change, some populations are able to become established; for example,
southern species such as mockingbirds _(Mimus polyglottus)_, cardinals
_(Cardinalis cardinalis)_, and tufted titmice _(Parus bicolor)_ have
settled in southeastern New England during the last 2 decades. These
southern species have received much publicity. But at the same time,
a less publicized dispersal of white-throated sparrows _(Zonotrichia
albicollis)_, hermit thrushes _(Catharus guttatus)_, and dark-eyed
juncos _(Junco hyemalis)_ has resulted in new nesting records of more
northerly species, also in southeastern New England.
The ability (or lack of ability) of some organisms to expand their
ranges over time has been a subject of consideration for a number of
years by plant and animal geographers. An important botanical paper on
this subject in the Bering Sea region was presented by Hultén (1937),
who analyzed the ranges of plants of the area of Kamchatka, eastern
Siberia, Alaska, and northwest Canada, showing that diverse floras
occur in some restricted geographic areas. He called these areas
"refugia," and postulated that many species had survived Pleistocene
glaciations in them because these refugia remained ice-free. He, like
Fernald (1925), was puzzled as to why only certain species had been
able to expand their ranges outward from these "areas of persistence,"
while other apparently more "conservative" species were unable to do
so. Similarly, there appear to be conservative endemic bird species
of the Bering Sea region: the extinct Commander Islands cormorant
_(Phalacrocorax perspicillatus)_, Steller's eider _(Polysticta
stelleri)_, spectacled eider _(Lampronetta fisheri)_, emperor goose
_(Philacte canagica)_, whiskered auklet _(Aethia pygmaea)_, least
auklet _(A. pusilla)_, parakeet auklet _(Cyclorrhynchus psittacula)_,
Aleutian tern _(Sterna aleutica)_, red-legged kittiwake _(Rissa
brevirostris)_, bristle-thighed curlew _(Numenius tahitiensis)_,
long-billed dowitcher _(Limnodromus scolopaceus)_, surfbird _(Aphriza
virgata)_, black turnstone _(Arenaria melanocephala)_, rock sandpiper
_(Calidris ptilocnemis)_, and western sandpiper _(C. mauri)_.
The ranges of horned puffins _(Fratercula corniculata)_, Kittlitz's
murrelet _(Brachyramphus brevirostris)_ and, perhaps, crested auklet
_(Aethia cristatella)_ suggest that some species of "Beringian"
seabirds have expanded their ranges from Hultén's (1937) "refugia."
_Dispersal and Regional Persistence of Marginal Populations_
The presence of several sub-elements of a species population and,
therefore, the opportunity for dispersion among alternative breeding
sites may be an important factor in the regional persistence of a
species on the margin of its range, as illustrated by the history of
laughing gulls _(Larus atricilla)_ in New England.
Between 1875 and 1900 there were fewer than 50 laughing gulls in
Massachusetts (Mackay 1893) and about 35 in Maine (Norton 1924). In
Massachusetts the laughing gulls all settled on one large island,
Muskeget, where by 1940 there were about 20,000 pairs (Noble and Würm
1943). Meanwhile, in Maine the population had been disturbed by sheep
and men and had shifted about among seven islands. The Maine population
grew to only about 350 pairs by 1940 (Palmer 1949).
The laughing gull population in both States has decreased since 1940.
In Massachusetts, where all pairs occupied one island, the population
had fallen to about 250 pairs by 1972, but the Maine population, still
divided into five colonies, stabilized at 250 pairs (i.e., the same as
instead of only 1% of the Massachusetts population).
Use of General Principles in Solving Conservation Problems
Game biologists have successfully maintained the populations of hunted
animals by using a number of classical principles of game management.
They have controlled mortality by regulating kill and have increased
standing stock by improving habitat on a local scale. This seems to
have worked in species which are short-lived, have large clutch sizes
or litters, and which occupy mosaics of highly productive "successional
habitat." Seabirds, however, contrast with these species in a number
of important biological characteristics. They have small clutches,
postpone breeding until they are several years old, and are subject to
periodic or chronic reproductive failures. Therefore, their populations
are skewed toward older animals and replacement of lost individuals
is slow. Many seabirds, like some geese, have a high level of site
tenacity and thus may resist recolonization or fail in the attempt to
recolonize a breeding site once eliminated from it. In those species
studied it appears that the breeding birds at a small percentage of
colonies are responsible for a large proportion of the annual crop of
young. It is probably dangerous, therefore, to risk either damage to or
elimination of well-established colonies.
Studies of kittiwakes by Coulson and White (1958, 1961), sooty terns
_(Sterna fuscata)_ by Ashmole (1963) and Harrington (1974), Atlantic
puffins by Nettleship (1972), and Cassin's auklets _(Ptychoramphus
aleutica)_ by Manuwal (1974), and the practice of eider "farming" in
Iceland indicate that the number of available territories or breeding
sites may limit the size of a population and that populations can be
increased by increasing the number of sites available. This suggests
one way in which direct steps can be taken to encourage the numbers of
breeding seabirds. Other studies indicate that seabirds will move into
synthetic habitat such as created by the window ledges on buildings
(Coulson and White 1958) or the islands created by dumping spoil from
channel dredging operations (Buckley and Buckley 1971, 1975; Soots and
Parnell 1975).
Most generalizations of population biology have been derived from the
study of insects, songbirds, or game species. It seems inadvisable
to assume that those principles will apply to seabirds without
modification. For example, predation by gulls and ravens may have a
disastrous effect on a seabird colony at low colony density but have
progressively less impact as the colony size and density increase. Fox
predation may have important effects over most ranges of prey density
because the presence of foxes has important psychological effects.
The habitats of seabirds include elements in which birds are widely
dispersed (feeding areas) and others in which birds are crowded
and narrowly localized (nesting sites). Thus effective programs of
conservation should include guarantees that a number of colony sites be
available in as widely dispersed a pattern as possible. Each productive
feeding ground should, if possible, have several colony sites available.
We have argued elsewhere (Drury and Nisbet 1972; Drury 1974_a_) that
one of the chief defenses any population has against extinction is
the combination of being divided into a number of population centers
with having some movement of individuals between the centers, but not
too much. Because it is highly improbable that a single catastrophe
will affect more than a part of a species' range at any time, the more
numerous and widely scattered the partially independent segments of a
population are, the better the species is insured against extinction.
This, of course, suggests that the size of each colony may be less
important for long-term survival than is the total number of colonies.
One intuitively concludes that "conservative" species, such as those
endemic to the Bering Sea region (whose dispersal and colonizing
mechanisms seem to be poorly developed), are especially vulnerable
to the effects of local population crashes. These "local" species
therefore deserve special consideration.
I would like to emphasize two points to be included in designing a
"management" program:
• It seems that the most promising management techniques will be built
upon ensuring the health of colonies and the associated feeding areas
at which reproductive success is high enough to "export" young. Thus
it is useful to identify those colonies which are exporting young and
to give special care to their preservation. As populations of prey
species change locally, so will the success of the local nesting birds.
A colony which is thriving at one time may be barely maintaining itself
at another (Ainley and Lewis 1974), or it may decrease, as in the case
of "guano birds" during El Niño years in the Peru Current.
• Because centers of abundance of marine birds shift (Fisher 1952;
Drury 1963, 1974_a_), it will be prudent to plan for large areas
and over long periods of time. Harrison Lewis, a pioneer in seabird
management in eastern Canada, said (personal communication) that just
as soon as he got approval of a new seabird sanctuary through the long
corridors of the distant government bureaucracies in Ottawa, the birds
would move to a new island and he had to start the process all over
again.
The objective is to maintain a variety of colony sites for populations
to move among as local patterns of productivity in the shallow sea
shift.
Goals for Research on Population Dynamics of Seabirds for Purposes of
Conservation
1. To learn the distribution and relative importance of seabird
colonies, the number of pairs nesting and nonbreeding individuals
at each colony, and the timing of breeding activities for each
geographical region. The most important step toward conserving marine
birds is to get public ownership and protection for their breeding
grounds.
2. To understand the life cycle of key species. Three needs are clear:
a. To identify key species whose biological characteristics can
conveniently be studied and measured. Studies of these species may be
useful in monitoring the "health" of seabird breeding areas.
If it is established that the reproductive success of certain species
varies similarly in response to changes in their marine habitat (such
as black-legged kittiwakes and horned puffins), one could use key
species (black-legged kittiwake) to assess the performance of those
species in a colony whose breeding success is difficult to measure
(horned puffin).
b. To develop efficient and practical ways of censusing and measuring
productivity of crevice-, scree-, and hole-nesting species such as
puffins and auklets.
c. To establish annual differences in reproductive success and
mortality rates by age classes of the key species, and from these to
identify rates of population turnover so as to be able to predict the
effects of mass mortalities.
3. To learn enough about the differences in behavior and productivity
among colonies to establish which colonies produce surplus young and
which have low productivity. At first, maximum efforts for conservation
should be concentrated at those sites which produce surplus young.
4. To learn about colonial behavior. Two needs are apparent:
a. To know enough about the lives of individually marked birds of known
age so as to be able to infer the behavior of population elements at
all stages of their life cycle.
b. To know enough about the lives of subadult birds to understand
what proportion of subadults visit and become established at breeding
sites, why the subadults visit the breeding sites and what effect their
presence has on the territories and breeding success of their neighbors
and biological relatives.
5. To know enough about places where seabirds, waterfowl, and
shorebirds gather on migration and during the winter to identify
those areas which need special protection from effects of economic
development.
a. It is important to determine the areas where marine birds gather at
sea when they are away from their breeding grounds. What factors of
habitat and food supply make certain places preferable to others? What
is the relation between gathering grounds and underwater topography
(banks and edges of the continental shelf)? What are the seasonal and
annual differences in preferred gathering grounds? What special hazards
exist, such as unusual extent of sea ice or exceptional storms?
b. It is important to plot coastal areas where waterfowl and shorebirds
gather on migration, for molting, and during the winter. Which open
leads in the ice and patches of open water at the mouths of rivers
are of especial importance in spring? What shorelines and beaches act
as "leading lines" during migration? Which capes and points result
in concentrated overflights of migrating waterfowl, and hence are
locations of unusually high kills by hunters? What wetlands, bogs,
coastal ponds, lakes, and lagoons are used as gathering grounds and
to what extent do waterfowl and shorebirds exchange between gathering
grounds? How much redundancy of wetlands is needed to make the wetlands
system maximally productive for waterfowl and shorebirds?
Answers to these questions will identify which geographic areas deserve
special protection during development. The answers will also identify
the kinds of influences which might lower the contribution of each
critical area to the survival of seabirds, waterfowl, and shorebirds.
Areas identified as important under these categories must be included
in policy decisions related to land-use planning and management.
6. To learn more about the effects of varying quantities of food on
breeding behavior and performance:
a. What are the effects of food abundance in early spring on date of
laying, clutch size, and egg size?
b. What effects do storms have at different stages of the reproductive
schedule?
c. What effects do quantitative and qualitative (species composition of
prey) changes in food supply have on the survival of chicks?
d. What are the similarities and differences between what parents eat
and what they feed their chicks?
Although this is important basic biological knowledge, it contributes
little to conservation efforts because food differences result from
changes in the ocean over which humans can have little effect.
7. To learn more about prey species and their availability to marine
birds:
a. To know more about the breeding areas, reproductive rates, growth
rates, and routes of dispersal of the major prey food species. In most
areas a few species of teleost fish (e.g., _Ammodytes_) or Crustacea
(e.g., copepods, euphausids, mycids, or amphipods) make up most of
the food of marine birds. Yet, the barest minimum is known about the
biology of such species. A good first estimate of the "condition" of
the marine environment can probably be made by measuring reproductive
rates and growth rates of these key prey species. Hence an efficient
(though indirect) way to measure those rates may be by monitoring
reproduction of birds.
b. To know more about the density and distribution of key prey items
season by season, and to learn more about the relation of their
abundance and distribution to their availability to birds, as Bédard
(1969) showed for _Calanus_ to least auklets, and _Thysanoessa_ to
crested auklets.
There are some indications that the population size of prey items can
vary widely without having a marked effect on the numbers of their
predators. Does commercial fishing for the large, predatory fish have
a measurable effect on the food available to marine fish? Do the large
pollock and salmon fisheries (high seas) make zooplankton available to
smaller alcids? Do marine birds affect a fishery?
c. To know more about the oceanography of continental shelf waters,
more specifically the waters between 6 and 60 m deep. The shallow
waters of continental shelves are some of the most productive of
sea waters, but are among the least studied. Although some species
(black-legged kittiwakes, tufted puffins, and fulmars) move into deep
waters, many species of marine birds of northern waters gather in
large numbers on preferred feeding grounds at or near the edges of
continental shelves during their winter season (Fisher 1952; Tuck 1960).
8. To know more about the potential effects of proposed developments on
seabirds and waterfowl.
a. To prepare models which will predict probabilities of contamination
of breeding and feeding areas (summer, winter, and during migration)
using existing knowledge of
(1) areas of proposed mineral development;
(2) areas that will be influenced by secondary development such as
dredging new harbors, laying subsurface pipelines;
(3) tidal and oceanic currents;
(4) numbers of marine birds or waterfowl using specific geographic
areas and habitats (e.g., waters below nesting cliffs, feeding grounds,
wintering grounds, and gatherings during migration);
(5) the distribution and patchiness of habitats (i.e., the redundancy
among and within habitats and the degree to which populations exchange
between alternative habitats);
(6) the biological importance of species in local ecosystems (Are they
predators whose effects increase diversity?);
(7) the human importance of the species (Are they endemics? Do they
have unusual "charisma" for the public?);
(8) the vulnerability of the species (Is its distribution restricted?
Is it subject to oil pollution? Are their preferred grounds near areas
of high development potential?);
(9) the types of biological effects (e.g., oil contamination of
plumage, PCB contamination of food chains); and
(10) whether the potential impacts are reversible or irreversible and
to what degree.
b. To understand more of the effects of hunting on the behavior of
marine birds and waterfowl on their breeding grounds, and to assess the
effects on breeding performance of changes in behavior which result
from human activities (such as hunting or studying the birds).
c. To understand the effects of the presence of predators (whether
introduced or native) on breeding colonies in order to assess the
importance of removing the predators or preventing their access to
breeding grounds.
The Relation of the Products of Biological Research to Programs for
Conservation of Marine Bird Resources
Although peaceful coexistence of wildlife populations and economic
development are here assumed to be practical, some new social
institutions are needed to control damaging activities of people during
economic development. Human activities and industrial products which
damage wildlife or their habitat must be identified, as must the space
and resources which wildlife require for survival and health.
1. What seabird cliffs, islands, lagoons, wetlands, river mouths, and
other habitat features are of first importance for breeding or for
maintaining the populations? Some small areas of habitat are critical
for the survival of some species during periods of stress. Those
habitats need official recognition. Steps are needed to ensure that the
habitats are maintained.
2. What physical expressions of economic development are of little,
modest, or serious impact on wildlife and its habitat? These activities
and constructions include harbors, storage sites, transshipment
facilities, roads, pipelines, summer camps, and suburban or vacation
developments.
3. What kinds of human activities will disturb, damage, or change the
behavior or accessibility of wildlife? Many activities of one group of
people have secondary effects which affect the enjoyment of resources
for other groups. These include
a. gill netting for salmon, which may kill large numbers of murres and
diving ducks;
b. release of predators on seabird nesting islands, which may kill
adults or inhibit their feeding their young;
c. free running of pets (such as dogs and cats) over wetlands or
wildlife habitat, because pets are predators and harass the wildlife
which may be feeding;
d. flights of aircraft, especially helicopters, near or over seabird
cliffs because such flights may cause serious damage to eggs and young;
e. hunting, because the game becomes timid and flees from those who
might enjoy watching wildlife;
f. snow machines, because their presence is disagreeable to many and
they provide easy access by which disturbing activities may reach into
areas where wildlife would otherwise be undisturbed.
4. What limitations or alterations are needed in the existing
legal institutions, such as the Marine Mammals Protection Act, the
instruments implementing native land claims, the process of Alaska
State lands withdrawal, the conditions for leasing State and Federal
lands for development of mineral resources, and traditional rights
of private property? All of these legal institutions are relevant to
problems of wildlife survival and restoration, and within most of
these institutions there exist conflicts between rights and benefits
of special political interests and the husbanding of renewable common
property resources.
Experience in Europe and in New England suggests that if reasonable
limitations are set on human activities and that if adequate money
charge is made against those who profit by economic development to
defray full social costs, wildlife can continue to do well. In most
cases where damage has occurred it is because those who administer the
public institutions have failed to include consideration of the common
property resources.
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Time-Energy Use and Life History Strategies of Northern Seabirds
by
Erica H. Dunn
Long Point Bird Observatory
Point Rowan, Ontario, Canada
Abstract
Time and energy budgets can be compared
among species of birds with very different
ecology as a way of summarizing differences
and as an approach to determining selective
pressures on each species. This paper reviews
time-energy use of northern seabirds. Energetic
cost of maintenance (basal metabolism,
thermoregulation, and procurement and
processing of food) depends largely on the
following factors: (1) small birds have higher
metabolic costs per unit size than do larger
ones; (2) body structure affects the cost of
locomotion as well as of food procurement; (3)
climate affects metabolic costs; and (4) food
availability and nutrition vary among food
types, and throughout the year within a food
type. Little is known of maintenance energetics
in seabirds. Time and energy allocations
to items beyond basic maintenance are also
compared. Patterns and costs of molt and
migration are known only in a general way, and
the variety of possible patterns suggests that
more research would be of value. Almost nothing
is known of location and daily activities of
seabirds outside the breeding season. The
review of breeding season activities is more
comprehensive, and stresses the variety of
factors known to affect timing, and the total
time devoted to and the energetic costs of
various aspects of reproduction. Some of these
factors are weather, year, geographic location,
feeding conditions, age, sex, and distance
of food source from the breeding colony.
Species characteristics such as clutch size,
egg and yolk size, developmental type, growth
rate, food type, and behavior combine with
environmental variables to make seabirds a very
diverse group in time and energy budgeting.
Time-energy studies and determination of
productive energy (energy remaining after
maintenance needs have been met) can be useful
in pinpointing those groups of birds and the
times of year when birds are most vulnerable
to environmental stress. Life history
considerations suggest that most seabirds are
adapted to low population turnover and would
not be able to recover quickly from sudden
increases in mortality.
Effective management of a population requires manipulation of the
factors most critical in causing population increase or decrease.
Deciding what these factors are and which are most suitable for
effective manipulation is very difficult due to the complexity of life
cycles and possible factors affecting demography. It takes a thorough
knowledge of a species and of its relationships with the biotic and
abiotic environment to make effective management decisions. The
following review of seabird time and energy use is meant to emphasize
the wide variation of species ecology within this avian group.
Time and energy patterning is being used as the basis of ecological
comparison for the following reason. Any activity of an animal requires
time and energy use; therefore, the patterning of use makes a common
thread to which allocation to all activities in a bird's life cycle
can be related. Time-energy patterns can be compared among birds with
diverse food types, habitats, life cycles, and life expectancy, and
therefore offer an opportunity for comparison not available through
other kinds of analysis (King 1974).
The amounts of time and energy allocated by an organism to different
aspects of survival and reproduction should be regarded as being molded
by natural selection to optimize (not necessarily to maximize) lifetime
reproductive output (Fisher 1958; Williams 1966; Schoener 1971). Thus,
differences in time and energy use between species should reflect
adaptation to different biotic and abiotic environments. By comparing
time and energy use, one can gain insight into the selective pressures
on each species and have a basis on which to compare complex ecology
more meaningfully than if one listed other types of differences.
This review of time-energy use in northern seabirds cannot be
comprehensive, largely because many of the necessary data are lacking.
It stresses major areas of difference, however, and points out aspects
about which little is yet known.
Cost of Living
Every animal must expend a basic amount of energy on normal
maintenance, excluding activities normally allocated to a relatively
narrow time span, such as reproduction. This "existence energy"
expenditure consists of basal metabolism, thermoregulation, and the
costs of gathering and processing food, and could also be referred to
as the animal's basic "cost of living." In discussing the components
of the cost of living, energy use is emphasized and time largely
ignored--partly because metabolism occurs irrespective of time (it is
not something the animal can turn off for a period) and partly because
time use in normal maintenance and foraging has been little studied.
_Metabolism_
Basal metabolic rate (BMR) depends greatly on body size (Lasiewski and
Dawson 1967; Zar 1968), and the costs per unit size are higher for a
small bird than for a large one (Fig. 1). The BMR is somewhat lower in
seabirds and other nonpasserines than in passerines of similar size
(Dawson and Hudson 1970).
[Illustration: Fig. 1. Energy cost of various metabolic functions
in relation to body size in birds. "0° Existence" refers to total
metabolic costs of caged birds held at 0°C. From Calder (1974).]
The relationship between BMR and body size is paralleled by that
between size and other metabolic costs, such as for thermoregulation
at a given temperature and for activity (Fig. 1; Kendeigh 1970; Tucker
1970; Schmidt-Nielsen 1972; Berger and Hart 1974; Calder 1974). Basal
metabolic rate can therefore be used as an index of the overall cost of
living as far as metabolic functions are concerned. Small birds must
allocate a greater proportion of their energy resources than larger
ones to merely staying alive, and have a higher cost of living.
The suggestion in Fig. 1 that it is easy to measure activity costs in
a straightforward manner is misleading, because the figure represents
measures taken under standard conditions. Factors known to affect the
cost of flight, for example, include anatomical adaptations (such
as wing loading and wing shape), the type of flight (ascending,
descending, gliding), and the speed of flight (Fig. 2; Tucker 1969,
1974; Hainsworth and Wolf 1975). The cost of a series of short flights
may be higher than that for a long one because of the extra energy
required for takeoff and landing. A few estimates have been made for
the cost of flight, mostly in birds moving almost constantly (Lasiewski
1963; Nisbet 1963; Tucker 1972, 1974; Utter and LeFebvre 1970; Berger
and Hart 1974), but the methods may be inadequate for birds that fly
short distances frequently.
[Illustration: Fig. 2. Energy cost of flying at different speeds
and angles as compared with basal metabolic rate (BMR). Solid
lines and solid circle refer to flight cost and BMR for budgerigar
_(Melopsitticus undulatus)_. Dashed line and open circle refer to
flight cost and BMR of the laughing gull. From Tucker (1969).]
Little work has been done on the cost of locomotion in seabirds: that
of Eliassen (1963) on great black-backed gulls _(Larus marinus)_,
Berger et al. (1970) on ring-billed gulls _(L. delawarensis)_, and
Tucker (1972) on the laughing gull _(L. atricilla)_, and indirect
calculations of soaring flight characteristics in albatrosses,
_Diomedea_ spp. (Cone 1964), and the fulmar, _Fulmarus glacialis_
(Pennycuick 1960). Swimming has been shown to be more costly than
flying in ducks (Schmidt-Nielsen 1972) and may be for seabirds as well.
More energy is also probably used in underwater swimming than in flying.
The energetic costs of thermoregulation under natural conditions
are not easy to estimate. Thermal energy is gained from and lost
to the environment, and the degree of exchange depends not only
on air temperature but also on metabolic rate, insulation, body
temperature, posture, humidity, convection, and radiation. Radiation,
in turn, depends on cloud cover, shade, and reflective and absorptive
characteristics of the organism and of the environment (Porter and
Gates 1969; Calder and King 1974). Most of these quantities are
changing constantly, and insulation and metabolic rate may vary on a
seasonal basis with acclimation (Dawson and Hudson 1970).
At present, no direct measurement technique exists for determining
natural thermoregulatory costs, although a few estimates have been made
(King 1974), including several for seabird nestlings (Dunn 1976_a_,
1976_b_ for double-crested cormorants, _Phalacrocorax auritus_,
and for herring gulls, _Larus argentatus_). For most birds, the
temperature environment actually faced over a year's time has never
been measured, and for no bird has a full description of the complete
thermal environment been made. It is clear that climate and degree
of exposure are important elements in the basic cost of living, and
that thermoregulatory costs average higher in small birds than in
larger ones, but beyond that little information is available. Work on
thermoregulatory costs of free-living chicks of two species of seabirds
suggests that insulative properties can lead to marked differences in
the metabolic costs of different species in an essentially identical
environment (Dunn 1976_a_, 1976_b_).
_Food Procurement and Processing_
Gathering and processing food is another major component of the cost
of living. Both the nutritional value of food and its availability (a
rather vague term covering both abundance and ease of capture) are
extremely diverse and variable, making estimations of foraging cost and
benefit difficult (Ashmole 1971; Fisher 1972; Sealy 1975_a_).
Availability of food varies throughout the year, particularly in
marine invertebrates that form the diet of many seabirds (e.g., Spaans
1971; Bédard 1969_a_). High arctic oceans have a very high peak of
productivity in the summer, whereas the low arctic has a lower, but
longer-lasting, peak (Ashmole 1971). Fish stocks increase in summer as
well (Snow 1960; Pearson 1968; Sealy 1975_a_), and decline or disperse
in autumn (Potts 1968). Catch-ability may also differ widely from year
to year (e.g., E. K. Dunn 1973).
Marine foods are likely to have a patchy distribution, which may make
food stocks difficult to locate, even in times of abundance (Ashmole
1971; Sealy 1975_a_). Birds in localities with low food abundance
frequently show alterations in time and pattern of foraging, sometimes
even changing diets (Cramp 1972; Henderson 1972; Hunt 1972; Lemmetyinen
1972). The time and energy expended in finding and capturing food
by different seabird species must vary widely according to the form
of foraging used: plunge-diving, beach scavenging, aerial robbing,
underwater pursuit, and so on. Even when different species have
traveled the same distance to an identical food stock, therefore, the
costs of procurement differ.
Time and energy spent foraging depends not only on abundance and ease
of capture, but also on nutritional return, and on the age and size of
the bird. Fig. 3 shows that the smaller species in a seabird community
may spend the most time foraging. Even though this illustration is
taken from the breeding season when food demands of the young must be
taken into account, it suggests a difference based on cost of living
according to size.
[Illustration: Fig. 3. Time spent foraging in the breeding season as a
function of body size. From Pearson (1968). AT = arctic tern _(Sterna
paradisaea)_, CT = common tern _(S. hirundo)_, ST = sandwich tern
_(Thalasseus sandvicensis)_, K = black-legged kittiwake, P = common
puffin, M = common murre, LBB = lesser black-backed gull, S = shag.]
Age of the bird affects time and energy commitment to foraging because
younger birds are often less skilled at capturing food. This has been
noted particularly in long-lived seabird species (Orians 1969; Dunn
1972; LeCroy 1972; Buckley and Buckley 1974; Barash et al. 1975). Older
juveniles may be excluded from feeding areas by more experienced,
territorial adults (Moyle 1966), whereas immatures are not (Drury and
Smith 1968; Ingolfsson 1969).
Nutritional and energetic return obtained from food is a very important
factor in foraging strategy that has not received the attention it
deserves. Table 1 lists the caloric value of various foodstuffs and
illustrates how little is known about foods eaten by seabirds. Although
caloric content and abundance of food have often been accepted as the
most important determinants of foraging strategies (Bookhout 1958;
Emlen 1966; West 1967; Bryant 1973), they may frequently be less
important than nutritional value and digestibility, also shown in Table
1 (Pulliam 1974).
Since fish seem to be highly digestible, most of the energy contained
in them is available to the consumer. There are, unfortunately, no data
on the digestibility of marine invertebrates, but those for insects
suggest that digestibility, at least of crustaceans with exoskeletons,
is somewhat lower than that for fish. A bird would therefore have to
eat a larger biomass of invertebrates than of fish to satisfy the same
energetic needs (although cost of procurement might not be as high as
for fish).
Table 1. _Nutritional value of foods eaten by birds._ After data
in Hunt (1972) and E. H. Dunn (1973).
A: Kcal/g fresh wt.
B: Digestive efficiency
C: Kcal metabolizable energy/g fresh wt.
------------------------------------------------------------------------------
Percent fresh wt.
composed of:
----------------------
Food type A H₂O Fat Protein B C
------------------------------------------------------------------------------
Vegetable 1.2-5.2 59-86 0.4-3 3-5 30-32 0.3-2.3
Tropical fruits 1.2 75 8 1
Various seeds 4.0-7.3 3-13 1-40 10-29 76-80 3.0-5.2
Various insects 1.4-5.2 65-75 1-3 9-18 66-69 0.9-3.5
Whiting (fish) 1.1 81 79 0.9
Various freshwater fishes 1.2 75 5 18 81
Mix of fish eaten by
double-crested cormorants 1.1 74 1 16 82 0.9
on NE coast
Fresh herring and mackerel 1.9 67 13 19
Garbage ("average" mix) 1.5 67 8 19
Crab with eggs 1.0 68 5 1
Euphausid shrimp 0.8 80 2 1
Clam (edible part only) 0.8 80 1 13
------------------------------------------------------------------------------
A bird must satisfy not only energetic needs, but also nutritional
requirements. Fish are high in protein (Table 1), but what little is
known of marine invertebrates suggests a low proportion of protein in
relation to total bulk. Protein is vital to growth of nestlings (Fisher
1972; Lemmetyinen 1972), and 4-8% protein in the diet seems to be
required for minimal maintenance of adults (Martin 1968; Fisher 1972).
Some seabirds (such as puffins, _Fratercula_) that eat a varied diet
raise their young exclusively on fish (Bédard 1969_b_; Nettleship 1972;
Sealy 1973_a_).
Other aspects of nutrition, such as vitamins and minerals, are also
important to avian health (Brisbin 1965; Fisher 1972). To further
complicate matters, nutritional values vary with season, as do birds'
requirements for them (Myton and Ficken 1967; Moss 1972). Adults must
adjust their time and energy allocation to foraging to optimize not
only energetic, but also nutritional return.
Optimal time and energy allocation has been studied in theory (Orians
1971; Schoener 1971; Pulliam 1974; Katz 1974) and some direct
observations have been carried out, largely on seedeaters (Bookhout
1958; Myton and Ficken 1967; Royama 1970; Moss 1972; Willson 1971;
Willson and Harmeson 1973). The direct studies, in particular,
point out the basic importance of studying cost-benefit ratios by
interrelating complex factors of food availability, searching patterns,
and type, size, and caloric and nutritional value of foods.
Time-energy Use Beyond the Cost of Living
This section concerns variation in time and energy allocated
by seabirds to activities above and beyond the cost of
living--particularly to migration, molt, and reproduction. Allocation
to such items as avoidance of predation and competition is not
considered here, because they are not readily analyzed as activities
to which time and energy are devoted in a specific part of the annual
cycle.
The previous discussion dwelt on energy considerations and could have
referred to almost any group of birds. The following treatment centers
on time use of northern seabirds. Little is known of energetics beyond
the cost of living, although estimates have been made for certain
aspects of migration, molt, and reproduction (Nisbet 1963; Hussell
1969; Hart and Berger 1972; Payne 1972; Ricklefs 1974). Essentially
nothing is known, however, of the relationship of such costs to the
amount of energy available to the bird once basic maintenance costs
have been met (productive energy). Because such complete data are not
available, the following account dwells largely on variation in timing
and total time devoted to activities beyond basic maintenance.
[Illustration: Fig. 4. Typical patterns of generalized annual cycles
in reproduction, migration, and wing molt in northern seabirds. Solid
line shows reproductive season, dotted line the period of migration
or dispersion, and dashed line the period of annual primary molt.
Data from Dorst (1961), Stresemann and Stresemann (1966), and Ashmole
(1971).]
_Migration_
Among northwestern North American seabirds, most coastal feeders, such
as gulls, cormorants, and many alcids and petrels, have only a short
southward migratory movement, and many others are more or less resident
(Dorst 1961; Ashmole 1971). Terns, on the other hand, migrate long
distances in a short time to places where small fish are available
near shore in the winter. Other long-distance migrants--Sabine's gull
_(Xema sabini)_, jaegers (_Stercorarius_ spp.), pelagic phalaropes
(_Phalaropus_, _Lobipes_), and kittiwakes (_Rissa_ spp.)--tend to
scatter widely over the southern ocean, concentrating near areas of
upwelling (Dorst 1961; Ashmole 1971). Groups such as murres (_Uria_
spp.), eiders (_Somateria_ spp.), and grebes (_Podiceps_ spp.) may
move considerable distances by swimming (Dorst 1961; Tuck 1960). True
migration tends to take place directly before and after reproduction,
whereas dispersal or nomadism takes place over a long period of the
winter (Fig. 4).
Among species remaining in the northern hemisphere, younger birds
frequently disperse greater distances than do breeding adults (Coulson
1961; Kadlec and Drury 1968; Southern 1967), and the degree of
dispersal can vary among colonies of the same species (Coulson and
Brazendale 1968).
Energy costs of migration must vary according to distances covered
and amount of time allocated to migration. Aside from the references
to cost of flight mentioned earlier, however, migratory costs have
scarcely been studied. Dolnik (1971) has estimated that chaffinches
_(Fringilla coelebs)_ expend about as much energy migrating south as
they would on thermoregulation if they overwintered on their breeding
grounds. Long-distance migration is presumably selected because the
birds are able to collect food more efficiently, because the risks of
death or injury in migrating are less than in residency, and so on.
Interspecific and intraspecific competition may also be involved (Cox
1968). In other words, migratory patterns are selected to optimize
survival and reproduction in alternating environments (Cohen 1967;
Drury and Nisbet 1972).
Table 2. _Wing molt in alcids._ After Stresemann and Stresemann
(1966).
---------------------------------------------------------------------
Rapidity of wing molt Timing of start of molt Species
and (indented) flight
capability in molt
Slow Retained During care of young Cassin's auklet,
parakeet auklet
_(Cyclorhynchus
psittacula)_,
whiskered auklet
_(Aethia pygmaea)_
Retained After young become Least auklet
independent _(A. pusilla)_,
crested auklet _(A.
cristatella)_
Rapid Poor After arrival in Marbled murrelet,
winter quarters Kittlitz's murrelet
_(Brachyramphus
brevirostris)_
Almost synchronous None After end of breeding Xantus' murrelet
_(Endomychura
hypoleuca)_
Synchronous None As soon as young go to Guillemots (_Cepphus_
sea spp.), murres,
razorbill _(Alca
torda)_, dovekie
_(Alle alle)_
None In winter, after body Puffins
molt
---------------------------------------------------------------------
Although one may suspect that location of winter food supply is the
main environmental factor affecting migratory patterns, there is little
direct evidence on the reasons for, or the benefits accruing from,
the different patterns seen in seabirds. Study of cost-benefit ratios
of foraging in different stages of migration might help clarify the
question.
_Molt_
Patterns of molt vary widely among seabirds. The commonest pattern is
for a prenuptial body molt to occur in spring, and for an extended wing
molt to begin after the breeding season and continue well into the
winter (Fig. 4). In short-distance migrants, molt may overlap slightly
with the end of breeding and can last up to 6 months, as in most gulls,
terns, alcids, nonmigratory jaegers, and cormorants (Stresemann and
Stresemann 1966).
Long-distance migrants frequently delay molt until in the winter
quarters (lesser black-backed gull, _Larus fuscus_; Sabine's gull;
jaegers; arctic tern, _Sterna paradisaea_; and marbled murrelet,
_Brachyramphus marmoratus_) and molt there may occur rapidly (3.5
months in the arctic tern). Certain other long-distance migrants
begin molt before leaving the breeding grounds (herring gull; skua,
_Catharacta skua_; Leach's petrel, _Oceanodroma leucorhoa_; and
fulmar), although molt may be interrupted during migration, as in
_Larus argentatus heuglini_ (Stresemann and Stresemann 1966). Duration,
timing, and rapidity of molt are particularly varied among the alcids
(Table 2).
A few unusual molt patterns are found in northern seabirds. The ivory
gull _(Pagophila eburnea)_ has its major annual wing and body molt
immediately before it breeds. In several other species such as the
glaucous gull _(Larus hyperboreus)_ and Cassin's auklet _(Ptychoramphus
aleuticus)_ the molt almost completely overlaps the reproductive cycle
(Johnston 1961; Payne 1965). Potts (1971) documented a molt pattern in
shags _(Phalacrocorax aristotelis)_ which is more typical of tropical
seabirds. Several cycles of wing molt take place simultaneously, each
lasting more than a year, and molt ceases in winter. By the time
breeding age is reached, each flight feather is replaced once a year.
Within these broad categories of molt pattern there are sometimes
variations according to age, sex, and even subspecies (Stresemann and
Stresemann 1966). Male common eiders _(Somateria mollissima)_ molt
directly after mating, when their reproductive role is completed,
whereas females molt only after they have taken their young to sea.
Nonbreeders and failed breeders frequently begin molt while other
adults are still raising young and not molting--e.g., many alcids,
gulls, storm-petrels, and fulmars (Stresemann and Stresemann 1966;
Ingolfsson 1970; Harris 1971; Harris 1974; Sealy 1975_b_). In ivory
gulls, which molt just before reproduction, and in Sabine's gulls,
which complete molt just before breeding, nonbreeders may extend wing
feather growth into the breeding season (Stresemann and Stresemann
1966).
There is little information on the energetic cost of molt, although
there are indications of at least some expense. Belopol'skii (1961)
showed that nonmolting seabird species tended to gain weight after
reproduction, whereas those that immediately started molt tended to
lose weight. Among other birds, however, it is common for individuals
to gain weight just before, and even during molt (Payne 1972). The BMR
is known to rise in molting birds (Blackmore 1969; Lustick 1970; Payne
1972), from as little as 5% to as much as 34% above nonmolting levels.
In one study, about 35-40% of the increased BMR represented extra
thermoregulatory costs incurred by lessening of insulation and increase
in heat loss from well-vascularized new feathers; the rest of the
increase represented the energetic cost of growing feathers (Gavrilov
1974). The fact that molt rarely overlaps with breeding suggests that
the energetic cost, even if slight, may be incompatible with the
already high costs of reproduction (Payne 1972). Cassin's auklets,
which do molt while breeding, may cease molt while feeding large young
(Payne 1965), and certain species interrupt molt during migration
(Stresemann and Stresemann 1966). Doubtless a rapid simultaneous molt
is more costly than a long gradual one.
Rapid molt appears to occur at a time in the annual cycle when food
resources are abundant (spring or late summer), whereas extended molt
generally occurs over winter (e.g., Bédard 1969_a_). If one speculates
that energy availability is the main determinant of molt patterns,
one can also speculate on the cause behind some of the more unusual
patterns. Possibly birds in which molt and breeding overlap either have
extraordinary available energy at that time or else face shortages
in other periods. For example, ivory gulls, which breed in the high
Arctic, molt when food resources have become abundant in the low Arctic
but before the high Arctic breeding grounds have thawed sufficiently
for reoccupation.
Speed of molt may also reflect availability of energy resources or
of nutrients needed for feather growth (Payne 1972), but must also
be influenced by the need for full flight capabilities to obtain
food. The eider duck and many alcids that shed wing feathers almost
simultaneously do not need their wings for flight after the young have
left the breeding colony. Hydrodynamic considerations suggest that
their fishing capabilities may even be improved (Storer 1960). This is
not true for the smaller species--e.g., _Aethia_ molts only one feather
at a time and retains full flight capabilities (Table 2). Climate may
also influence simultaneity of molt if heat loss in rapid molt is
particularly severe.
_Reproduction_
Time use of seabirds is best known for the reproductive period, when
the birds are on relatively accessible breeding grounds, the weather is
most suitable for observation, and academic researchers are freed from
their jobs. Even so, the details of timing are known for only a few of
the species and localities on the northwest North American coast (e.g.,
Drent and Guiguet 1961; Drent et al. 1964; Cody 1973; Sealy 1973_a_,
1975_b_, 1975_c_). The following discussion emphasizes the multitude
of environmental factors known to influence timing and total length of
time devoted to various aspects of the reproductive cycle.
Timing of the Season
Each species of seabird returns to the colony site when weather
conditions have ameliorated sufficiently to meet its particular needs.
For example, the early arrivals to islands in the Barents Sea are
murres, kittiwakes, and herring gulls, which need only small cracks in
the sea ice to meet their feeding requirements (Belopol'skii 1961).
Eiders in North America also return early, when a few ice leads have
formed (Schamel 1974). Common puffins _(Fratercula arctica)_ and mew
gulls _(Larus canus)_ are somewhat later arrivals, and terns and a few
parasitic jaegers _(Stercorarius parasiticus)_ are the latecomers to
Barents Sea colonies (Belopol'skii 1961).
The timing of the season (as illustrated in Fig. 5) varies widely
among localities, and because of local weather patterns and ocean
currents, this variation can be unrelated to latitude (Belopol'skii
1961). Examples of such variation are also known in North America: for
instance, Leach's storm-petrels in Alaska lay eggs 2 to 3 weeks later
than do those in California (Harris 1974); however, the details of
timing are largely unknown for many species in this region. Progression
of thaw, which also varies from year to year, causes variation in the
timing of the breeding season (Belopol'skii 1961; Evans and McNicholl
1972). Fig. 6 shows the diversity in start of the breeding season for
different species on the same island in the Barents Sea as well as
variation in time devoted to various components of the reproductive
cycle.
[Illustration: Fig. 5. Differential average arrival on breeding grounds
and average duration of prenesting period of thick-billed murres
_(Uria lomvia)_ and black-legged kittiwakes on various colonies in the
Barents Sea. From Belopol'skii (1961). Length of prenesting period in
days (shaded bars) indicated on right. Letters represent locations as
follows: A = Novaya Zemlya, Kara Straits; B = Novaya Zemlya, Karmakuly
Bay; C = Franz Josef Land; and D = East Murman.]
Prenesting Activities
Some species are apparently able to delay maturity of sexual organs
until environmental conditions are suitable for nesting--e.g., burrow
and crevice nesters in the Barents Sea do not become sexually mature
until snowmelt (Belopol'skii 1961). Many others, however, reach sexual
maturity soon after arrival on the breeding grounds, and a few (such as
jaegers and kittiwakes) mature in migration or on the wintering grounds
(Belopol'skii 1961). Northern phalaropes _(Lobipes lobatus)_ sometimes
lay eggs as early as 1 week after arrival (Hilden and Vuolanto 1972).
This factor, in combination with timing of arrival, affects the amount
of time spent in prenesting activities (Fig. 6). Most species gain
weight during this period (Belopol'skii 1961), and the time required
for each species to reach full breeding condition must also depend on
feeding conditions and the state of the bird on its arrival at the
nesting site. These factors help explain why early arriving species are
not necessarily early nesters (Fig. 6).
[Illustration: Fig. 6. Variation in timing of events in the
reproductive cycle of Barents Sea seabirds nesting on the same island.
Data from Belopol'skii (1961). Shaded bars at left indicate the
prelaying periods, open bars the incubation periods, and shaded bars at
right the portion of the growth period in which the chick remains at
the nest site. Total length of time indicated is about 6 months.]
Aside from nest building, most prenesting activity consists of
courtship and territorial behavior. These activities have been well
described for representative seabird species, but because assessments
of time and energy devoted to them have been almost completely
neglected, they are not discussed further here. For examples, see
accounts in Gross (1935) for Leach's storm-petrel; Tinbergen (1935),
Bengtson (1968), Höhn (1971), and Howe (1975) for phalaropes; Storer
(1952) for common murre, _Uria aalge_, and black guillemot, _Cepphus
grylle_; Tschanz (1959) for common murre; Brown et al. (1967) for
Sabine's gull; Tinbergen (1960) for herring gull; McKinney (1961) for
eiders; Snow (1963) for shag; Thoresen (1964) for Cassin's auklet;
Vermeer (1963) and James-Veitch and Booth (1974) for glaucous-winged
gull _(Larus glaucescens)_; and Andersson (1973) for jaegers.
Nest Building
Although many northern seabirds have essentially no nest, they may
spend considerable time working or displaying at the site (Belopol'skii
1961). Black-legged kittiwakes _(Rissa tridactyla)_ have substantial
nests, but they are built in a comparatively short time (about a week)
soon after the birds arrive (Fig. 6). Shags also have substantial
nests, but they are not completed until about 1 or 2 weeks before the
first egg is laid (Snow 1963). Herring gulls build smaller nests, 5
to 10 days before laying, although in the Far North they and glaucous
gulls may not start building the nest until the first egg is laid
(Belopol'skii 1961). The eider always begins preparing the nest when
the first egg is laid (Belopol'skii 1961; Schamel 1974), and terns
and skuas, which build no nests, choose their sites at that time.
Murres, which frequently lay their eggs directly on snow, choose
a site somewhat earlier and spend considerable time protecting it
(Belopol'skii 1961). Burrows may be dug within a period as short as 3
days for Leach's storm-petrel (Gross 1935) to one as long as several
weeks in Cassin's auklets (Manuwal 1974_a_). Overall, the prelaying
period is longer for burrow nesters than for those using crevices
(Sealy 1973_a_).
The amount of time and energy spent by the male and female in nest
building differs among species. In Leach's storm-petrel, the male digs
the burrow (Gross 1935), whereas in eiders, the nest is built entirely
by the female. In most seabird species, the sexes share in nest
construction, but roles may still be separated. For example, in shags
the male collects the nest material and the female builds the nest
(Snow 1963).
Egg Laying
Timing of egg laying is influenced not only by weather (Erskine 1972;
Sealy 1975_c_), but also by numerous biotic factors. Smith (1966)
showed that where glaucous gulls, herring gulls, and Thayer's gulls
_(Larus thayeri)_ breed in mixed colonies, the peak of sexual activity
and egg laying in Thayer's gull is about midway between the peaks for
the other two species (Fig. 7). In nearby colonies where herring gulls
are absent, however, the peak of sexual activity in Thayer's gulls is
delayed about a week, and activity continues for a significantly longer
period (Fig. 7).
[Illustration: Fig. 7. Timing of peak sexual activity (a combined
measure of egg laying and testes size) in colonies of arctic gulls of
different species composition. From Smith (1966).]
Annual variations in food supply also will affect the start of the
egg-laying season. Belopol'skii (1961) cited an example from the
Barents Sea in 1940 when a series of storms made it difficult for
certain seabirds to find food. Murres and kittiwakes, which were able
to catch fish, started reproductive activities on schedule. Gull
breeding was delayed, however, and egg laying began in force only after
fishing boats arrived and started discarding offal. Onset of egg laying
in great cormorants _(Phalacrocorax carbo)_ is correlated to April air
temperatures (Erskine 1972), and this may also be related to variations
in spring increase of food availability. In certain birds the breeding
season has been shown to start particularly early when food supplies
are unusually abundant (Högstedt 1974; Källender 1974), but this has
not yet been demonstrated in seabirds.
Lastly, age and sex of seabirds are known to affect the timing of
egg laying (e.g., Coulson and White 1960; Lack 1966); older, more
experienced birds tend to lay earlier than do younger ones. In shags,
males tend to breed progressively earlier as they increase in age, but
females do not (Snow 1963).
Contrary to the situation in passerines, seabirds tend to lay their
clutches with relatively large time intervals between eggs. Eggs may be
laid every 2nd or 3rd day in alcids, larids, sternids, stercorariids,
and phalacrocoracids (Lack 1968), but every day in phalaropes (Howe
1975). Inasmuch as clutch size in northern seabirds varies from one
to five or six, the length of the laying period varies widely among
species.
Energetic costs of egg laying depend on the actual caloric content
of the egg and the speed with which the ova are developed (Ricklefs
1974). The energy in the egg is contained mainly in the yolk, and yolk
size depends largely on the developmental pattern shown by the young
after hatching (Table 3). Precocial chicks are hatched at a relatively
advanced stage, are covered with down, and have open eyes, can maintain
reasonably homeothermic body temperature, and leave the nest site to
feed themselves after a few hours or days. At hatching, semiprecocial
chicks appear similar to precocial chicks, although they are slightly
less well developed (Ricklefs 1974; Dunn 1975_a_). In contrast to
precocial chicks, they remain at the nest site for some time, are fed
by their parents, and tend to grow rather rapidly (Ricklefs 1968).
Altricial nestlings hatch at a much less advanced stage of development.
They are naked, blind, helpless, essentially poikilothermic, and depend
completely on their parents for food and shelter. They usually remain
at the nest until full grown. Semialtricial chicks show somewhat
intermediate characteristics (Nice 1962).
Table 3. _Amount of yolk in eggs of different types of birds._
After Ricklefs (1974).
------------------------------------------------
Developmental Percent yolk
type (by weight)
------------------------------------------------
Precocial 30-60
Semiprecocial 25-30
Altricial 15-25
+----------------------------------------------+
The amount of yolk (and therefore energy) in an egg is positively
correlated to the degree of development at hatching (Table 3). The same
is true for egg size: altricial and semialtricial birds have smaller
eggs relative to adult body weight than do semiprecocial and precocial
birds (Fig. 8). Clutch size, however, is unrelated to energy content
of the eggs. For example, shags (which are altricial) and eiders
(precocial) have among the largest clutches of northern seabirds (four
to six eggs).
[Illustration: Fig. 8. Egg weight as a function of body weight in
various northern seabirds. Solid symbols represent precocial and
semiprecocial species, and open symbols altricial and semialtricial
species: solid circles, alcids; solid triangles, gulls, terns, and
jaegers; solid squares, eiders; open squares, cormorants and _Morus
bassanus_; and open circles, petrels. Data from Belopol'skii (1961);
Drent (1965); Schönwetter (1967); Lack (1968); Bédard (1969_a_); Cody
(1973); Sealy (1973_b_); Harris (1974); and Manuwal (1974_a_).]
The energetic cost of egg laying depends not only on caloric content
of the egg and clutch size, but also on speed of development.
Ricklefs (1974) has shown that the energetic cost per day of egg
laying can be calculated from the energy content of the yolk and
white, clutch size, the amount of follicular growth per day, and the
laying interval between eggs. The energy content of a single egg
(expressed as percentage of BMR) has been estimated as follows: 45
(altricial passerines), 103 (semialtricial raptors), 126 (precocial
galliformes), 180 (precocial ducks), 226 (precocial shorebirds), and
320 (semiprecocial gulls and terns). Gulls and terns thus have very
costly eggs, as well as a moderately high clutch size (three). However,
the development time for a single ovum in the herring gull is unusually
long--9 to 10 days (King 1973). Ricklefs (1974), who calculated the
energetic cost per day (expressed as percentage BMR), estimated the
cost of a clutch in gulls and terns (120% BMR per day) to be similar
to that for various groups of precocial birds (about 125-180% BMR per
day). Unfortunately, the data required for calculation of the average
energetic cost of a clutch are not available for other northern
seabirds.
For no species have all the additional factors influencing the
energetic cost of a clutch been taken into account. For example,
eggs in a clutch may vary in size (and caloric content) according to
sequence in the clutch (Preston and Preston 1953; Snow 1960; Coulson
1963; Coulson et al. 1969). Age has a definite effect on laying
energetics, as older birds lay larger eggs (Coulson and White 1958;
Snow 1960; Coulson 1963; Coulson et al. 1969) and lay larger clutches
(Coulson and White 1960; Snow 1960). They also lay, on average, earlier
in the season (Coulson and White 1958; Snow 1960; Coulson et al. 1969),
and eggs laid late in the season (whether by young birds or older ones
in re-nesting attempts) tend to be smaller and contain less energy. In
addition, egg quality can vary with food supply: Snow (1960) found eggs
to have more yolk in years when food was abundant than in years when
food was scarce.
Egg-laying costs are, of course, borne entirely by the female,
although males may contribute some time and energy toward egg laying
through courtship feeding (Ashmole 1971; Henderson 1972; Nisbet 1973).
Courtship feeding takes place in most lariforms but not in eiders,
phalaropes, or cormorants.
The time and energy expended on egg laying can be profoundly influenced
by the degree of nest destruction, since females usually lay a
replacement clutch if the loss of the first does not occur too late in
the season. Factors causing egg destruction are numerous, but among
the most important in the north is predation. As is shown in Table 4,
the degree of egg predation in common murres is correlated to degree
of exposure of the nest--so even such an unlikely sounding factor as
physical characteristics of the nest site can affect the average time
and energy expended on egg laying by a given species or population.
Genuine second clutches are occasionally laid by phalaropes (Hilden and
Vuolanto 1972) and Cassin's auklets (Manuwal 1974_a_).
Table 4. _Predation on nests of common murres according to degree
of exposure._ From Belopol'skii (1961).
--------------------------------------------
Nests destroyed by
Nest exposure predators (%)
-------------------------------------------
Completely hidden 3.2
Partly exposed 5.8
Largely exposed 13.6
Completely exposed 18.2
--------------------------------------------
In short, time and energy devoted to egg laying depend not only on the
species, but also on a multitude of other biotic and abiotic factors,
such as age, sex, degree of nest destruction, weather, other species
present, and feeding conditions.
Incubation
The total time devoted to incubation does not depend directly on
developmental type or egg size but differs markedly among families
(Lack 1968). Since incubation period seems to be closely linked to
fledging period, factors affecting growth rate (discussed later)
apparently affect incubation period as well.
Each species has a different incubation rhythm. In birds in which the
sexes share in incubation, the sexes exchange places at intervals that
differ widely among different birds: several hours in lariforms and
some alcids (Drent 1965; Lack 1968; Preston 1968; Drent 1970); about
4 h in shags (Snow 1963); up to 11 h in the ivory gull (Bateson and
Plowright 1959); up to 24 h in certain other alcids (Manuwal 1974_a_;
Sealy 1975_a_); 33 h (on the average) in common puffins (Myrberget
1962); 72 h in ancient murrelets, _Synthliboramphus antiquus_ (Sealy
1975_a_); and 96 h in Leach's storm-petrel (Gross 1935). Degree of
attentiveness once a bird is on the nest also varies. Petrels may leave
the egg for several days (Gross 1935), whereas herring gulls cover
their eggs 98% of the time (Drent 1970).
The sexes share in incubation in most seabirds (Snow 1960; Drent 1965,
1970; Bédard 1969_a_), although females frequently take on the greater
role (Belopol'skii 1961). Only male phalaropes incubate the eggs, and
only female eiders. Eider hens do not feed during the entire incubation
period (25 days) and leave the nest only for short periods of about 10
min (Belopol'skii 1961; Schamel 1974).
Several methods exist for calculating the amount of heat input
necessary for normal development of a clutch of eggs (Ricklefs 1974).
There is controversy, however, as to whether an adult can provide
this warmth from excess body heat lost during the course of normal
metabolism or whether the adult must raise its metabolic level to
produce extra heat (Kendeigh 1973; King 1973; Ricklefs 1974). Several
studies of incubating birds suggest that, in at least some situations,
adults need not raise metabolic levels, but in others (large clutch,
severe weather), they probably do (Ricklefs 1974). Drent (1972)
estimated that herring gulls raise metabolic levels to a significant
degree during incubation.
In spite of the lack of quantitative data, one can surmise that the
cost of incubation varies among seabirds. Precocial and semiprecocial
birds tend to have a larger clutch weight relative to body weight
than do altricial birds (Fig. 8; Lack 1968), and therefore require
greater heat input to the eggs. These costs may be reduced by heavily
insulating the nest (e.g., eiders), or by nesting in burrows, which
have much more moderate and even climates than do external nests
(Richardson 1961; Manuwal 1974_a_). Other semiprecocial species,
however, such as the murre, may sometimes lay eggs directly on snow
or ice (Belopol'skii 1961)--presumably at increased incubation
costs. Lastly, certain species incubate eggs with their feet (e.g.,
cormorants), rather than develop featherless brood patches. There are
no measurements of comparative heat flow from feet versus brood patches.
Raising Nestlings
The length of the nestling period (hatching until departure from the
nest) varies greatly among northern seabirds (Fig. 6). Nestling period
depends on the stage of growth at which the young leave the nest and
the rate at which they attain that stage. Growth rate in turn depends
largely on body size and developmental type.
The stage of growth attained when birds leave the nest varies
considerably (Fig. 9). Precocial eiders leave the nest within a day of
hatching, whereas altricial shags remain until completely grown. The
young of semiprecocial species, on the other hand, leave the nest at
all stages between these extremes. Larids normally remain at the nest
until 75-90% grown, but certain alcids leave much sooner--well before
the young can fly.
[Illustration: Fig. 9. Percentage of total growth completed in the
egg (shaded bar at left), at the nest site (open bar), and after
nest-leaving (shaded bar at right) in various northern seabirds. From
Belopol'skii (1961).]
Growth rate depends both on body size and developmental type (Fig.
10). The length of stay at the nest for precocial young is unaffected
by growth rate (which is typically very slow), since they leave soon
after hatching. The nestling period of semiprecocial and altricial
seabirds is, however, affected by the rate at which the young grow to
the nest-leaving stage. This depends mainly on body size (Fig. 10)
and to a certain degree on developmental type, as some semiprecocial
species grow rather slowly. Certain seabirds with clutches of one egg
grow particularly slowly (petrels, some alcids, sulids). Several other
alcids with single-egg clutches, however, grow at rates normal for
semiprecocial chicks (Fig. 10). Very slow growth may be related to
food stress (Lack 1968; Ricklefs 1968) or to reduction of reproductive
effort in the adults (discussed later). Contrary to Cody (1973), slow
growth in alcids does not correlate to the distance adults must commute
for food. (Cody tried to directly compare growth in birds of different
sizes.) Chicks in nocturnal species, however, tend to have slow growth
rates (Sealy 1973_b_).
[Illustration: =Fig. 10.= Growth rate as a function of body weight.
Growth rate ᵗ10-90 represents the number of days to grow from 10% to
90% of asymptotic weight (Ricklefs 1968). Data from Ricklefs (1968,
1973), E. H. Dunn (1973), and Sealy (1973_b_). Solid circles and
regression line, altricial birds; solid triangles, semiprecocial birds
except for seabirds with one-egg clutches; open circles, precocial
shorebirds; open triangles, precocial ducks, rails, and gallinaceous
birds; solid squares, alcids with one-egg clutches; and open squares,
northern petrels, gannet, and Manx shearwater _(Puffinus puffinus)_.]
Daily time budgets of adults raising nestlings also vary widely,
depending on the amount of brooding required, food requirements of the
young, and foraging costs (which differ in the breeding season from
those at other times of the year).
Nestlings have imperfect control of body temperature at hatching
(Fig. 11) and develop this capacity only gradually. Altricial birds
are hatched at a particularly undeveloped stage; e.g., double-crested
cormorants attain reasonable control of body temperature in moderate
ambient temperatures only after about 14 days (Fig. 11; Table 5).
Semiprecocial seabirds, which are more fully developed physically at
hatching, attain control of body temperature much sooner, in a matter
of several days, and precocial eiders can thermoregulate within a few
hours after hatching (Table 5).
Until the age of temperature control, nestlings must be brooded
almost constantly, and occasional brooding takes place for some time
afterward, especially in severe weather, in all species studied
(Tinbergen 1960; Belopol'skii 1961; Weaver 1970; Dunn 1976_a_,
1976_b_). Thermoregulatory capabilities in cold weather are better
in ducklings of species nesting at high latitudes than at lower ones
(Koskimies and Lahti 1964), and the same may be true of gull species
(Dawson et al. 1972). The cooling mechanisms of double-crested
cormorants are better than in the more northerly distributed pelagic
cormorant, _Phalacrocorax pelagicus_ (Lasiewski and Snyder 1969). Thus,
variation in cost of thermoregulation due to different environments may
be reduced through adaptation.
Food requirements of the chick depend on growth rate, amount of fat
deposition, cost of thermoregulation, degree of activity and other
factors (E. H. Dunn 1973). Estimated energy budgets for nestling
double-crested cormorants and herring gulls in the same year and
locality (Fig. 12) indicate that these factors vary according to
developmental type, and comparison with budgets for nonseabird species
suggests wide variation within developmental types according to the
particular adaptations of each species to its own environment (E. H.
Dunn 1973).
[Illustration: Fig. 11. Development of thermoregulatory capabilities in
nestling double-crested cormorants. From Dunn (1976_a_). Ages at right
refer also to corresponding oxygen consumption data on the left. Thin
diagonal lines show equality between body and air temperature. All data
taken after 2 h of exposure.]
Thus, the energy demands of nestlings are not easy to predict. Brood
size differences multiply variation in food demand on adults (except
in precocial birds whose young feed themselves). Energy demands
are labile, however, particularly in requirements for activity and
growth, and adults can frequently raise young successfully without
providing optimum amounts of food (Spaans 1971; Kadlec et al. 1969;
LeCroy and Collins 1972; Lemmetyinen 1972; Cody 1973; E. H. Dunn and
I. L. Brisbin, manuscript in preparation). Studies of double-crested
cormorants by Dunn (1975_b_) and pigeon guillemots _(Cepphus columba)_
by Koelink (1972) have suggested that each adult providing optimum
amounts of food to a normal-sized brood would have to approximately
double the amount of food gathered each day over the amount gathered by
nonbreeders. This relation does not imply, however, that the time and
energy allocation of the adults would be the same for the two species.
[Illustration: Fig. 12. Energy budgets of nestling double-crested
cormorants and herring gulls. Data from E. H. Dunn (1973) and Brisbin
(1965).]
Cost-benefit ratios of food gathering in the nestling period differ
from those at other times. Besides facing increased food demands,
costs of delivery to the nest, and changes in food availability, the
parents' choice of foods is constrained by the need to forage within
reasonable commuting distance of the nest and perhaps by concentrated
competition with conspecifics and other seabird species. In addition,
small nestlings are frequently unable to eat foods normally eaten
by adults (Drent 1965; personal observation). In the face of these
constraints, adults often shift food preferences while raising
nestlings (Belopol'skii 1961). For example, female mew gulls in the
Barents Sea forage in the tidal zone, eating more small invertebrates
than at other times of the year, while males continue to forage at sea
and consume larger quantities of fish (Fig. 13).
Table 5. _Age of thermoregulatory control in various species of
northern seabirds._
Species Age when Source
moderate
temperature
control is
attained
(days)
Common eider 0.1-0.3[41] V. V. Rolnik, in Belopol'skii
(1961)
Herring gull 1.5-2 V. V. Rolnik, in Belopol'skii
(1961)
2-3 E. H. Dunn (1976_b_)
Leach's storm-petrel [2] Ricklefs (1974)
Mew gull 2-3 V. V. Rolnik, in Belopol'skii
(1961)
Lesser black-backed gull 2-3 E. K. Barth (in Farner and
Serventy 1959)
Greater black-backed gull 2-3 E. K. Barth (in Farner and
Serventy 1959)
Pigeon guillemot 2-4 Drent (1965)
Common tern 3 LeCroy and Collins (1972)
Roseate tern _(Sterna 3 LeCroy and Collins (1972)
dougallii)_
Common murre 3 V. V. Rolnik and Yu. M.
Kaftonowski (in Sealy 1973_b_)
Razorbill _(Alca torda)_ 3 V. V. Rolnik and Yu. M.
Kaftonowski (in Sealy 1973_b_)
Black guillemot 3-4 V. V. Rolnik, in Belopol'skii
(1961)
Tufted puffin 3.5[42] Cody (1973)
Northern phalarope 4-5[43] Hilden and Vuolanto (1972)
Cassin's auklet 5-6 Manuwal (1974_a_)
Horned puffin _(Fratercula 2-6 Sealy (1973_a_)
corniculata)_
Common puffin 6-7 V. V. Rolnik and Yu. M.
Kaftonowski (in Sealy 1973_b_)
Black-legged kittiwake 6-7 V. V. Rolnik, in Belopol'skii
(1961)
Double-crested cormorant 14 Dunn (1976_a_)
Shag 12-15 V. V. Rolnik, in Belopol'skii
(1961)
Commuting distances vary tremendously among species (Fig. 14), but
the number of feeding trips to the nest per day does not correlate
with foraging distance (Cody 1973; Sealy 1973_a_, 1973_b_). There
is not, therefore, a simple relationship between time and energy
expenditures of the adults and foraging distances. Nocturnality, on
the other hand, correlates with reduced feeding rates (usually one
visit to the nest each night). Seabirds feeding far from the colony
tend to show adaptations for bringing larger amounts of food per visit,
such as carrying more than one fish at a time, as in tufted puffins,
_Lunda cirrhata_, and rhinoceros auklets, _Cerorhinca monocerata_,
vs. guillemots and murres (Richardson 1961; Cody 1973; Sealy 1973_a_,
1973_b_); developing a sublingual storage pouch, as in Cassin's auklets
(Speich and Manuwal 1974); or concentration of food into stomach oil,
as in petrels and albatrosses (Ashmole 1971). Commuting costs are
largely eliminated when the young leave the nest, but only in the
alcids does nest leaving occur long before attainment of full growth.
Early nest leaving may allow adults and young to disperse to better
feeding areas than are exploitable from the colony site (Sealy 1973_b_)
and probably involves a major change in optimal food size and type as
well (Lind 1965).
Patterning of adult time budgets may differ between geographical
regions. For example, rhinoceros auklets are nocturnal in the far north
(where the summer night is particularly short), crepuscular in the
Olympic Peninsula, and mainly diurnal in the Farallon Islands (Manuwal
1974_a_).
[Illustration: Fig. 13. Foraging ranges of a pair of mew gulls during
the breeding season, on a Barents Sea colony. From Belopol'skii (1961).]
Food demands of nestlings have a great influence on the time and energy
allocation of breeding over nonbreeding seabirds. Because food is
particularly abundant in the reproductive season, however, one cannot
ascertain whether the vulnerability of breeding birds to time or energy
crises is far different from that at other times of the year.
Post-fledging Care
Little is known about the amount of care provided by adults to young
after they are fully grown. At least some species, such as gannets and
procellariiformes (Ashmole 1971), are known to desert their young,
whereas others are known to feed their young, at least occasionally,
for some weeks or months after they can fly--e.g., terns and gulls,
many alcids, and shags (Snow 1963; Vermeer 1963; Drury and Smith 1968;
Ashmole and Tovar S. 1968; Potts 1968; Ashmole 1971; LeCroy 1972).
[Illustration: Fig. 14. Percentage observations of foraging seabirds
at different distances from the nest site. After Cody (1973). Each
vertical bar represents 5% of total observations. Note nonlinear
horizontal scale.]
Annual Time and Energy Budgets
The discussion of time and energy allocation during reproduction was
complex and detailed because so much more is known about the influences
altering budgeting during this period than during other times of the
year. It is likely that influences on molt and migration will prove to
be equally complicated, once more is learned about them.
If all data on time and energy allocation for a single species were
known, it would be possible to make up detailed budgets for birds
of different age, sex, and experience throughout the year. However,
such detailed data have not been collected for any species. An annual
time budget for male and female yellow-billed magpie, _Pica nuttalli_
(Verbeek 1972), points out the great amount of difference between
the sexes (Fig. 15). A time and energy budget for the reproductive
season only (Fig. 16) shows large differences between two closely
related species, as well as between sexes; it also indicates the wide
difference between the budgeting of energy as opposed to budgeting of
time. All other time-energy budgets to date are for nonseabird species
and for only a portion of the annual cycle (Verbeek 1964; Verner 1965;
Schartz and Zimmerman 1971; Stiles 1971; Wolf and Hainsworth 1971;
Smith 1973; Utter and LeFebvre 1973).
[Illustration: Fig. 15. Time budget of male (upper panel) and female
(lower panel) yellow-billed magpies throughout the year. From Verbeek
(1972). Non-labeled portions in each graph correspond to labeled
sections in the other.]
Time-energy budget analysis can be useful in determining the leeway
a bird has in surviving unusual stress at different times of the
year. For example, a study by Feare et al. (1974) showed that rooks
_(Corvus frugilegus)_ in the dry part of the summer spent 90% of 15 h
of daylight to collect 150 kcal of food energy. In winter, foraging in
snow, the same birds were able to collect 240 kcal of food in only 30%
of a 10-h day. This suggests that rooks would be far more vulnerable
to unexpected periods of stress in late summer than in winter. Such
information would clearly be useful in making management decisions.
A more precise measure of vulnerability, although much more difficult
to determine, is that of productive energy--the amount of caloric
intake left over after the birds' cost of living (metabolic functions
and procurement and processing of food) have been accounted for. Costs
are highest when temperatures are extremely hot or cold or when food
is most difficult to obtain. Productive energy is highest in summer
(Kendeigh 1972), and that is presumably why reproduction normally takes
place then. It is unknown whether birds are more vulnerable to time and
energy shortages in the harder nonbreeding season or in the breeding
season after the extra demands of reproduction have been accounted for.
Vulnerability may also differ between sexes and among age groups.
Time-energy studies, although useful in comparing ecology, determining
vulnerability, and cataloging location of birds, do have limitations.
Careful studies are time-consuming and are not the best approach to
determining key factors influencing population increase or decrease.
Even when different kinds of data are being sought, however, it is
worthwhile keeping the time-energy framework in mind as a "big picture"
into which other facts can be fitted and their significance considered.
Life History Strategies
The study of life history strategies is largely theoretical, and in the
following discussion I do not comment on current theoretical arguments.
On the other hand, life history strategies can be regarded as time and
energy allocation on a grand scale, and it therefore seems appropriate
to look briefly at their implications for seabird management.
Annual reproduction evidently has a negative effect on resources
remaining for other functions, and may reduce the chances for an
organism to reproduce again in a later season (Cody 1966, 1971;
Williams 1966; Gadgil and Bossert 1970; Gadgil and Solbrig 1972;
Hussell 1972; Trivers 1972; Calow 1973). If the chances of survival
to another breeding season are small, the selective advantage lies
with the bird putting the most effort into early reproduction, in
spite of its negative effects on survival, because future chances of
reproduction are small. If chances of survival are good, however,
it may be more advantageous to reduce annual reproductive effort and
allocate resources to other functions.
[Illustration: Fig. 16. Time and energy budgets of male and female
red-winged _(Agelaius phoeniceus)_ and tricolored _(A. tricolor)_
blackbirds in the breeding season. From Orians (1961). Dotted lines
show male (M) activity, dashed lines show female (F) activity, and
solid lines show shared activities.]
Seabirds are generally long-lived, have small clutches, and generally
delay first breeding until at least the 2nd year, and usually longer
(Table 6). Phalaropes seem to differ from this pattern (Hilden and
Vuolanto 1972; Howe 1975). Several ecological factors (not entirely
independent) are believed to contribute to the evolution of the long
life and low reproductive effort pattern favored by seabirds.
First, if population size is determined largely by density-dependent
mortality, individuals may be favored that allocate resources to
attaining longer life (and more chances to reproduce) or insuring
greater chances of survival of their offspring (Murphy 1968; Hairston
et al. 1970). Density-independent mortality, on the other hand, is so
unpredictable that there is no advantage in allocating resources toward
protection against it (Gadgil and Solbrig 1972).
Two factors closely linked with density-dependence are high levels of
competition, and perennial difficulties in obtaining food. In adapting
to these difficulties, a bird may be selected which develops more
efficient foraging techniques, wider dispersal, or better abilities to
defend nesting territory--all of which may reduce resources available
for reproduction. As mentioned earlier, marine foods tend to be
patchily distributed, and a long learning period seems to be necessary
before seabirds become proficient at foraging. In addition, there is
evidence that food availability is low, at least in the tropics, and
perhaps in the winter in other regions (Ashmole 1971). If nesting
places are in short supply, long life may be favored so that the bird
can live long enough for a place to become vacant. Several authors
feel that competition is a serious factor in the life of seabirds,
both for food (Lack 1966; Cody 1973) and for nesting space (Snow 1960;
Belopol'skii 1961; Lack 1966; Manuwal 1974_b_). Others, however,
disagree, at least for the breeding season (e.g., Pearson 1968).
Table 6. _Life history data for certain northern seabirds._[44]
Annual adult Age at first
survival breeding Clutch
Species (%) (years) size
Fulmar 94 7+ 1
Gannet _(Morus bassanus)_ 94 (4)-5+ 1
Manx shearwater 93-96 (4)-5+ 1
Shag 85 (♂) (2)-3 3-4
80 (♀)
Herring gull 91-96 3.5 (♂) (2)-3
5 (♀)
Black-legged kittiwake 88 4-5 (♂) 3
3-4 (♀)
Arctic tern 89-91 (2)-3+ 2
75
82[45]
Common murre 87 3+? 1
Black guillemot 88+[46] 3?[46] 2[46]
Cassin's auklet 83[47] 3[47] 1
There is some evidence of density-dependent population size control in
seabirds, although much of it is circumstantial. For example, there
are large nonbreeding populations in such diverse species as shags,
herring gulls, and Cassin's auklets, which move into a breeding area
when established adults are removed or colonize new breeding areas
(J. C. Coulson, personal communication; Kadlec and Drury 1968; Drury
and Nisbet 1972; Manuwal 1974_b_). Lack (1966) and Ashmole (1971)
presented other arguments for density-dependence. Density-dependent
mortality is difficult to demonstrate, at best, and may be obscured by
interpopulation movements (Drury and Nisbet 1972).
If long life is a life history option, a low annual reproductive
effort could be favored in several ways. First, it may be necessary
for insuring long life, if breeding has a serious negative feedback on
life expectancy (Calow 1973). Second, if survival of offspring is more
unpredictable than that of adults, low annual effort may be selected
so that reproductive effort will not be wasted in years when young
have poor chances of survival. Unpredictable and variable first-year
survival in seabirds has been documented (Potts 1968; Drury and Nisbet
1972). In addition, some seabirds show adaptations that allow high
reproductive success in any given year but which do not drain off
resources if the season turns out to be poor (e.g., small last eggs in
the clutch or asynchronous hatching, both of which lead to elimination
of the smallest chicks when conditions are poor [Parsons 1970; E. H.
Dunn 1973]).
It should be emphasized that the factors involved in the evolution of
life histories are complex and poorly understood, and simple formulas
should not be expected to apply to all situations (Wilbur et al. 1974).
In the framework of life-history strategies, small clutch sizes and
slow growth rates exhibited by some seabirds can be explained as
adaptive reductions in annual reproductive effort, rather than as
responses to immediate food shortages. Arguments for this view are
presented on theoretical grounds (Dunn 1973) and by the fact that
many seabirds are able to raise larger than normal broods in certain
situations (Vermeer 1963; Nelson 1964; Harris 1970; Hussell 1972;
Ward 1972; Corkhill 1973). In addition, seabirds with particularly
slow growth rates all grow at about the same rate, regardless of body
size (contrary to the situation in other birds). This suggests that
low growth rates do not reflect variations in feeding abilities among
species (Ricklefs 1968).
Several conclusions relating to management of seabird populations
can be drawn from the above discussion. First, if population size is
determined largely by density-dependent factors, the birds are not
adapted to precipitous and unexpected declines in population levels.
Because there is low annual reproductive effort geared to a world in
which there is slow turnover in population, seabirds are not able to
rebound quickly from disasters. Provision of excess food should not be
expected to improve breeding performance, at least in experienced birds.
Second, because seabirds are able to reproduce in many different
seasons and are adapted to a low reproductive effort within a given
season, one should expect them to be easily disturbed and to fail to
complete the reproductive cycle during any given breeding attempt. A
few indications of such failures have already been observed (Erskine
1972; Manuwal 1974_a_; Nettleship 1975).
Again, the tentative nature of this discussion should be emphasized,
and conclusions drawn from it may not apply equally to all seabird
species.
Conclusions
In this discussion I have tried to emphasize the variety of factors
affecting seabird life cycles and the diverse responses among different
species to their environment. The main conclusion I stress is that each
species (and age group and sex within that species) has a different
vulnerability to stress, which may be most severe at different times
of the year for each group. To determine these periods of stress,
researchers may find a time-energy approach to be useful.
As for northwestern North American seabirds in particular, ignorance is
vast. Twelve years ago, Bourne (1963:846) noted the following needs in
seabird research (among others): "The investigation of seabird biology
has been reduced to a routine, but there is a great need for more study
of some other aspects of the life or annual cycle, including events in
the period immediately after fledging, and behaviour and survival in
the immature period and outside the breeding season. Much more accurate
information is needed about breeding distribution and seasons in many
parts of the world, about molting seasons and ranges in most parts, and
the distribution of birds of different age groups during these periods
in practically all areas."
Since the time of Bourne's remarks, a number of excellent studies have
provided data on the breeding biology of certain northwestern seabird
species. Scientists remain largely ignorant, however, about where birds
of different age groups are located throughout the year. Such knowledge
is necessary for effective protection and is basic to understanding
population dynamics, even if it does not elucidate causes. Studies
of timing of annual cycles and movements should be carried out hand
in hand with resource analysis--not just finding what birds eat, but
discovering where the food is at what times, how hard it is to catch,
and what the nutritional return is. Much careful field work must be
done before effective management of most of our northwestern seabirds
can become a reality.
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FOOTNOTES:
[41] Common eider, 2 to 7 h.
[42] No data given.
[43] Indirect evidence that young are brooded this long.
[44] Data from Lack (1968) and Ashmole (1971) unless otherwise noted.
[45] Cullen (1957).
[46] Birkhead (1974).
[47] Speich and Manuwal (1974).
Zoogeography and Taxonomic Relationships of Seabirds in Northern North
America
by
M. D. F. Udvardy
California State University
Sacramento, California 95819
Abstract
The zoogeography and taxonomic relationships
among 42 living and 1 extinct species of marine
birds from the northern and northwestern coasts
of North America are described. Seventeen
species are circumpolar in distribution; 17 are
endemic to Beringia, and 8 have origins in the
North Pacific.
This discussion concerns the northern and western coasts of the
continent, from about the Mackenzie Delta westward and southward to
the mouth of the Columbia River. Besides bona fide seabirds, I include
marine birds that predominantly breed and feed on or around the marine
littoral, but exclude two groups: shorebirds, jaegers, and phalaropes,
which breed inland and move out from the Arctic after an undetermined
postbreeding period; and Anseriformes which become "marine birds" in
their southern winter quarters. What remains is 42 living species
(Table 1).
The Procellariiformes, or tube-nosed seabirds, have a predominantly
southern hemispheric, Gondwanan distribution. The North Pacific basin
is an important feeding ground of several shearwaters (_Puffinus_
spp.) that breed in the South Pacific and subantarctic. Only three
species breed in the area under consideration: the fulmar _(Fulmarus
glacialis)_ and two storm-petrels (_Oceanodroma_ spp.), all of which
are still relatively widespread.
Of the Pelecaniformes, the very successful, worldwide cormorants
(_Phalacrocorax_ spp.)--inland water as well as coastal and
"amphibious" species are on every continent--are ancient Pacific
dwellers, with a high grade of endemism here: Of the two subarctic
species, one _(P. perspicillatus)_ became extinct long ago, and the
other, the red-faced cormorant _(P. urile)_, is very restricted,
and deserves our greatest attention. The pelagic cormorant _(P.
pelagicus)_, Brandt's cormorant _(P. penicillatus)_, and the
double-crested cormorant _(P. auritus)_ are widespread and successful,
extending south of the area here considered; double-crested cormorants
also breed inland and across toward the North Atlantic coast. As
fish-eaters they are often persecuted where coastal fishermen possess
firearms, and thus are sensitive to increasing human influence on the
coasts.
Two species of arctic geese need special attention. The emperor goose
_(Philacte canagica)_ is a Beringean endemic and lives in a very
restricted area of both sides of this sea; its status (endangered?)
is unknown to me. Since the black brant _(Branta bernicla)_ is a
long-range migrant, it is hunted as a game bird at its winter grounds,
and subject to management measures. Whereas the emperor goose is a
unique offshoot of the genus Anser, the Pacific brant is considered a
subspecies; its general distribution is circumpolar.
Five arctic ducks, and one other, constitute the sea ducks of the
area. The common eider _(Somateria mollissima)_, king eider _(S.
spectabilis)_, and the oldsquaw _(Clangula hyemalis)_ are widespread,
and circumpolar or nearly so; hunting and down-robbing in other
parts of the Arctic may provide clues as to their relative tolerance
of primitive or advanced civilization. The spectacled eider _(S.
fischeri)_ and Steller's eider _(Polysticta stelleri)_ are restricted
to the Bering Sea coasts and neighboring High Arctic coasts,
respectively; their status is precarious.
Table 1. _Seabirds in northwestern North America._ (x = breeding,
w = wintering or transient, () = either scarce or restricted
distribution, * = stragglers only, nesting status unclear)
Distribution
---------------------------------------------
|Circumpolar
| |Widespread in North Pacific
| | |North coast of Alaska
| | | |Beringia[48]
| | | | |Aleutian Islands
| | | | | |South coast of Alaska[49]
| | | | | | |Temperate northeast
Species | | | | | | |Pacific coast[50]
_Fulmarus glacialis_ x w x x x w
_Oceanodroma furcata_ x x x x
_O. leucorhoa_ x x x x x
_Phalacrocorax auritus_ x x x
_P. penicillatus_ (x) x
_P. pelagicus_ x x x x x
_P. urile_ x x x
_Branta bernicla_ x x x (w) (w) w
_Anser canagicus_ x w w
_Clangula hyemalis_ x w x x w w w
_Histrionicus histrionicus_ x w w w w w
_Polysticta stelleri_ x x (w)
_Somateria mollissima_ x x x x x
_S. spectabilis_ x x x w (w)
_S. fischeri_ x x
_Larus hyperboreus_ x w x x w w w
_L. glaucescens_ x x x x
_L. occidentalis_ (x)
_L. argentatus_ x w x (x)w
_L. thayeri_ w x w w w w
_L. canus_ x w x x (x)w
_Rissa tridactyla_ x w x x x x w
_R. brevirostris_ x x (x)
_Xema sabini_ x x x w
_Sterna paradisaea_ x w x x x w
_S. aleutica_ x x
_Uria aalge_ x x (x) x x x x
_U. lomvia_ x x x x x x
_Alle alle_ x *
_Cepphus grylle_ x x w
_C. columba_ x x x x x
_Brachyramphus marmoratus_ x (x) x x
_B. brevirostris_ x x x
_Synthliboramphus antiquus_ x x x x x
_Ptychoramphus aleuticus_ x x x
_Cyclorrhynchus psittacula_ x x
_Aethia cristatella_ x x
_A. pusilla_ x x
_A. pygmaea_ x
_Cerorhinca monocerata_ x x x
_Fratercula corniculata_ x x x x x
_Lunda cirrhata_ x x x x x
Total number of nesting species 17 11 15 27 25 24 17
Total number of wintering species 9 4 7 9 9
Grand total 17 20 15 31 32 33 26
The harlequin duck _(Histrionicus histrionicus)_ stands alone without
close relatives. It often breeds far from the sea, but spends the
shortest time--only a few weeks--away from the rocky coast. There
is a year-round population of yearlings in the sea. The drakes
of the nearest breeding pairs at lower latitudes are back to the
sea, abandoning their mates at the breeding stream when the alpine
stream-dwellers are still at sea awaiting the thawing of their breeding
grounds. Harlequin ducks live in large parts of Siberia, from arctic
Alaska to central California and Colorado, and also in the eastern
Arctic. They do not seem to me to be in immediate danger globally,
though perhaps they are locally.
Gulls are a highly successful group of seabirds, and of the eight
species on our coasts the four more southern ones--the western gull
_(Larus occidentalis)_, glaucous-winged gull _(L. glaucescens)_, common
gull _(L. canus)_, and herring gull _(L. argentatus)_--are expanding
wherever civilization creates new scavenging opportunities. Nothing
is said about the populations of the kittiwake _(Rissa tridactyla)_,
black-legged kittiwake _(R. brevirostris)_ and Sabine's gull _(Xema
sabini)_, or of the other two high arctic species (_Pagophila eburnea_,
_Rhodostethia rosea_) which do not nest regularly in the area
considered here.
The arctic tern _(Sterna paradisaea)_ is circumpolarly widespread
and successful, whereas the Aleutian tern _(S. aleutica)_ is a very
restricted Beringean endemic, and its status needs to be exactly known.
Almost one-third of the seabirds in this area are alcids, a family
centered in the North Pacific and, more specifically, in the
Bering Sea. Most species breed in enormous rookeries. Any impact
of civilization is highly detrimental under such circumstances. Of
the four circumpolar species the two _Uria_ guillemots (murres) are
important. The dovekie _(Alle alle)_ is a sparse pioneer of Bering
Strait, as is the black guillemot _(Cepphus grylle)_ on our side of
the Arctic Sea. Its congener, the pigeon guillemot _(C. columba)_, is
common and successful all the way to coastal central California. Of the
remaining 11 species, special attention should be paid to the whiskered
auklet _(Aethia pygmaea)_ of the Aleutian chain; the Kittlitz's
murrelet _(Brachyramphus brevirostris)_ of the eastern Beringean
and southern Alaska coast; and to the widespread, but very sporadic
rhinoceros auklet, or puffin _(Cerorhinca monocerata)_.
To sum up, I have tabulated these 42 species, and indicated whether
modern life-history and population studies are extant:
No. No.
species studied
Procellariiformes 3 2
_Phalacrocorax_ 4 2
Anseres 2 1
Anates 6 --
Lari 9 2
Sterni 2 --
Alcidae 16 7
Total 42 14
Thus, 28 species await studies preliminary to, and highly necessary
for, conservation measures.
Seventeen species of marine birds are spread either circumpolarly
around the northern perimeter or along the north-south coasts of the
Laurasian continents. Four of these are of the High Arctic (_Branta
bernicla_, _Somateria spectabilis_, _Xema sabini_, _Alle alle_);
another seven penetrate the Bering Sea as well (_Fulmarus glacialis_,
_Somateria mollissima_, _Clangula hyemalis_, _Larus hyperboreus_,
_Rissa tridactyla_, _Sterna paradisaea_, _Uria lomvia_); and six are
panboreal-subboreal, widespread in their distribution--_Oceanodroma
leucorhoa_ (extends far south), _Histrionicus histrionicus_, _Larus
argentatus_ (widespread latitudinally), _L. canus_ (also inland), _Uria
aalge_, and _Cepphus grylle_.
Seventeen species of marine birds are endemic to Beringia: _Anser
canagicus_, _Polysticta stelleri_, _Somateria fischeri_, _Rissa
brevirostris_, and _Aethia pusilla_ (and the extinct _Phalacrocorax
perspicillatus_); _P. urile_, _Sterna aleutica_, _Aethia pygmaea_,
_A. cristatella_, and _Cyclorrhynchus_ extend westward to the Sea of
Okhotsk, as do _Brachyramphus brevirostris_ and _Larus glaucescens_,
which also extend eastward; and _Phalacrocorax pelagicus_, _Cepphus
columba_, _Fratercula corniculata_, and _Lunda cirrhata_ are
amphipacific species in Beringia.
Eight species of marine birds are associated with the North Pacific.
Four are found on both sides of the ocean--_Oceanodroma furcata_,
_Brachyramphus marmoratus_, _Synthliboramphus antiquus_, and
_Cerorhinca monocerata_ (very disjunct). The four others occur on only
the North American side--_Phalacrocorax auritus_ (also inland), _P.
penicillatus_, _Larus occidentalis_ (albeit barely), and _Ptychoramphus
aleuticus_.
Finally, one species, _Larus thayeri_, is endemic at the central
Canadian Arctic, extending westward into the area here considered.
FOOTNOTES:
[48] Beringia comprises the islands and coasts of the Bering Sea.
[49] South coast of Alaska extends from the tip of the Alaska Peninsula
to Glacier Bay.
[50] Temperate northeast Pacific coast extends from Glacier Bay south
to the mouth of the Columbia River.
CONFLICTS BETWEEN THE CONSERVATION OF MARINE BIRDS AND USES OF OTHER
RESOURCES
Social and Economic Values of Marine Birds
by
David R. Cline[51] and Cynthia Wentworth
U.S. Fish and Wildlife Service
Anchorage, Alaska
and
Thomas W. Barry
Canadian Wildlife Service
Edmonton, Alberta, Canada
Abstract
Throughout history, marine birds have provided
tangible and intangible benefits to human
societies. Unregulated exploitation of some
species by explorers, mariners, and colonists
led to the extinction of the great auk
_(Pinguinus impennis)_ and near extinction
of others, including the Bermuda petrel
_(Pterodroma cahow)_ and the North Pacific
albatrosses (_Diomedea_ spp.). Marine birds
continue to provide commercial, subsistence,
recreational, scientific, and educational
values to people of many nations, while playing
critical roles in the economies of the world's
oceans.
Annual harvest of slender-billed shearwaters
_(Puffinus tenuirostris)_ known as
"muttonbirds" in Australia, sooty tern _(Sterna
fuscata)_ eggs in the Caribbean, murres
(_Uria_ spp.) and eiders (_Somateria_ spp.)
in Greenland and the Soviet Union, and guano
in Peru and Africa represent the principal
commercial uses of marine birds and their
products. Residents of the Faeroes Islands and
thousands of native people in Greenland and
arctic Canada and Alaska use various species
for subsistence. The annual rituals of bird
hunting and egg gathering are deeply ingrained
in the sociocultural traditions of these
peoples and continue to be important to their
social welfare.
Most countries of the world are currently
providing at least some protection to their
marine bird resources. However, the destruction
of bird habitats by man's developments and
the contamination of marine environments by
industrial pollutants are posing increasingly
serious threats to many species. If managed and
used in accordance with scientific principles
of sustained yield, some of the more abundant
species of marine birds can continue to provide
long-term social and economic benefits to man.
Increasing numbers of people are expending
considerable sums of money to reach marine
bird viewing areas off the coasts of North
American States and Provinces. Preliminary
evidence indicates such nonconsumptive pursuits
are contributing significant amounts of money
to regional economies and helping businessmen
earn a living. An accurate evaluation of both
biological and economic impacts resulting from
these nonconsumptive activities is urgently
needed.
The possibility of establishing an excise tax
on designated outdoor recreational equipment
appears to hold considerable potential for more
adequately funding marine bird programs, as
well as those for other nongame wildlife.
Greater citizen involvement in sociopolitical
processes will, to a large extent, determine
the success of marine bird conservation
programs. Sound conservation legislation
that insures adequate protection of habitat
and provides for enlightened and innovative
thrusts in conservation, education, research,
management, and law enforcement will help
insure the survival of all species of marine
birds and, in turn, provide social and economic
benefits to people across generations. #/
In its 17 March 1975 issue, _Time_ magazine reported battalions
of observers from all over the country flocking to Salisbury,
Massachusetts, armed with telescopes, cameras dwarfed by huge telephoto
lenses, sketch pads, and binoculars. There, 1,500 strong the first
weekend alone, they took up vigil along the seawall of the Merrimack
River. A local businessman circulated among the chilly bird-watchers
with free coffee and hot chocolate, while handing out a pamphlet
advertising his restaurant.
The cause of the commotion was the appearance of a single, unassuming,
pigeon-like seabird called a Ross' gull _(Rhodostethia rosea)_,
almost never seen south of the Arctic Circle and never before in the
contiguous 48 States. Time stated that "for those who care about such
matters the event was as electrifying as the descent of a Martian
spaceship."
Meanwhile, far above the Arctic Circle at Point Barrow on the Arctic
Ocean, Eskimo hunters probably puzzled at the strange ways of the white
"birdmen," as they recalled the savory dishes Ross' gulls provided many
of them during the previous fall hunting season. This particular gull
is considered a delicacy by the Eskimos, and the birds are actively
sought each year as they fly near shore during their fall wanderings
from Asian breeding grounds.
Perhaps this dichotomy of people's interests in a single species is
indicative of the broad spectrum of social and economic values man
derives from marine birds. Perhaps, too, it represents the challenge
that wildlife professionals, administrators, and citizen conservation
leaders face in today's complex world in striving to sort out
priorities in allocation of such common property (amenity) resources
among beneficial users.
As with the Ross' gull, socioeconomic values of marine birds involve
both consumptive and nonconsumptive uses. Consumptive uses may provide
socioeconomic values in the form of meat, eggs, oil, feathers, down,
and guano. Cultural and recreational benefits may also be involved.
Nonconsumptive uses benefit the tourist and recreation industries
as well as providing less tangible social values, such as esthetic
appreciation and environmental education and scientific study
opportunities.
In this paper we examine some social and economic indicators that are
believed to demonstrate people's growing awareness and interest in
marine birds. These indicators involve a broad spectrum of values and
illustrate the critical need for adoption of a strong North American
marine bird conservation program.
Historical Perspective
Since earliest times, marine birds have accompanied the evolution of
human societies in coastal and insular environments of the world.
Their social value is in part recorded in kitchen middens of ancient
campsites and villages. From the time man first inhabited the seacoasts
and ventured out in ships, the company of seabirds has added life and
inspiration to what otherwise would be a bleak and desolate landscape.
Fishermen long ago learned to use seabirds to show them where the rich
fishing grounds were located, and the cries of birds were often used to
guide mariners away from dangerous cliffs during foggy weather.
At the time of the first contact with Europeans, native peoples of
arctic Canada and Alaska reportedly took birds with bolas, snares,
spears, arrows, and nets; they herded flightless waterfowl and gathered
eggs as well. Brandt (1943) said that Alaskan Eskimos would have been
destitute if eiders (_Somateria_ spp.) had not been available for food
and clothing, and Ekblaw (1928) believed the dovekie _(Plautus alle)_
saved the polar Eskimo from extinction.
Marine birds have often served as an emergency food supply for
explorers, sailors, and others: according to Tuck (1960) "The accounts
of early arctic explorers and marooned whalers describe many instances
in which starvation was averted by eating murres" (_Uria_ spp.).
One burrowing petrel of Australia was given the title "the bird of
providence" because it saved the lives of shipwrecked mariners and
convicts when supply ships from Sydney failed to reach them between
March and August of 1790 (Serventy 1958).
Marine birds have also been taken because of the economic values of
their feathers and oil. When economic overutilization has occurred,
entire species were sometimes totally destroyed. This in fact happened
to the great auk _(Pinguinus impennis)_. When Jacques Cartier visited
the Funk Islands off Newfoundland in May 1534, he and his crew filled
several barrels with great auks and salted them down for future
consumption. So severe was the slaughter in the next 3 centuries
that the species became extinct in its known breeding haunts, which
originally extended from Newfoundland through Greenland and Iceland, to
the Hebrides. The last one was killed at a stack rock off Iceland in
1884 (Lockley 1973).
Other species have been almost totally destroyed. Colonization of
Bermuda by Spain in the 17th century resulted in the near annihilation
of the Bermuda petrel _(Pterodroma cahow)_ there. Ships' crews found
the birds to be fat and delicious, and they dried and salted those that
could not be eaten fresh. Today, only about 20 breeding pairs remain,
and are under strict protection by the Bermudan government (Lockley
1973).
The North Pacific albatrosses (_Diomedea_ spp.) were nearly
exterminated by Japanese feather hunters near the end of the 18th
century. The short-tailed albatross _(D. albatrus)_ was also nearly
wiped out at its breeding colonies west of the Hawaiian Islands (Bourne
1972).
Other species that were carelessly exploited for their meat and plumage
in the past, but which have since regained their numbers, include
the fulmar _(Fulmarus glacialis)_ on St. Kilda Island in the North
Atlantic; and the North Atlantic, South African, and Australian gannets
(_Morus bassanus_, _M. capensis_, and _M. serrator_) (Bourne 1972;
Lockley 1973). In some instances entire breeding colonies of a species
have been destroyed while others have survived. On the Abrothos Islands
in western Australia, for example, large nesting colonies of sooty
terns _(Sterna fuscata)_ and common noddies _(Anous stolidus)_ appear
to have been wiped out on Rat Island by indiscriminate "egging" for
food, whereas similar-sized colonies survive on other islands, where
they are now controlled by the Fisheries and Fauna Department (Serventy
et al. 1971).
Historically, it has probably been man's unregulated harvest of marine
birds that has been the primary cause of their destruction. Generally,
the loss of a species because of unregulated harvest is no longer
a matter of major concern, because most countries of the world are
providing at least some protection for their marine birds. However,
other factors such as habitat destruction and contamination of the
marine environment by industrial pollutants are posing increasingly
serious threats to many.
Social and Economic Indicators
Economic indicators concerning consumptive uses of wildlife, including
marine birds, are frequently misunderstood. In a dollar-oriented and
over-consumptive society like ours, economic values are usually seen as
being in conflict with esthetic values. "Economic use" usually conjures
up images of man's overutilization and, hence, long-term depletion
of wildlife resources. However, when speaking of economic use, it is
important to distinguish between such overuse and sustained-yield
management.
Although both types of use have provided economic benefits over the
years, overharvest that results in long-term resource depletion is not
usually the most or best economic use in the long run; obviously a
"harvest" cannot be sustained at a given level when the resource base
is constantly being depleted. On the other hand, when certain species
of marine birds are used in accordance with principles of sustained
yield, they can provide long-term economic values to society in
conjunction with the social, esthetic, and intangible values that their
preservation insures. Of course, for many species esthetic values far
outweigh economic ones derived through commercialization.
_Commercial Uses_
Muttonbirds
The muttonbird industry of Australia is an excellent example of the
commercial use of marine birds on a sustained-yield basis. Fledgling
Tasmanian muttonbirds, or slender-billed shearwaters _(Puffinus
tenuirostris)_, are commercially harvested each year from their
colonies on islands of Bass Strait, mainly in the Flinders Island
group.
These muttonbirds are marketed as fresh or salted "Tasmanian squab."
Various by-products, including oil, body fat, and feathers, are also
sold. In 1968, a total of just under one-half million young birds were
taken. Prices to the producers varied from $12 to $14 (Australian
dollars) per hundred salted birds and $16 per hundred fresh birds.
Stomach oil brought 75¢ per gallon. Assuming the average price per
hundred birds to be $14, the meat alone was worth about $70,000 per
year to the producers. The retail value was of course much higher.
Although the muttonbird harvest is no longer the mainstay of the
Flinders Island economy, according to Serventy (1969) it is still a
picturesque and important annual social event.
Serventy et al. (1971) believed the commercialization of the muttonbird
preserved its numbers: "Had there been no vested interests to preserve
the 'birding islands' as such, many of them would in the course of time
have been 'improved' as sheep stations and the shearwater populations
would have declined and vanished."
Sooty Terns
The Caribbean is the home of the world's most important wild egg
producer--the sooty tern. In some years about 2 million sooty tern eggs
from the Seychelles and 0.6 million from Morant and Pedro bays have
reached Caribbean markets (Tuck 1960).
Eiders and Murres
Although the shooting of birds is not as important economically to
Greenland's approximately 50,000 residents as are sealing, whaling, and
fox hunting, the harvest of seabirds is an ancient tradition that still
means production of an important food source that the many Greenlanders
could not exist without. About 30 species of marine birds are harvested
for human consumption, eider ducks and murres being by far the most
important. In west Greenland about 750,000 birds (equivalent to about
825 tons of meat) and 10,000 eggs are harvested annually. Murres
constitute the main dish in summer at small coastal outposts with
access to rookeries. Great quantities are also dried and salted for
use in winter. Murre canneries at Upernavik have supplied southern
cities with the frozen meat of about 25,000 to 30,000 murres annually.
However, this commercial activity would be prohibited by a proposed new
Greenland game law (Salomonsen 1970).
Banding has shown that about 22% of Greenland's eider population,
or about 150,000 birds, is shot annually. Collecting of eider eggs
is now prohibited except in the Thule District, where 10,000 are
taken annually. Eider down is still collected from nests for sale to
a trading company for the manufacture of much demanded eider-down
coverlets (Salomonsen 1970).
A growing human population, the widespread use of modern firearms, and
the increasing use of speedboats in hunting have resulted in serious
declines in many of Greenland's marine bird populations. The Greenland
government has demonstrated its concern by instituting protective
measures in response to Danish expert advice. For example, the common
puffin _(Fratercula arctica)_ was given 10 years of total protection
in 1961 after bird numbers had seriously declined as a result of
over-harvesting of the birds and their eggs (Lockley 1973). This
protection was extended in 1970. Also, it is now illegal to discharge
firearms at most marine bird rookeries in Greenland.
With protection of bird habitats from human intrusion and toxic
environmental pollutants, adequate enforcement of sound conservation
laws, greater efforts in conservation education, and scientific
regulation of harvests, Greenland's valuable marine bird resource could
probably withstand intensive utilization indefinitely (F. Salomonsen,
personal communication). Salomonsen has been quick to point out,
however, that people should not be encouraged to believe that the value
of seabirds for food is the only reason they should be saved.
Although several species of marine birds serve as sources of food in
the Soviet Union, down of eider ducks and eggs of murres are considered
to be the most important to the economy. These birds are referred to as
trade birds due to their commercial importance (Belopol'skii 1961).
Guano
Peruvian guano beds are currently being managed on a sustained-yield
basis; the harvest, as in the days of the Incas, depends entirely on
the amount of guano deposited each year. Conservation and management
policies have resulted in a steady increase in the amount extracted,
from around 20,000 tons in 1900 to over 200,000 tons in 1971 (Lockley
1973).
The islands off south and southwest Africa are also commercial
producers of guano. The annual yield from these breeding colonies
averaged 3,971 tons in the 12-year period, 1961-72. In 1969, guano
brought 4.75 Rands (equivalent to $7.11) per 200-pound bag. South
African gannets are apparently depositing guano that is worth twice as
much as the fish they consume to produce it (Jarvis 1971).
_Indirect Commercial Benefits_
Marine birds also play significant roles in the economies of the
world's oceans, where algae, invertebrates, fish, seabirds, mammals,
and man interact in complex ways. The bioenergetics and nutrient
cycling in ocean ecosystems is even less well understood than the
contributions seabirds make to man's dollar economies.
Sanger (1972) has conservatively estimated that in the subarctic
Pacific region alone, birds consume from 0.6 to 1.2 million tons of
food and return from 0.12 million to 0.24 million tons of feces each
year.
Marine bird excrement is especially rich in nitrates and phosphates,
which phytoplankton, the basis of ocean food pyramids, requires. Marine
birds then, at least to some extent, help to sustain the northern
commercial, recreational, and subsistence fishing industries. The
fisheries in turn sustain seals and certain other mammals which are
also essential elements of northern subsistence and recreational
economies. Thus, marine birds contribute economic benefits indirectly
as well as directly by serving as critical links in ecosystem food
chains (Tuck 1960).
_Subsistence Uses_
The use of marine birds and their products does not have to be
commercial to be economic. Economics is the science of the allocation
of scarce resources. Any resource, regardless of whether it is bought
or sold, has value to people and is therefore an economic commodity.
Thus, any society has an economy whether or not it uses cash, and when
the meat, feathers, or oil of marine birds are used, the birds have
economic value. The problem, of course, is that of trying to determine
just what this value is when a cash medium does not exist.
One of the ways to estimate this value is to assign implicit gross
dollar values to seabirds, based on what it would cost to replace
products derived from them with store-bought items of a similar, or
substitutable, nature (this is a gross rather than a net value because
it does not include the cost of guns, ammunition, transportation, etc.,
required to harvest and process the resource).
There have been many occasions in the past when it would have been
physically impossible to find substitutes for seabird products. In such
cases, and where seabirds may well have meant the difference between
life and death, the economic value of the resource could be considered
a plus infinity.
There are probably few, if any, places in the world today where people
would starve if they could not obtain marine birds. However, there are
still many situations where available substitutes are poor, or very
expensive. And there are others where, even though the birds are no
longer necessary for economic survival, they are still very important
in terms of sociocultural traditions. According to Tuck (1960),
"Wherever a wild animal is important to the economy of a people, its
capture and use become part of the tradition of that people." Thus,
while economic values can be measured in terms of substitutable
store-bought foods, social and cultural values cannot be. To force
complete dependence on a people by flying in foods from "Outside" is
often socially intolerable because it tends to remove pride, a sense of
worth, and therefore the reasons for living.
Marine birds have served as important sources of food in the Faeroes
Islands for centuries, the puffin being unquestionably the most
valuable. Williamson (1945) reported that in a good year the total
puffin catch may be between 400,000 and 500,000. In addition, as
many as 120,000 murres are snared or shot annually by the Faeroese,
and at least twice that many eggs are taken and Tuck (1960) stated,
"The economic necessity of 'fowling' in the Faeroes has by virtue of
long centuries of usage become part of the national life, affecting
folklore and customs, and providing outlets for the sporting instinct
inherent in the people." A Faeroese guidebook even suggests that its
importance to the Faeroese culture has been in no way diminished by
the influence of modern civilization. Current Faroese game laws appear
to be effective in assuring a sustained yield of marine birds while
guaranteeing their long-term survival.
Seabirds and their eggs constitute a small, but still very important,
part of the total diet of the Eskimos and Indians living along the
Arctic coast of the Northwest Territories and Alaska. In spite of
the many changes occurring in the North, there is, even for the wage
earner, a strong psychological attachment to the land and sea and
the free life it represents. In spring, the release from the long
monotonous winter is marked by the rites of ratting, fishing, sealing,
whaling, or marine bird hunting and egg gathering, according to village
tradition.
For those living off the land in such remote coastal outposts as Sachs
Harbor on Banks Island, Holman Island on the Mackenzie Delta, Point
Hope and Point Barrow in northern Alaska, Inalik on Diomede Island in
the Bering Strait, or Hooper Bay on the Yukon-Kuskokwim Delta, the
spring marine bird hunt represents a change of diet and activity. It
offers opportunity to renew age-old traditions and continues a cultural
bond among those confined to jobs in the settlements--vacationing and
absenteeism from jobs and schools are always highest during late May
and early June.
Marine birds yield between a few grams and 2 kg of meat, depending on
the species. Usually the birds are either consumed soon after they are
taken or stored in an icehouse for use throughout the summer. Most
often the meat is cooked into a soup or stew with rice, noodles, and
onions. A few birds may be dried or salted so that they can be used for
special holiday feasts during the winter. Sometimes feathers are saved
for the manufacture of parkas, ceremonial fans, and masks. In some
areas of the Yukon Delta, goose and duck down is still saved and used
in quilts that can be found in nearly every home. In the spring 1975
issue of the catalog of a Seattle, Washington, outfitter, down quilts
for single beds were listed at $95. Thus, there is a substantial cash
savings by home manufacture of such items.
The Yukon Delta in western Alaska is the area where the use of marine
birds is most extensive and significant. Klein (1966) provided harvest
data by village for the entire area and showed that, in general, geese
were more important than ducks, representing about two thirds of the
take in both the spring and the fall. The average numbers of ducks
(mostly pintails, _Anas acutus_) and geese (primarily white-fronted
geese, _Anser albifrons_); emperor geese, _Philacta canagica_; cackling
Canada geese, _Branta canadensis minima_; and black brant, _Branta
nigricans_, taken per household were 77 by the Yukon River villages,
69 by the Kuskokwim River and tundra villages, and 94 by the Bering
Sea coastal villages. Although eggs gathered by Yukon River villagers
averaged less than a dozen per household, Kuskokwim people took about 3
dozen and coastal people about 6.5 dozen on the average. Eggs of black
brant and cackling Canada geese were especially favored, but even those
of small passerines were acceptable. The average size of households for
all areas was believed to be between 5.5 and 6.5 persons.
A 1968 survey of waterfowl taken in the Mackenzie Delta region, made
by the Canadian Wildlife Service, showed an average take per household
of about 70 birds, a figure comparable to that for the Yukon Delta. In
the Mackenzie region, however, ducks were more important than geese,
representing about 60% of the harvest.
More recent data on Alaska waterfowl harvest per household is available
for other coastal regions. Data provided by two regional native
corporations for the Joint Federal-State Land Use Planning Commission
for Alaska in 1973 showed an average per-household waterfowl harvest
of 33 ducks and geese for Kotzebue area villages, 68 for Norton Sound
villages, 24 for northwest Seward Peninsula villages, and 37 for St.
Lawrence, Diomede, and King Island villages.
A 1974 subsistence survey carried out jointly by the University of
Alaska and the Bristol Bay Native Corporation showed that, in 20
Bristol Bay villages, 57% of the households harvested waterfowl. The
average kill was 32 birds per household.
Eider ducks are the most important marine birds taken by residents
of Barrow, Alaska. Johnson (1971) interviewed 31 adult hunters
with average kills of 88 birds per hunter. Barrow people also take
substantial numbers of geese at Atkasook, a summer camp on the Meade
River 80 miles southeast of Barrow.
Point Hope, Alaska, villagers also favor eider ducks above all
others. Pederson (1971) indicated that each household that hunted
took about 150 eiders in the summer of 1971. Each summer, Point Hope
and Kivalina residents travel to the Cape Thompson and Cape Lisburne
cliffs to gather murre eggs. Both Pederson (1971) and Kessel and Saario
(1966) showed an average harvest of 5 to 10 dozen eggs per household
(equivalent in weight to 10 to 20 dozen chicken eggs).
To our knowledge, there is no available evidence to indicate that the
number of migratory birds taken in the North in spring and fall is a
significant factor in the survival of a particular species. The birds
are, however, a significant factor in the economy and culture of the
people of the Mackenzie Delta region and much of coastal Alaska. This
may not always be true, for their social and economic conditions are
changing rapidly.
With the native birthrate twice the national average and with hunting
technology improving yearly, the day will undoubtedly come when
marine birds and other wildlife resources are not able to withstand
intensified harvest pressures without more regulation and control. An
obvious need exists for government conservation agencies to work more
closely with the native people of northern regions in conservation
education and development of sound harvest regulations.
_Recreational Uses_
No attempt was made in this evaluation to affix dollar values to
every marine bird enjoyed by recreationists. Goldstein (1971), in his
economic study of wetlands, found it impossible to fix the value of the
production and harvest of migratory waterfowl in Minnesota.
The amount of money spent by recreationists in seeking enjoyment from
marine birds does not measure the values they derive; it measures
only their costs to participate in such ventures. The analogy that
could be made is that the value of a diamond is equal to the cost
of mining it. Nevertheless, expenditure data for services and goods
provided by air-taxi and charter boat operators and merchants selling
bird guides, binoculars, and other outdoor recreational equipment are
useful indicators in establishing the secondary or indirect benefits of
recreational activities associated with marine birds.
The normal economic concept of net benefits from marine bird recreation
would include only those accruing to individuals who provide goods and
services to the recreationists, gross revenues minus the costs (Wollman
1962; Pearse and Bowden 1969). This economic return, however, in no way
measures direct benefits of marine bird resources to the recreationists.
Another important consideration in evaluating recreational use of
marine birds is to recognize that many of the nonparticipants either
value the option of being able to take advantage of them in the future,
or simply believe that the availability of such resources benefits
society (Stegner 1968). Such benefits are difficult, if not impossible,
to quantify yet may be exceedingly important due to the uniqueness of
the marine bird resource and because many decisions affecting it may
prove irreversible.
Increasing numbers of bird enthusiasts throughout North America are
discovering the excitement and pleasures derived from visiting marine
bird rookeries. As pointed out by Sowl and Bartonek (1974), and as
anyone can attest who has ever had the privilege of watching the antics
of tufted puffins _(Lunda cirrhata)_ near their colonies on a day when
the sun is obscured and the air buoyant, watching seabirds is fun.
We have found that organizations and businesses in practically
every North American coastal State and Province, from Nova Scotia
to Florida and Alaska to California, are busy scheduling boat or
airplane excursions to marine-bird viewing areas off their shores.
The Alaska and Washington State ferry systems have for years been
providing passengers opportunity to enjoy seabirds of the North Pacific
coast. Audubon chapters in San Diego, Los Angeles, Monterey, Seattle,
Anchorage, and other cities sponsor annual excursions to seabird
colonies.
In 1975 a charter airline service in Anchorage, Alaska, booked 530
people in 51 tours to fly to the Pribilof Islands in the Bering Sea
to view the outstanding seabird and fur seal colonies there. Included
in the bookings were three National Audubon Society International
Ecology Workshops, the Massachusetts Audubon Society, the National
Wildlife Federation, and Canadian Nature Federation. Participants paid
from $1,500 to $2,000 for these tour packages to Alaska. At $300 to
$380 per person, depending on the length of the excursion, the air
charter service grossed about $160,000 from these tours (Reeve Aleutian
Airways, personal communication).
Fairweather Outings, a small cruise business based in Sitka, Alaska,
takes people on wilderness excursions in the west Chichagof-Glacier
Bay area of the southeastern part of the State. The seabird rookeries
are one of the principal attractions for the 90 people taking these
trips each year. Over one-third of the clientele has been from outside
Alaska; thus their dollars are new dollars to the State's economy.
Fairweather Outings grossed about $11,000 in 1974 (Charles Johnstone,
personal communication).
These examples illustrate how seabirds, both directly and indirectly,
help small coastal businessmen earn a living. It is also important to
recognize that the multiplier effects generated by the expenditures
in all of the above examples ripple through the regional and State
economies.
Despite the great social and economic significance of such activities
along our coasts, apparently no attempt is being made to determine
the number of people involved in such pursuits and how much they are
spending. A study of the phenomenon would undoubtedly produce startling
results.
The Wildlife Management Institute (1975) revealed that the national
estimated value of manufacturers' shipments in 1972 was $157 million
for camping equipment, $5 million for binoculars, and $19.9 million for
bird feed. Sales of wild bird feed have been increasing 5 to 10% per
year recently. These are all economic indicators of recreation trends
of which enjoyment of marine birds is a part.
A major use of photographic equipment and related products and services
is in the natural and scenic areas of the nation. Manufacturers'
shipments of photographic equipment, and photofinishing, were valued
at $2.3 billion in 1972. A 5% excise tax on these items would have
generated nearly $118 million (Wildlife Management Institute 1975).
Since inadequate funding plagues most nongame management initiatives,
the Wildlife Management Institute (1975) recommended that Congress
authorize a matching grant-in-aid program to benefit nongame fish and
wildlife. Funds would be obtained from new manufacturers' excise taxes
on designated outdoor recreational equipment to initially yield at
least $40 million annually.
The Executive Committee of the International Association of Game, Fish
and Conservation Commissioners and the Council of the Wildlife Society
have already endorsed model legislation for a State program for nongame
wildlife conservation (Madson and Kozicky 1972). We urge that these
proposals be given serious consideration in terms of future funding of
marine bird conservation programs in North America.
It is encouraging to note that several States, including Washington,
Oregon, and California, have recently initiated nongame wildlife
programs that have resulted in substantial benefits to their citizens.
The California legislature, for example, enacted a law in 1974 to
provide a means for individuals and organizations to donate funds for
supporting nongame species management. The California Department of
Fish and Game has increased its nongame staff and appointed a citizen
Nongame Advisory Committee to help develop and implement nongame
programs.
Because most species of marine birds are not hunted by sportsmen
in North America, this increased emphasis on nongame species may
eventually benefit research and management programs for seabirds
substantially.
_Scientific Research_
Even now, marine-bird research studies and inventories require the
expenditure of several million dollars annually along our coasts.
In Alaska a multimillion dollar Federal effort has been initiated
to assess the environmental risks of developing offshore petroleum
potential in the Gulf of Alaska and five other key areas of the
State. These areas represent 60% of the nation's total continental
shelf and support some of the largest marine-bird populations in
the world. The program to examine life-forms and the physical
environment of the petroleum lease areas will require 4 to 5 years to
complete. Approximately $1.5 million has been allocated to conduct
an environmental assessment of marine bird resources in the first 18
months alone.
The U.S. Fish and Wildlife Service is spending about $40,000 to
determine the seasonal occurrence, density, and distribution of marine
birds in coastal waters adjacent to new national wildlife refuges in
Alaska being proposed pursuant to the Alaska Native Claims Settlement
Act of 1971, and almost $200,000 to study and manage migratory
birds--including marine birds--on existing refuges.
Although generated by external events (including requirements pursuant
to the National Environmental Policy Act of 1969) rather than by the
resources themselves, these expenditures at least indirectly reflect a
social concern for the welfare of marine birds.
_Citizen Involvement (Social Indicator)_
Another encouraging aspect of seabird conservation and its meaning
to society is the increasing involvement of citizens in the issue.
Although agencies have not been as responsive as many would like,
administration of government at all levels has been shaken and
stimulated by citizen participation. As Russell W. Peterson, Chairman
of the Council on Environmental Quality, has stated, "Citizen action is
the essence of democracy. Citizen movements should be encouraged and
expanded. The involvement of people is necessary to counterbalance the
disproportionate influence of the professional lobbyists and public
relations operators hired to further the special interests of their
clients." Mr. Peterson further emphasized that government thrives
much better on citizen concern and attention than on indifference and
neglect.
Therefore, it is highly significant that the Pacific Seabird Group
has many nonprofessional, as well as professional, members and
that the 1975 International Symposium on Conservation of Marine
Birds of Northern North America had strong citizen involvement and
participation. As everyone recognizes, nothing works in government
unless people, be they doctors, lawyers, college professors, students,
environmentalists, or Indian chiefs, make it work.
Educators must upgrade training in environmental sciences so that an
environmental awareness (conservation ethic) is instilled in young
people. In this regard, an Alaskan bird study program proposed for
Alaska schools by J. G. King, Jr., of the U.S. Fish and Wildlife
Service in 1962 deserves close scrutiny. This highly innovative and
practical environmental education proposal apparently arrived before
its time, for nothing was ever done to institute it. Possibly, now
would be a good time to give it a closer look.
Conclusions
Success in more adequately recognizing and using social and economic
indicators to strengthen and broaden seabird programs will depend
on the ability of the resource management agencies to blend the old
with the new. It is obvious to most that new alignments, programs,
authorities, and sources of funds are needed, but by themselves,
they will not be enough to overcome the continuing massive losses of
wildlife habitat due to population growth and technological impacts
resulting from various developmental programs.
No marine bird programs will be successful without a strong political
base. If this is to be assured, resource agencies must be more
responsive to the needs of both consumptive and nonconsumptive users
and involve them in their programs from early in the planning process.
Because marine birds and the natural environments they inhabit are
jointly valued over time and are jointly owned, it is important to
ask not only what is efficient from the point of view of the present
generation but also what is equitable across generations.
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legislation for a State nongame wildlife conservation program.
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Pearse, P. H., and G. K. Bowden. 1969. Economic evaluation of
recreational resources: problems and prospects. Trans. N. Am.
Wildl. Nat. Resour. Conf. 34:283-293.
Pederson, S. 1971. Status and trends of subsistence resource use at
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Salomonsen, F. 1970. Birds useful to man in Greenland. Pages
169-175 _in_ Productivity and conservation in northern circumpolar
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Sanger, G. A. 1972. Preliminary standing stock and biomass
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Serventy, D. L. 1958. Mutton-birding. Pages 233-234 _in_ A. H.
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FOOTNOTES:
[51] Present address: National Audubon Society, 2 Marine Way, Juneau,
Alaska 99801.
Resource Development Along Coasts and on the Ocean Floor: Potential
Conflicts with Marine Bird Conservation
by
Donald E. McKnight
Alaska Department of Fish and Game
Subport Building
Juneau, Alaska 99801
and
C. Eugene Knoder
National Audubon Society
Lakewood, Colorado
Abstract
Although development of hard mineral
resources, expansion of the timber industry,
and resultant increases in human pressures
along the North Pacific and Arctic coasts
will ultimately adversely affect northern
marine bird populations, current and proposed
activities of the petroleum industry are the
most immediate threat to marine birds. The
Federal Government's recently announced plans
for oil and gas leasing on the Pacific outer
continental shelf eclipse the significance of
North Slope and Cook Inlet oil developments.
Within a few years, onshore storage facilities
and supertankers plying these waters will
undoubtedly result in widespread chronic
and localized catastrophic contamination of
northern marine ecosystems.
Coastal and offshore waters south of the
reaches of the seasonal ice pack are
tremendously productive, supporting a diverse
wealth of bird life throughout the year.
Because these ecosystems are relatively stable
and the impact of temporal oscillations on the
physical environment is not as great as in the
Arctic, birds in these areas are probably least
susceptible to man's influence on a long-term
basis.
Avifaunal associations of the Arctic are less
diverse and have shorter food chains than more
southerly ones; consequently they are more
susceptible to environmental perturbations.
Slow growth and maturation rates of arctic
species and resultant prolonged population
recovery periods further aggravate this
situation.
Available knowledge of northern seabirds
and their environmental requirements is in
inverse relation to the latitude at which they
are found and to the ecological stability
of the ecosystems involved. Arctic bird
associations and their fragile environments
are least understood, but are doubtless the
most vulnerable to the detrimental effects
of man-caused environmental degradation. The
paucity of knowledge about them limits the
possibility of predicting the consequences
of petrochemical exploitation and thereby
safeguarding against potential problems.
Existing technology and support system
capabilities of the oil industry are more
poorly defined for arctic areas, further
compounding this problem. Regardless
of information amassed in the future
and precautionary measures taken during
exploitation of arctic petroleum reserves,
the potential for disastrous and perhaps
irrecoverable losses to northern marine bird
species and populations is great. Losses of
major magnitude could appreciably alter the
productivity of northern marine ecosystems.
Although the coastal waters of the northwestern United States and
western Canada support a plenitude of marine life, including marine
birds, relatively little is known about these ecosystems. Sustained
interest in quantitative aspects of this area's marine bird populations
has developed only within the past few years. As Sowl and Bartonek
(1974) indicated, seabirds are the most visible component of a marine
ecosystem and, at the same time, they are the least understood.
Management information has been haphazardly gathered, and because
seabirds occur in incredibly large numbers in north Pacific and arctic
waters, it has been convenient to assume that, in the absence of
problems, systematized data gathering and analysis were unnecessary.
The sudden emergence in the late 1960's of Alaska and portions of
northwest Canada as potential major oil production areas has changed
this situation dramatically. Ongoing and planned petroleum development
in the North and the concurrent expansion of hard mineral extraction
and logging activities now threaten to adversely affect these marine
bird resources. Alaska's human population, which numbered only slightly
over 400,000 in 1975, will probably double within the present decade.
Doubtless, increased numbers of people, oriented toward mineral and
other resource exploitation rather than toward traditional wildland
values, will compound these problems. Pressures on State and local
governments for increased services necessitated by increasing
populations will require additional expenditures. In Alaska, at least,
these demands are being imposed before revenues from minerals become
available. This necessitates additional oil leases, timber sales, and
other means for obtaining immediate funding, thereby adding to the
acceleration and irreversibility of industrial expansion into the North.
This atmosphere of change has spawned major government-and
industry-supported programs to broaden knowledge of northern marine
ecosystems, including their avifauna. There has been a recent flurry
of publications on seabird populations and biology and a proliferation
of papers stressing the need to learn more about the biota of this
area. Nevertheless, environmental impact statements on proposed
developmental programs in the North still raise more questions than are
being answered. Attempts are being made to apply available information
on oil spills, human disturbance, and other aspects of environmental
degradation gathered from experiences in other areas to expected
problems in northern environments, but one must realize that much of
the information gained from experience elsewhere is not applicable to
these areas. It is realistic to assume that, until development-related
problems occur in the North, biologists cannot estimate the magnitude
or ecological dimensions of their effects. However, existing knowledge
of ecological "laws" and of the biology of some species provides the
base for limited predictive efforts.
It is the purpose of this paper to describe significant current and
proposed resource development along the coasts and the ocean floors,
to summarize existing knowledge of the ecology of marine birds in
these areas, and to identify potential conflicts with marine bird
conservation. We hope that identification of these problems will
provide impetus to data gathering and management programs necessary for
conservation of these valuable resources.
The Region and its Avifauna
The region discussed here encompasses nearly half of the United States
and Canadian coastlines, extending from Washington to the eastern
edge of the Northwest Territories. Alaska alone has two-thirds of the
United States' continental shelf (Bartonek et al. 1971). This region's
marine and estuarine waters are some of the most productive in the
world and support a diverse wealth of bird life throughout the year.
Sanger (1972), for example, estimated total summer standing stocks of
some 21 million birds in an area approximating the outer continental
shelf from the Bering Strait south along the coasts of the Aleutian
Islands and North America to central California. Sanger and King (this
volume), to whom more data were available, revised this estimate upward
to 45 million. Bartonek et al. (1974) provided estimates of year-round
standing stocks of 27 million birds in the Bering Sea alone.
North and east of the Bering Strait, population estimates of the
bird fauna are less complete. Swartz (1966) estimated, however, that
seabird populations of five colonies in the vicinity of Cape Thompson
in the Chukchi Sea exceeded a total of 420,000 breeding birds in 1960.
Information provided by Bartonek and Sealy (this volume) indicates that
large colony complexes at Cape Lisburne and Little Diomede Island each
number, in aggregate, over 1 million breeding birds, mainly alcids,
kittiwakes (_Rissa_ spp.), gulls (_Larus_ spp.), fulmars _(Fulmarus
glacialis)_, and cormorants (_Phalacrocorax_ spp.). Although the
Chukchi Sea coast north of Cape Lisburne has no rocks suitable for
cliff-nesting seabirds, large numbers of tundra-nesting species use
the inshore waters as a migratory pathway, and many nonbreeding cliff
nesters summer in these waters (J. M. Scott, comments by Pacific
Seabird Group on U.S. Department of the Interior Draft Environmental
Statement 74-90). According to Scott, sea ducks and gulls are the most
numerous birds in the Beaufort Sea. Observations by Thompson and Person
(1963) of an estimated 1 million eiders, mostly king eiders _(Somateria
spectabilis)_ and Pacific eiders _(S. mollissima)_, passing over
Point Barrow en route to molting areas, reflect the numbers involved.
Oldsquaws _(Clangula hyemalis)_ use coastal waters of the Beaufort Sea
for postbreeding wing molts; Bartels (1973) estimated their numbers at
nearly 400,000 in the fall and perhaps more during the molting period.
Shorebirds, jaegers (_Stercorarius_ spp.), gulls, and terns, most of
which use coastal waters at some time during the summer season, swell
bird numbers by several millions in this area (Arctic Institute of
North America 1974).
As indicated by Sanger (1972), the seabirds inhabiting coastal areas
south of Bering Strait are mainly members of the Procellariidae
in summer and Alcidae in winter. Sooty shearwaters _(Puffinus
griseus)_ are the prevalent summer species and ancient murrelets
_(Synthliboramphus antiquus)_ and marbled murrelets _(Brachyramphus
marmoratus)_ are the most abundant winter species. Sanger's central
subarctic domain (offshore waters including the Gulf of Alaska) had a
different species composition. During the summer, procellariids--mostly
slender-billed shearwaters _(Puffinus tenuirostris)_ and sooty
shearwaters--made up 94% of the biomass. Procellariids, including
fulmars, larids (largely glaucous-winged gulls, _Larus glaucescens_),
black-legged kittiwakes _(Rissa tridactyla)_, and large alcids,
including the tufted puffin _(Lunda cirrhata)_, made up 87% of the
winter biomass in this domain (Sanger 1972).
Although most of the arctic waters, including the Bering, Chukchi, and
Beaufort seas, are unavailable to birds during the winter because of
pack ice, they seasonally host an avifauna dominated by colony nesters,
such as common and thick-billed murres (_Uria aalge_ and _U. lomvia_),
and tundra nesters, such as oldsquaws and eiders. In far northern
waters, sea ducks (mainly eiders and oldsquaws), red phalaropes
_(Phalaropus fulicarius)_, and gulls are the predominant species.
Intertidal areas throughout the Alaska, British Columbia, and
Washington coasts support characteristic assemblages of shorebirds,
including the black oystercatcher _(Haematopus bachmani)_, rock
sandpiper _(Erolia ptilocnemis)_, wandering tattler _(Heteroscelus
incanum)_, surfbird _(Aphriza virgata)_, and black turnstone _(Arenaria
melanocephala)_ as reported by J. M. Scott (comments by Pacific Seabird
Group to U.S. Department of the Interior Draft Environmental Statement
74-90). Perhaps the greatest concentrations of shorebirds in this whole
region occur during spring and fall migrations in Prince William Sound.
The tremendous numbers of migrating birds using these tidal and marsh
areas are hard to imagine, but densities of up to 250,000 shorebirds
per 259 hectares (ha) on portions of the more than 51,820-ha tidal
flats of the Copper River Delta have been recorded (Isleib and Kessel
1973).
Although this region's avifauna is remarkable from the numerical
standpoint, it is important to remember also that some of its
species are limited in distribution to this area. According to
Bartonek et al. (1971), Alaska is the only known breeding area for
black turnstones, bristle-thighed curlews _(Numenius tahitiensis)_,
surfbirds, western sandpipers _(Ereunetes mauri)_, and Kittlitz's
murrelets _(Brachyramphus brevirostris)_. Several waterfowl species,
including the dusky Canada goose _(Branta canadensis occidentalis)_,
cackling Canada goose _(B. c. minima)_, Aleutian Canada goose _(B. c.
leucopareia)_, and Aleutian common teal _(Anas crecca nimia)_ nest only
in Alaska coastal areas (Bartonek et al. 1971). Izembek Lagoon on the
Alaska Peninsula annually hosts the entire population of black brant,
_Branta nigricans_ (Hansen and Nelson 1957), and many other waterfowl,
seabird, and shorebird species nest or live in this region in numbers
important to their worldwide welfare.
Current and Planned Resource Development
The immense nonrenewable resource wealth of Alaska and other arctic
regions has remained virtually unrecognized or unexploited until
recently because of the availability of these resources in more
accessible locations. As supplies have diminished or been exhausted
elsewhere and demands have increased, however, it has become
economically feasible or necessary to tap supplies in less-accessible
regions. For this reason, the petroleum industry has recently expanded
its exploratory efforts in the far North with well-known success.
Deposits of metallic ores, coal, and other raw materials to feed
industry have likewise been discovered and plans devised for their
extraction and sale. Pressed with decreased availability of commercial
timber elsewhere, the logging industry has similarly begun to broaden
its efforts into Alaska. Expansion of industrial activities into
the North is proceeding at a rapidly accelerating pace, and these
industries, their associated support industries, and expanded human
populations are having and will continue to have unprecedented impact
on these marine ecosystems, including their avifauna.
_Petroleum Development_
The existence of potentially marketable oil and gas deposits in Alaska
has been recognized since the early 1900's, but it was not until the
Swanson River, Alaska, oil field was discovered in 1957 and later
developed that the Arctic entered the modern era of oil development
(McKnight and Hiliker 1970). This field and offshore fields in the
Upper Cook Inlet basin have been producing oil for nearly a decade. The
discovery of petroleum reserves on Alaska's North Slope and Canada's
Mackenzie River Delta is common knowledge, and a pipeline has been
constructed to transport Alaska oil to a tanker facility at Valdez in
Prince William Sound. Alternative proposals to pipe North Slope natural
gas along the existing corridor to a facility in Prince William Sound
or to build a new pipeline to take this gas to existing fields, and a
planned pipeline on the Mackenzie River Delta and south through Canada,
are being considered. Construction of a gas liquefaction facility in
Prince William Sound and tanker traffic through the Sound and the Gulf
of Alaska are potential ramifications of an Alaska gas pipeline.
As McKnight and Hiliker (1970) and Bartonek et al. (1971) pointed
out, the greatest potential problem for marine bird populations from
North Slope oil will be associated with the operations of the Alyeska
Pipeline system's terminal at Valdez. Oil storage and ship-loading
facilities at this port and heavy tanker traffic through Prince William
Sound represent a pollution source that could result in significant
seabird and waterfowl mortalities. Certainly, development of gas
liquefaction facilities in the Sound, with inherent increases in human
populations and tanker traffic, would compound this potential problem.
Although future impacts from existing petrochemical developments
are cause for concern, the Federal Government's recently announced
plans for oil and gas leasing on the Pacific outer continental shelf
(Fig. I) eclipse the significance of North Slope and Cook Inlet oil
developments. It now appears the Gulf of Alaska is the most favorable
area of the outer continental shelf for oil and gas production
(Council on Environmental Quality 1974). This area, covering more
than 10.3 million ha, has already been subjected to extensive seismic
investigations, and estimates of its undiscovered, economically
recoverable crude oil and natural gas resources range from 3 to 25
billion barrels and 15 to 30 trillion cubic feet, respectively (Council
on Environmental Quality 1974).
[Illustration: Fig. 1. North Pacific, showing portions of the outer
continental shelf being considered for gas and oil leasing by the
Federal Government (vertical hatching) and areas leased or proposed for
leasing by the State of Alaska (cross hatching).]
Kinney et al. (1970) reported that in Cook Inlet, Alaska, an estimated
0.3% of the oil produced and handled in offshore platform wells is
spilled. Several routine offshore operations result in discharges of
oil and other materials into water, and, unlike accidental spills,
the probability of their occurrence is 100% (Council on Environmental
Quality 1974). During drilling operations, cleaned drilling mud and
drill cuttings are discharged overboard. Drilling mud may consist of
such substances as bentonite clay, caustic soda, organic polymer,
proprietary defoamer, and ferrochrome lignosulfate. Waters from
geological formations are often produced and discharged into the
sea while the wells are in production. These waters may be fresh or
saline, and often contain small amounts of oil. All of these pollutants
increase the adverse effects of offshore oil production, and when
potential spills are also considered, the ultimate impact on the marine
ecosystem may be substantial.
The State of Alaska has already leased offshore sites in Kachemak Bay,
and present considerations for future leases in the lower Cook Inlet
and Beaufort Sea further reflect the widespread and massive nature of
petrochemical developments in the Arctic planned for the next 2 decades
(Fig. 1). Proved crude oil reserves are less than 1 billion barrels and
natural gas reserves are less than 2 trillion cubic feet in Cook Inlet,
but it appears that undiscovered recoverable oil and gas resources
may be much greater (Council on Environmental Quality 1974). There
are also indications that known onshore oil reserves along Alaska's
northwest coast will soon be opened for development by the Arctic
Slope Regional Corporation, landowners in the area as a result of the
Native Land Claims Act of 1971. This group is at least considering the
transportation of these petroleum products to market in tankers, from
an open-water port in the Chukchi Sea--thereby adding to the tanker
traffic in northern waters.
_Hard Mineral Resource Development_
As indicated by Bartonek et al. (1971), there has been renewed interest
in opening up Alaska's hard mineral resources to economic development
as new transportation routes and modes have been developed. Plans
are being completed to develop the Bering River coal field, with the
eventual goal of exporting coking coal to Japan. Although mining
operations might ultimately affect freshwater environments to the
detriment of several waterfowl species, including the trumpeter swan
_(Olor buccinator)_, the chief cause for concern will be additional
freighter traffic through Prince William Sound. Similar plans to
develop Klukwan and Snettisham iron deposits in southeastern Alaska for
the use of Japanese industry (Bartonek et al. 1971) may result in the
imposition of further traffic in Alaska shipping lanes.
Plans are under way to strip-mine coal deposits in the Beluga field
near the west side of Cook Inlet and transport a coal slurry via
pipeline to a thermal electric generation plant opposite Anchorage on
the Inlet. Impact on tidal areas may be minor, but thermal pollution of
the waters is a possibility.
Development plans for tin and tungsten deposits in the Lost River area
of Alaska's Seward Peninsula are under way after several years of
faltering starts and stops. These activities and possible extraction of
gold lying offshore from Nome may ultimately have some effect on these
coastal areas. Methods for recovering gold, regardless of the type,
would disrupt marine and estuarine environments used by marine birds
(Bartonek et al. 1971), and transportation of ores would also increase
freighter traffic in the Bering Sea.
_Timber Resource Development_
Although the timber industry has long been established along the coast
from Washington north through southeastern Alaska, timber harvests
are rapidly expanding on U.S. Forest Service lands in Alaska. The
impact of this industry is principally on terrestrial ecosystems, but
certainly log rafting in estuarine areas, disposal of wastes from
pulp mills, and freighter traffic transporting wood pulp or logs to
Japan and west coast markets contribute to the chronic degradation
of marine bird environments. Recent meager studies on the Vancouver
Canada goose _(Branta canadensis fulva)_ in southeastern Alaska have
pointed out the importance to this species of coastal timber stands for
nesting and estuarine environments for brood rearing and wintering.
This essentially nonmigratory goose (Hansen 1962) may be particularly
vulnerable to logging activities in these areas. Similarly, recent
evidence indicates that marbled murrelets may nest in large conifer
trees adjacent to the coast, from northwestern California to
northern southeastern Alaska (Harris 1971; Savile 1972). If this is
true, logging may eventually greatly restrict the breeding of this
numerically important inhabitant of northern coastal waters.
Assessment of Resource Development and Potential Conflicts with Marine
Bird Conservation
Although extraction of hard mineral resources, expansion of the timber
industry, and resultant increases in human pressures along North
Pacific and Arctic coasts will ultimately affect northern marine bird
populations, current and proposed activities of the petroleum industry
pose the most immediate threat to marine birds. Chronic degradation of
estuarine and marine coastal waters by logging wastes, pulp mill and
sewage effluents, and bilge oils is an insidious process, the impacts
of which will be difficult, at best, to quantify. Results of a major
oil spill or even low-level contamination of marine ecosystems with oil
will be more apparent, however. For this reason, and the fact that the
industry is expanding rapidly into the North, most of this discussion
will be directed at the impacts of oil development on northern marine
birds.
Potential sources of adverse environmental degradation affecting
these birds resulting from oil and gas exploration, development,
and production include: (1) oil discharges into marine waters, both
chronic and catastrophic, (2) gravel excavation and dumping in coastal
areas, (3) seismic activities, (4) discharge of drilling mud and drill
cuttings into marine waters, including toxic heavy metal constituents
of drilling mud, (5) disturbance resulting from petrochemical
activities, and (6) increased human populations resulting in
interference with critical life processes and increased hunting of game
species. Each source of environmental change will vary by latitudinal
and seasonal factors in their effects upon the birds. We consider
herein only coastal and ocean floor developments and their anticipated
generalized impacts on populations.
Although this is a discussion of "northern" marine birds, it is
important to remember that we are considering a diverse avifauna
existing in an environmental gradient from temperate to polar regions.
In general, the more southerly portions of this marine environment
are characterized by a greater diversity of species, more complex
food chains, and a resultant greater stability (Dunbar 1968). Arctic
marine ecosystems, on the other hand, are characterized by numerical
dominance by a few species, relatively simple food chains, and an
inherent instability or fragility (Dunbar 1968). According to Dunbar,
arctic systems are regulated primarily by temporal oscillations in
the physical environment, whereas biological interactions (e.g.,
competition, predation) are considered more significant in the
maintenance of temperate and tropical ecosystems.
Because of their relative instability, arctic ecosystems are more
susceptible to alteration by extreme environmental perturbation,
either natural or man-imposed (Burns and Morrow 1973). Slow growth and
maturation rates of the avian constituents of these ecosystems and
resultant long recovery periods (Ashmole 1971) further aggravate this
situation.
Regardless of their seasonal availability, these arctic waters
constitute some of the most productive areas for seabirds in the
western hemisphere (Bartonek et al. 1974). Upwelling, nutrient-rich
waters, combined with intense and prolonged incident radiation, result
in lush phytoplankton "blooms" that form the foundation of relatively
simple but numerically strong plant and animal communities (Ashmole
1971). A relatively small number of avian species have evolved to take
advantage of this seasonally available food supply, and the ability
to migrate to lower latitudes in winter is a characteristic of most
arctic-nesting species. Because summers are short in arctic regions,
early arrival and a synchronous breeding schedule are necessary
to enable the young to leave the breeding grounds before severe
weather conditions prevail (Ashmole 1971). Arrival of these birds
generally coincides closely with the earliest availability of nesting
habitat and food (Williamson et al. 1966). Migration, molting, and
reproduction place tremendous stresses on these birds, and as a result,
arctic-nesting species tend to reproduce less often and at older ages
than do those of more temperate regions (Ashmole 1971).
In spite of these adaptations, arctic bird species tread a thin line
between extinction and survival, and natural disasters take a heavy
toll. Bailey and Davenport (1972) reported a massive mortality in a
pelagic population of common murres in Bristol Bay, Alaska, during
April 1970. They felt that this disaster, resulting in the death of
probably 100,000 or more birds, most likely resulted from starvation
precipitated by severe weather. Barry (1968) reported a similar loss to
starvation of about 100,000 eiders along the Beaufort Sea coast during
the extremely cold spring of 1964. Observers along Alaska's Beaufort
Sea reported finding eiders and oldsquaws dead and dying from the
effects of cold weather in 1970 (Bartonek et al. 1971). It is readily
apparent that the tenuous existence into which these birds have evolved
leaves them particularly vulnerable to the man-induced stress of
developments during the arctic summer.
_Direct Effects of Oil Pollution_
The most obvious, and perhaps the most disastrous consequence of
petrochemical development on northern marine bird populations is that
of a major oil spill or a well blowout into marine waters. Although
temperate and tropical waters are apparently able to assimilate
oil spills and chronic pollution from petroleum and its products
(Nelson-Smith 1972), this has not been demonstrated to be true for
arctic waters. In fact, studies in the Beaufort Sea have shown that
the bacteria that degrade oil do not use hydrocarbons at the ambient
temperatures of the Arctic (Glaeser and Vance 1971). Therefore, a large
oil spill in the Arctic could persist for many years. As demonstrated
by Campbell and Martin (1973), the diffusion and transport mechanisms
generated by the pack-ice dynamics of the Beaufort Sea and the slow
rate of oil biodegradation under arctic conditions would combine to
diffuse an oil spill over the sea and eventually deposit oil on the
ice surface. This, in turn, would lower the natural albedo over a
large area and melt the ice in the area of the spill. This pack ice
supports an under-ice community which is an important food source for
phalaropes, jaegers, gulls, terns, and other seabirds (Watson and
Divoky 1972).
As indicated by Nelson-Smith (1972) many investigators have stated that
a spot of oil "no bigger than a dollar" on the breast of a bird is
enough to bring about death by exposure, at least in the colder seas.
It is easy to see the relative vulnerability of already stressed birds
in arctic areas to a spill, and because of the concentration of these
birds in available open-water areas, possibilities for catastrophic
mortalities are evident.
Such disasters already have occurred in north Pacific waters. Dickason
(1970) reported an incident in which diesel oil reaching the Alaska
coast, probably from the sinking of two Japanese freighters some
distance offshore, affected an estimated 90,000 murres. J. G. King, Jr.
(cited in Bartonek et al. 1971) estimated that at least 100,000 birds,
mostly alcids and waterfowl, died in the vicinity of Kodiak Island
during winter 1970 as a result of oil pollution (probably ballast
dumped by tankers entering Cook Inlet). It must not be forgotten that
chronic pollution in similar areas where oil development and transport
activities are taking place probably kills more birds every year than
die after a single catastrophic spill. Total annual losses due to oil
in the North Sea and North Atlantic, excluding disasters, amount to
150,000 to 450,000 seabirds (Nelson-Smith 1972).
That oil pollution, both chronic and catastrophic, can dramatically
affect populations of marine birds has already been demonstrated
elsewhere. Uspenskii (1964) reported that more than 30,000 wintering
oldsquaws perished from oil pollution near Botland Island in the Baltic
and that in later years this species had almost disappeared from
Swedish Lapland. Jackass penguins _(Spheniscus demersus)_, found only
in South Africa, have suffered losses from pollution caused by oil
traffic around the Cape of Good Hope (Stander and Venter 1968). Their
total population was estimated at 100,000 in 1960, and in two separate
but not isolated incidents 1 to 2% of this number were known to have
been killed by oil. Unknown but considerable numbers were uncounted
or were lost at sea. Colony nesters, including puffins _(Fratercula
arctica)_, razorbills _(Alca torda)_, and murres in the southerly
portions of the North Sea are declining rapidly (Nelson-Smith 1972).
Puffins, which numbered 100,000 on Annet in the Scilly Isles in 1907,
were reduced to 100 birds by 1967; by then, colonies farther east
on the Great Britain coast were already extinct. Pollution from the
_Torrey Canyon_ disaster alone killed five-sixths of the puffins in
the main French colony on the Sept Isles in Brittany and reduced the
razorbills to a mere 50 birds, one-ninth of previous numbers (Bourne
1970).
There is every reason to believe that similar reductions in numbers
could occur along the tanker route from Valdez to Puget Sound, with
localized extirpation of colonies. Even more disastrous, however, would
be an inopportune well blowout or other major spill in arctic waters.
Massed concentrations of birds, already stressed by severe weather and
food shortages, would be extremely vulnerable to this type of situation.
As pointed out by Nelson-Smith (1972), peculiarities of bird behavior
determine, to some extent, the vulnerability of a species to oil
spills. Auks, murrelets, and puffins (all Alcidae), loons (_Gavia_
spp.), grebes (_Podiceps_ spp.), and diving ducks may be most
susceptible to oiling. Auks and loons, because they float low in the
water, may more readily become completely covered by oil. Diving
species that become flightless during their molt, such as alcids and
waterfowl, or which do not fly because of social bonds between adults
and flightless young (common murre) and spend most of their lives on
the water, would be particularly vulnerable (J. M. Scott, comments
by Pacific Seabird Group on U.S. Department of the Interior Draft
Environmental Statement 74-90). All divers can easily surface into
oil, and their reaction is to dive again, which in a large spill could
result in surfacing into more oil. Phalaropes (_Phalaropus_ spp.),
which flock to feed in eddies which concentrate drift, may similarly be
vulnerable to adverse effects of oil that would also concentrate in
these areas. On the other hand, gulls swimming along the surface are
likely to take wing before becoming seriously contaminated.
Nelson-Smith (1972) reported that gannets _(Morus bassana)_, which
collected oiled sea-weed for building nest mounds, contaminated
themselves and their eggs. Behavioral problems associated with oil
spills can be more subtle, however, and Darling's (1938) conclusions
that the display of adjacent males contributes to stimulation of the
female during courtship in seabirds breeding in massed colonies, is a
good example. If Darling was correct, this behavioral characteristic
could further impede the recovery of a population of auks, for example,
from mortalities resulting from catastrophic losses to spills.
* * * * *
On the basis of this information it is possible to predict that alcids,
which make up the bulk of the birds inhabiting the coastal areas during
winter (Sanger 1972), would be very susceptible to oil spills from
future tanker traffic in these waters. The potential exists, therefore,
for a tremendous impact (from a single inopportune oil spill) upon
these species and upon the entire ecosystem. Sea ducks too, because of
their diving behavior, propensity for flocking, and flightless molt
period, would be very vulnerable to oil spills. Wintering flocks of
oldsquaws and several species of scoters along the coasts of Alaska,
British Columbia, and Washington can be expected to dwindle as North
Slope oil begins to be transported to Puget Sound ports.
It is recognized now that seabirds transfer and recycle nutrients and
energy between trophic levels and between regions of an ocean (Sowl and
Bartonek 1974). Although the significance of this role in the marine
ecosystem can only be surmised at present, conservative estimates by
Sanger (1972) indicated that birds consume from 0.6 to 1.2 million
tons of food and return from 0.12 to 0.24 million tons of feces into
the subarctic Pacific region annually. G. A. Sanger's (personal
communication) revised estimates of these bird populations indicated
that his 1972 estimates should be doubled. Regardless, it appears that
the disastrous effects of such a spill would extend beyond the bird
populations involved.
_Indirect Effects of Oil Pollution and Petrochemical Developments_
By no means would direct losses attributable to contamination by oil be
the only threat to marine bird populations as a result of petrochemical
expansions into these waters. Some water birds that become contaminated
with nonlethal doses of petroleum during the breeding season are
not likely to breed (J. M. Scott, comments by Pacific Seabird Group
on U.S. Department of the Interior Draft Environmental Statement
74-90). Viability of embryos is greatly reduced when the eggshell
becomes smeared with oil from the contaminated plumage of the female
(Hartung 1965). Degradation of habitat, particularly to nesting areas
and food supplies, will certainly occur, and its most pronounced
effects will be felt in the Arctic. Gravel removal for construction of
offshore drilling pads, causeways, and onshore production facilities
would displace nesting birds and, combined with subsequent discharge
of drill cuttings, perhaps have an adverse impact on bottom food
organisms. Nesting habitat loss through destruction or the inability
of birds to accept disturbance could be substantial, particularly
along the Beaufort Sea coasts of Alaska and Canada, where offshore
barrier islands and tundra-covered islands provide protection from
mammalian predators for nesting by Pacific eiders, Sabine's gulls
_(Xemia sabini)_, Arctic terns _(Sterna paradisaea)_, black guillemots
_(Cepphus grylle)_, and other species (Arctic Institute of North
America 1974). Flaxman Island near the mouth of the Canning River is a
tundra island supporting a nesting population of whistling swans _(Olor
columbianus)_, and the only nesting colony of the Alaska snow goose
_(Chen caerulescens)_ is on Howe Island in the Sagavanirktok River
Delta (Arctic Institute of North America 1974).
* * * * *
Although there would probably be little actual nesting habitat loss for
cliff-nesting species, human disturbance to colonies during the nesting
period, particularly from helicopter and fixed-wing aircraft flybys,
could have considerable impact (Sowl and Bartonek 1974). The "living
waterfall" effect of thousands of seabirds pouring off a rookery is
truly spectacular, but each such occurrence during incubation and
brooding periods causes a rain of eggs or young to fall from the cliffs
(Sowl and Bartonek 1974). Temporarily abandoned chicks and eggs are
susceptible to predation by gulls or jaegers.
Even for species nesting on level ground, aircraft overflights close
to breeding colonies may cause major losses to young and eggs. Sladen
and LeResche (1970) reported that flights by an LH-34 helicopter (at
305 m altitude) over an Adelie penguin _(Pygoscelis adeliae)_ colony
caused some egg loss. Landing this aircraft 183 m from the colony
caused 50 to 80% of the birds to flee territories, resulting in egg
and chick loss. Disturbance caused by visitors walking through or near
nesting areas of the South African gannet _(Sula capensis)_ on Bird
Island, Lamberts Bay, South Africa, caused desertion of nesting sites
(Jarvis and Cram 1971). Studies of disturbance on breeding black brant,
Pacific eiders, glaucous gulls _(Larus hyperboreus)_, and arctic terns
at Nunaluk Spit and Phillips Bay, Yukon, in July 1972 indicated that
human presence was the most critical form of disturbance affecting
incubating behavior of these species (LGL Limited 1972_a_). Disturbance
by aircraft--especially helicopters--affected the normal incubating
behavior of all species except Pacific eiders. Nesting success of black
brant and arctic terns was reduced by this disturbance.
Disturbance can adversely affect molting birds. The process of molting
places heavy energy demands on birds, and particularly on waterfowl
whose molt results in a flightless period; few areas provide adequate
protection from predators necessary during this period. Prime molting
areas are scarce along the arctic coast, yet are vital to the welfare
of thousands of sea ducks and seabirds. Studies conducted by LGL
Limited (1972_b_) indicated that aircraft traffic over sea duck molting
areas altered normal behavior, and therefore had a detrimental effect.
Recommendations resulting from these studies were that air traffic be
suspended over these areas during the molting season.
For some arctic-nesting waterfowl, premigration staging activity,
during which fat reserves to sustain southward migration are stored, is
a very important component of the annual cycle (Delacour 1964). Snow
geese, breeding mainly in arctic Canada, concentrate in large numbers
on staging grounds along the Beaufort Sea coast of eastern Alaska and
the Yukon. Because gas compressor stations would be required along the
proposed arctic gas pipeline route, experimental studies were conducted
in September 1972 to determine the effect of disturbance from sounds
generated by compressors (LGL Limited 1972_c_). These studies indicated
that compressor noise was disruptive to staging geese.
Indirect effects on marine bird resources resulting from development
activities may ultimately prove to be more detrimental than the
aforementioned direct factors. It is conceivable that the impact of
these industries, mainly on the benthic and demersal fauna of the
coastal areas, could greatly lower the carrying capacity of this
habitat for marine birds (Bartonek et al. 1974). Because of the
simplified and short arctic food chains and the lack of alternative
food sources in these areas, arctic ecosystems would be particularly
vulnerable to this type of problem (Burns and Morrow 1973).
Ecological or toxic influences on several food species could result
in substantial declines in bird populations. In the Arctic, where
temperatures are low, and bacterial and other decompositional
activities are consequently slow, spilled oil would persist for many
years, with concomitant deleterious effects on the marine organisms of
the area (Burns and Morrow 1973). Reduced recruitment of young would no
longer balance inevitable or density-independent population mortality
(Ashmole 1971). Although indications are that arctic species are the
most vulnerable to this type of impact, the lack of knowledge of the
feeding niches of most seabirds discourages further evaluation of this
potential problem. It is obvious, however, that ecology of arctic birds
is least understood, and these species are the most vulnerable to the
detrimental effects of man-caused environmental degradation.
Conclusions
Predictability of the impact of resource development on marine birds in
northern waters is limited by our relative ignorance of these birds
and their ecology. Just as there exists a latitudinal gradient in the
ecological stability of the ecosystems involved, available knowledge of
these ecosystems is in inverse relationship to the latitude at which
they occur. Arctic bird associations and their fragile environments
are least understood but are doubtless the most vulnerable to the
detrimental effects of man-caused environmental degradation. Existing
technology and support system capabilities of the oil industry are
poorly defined for Arctic areas, further compounding this problem
(Arctic Institute of North America 1974).
Although activities associated with the extraction of hard minerals
and the timber industry will ultimately affect northern seabirds,
petrochemical developments pose the most immediate threat to this
resource. Exploration and development of many coastal and offshore
sedimentary basins with a potential for oil or gas production are
proceeding rapidly. Within a few years, oil storage and loading
facilities at Valdez, Alaska, and supertankers plying northern waters
will probably result in widespread chronic and localized catastrophic
contamination of northern marine environments. Experience in other
areas has demonstrated that oil spills are a considerable potential
threat to these bird populations, directly through widespread mortality
and indirectly through effects on the environment. This threat is of
such magnitude that entire populations or species could be lost to a
single spill if it occurred at the wrong place at the wrong time of
year. Because many of these species require 3 to 4 years for maturation
and may rear only one or two young per year, recovery time for their
populations is great (Ashmole 1971). For these and other reasons, the
Council on Environmental Quality (1974) concluded that the Gulf of
Alaska appeared more vulnerable to major environmental damage from
outer continental shelf oil and gas development than sites off the
Atlantic coast.
As Bartonek et al. (1971) pointed out, it would be a national
tragedy if the great nongame bird populations along Alaska's coast
were decimated during the "Environmental Decade" without even being
properly described. Regardless of information amassed in the future and
precautionary measures taken during exploitation of arctic petroleum
reserves, the potential for disastrous and perhaps irrecoverable losses
to northern marine bird species and populations is great. Losses of
major magnitude could appreciably alter the productivity of northern
marine ecosystems, to the detriment of other renewable resources.
Knowledge of northern marine birds, their environments, and their
ecology must be greatly expanded if the consequences of petrochemical
exploitation are to be predicted and safeguards established against
potential problems. To the extent possible, oil exploration and
development activities should be limited to temperate, more stable,
marine ecosystems, at least until more northerly areas are better
understood. Similarly, these activities must be conducted in such
places and at such times that impact on the environment will be
minimized. State and federal governments and the petroleum industry are
ultimately answerable for this responsibility.
The Nation must be aware of the potential costs of energy independence
set forth as a goal of proposed oil and gas leasing of Alaska's outer
continental shelf. We must ask ourselves if we are willing to risk
extermination of species to reach this goal, or if we can afford the
luxury of reducing the biological productivity of these waters.
References
Arctic Institute of North America. 1974. The Alaskan arctic
coast--a background study of available knowledge. 551 pp.
Ashmole, N. P. 1971. Seabird ecology and the marine environment.
Pages 223-286 _in_ D. S. Farner and J. R. King, eds. Avian
biology. Vol. I. Academic Press, New York.
Bailey, E. P., and G. H. Davenport. 1972. Die-off of common murres
on the Alaska Peninsula and Unimak Island. Condor 74(2):215-219.
Barry, T. W. 1968. Observations on natural mortality and native
use of eider ducks along the Beaufort Sea coast. Can. Field-Nat.
82(2):140-144.
Bartels, F. B. 1973. Bird survey techniques on Alaska's north
coast. M.S. Thesis. Iowa State Univ., Ames. 47 pp.
Bartonek, J. C., J. G. King, and H. K. Nelson. 1971. Problems
confronting migratory birds in Alaska. Trans. N. Am. Wildl. Nat.
Resour. Conf. 36:345-361.
Bartonek, J. C., R. Elsner, and F. H. Fay. 1974. Mammals and birds.
Pages 23-28 _in_ E. J. Kelley and D. W. Hood, eds. Probes: a
prospectus on processes and resources of the Bering Sea shelf,
1975-1985. Univ. Alaska, Inst. Mar. Sci. Publ. Inf. Bull. 74-1.
Bourne, W. R. P. 1970. Special review after the "Torrey Canyon"
disaster. Ibis 112:120-125.
Burns, J. J., and J. E. Morrow. 1973. The Alaskan Arctic marine
mammals and fisheries. Arctic oil and gas problems and
possibilities, 5th International Congress. 24 pp.
Campbell, W. J., and S. Martin. 1973. Oil and ice in the Arctic
Ocean: possible large-scale interactions. Science 181:56-58.
Council on Environmental Quality. 1974. OCS oil and gas--an
environmental assessment. Vol. I. Washington, D.C. 214 pp.
Darling, F. F. 1938. Bird flocks and the breeding cycle; a
contribution to the study of avian sociability. Cambridge Univ.
Press, N.Y.
Delacour, J. 1964. The waterfowl of the world. Vol. IV. Country
Life Ltd., London. 364 pp.
Dickason, O. E. 1970. Center for short-lived phenomena event
report. Smithsonian Institution, Cambridge, Massachusetts,
36(1970):926.
Dunbar, M. J. 1968. Ecological development in polar regions. A
study in evolution. Prentice-Hall, Inc., Englewood Cliffs, N.J.
119 pp.
Glaeser, J. L., and G. P. Vance. 1971. A study of the behavior of
oil spills in the Arctic. U.S. Coast Guard, Office of Research
and Development, Washington, D.C. 60 pp.
Hansen, H. A. 1962. Canada geese of coastal Alaska. Trans. N. Am.
Wildl. Nat. Resour. Conf. 27:301-320.
Hansen, H. A., and U. C. Nelson. 1957. Brant of the Bering
Sea--migration and mortality. Trans. N. Am. Wildl. Nat. Resour.
Conf. 22:237-256.
Harris, R. D. 1971. Further evidence of tree nesting in the marbled
murrelet. Can. Field-Nat. 85(1):67-68.
Hartung, R. 1965. Some effects of oiling on reproduction of ducks.
J. Wildl. Manage. 29(4):872-874.
Isleib, M. E., and B. Kessel. 1973. Birds of the north gulf
coast--Prince William Sound region, Alaska. Biol. Pap. Univ.
Alaska 14. 149 pp.
Jarvis, M. J. F., and D. L. Cram. 1971. Bird Island, Lamberts
Bay, South Africa: an attempt at conservation. Biol. Conserv.
3(4):269-272.
Kinney, P. J., D. K. Button, D. M. Schell, B. R. Robertson, and J.
Groves. 1970. Quantitative assessment of oil pollution problems
in Alaska's Cook Inlet. Univ. Alaska Inst. Mar. Sci. Rep.
R-69-16. 43 pp.
LGL Limited. 1972_a_. Disturbance studies of breeding black brant,
common eiders, glaucous gulls and Arctic terns at Nunaluk Spit
and Phillips Bay, Yukon Territory. Report prepared for Northern
Engineering Service, Ltd. 50 pp.
LGL Limited. 1972_b_. Aircraft disturbance to molting sea ducks,
Herschel Island, Yukon Territory. Report prepared for Northern
Engineering Service, Ltd. 31 pp.
LGL Limited. 1972_c_. Gas compressor noise simulator disturbance to
snow geese, Kamakuk Beach, Yukon Territory. Report prepared for
Northern Engineering Service, Ltd.
McKnight, D. E., and B. L. Hiliker. 1970. The impact of oil
development on waterfowl populations in Alaska. Proc. Western
Assoc. State Game Fish Comm. 50:286-297.
Nelson-Smith, A. 1972. Oil pollution and marine ecology. Paul Elek,
Ltd., London. 260 pp.
Sanger, G. A. 1972. Preliminary standing stock and biomass
estimates of seabirds on the subarctic Pacific region. Pages
589-611 _in_ A. Y. Takenouti et al., eds. Biological oceanography
of the North Pacific. Idemitsu Shoten, Tokyo.
Savile, D. B. O. 1972. Evidence of tree nesting by the marbled
murrelet in the Queen Charlotte Islands. Can. Field-Nat.
86(4):389-390.
Sladen, W. J. L., and R. E. LeResche. 1970. New and developing
techniques in antarctic ornithology. Pages 585-616 _in_ M. W.
Holdgate, ed. Antarctic Ecology. Vol. I. Academic Press.
Sowl, L. W., and J. C. Bartonek. 1974. Seabirds--Alaska's most
neglected resource. Trans. N. Am. Wildl. Nat. Resour. Conf.
39:117-126.
Stander, G. H., and J. A. V. Venter. 1968. Oil pollution in South
Africa. Pages 251-259 _in_ Proceedings of the International
Conference on Oil Pollution of the Sea.
Swartz, L. G. 1966. Sea-cliff birds. Pages 611-678 _in_ N. J.
Wilimovsky and J. N. Wolfe, eds. Environment of the Cape Thompson
region, Alaska. U.S.A.E.C., Div. Tech. Inf., Oak Ridge, Tennessee.
Thompson, D. Q., and R. A. Person. 1963. The eider pass at Point
Barrow, Alaska. J. Wildl. Manage. 27(3):348-356.
Uspenskii, S. M. 1964. Present day problems of nature conservation
in the Arctic. Problems of the North 7:171-178.
Watson, G. E., and G. J. Divoky. 1972. Pelagic bird and mammal
observations in the eastern Chukchi Sea, early fall 1970. Pages
111-172 _in_ C. I. Merton et al., eds. An ecological survey in
the eastern Chukchi Sea. U.S. Coast Guard Oceanogr. Rep. 50.
Williamson, F. S. L., M. C. Thompson, and J. Q. Hines. 1966. Pages
437-480 _in_ N. J. Wilimovsky and J. N. Wolfe, eds. Environment
of the Cape Thompson region, Alaska. U.S.A.E.C., Div. Tech. Inf.,
Oak Ridge, Tennessee.
Mortality to Marine Birds Through Commercial Fishing
by
Warren B. King
International Council for Bird Preservation
Smithsonian Institution, Washington, D.C.
R. G. B. Brown
Canadian Wildlife Service
Dartmouth, Nova Scotia, Canada
and
Gerald A. Sanger[52]
U.S. National Marine Fisheries Service
Seattle, Washington
Abstract
Commercial fishing has been responsible for
incidental mortality of seabirds for centuries,
but with the advent of offshore salmon gill-net
fishing in the North Pacific in 1952 and in
the North Atlantic in 1965, the magnitude of
this kill has increased, and there is strong
indication that populations of some seabirds
are being adversely affected. Murres (_Uria_
spp.) are most frequently killed, although
several other species are caught in lesser
numbers. The seabird resources of several
nations are involved in this mortality.
Longline fishing and inshore gill-net fishing
for salmon and cod also are responsible for
mortality of seabirds, although usually not in
significant numbers.
That the activities of commercial fishermen have caused mortality of
marine birds surprises no one nowadays. Traditions of exploitation of
marine birds by fishermen date from previous centuries, and fishing
has contributed to the extinction of some species. For example, great
auks _(Pinguinus impennis)_ and other birds were used as food by
fishermen fishing for Atlantic cod _(Gadus morhua)_ on the Grand Banks
of Newfoundland since the beginning of that fishery in the early 16th
century (Collins 1884; Lucas 1890). The last great auk died in 1844,
but smaller species, such as storm-petrels (Hydrobatidae), greater
shearwaters _(Puffinus gravis)_, and black-legged kittiwakes _(Rissa
tridactyla)_, were used for food until rather recently (Templeman
1945). This practice has now lapsed, however.
Inshore Fisheries
Until the advent of the offshore salmon gill-net fisheries in the North
Pacific in 1952 and the North Atlantic in 1965, most seabird mortality
in these areas was the result of local fishing close to shore. Several
records of such bird mortality have been published. For example,
8,000-10,000 seabirds--presumably mostly alcids--were reported caught
annually off Hammerfest in northern Norway (Holgersen 1961). E. Brun
(personal communication) reported that the longline fishery off the
coast of Norway is having serious consequences on Norwegian populations
of murres.
Numbers of alcids are caught in nets set for Atlantic salmon _(Salmo
salar)_ around the coasts of Ireland and Scotland (Biddy 1971). A
similar situation exists along the west Greenland coast, although it
is overshadowed there by the direct exploitation of huge numbers of
alcids by hunting. Nonetheless, in 1967 for example, 15,000 alcids
were recovered from fish nets in southwestern Greenland, where they
were sold as food (Evans and Waterston 1976). The annual salmon catch
of the west Greenland inshore fishery has fluctuated between 60 and
1,500 metric tons and has averaged about 1,000 tons. There are no data
comparing the relative catch of birds and fish in this fishery.
Atlantic cod follow the spawning capelin _(Mallotus villosus)_ inshore
along the east coast of Newfoundland in late June and early July. They
are traditionally fished with traps and handlines along this coast,
but there has been a recent trend toward using drift nets set on the
bottom. Since alcids feed extensively on capelin at this time, many are
caught in the cod nets set in areas close to the large colonies off
Witless Bay (D. N. Nettleship, personal communication). Additionally,
gill nets are set at the surface for salmon in the same area. Common
murres _(Uria aalge)_ are most affected, but Atlantic puffins
_(Fratercula arctica)_ are also taken.
There are as yet no estimates of the total alcid mortality from this
fishery, although the annual catch of birds is believed to be smaller
during the present than during the last decade because the fishing
effort is reduced, and fishermen in the area now avoid setting nets
near alcid concentrations because of the annoyance of having to remove
the birds from their nets. The Witless Bay colonies contain over 77,000
pairs of common murres, or 11% of the total eastern North American
population, and over 235,000 pairs of Atlantic puffins, or 71% of the
North American population outside of Greenland (Brown et al. 1975). The
potential danger is obvious.
There are few data on mortality of seabirds from inshore commercial
fisheries in the North Pacific. Some mortality of alcids has been shown
to take place in Cook Inlet, Alaska, from beach-netting for Pacific
salmon (_Oncorhynchus_ spp.) adjacent to seabird rookeries and from
drift-netting in the inlet (D. A. Snarski, personal communication), but
this mortality has not been quantified.
Bilateral agreements between the United States and Japan, the U.S.S.R.
and the Republic of Korea, concerning the use of inshore waters
adjacent to some of the Aleutian Islands, Kodiak, Nunivak, St. Matthew,
St. George, Kayak, and Forrester Islands permit trawling, longlining,
and loading fish and fuel in some of these areas and at certain
periods. Although these activities may affect the seabirds of these
areas, the extent of the effects are not known (U.S. Department of the
Interior, Alaska Planning Group 1974). Murie (1959) indicated, however,
that the disappearance of the ancient murrelet _(Synthliboramphus
antiquus)_ from Sanak Island, Gulf of Alaska, was probably due as much
to fisheries as to the blue fox industry. It has been suggested that
the Japanese murrelet _(Synthliboramphus wumizusumi)_ may have declined
as the result of fishing activities near breeding sites off the coast
of Japan (Bourne 1971).
Atlantic Offshore Gill-net Fishery
In 1965, Denmark began an offshore gill-net fishery for Atlantic salmon
in the Davis Strait off the coast of west Greenland. The offshore
fishery catch increased from 36 metric tons in 1965 to more than 1,200
metric tons in 1969, and then gradually decreased.
The fact that large numbers of seabirds--almost entirely thick-billed
murres _(Uria lomvia)_--were being drowned in the salmon gill nets
was brought to the attention of the International Council for Bird
Preservation at its 15th World Conference in 1970. The Council's
recommendation was submitted to the Danish government and stated:
"... having noted that during the 1969 fishing season about 250,000
individuals of Brunnich's guillemot or thick-billed murre _(Uria
lomvia)_, a pelagic diving bird, were caught in these drift nets
and drowned, which number represents no less than 25 percent of the
Greenland population and exceeds its annual reproductive capacity;
urges the Danish Government, and the national governments of all other
countries involved in this fishing, to take all possible measures to
eliminate this very serious problem."
The figures in the recommendation were not supported by research; they
appeared instead to have been derived from the observed mortality on
an offshore fishery vessel in 1965, which was then related to the
salmon catch on that vessel and applied to the total catch of the
inshore fishery in 1964 (Anonymous 1969). Studies in 1969 and 1970 by
the Fisheries Research Board of Canada finally gave a firm basis for
the earlier, though poorly substantiated concern. On the basis of the
assumption that the ratio of salmon to murres caught in experimental
fishing applied to the commercial fishery, an estimate of an annual
mortality of 0.5 million murres (±50%) was made on the basis of a
salmon catch of 1,200 metric tons (Tull et al. 1972).
The birds being killed were from colonies in west Greenland, the
eastern Canadian Arctic, and possibly east Greenland and Spitzbergen.
Coupled with other known causes of mortality (particularly hunting
on the Greenland and Newfoundland coasts, an unknown but definitely
substantial kill from oil pollution, a calculated mortality of
pre-fledging young, and an unknown natural post-fledging mortality)
there is no doubt that the estimated annual production of 1.5 million
chicks from west Greenland and the Canadian Arctic was less than the
estimated total annual mortality (Tull et al. 1972). Thus, it comes as
no surprise that recent surveys of murre populations of west Greenland
and the Canadian Arctic have revealed massive declines in numbers
(Evans and Waterston 1976; D. N. Nettleship, personal communication).
It is therefore encouraging news that, as a result of an agreement
between the United States and Denmark, the offshore salmon gill-net
fishery was terminated at the end of the 1975 season. The inshore
fishery remained in operation, however, but was restricted to a total
annual salmon catch of 1,100 metric tons.
Pacific Offshore Salmon Gill-net Fishery
In the north Pacific Ocean, the Japanese gill-net fisheries for salmon
(_Oncorhynchus_ spp.), which have operated since 1952, might be
expected to have an even more destructive effect on seabirds, since the
annual salmon catch by the three Japanese salmon drift-net fisheries
was about one hundred times that in west Greenland in recent years. The
first, the mothership fishery, comprising about 369 catcher-boats[53]
serviced by 11 mother-ships, operates west of 175°W and generally north
of 46°N during the summer. The second, the land-based fishery of about
325 ocean-going vessels, operates west of 175°W and south of 46°N;
and the third, the coastal fishery, made up of about 1,380 short-haul
vessels, operates off Hokkaido. The relative salmon catches of these
three fisheries is on the order of 1:1.34:0.65.
Data collected on U.S. National Marine Fisheries Service research
vessels in 1974 (obtained through the cooperation of Francis M.
Fukuhara and Richard Bakkala, Northwest Fisheries Center, Seattle,
Washington) give, for the first time, an estimate of the magnitude of
the incidental seabird kill of the Japanese salmon gill-net fishery.
The kill data are available only from the mothership area and from an
area east of it to 165°W. The Japanese salmon fishery is restricted
to waters west of 175°W by agreement with the United States. Bird
kills from the other two areas may be estimated by the relative salmon
catch figures for the areas, assuming that seabird densities, species
composition, and catch effort are similar.
An estimate of the total kill of seabirds in the mothership area may
be made by calculating the bird mortality per length of gill-net set
by research vessels, multiplied by the total length of gill nets set
by the 369 catcher-boats of the Japanese mothership fishery. About
4,666 km of nets are set and retrieved daily during the approximately
65-day fishing season. The estimated annual mortality in the mothership
area is about 75,000 to 250,000 birds. The lower number is based on
data from 10 cruises (450 km of nets set) west of 175°W, within the
area of the mothership fishery. The higher number is based on data
from 20 cruises, including those in the first figure, west of 165°W,
and covering the period 18 April to 3 September 1974 (956 km of nets
set), whereas the mothership fishery usually operates between mid-May
and late July. Assuming similar seabird densities and catch per unit
of effort in the areas of the land-based and coastal fisheries, the
estimated annual mortality is between 214,500 and 715,000 birds. Since
1952, as many as 4.7 million birds may have been killed by the Japanese
salmon gill-net fishery. It must be stressed that seabird densities
and catch per unit of effort are not known to be similar for the areas
in question; consequently the projection of bird kill figures from one
area to all three is speculative.
In the mothership area and adjacent seas to the east, in addition to
murres (48% of birds killed), significant numbers of shearwaters,
_Puffinus_ spp. (27%); puffins (9%); and fulmars, _Fulmarus glacialis_
(5%) are killed, as are lesser numbers of small alcids, albatrosses
(_Diomedea_ spp.), and storm-petrels. The murres and puffins taken
in the mothership area are of U.S. and U.S.S.R. origin, and the
shearwaters come from New Zealand, Australia, and Chile. In the coastal
fishery area, Japanese and U.S.S.R. alcids are taken. Available
knowledge of the populations of the species making up the bulk of the
kill, which has been taking place for 20 years, is insufficient to
suggest whether their annual reproduction can tolerate such losses.
Prohibition of fishing within 160 km of North Pacific seabird breeding
islands would help to decrease losses of alcids of U.S. origin, but
would not help the shearwaters from the southern hemisphere.
Comparison of statistics of the salmon fisheries and associated bird
kills from the North Atlantic and the North Pacific shows that the
North Atlantic salmon fishery is concentrated in a relatively small
area which is also along a major migration pathway of murres. Virtually
all seabird mortality is confined to one species. Enough information is
at hand to indicate that this cause of mortality, in conjunction with
others known to be significant, is causing a drastic decline in the
thick-billed murre population.
In the North Pacific, on the other hand, the fishery is more widely
dispersed and the ratio of seabirds to salmon caught is much lower.
Furthermore, several species are subject to mortality. No information
is available to indicate whether alcid populations (which make up
two-thirds of the kill) are stable or decreasing. The shearwaters,
primarily sooty _(Puffinus griseus)_ and slender-billed _(P.
tenuirostris)_, appear to be able to sustain not only these losses but
also a sizable harvest of birds of the year (the so-called muttonbirds)
on their New Zealand and Australian breeding grounds. Thus, although
the latest estimates of the total standing stock of seabirds in the
North Pacific in summer may be as high as 100 million (Sanger and King,
this volume), and thus only about 1 of every 200 birds in the North
Pacific region may be caught, the fact that a few species, particularly
murres, are selectively caught raises questions about the impact of
this fishery on populations of these species.
The U.S.-Japan Migratory Bird Convention of 1973 specifically protects
all of the species thought to be subject to gill-net mortality in
the Pacific. Thus, the Japanese salmon fleet apparently operates in
constant violation of this convention.
Mortality of Albatrosses
A recent analysis of recoveries of Laysan albatrosses _(Diomedea
immutabilis)_ and black-footed albatrosses _(D. nigripes)_ banded on
the northwest Hawaiian chain from 1937 to 1969 showed that of a sample
of 532 recovered birds, 57.4% of the Laysan species and 49.5% of the
black-footed species were caught on fishhooks or in nets, and the means
of recovery of many additional birds was thought to have been the same
(Robbins and Rice 1974). It is likely that the large majority are taken
on Japanese and U.S.S.R. longline tuna fishing gear. Although this
cause of mortality is insignificant in terms of the total population
of either species (only 0.2% of banded Laysan and 0.8% of banded
black-footed albatrosses have been recovered by any means away from
their breeding grounds), these species are protected by the U.S.-Japan
Migratory Bird Convention. Furthermore, the possibility exists that
individuals of the endangered short-tailed albatross _(Diomedea
albatrus)_ might be killed in this manner.
Long-term Effects of Developing Capelin Fishery in Northwest Atlantic
Capelin are important food fish for many seabirds in the northwest
Atlantic, and the development and expansion of this fishery off
eastern Canada must be carefully monitored. In theory, the capelin
fishery ought not to seriously affect the birds because it is
designed to exploit a surplus of capelin artificially created by the
overfishing of Atlantic cod, the capelin's most important predator. It
is hoped that there is no prospect of the overfishing that may have
contributed to the recent drastic decline of the Peruvian anchovy
_(Engraulis ringens)_ and the seabird species dependent on it (Paulik
1971). However, the relative influence of overfishing and "El Niño"
oceanographic conditions on the decline remains unclear. North Atlantic
seabirds are, in any case, more versatile in their feeding habits
(Belopol'skii 1961). But, the threat may be a subtle one. The important
point to the seabirds may well be not merely the survival of a
reasonably large capelin stock, but the presence of capelin schools in
high densities in certain areas or at certain seasons. Lower densities
might, for example, reduce the foraging efficiency of breeding birds,
and hence their nesting success. The very large common murre colony
on Funk Island, Newfoundland (500,000 pairs: Tuck 1960), might be
particularly vulnerable. It lies close to an area where capelin are
especially abundant and one which is already being exploited by the
developing fishery.
References
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Belopol'skii, L. O. 1961. Ecology of sea colony birds of the
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Biddy, C. J. 1971. Auks drowned by fishnets. Seabird Rep. No. 2.
Bourne, W. R. P. 1971. General threats to seabirds. ICBP [Int.
Counc. Bird Preservation] Bull. 11:200-219.
Brown, R. G. B., D. N. Nettleship, P. Germain, C. E. Tull, and
T. Davis. 1975. Atlas of eastern Canadian seabirds. Canadian
Wildlife Service, Ottawa. 220 pp.
Collins, J. W. 1884. Notes on the habits and methods of capture of
various species of seabirds that occur on the fishing banks off
the east coast of North America and which are used as bait for
catching codfish by New England fishermen. U.S. Comm. Fish Fish.
Rep. 1882:311-335.
Evans, P., and G. Waterston. 1976. The decline of the thick-billed
murre in Greenland. Polar Rec. 18:283-286.
Holgersen, H. 1961. On the movements of Norwegian _Uria aalge_. (In
Norwegian, English summary.) Sterna 4:229-240.
Lucas, F. A. 1890. Expedition to the Funk Island, with observations
on the history and anatomy of the Great Auk. Rep. U.S. Natl.
Mus., 1887-1888:493-529.
Murie, O. J. 1959. Fauna of the Aleutian Islands and Alaska
Peninsula. U.S. Fish Wildl. Serv., N. Am. Fauna 61. 406 pp.
Paulik, A. J. 1971. Anchovies, birds, and fishermen in the Peru
Current. Pages 156-185 _in_ W. W. Murdoch, ed. Environmental
Resources and Society. Sinauer Associates, Inc., Stamford, Conn.
Robbins, C. S., and D. W. Rice. 1974. Recoveries of banded Laysan
albatrosses _(Diomedea immutabilis)_ and black-footed albatrosses
_(D. nigripes)_. Pages 232-271 _in_ W. B. King, ed. Pelagic
studies of seabirds in the Central and Eastern Pacific Ocean.
Smithson. Contrib. Zool. 158.
Templeman, W. 1945. Observations on some Newfoundland seabirds.
Can. Field-Nat. 59:136-147.
Tuck, L. M. 1960. The murres. Canadian Wildlife Service, Ottawa.
260 pp.
Tull, C. E., P. Germain, and A. W. May. 1972. Mortality of
thick-billed murres in the west Greenland salmon fishery. Nature
(Lond.) 237 (5349):42-44.
U.S. Department of the Interior, Alaska Planning Group. 1974. Final
environmental impact statement, proposed Alaska Coastal National
Wildlife Refuges. 678 pp.
FOOTNOTES:
[52] Present address: U.S. Fish and Wildlife Service, Office of
Biological Services--Coastal Ecosystems. 1011 E. Tudor Road, Anchorage,
Alaska 99503.
[53] This figure is based on data through 1971. Since then, the number
of catcher-boats has decreased to 332 in 1974 (F. M. Fukuhara, personal
communication).
Interactions Among Marine Birds and Commercial Fish in the Eastern
Bering Sea
by
Richard R. Straty and Richard E. Haight
National Marine Fisheries Service
Auke Bay Fisheries Laboratory
Auke Bay, Alaska 99821
Abstract
The high primary and secondary productivity
of the eastern Bering Sea makes it one of
the greatest producers of commercial fish
and largest congregating areas of marine
birds in the world. The fish and birds are so
interrelated that fluctuations in the abundance
of one may well be responsible for changes in
the abundance of the other. The seasonal and
annual variation in the impact of birds on fish
is a function of the life history, food habits,
growth rate, and final size of the fish species
of concern and of the distribution, abundance,
and feeding habits of bird populations--plus
the effects of the environment on these
factors. Stages in the life history of some of
the important commercial fish and shellfish
of the Bering Sea directly or indirectly
influenced by marine birds are identified.
The eastern Bering Sea is one of the world's richest fish-producing
areas and is also one of the world's major congregating areas for
marine birds. The large extent of the continental shelf and the
climatic and oceanographic characteristics of the eastern Bering Sea
combine to make this region extremely productive biologically. The
distribution and abundance of plankton, benthos, and fish determine the
distribution, time, and character of the migration of marine birds in
the eastern Bering Sea (Shuntov 1961). Several studies have illustrated
the close relation between marine birds and the biological properties
of surface waters (Tuck 1960; Bourne 1963; Solomensen 1965). Spatial
and temporal variations in the abundance of the fish families Clupeidae
(herring), Gadidae (codfish), Osmeridae (capelin), and Ammodytidae
(sand lance) are thought to be major determinants of the breeding
seasons, breeding places, and movements of boreal seabirds (Ashmole
1971). The timing of breeding among larids and alcids is related to the
seasonal changes in the surface waters inhabited by Ammodytidae and
Clupeidae in the North Sea (Pearson 1968).
The eastern Bering Sea contains members of these and other fish
families that are extensively exploited by man; the fish are also
important as forage for other species of commercial fish, marine
mammals, and marine birds. During some part of their life cycles, all
fish species feed on plankton, nekton, benthos, or other fishes.
The incidental use or dependence of marine birds on commercial fish
and the items on which the fish feed account for the major interaction
between man and these two groups of animals.
In this paper, we consider how marine birds and fish interact. Although
some of what we present is only speculative, we identify certain areas
that have received little or no scientific study, areas in which
further research is needed for a better understanding of the role of
commercial fish in the ecology and dynamics of marine birds in the
eastern Bering Sea.
Commercial Fish Resources of the Eastern Bering Sea
Most of the fishing in the eastern Bering Sea is done by Japan and the
Soviet Union. Japan resumed fishing in the Bering Sea in 1953 (7 years
after World War II), the Soviet Union started fishing in the region in
1959, and since the early 1960's both nations have accelerated their
exploitation of Bering Sea fish stocks (Chitwood 1969).
Species of major concern to Japan and the Soviet Union include
fish--walleye pollock _(Theragra chalcogramma)_, yellowfin sole
_(Limanda aspera)_, Pacific cod _(Gadus macrocephalus)_, Pacific ocean
perch _(Sebastes alutus)_, Pacific herring _(Clupea harengus pallasi)_,
and sablefish _(Anoplopoma fimbria)_--and snow crabs (_Chionoecetes_
spp.). The distribution of the principal species being harvested in
Bristol Bay and the eastern Bering Sea are shown in Figs. 1, 2, and
3. The weight of each of the major species in the total catches made
by foreign and domestic fishermen in 1973 is shown in Table 1. In
1972, the catch of commercial finfish in the eastern Bering Sea alone
amounted to 5% of the total world catch of marine fishes (H. Larkins,
personal communication).
Most species of commercial fish in the Bering Sea are in a state of
decline or in a depressed condition from overexploitation (Table 1).
This is indicated by a reduction in the catch per unit of effort and
in the mean size of fish in the commercial catch (H. Larkins, personal
communication). The notable exception is the king crab (_Paralithodes_
sp.), which has increased in abundance in recent years as a result of
reduced foreign fishing.
Table 1. _Foreign and domestic catch of fish and shellfish in the
eastern Bering Sea, including Bristol Bay, 1973._
----------------------------------------------
Catch
Species (metric tons)
----------------------------------------------
Fish
Pollock 1,500,000
Flatfish 125,000
Pacific cod 45,000
Herring 35,033
Salmon 11,785
Sablefish 7,000
Pacific halibut 222
Other 40,000
Shellfish
King crabs 26,798
Snow crabs 17,694
Shrimp Minor
----------------------------------------------
[Illustration: =Fig. 1.= Areas of major concentrations of ground fish
(Pacific pollock, halibut, yellowfin sole, rock sole, flathead sole,
Pacific ocean perch, and Pacific cod) in Bristol Bay and the Bering
Sea.]
[Illustration: =Fig. 2.= Areas of major winter and spring
concentrations of Pacific herring in Bristol Bay and the Bering Sea.]
[Illustration: =Fig. 3.= Areas of major concentrations of king and snow
crab in Bristol Bay and the Bering Sea.]
Routes of Interaction Between Marine Birds and Commercial Fish
The obvious ways in which marine birds and fish of commercial
importance interact in the eastern Bering Sea are illustrated by the
simplified food web diagram in Fig. 4. The major animal groups and
species included in two of the categories in this figure--secondary
producers (invertebrate forage) and intermediate carnivores (commercial
and forage marine fish and shellfish)--are as follows:
_Secondary producers_
Zooplankton and micronekton
Copepods
_Calanus_ spp.
_Eucalanus_ spp.
Euphausiids
_Thysanoessa_ spp.
Amphipods
_Parathemisto_ spp.
_Gammarus_ spp.
Pteropods
_Spiratella_ spp.
_Clione_ spp.
Chaetognaths
_Sagitta_ spp.
Benthos
Polychaetes
_Nereis_ spp.
_Euroe_ spp.
Molluscs
_Mytilus edulis_
_Tonicella_ spp.
_Fusitriton oregonensis_
Echinodermata
_Strongylocentrotus_ spp.
Crustacea
Gammaridae
Mysidae
_Idothea_ spp.
_Pagurus_ spp.
_Hapalogaster_ spp.
_Sclerocrangon_ spp.
_Intermediate carnivores_
Eggs (littoral, adhesive)
Clupeidae
Pelagic larvae
Gadidae
Pleuronectidae
Osmeridae
Ammodytidae
Salmonidae
Gadidae
Pandalidae
Juvenile and small adults
Clupeidae
Osmeridae
Ammodytidae
Salmonidae
Gadidae
Pandalidae
Large adults
Clupeidae
Gadidae
Pleuronectidae
Salmonidae
Scorpaenidae
Lithodidae
Majidae
Pandalidae
Marine birds
Alcidae
Procellariidae
Laridae
Phalacrocoracidae
[Illustration: Fig. 4. Food web in the eastern Bering Sea, showing
routes of interaction between marine birds and the various life history
stages of commercial fish and shellfish.]
In our discussion, we mainly consider predation by birds on commercial
fish and competition between birds and commercial fish for food.
The extent of these interactions determines the potential for birds
and fish to influence each other's abundance. The extent of the
interactions also determines the impact of man's commercial harvest
of fish on the abundance of birds or of the bird's harvest on the
abundance of fish.
The extent of the interaction between marine birds and commercial
fish depends on the abundance, distribution, feeding habits, and life
history of the fish species of concern. We have limited our discussion
to examples of the major commercial pelagic and demersal fish and
shellfish of the eastern Bering Sea. We also use as examples those
species of marine birds whose abundance in the eastern Bering Sea and
feeding habits give them the greatest potential for influence on, or
being influenced by, fish abundance.
Abundance and Feeding Habits of Marine Birds in the Eastern Bering Sea
Information on the general abundance and distribution of the most
important marine birds in the eastern Bering Sea in the summer and
winter is scattered among many published and unpublished reports:
Shuntov (1961, 1966), Sanger (1972), Bartonek and Gibson (1972), and
Ogi and Tsujita (1973); and surveys by D. T. Montgomery and W. E. Oien
("Bristol Bay waterbird survey, 1972," unpublished report of the U.S.
Bureau of Sport Fisheries and Wildlife, Alaska area) and by J. G.
King and D. E. McKnight (1969, "A waterbird survey in Bristol Bay and
proposals for future studies," unpublished report of the U.S. Bureau
of Sport Fisheries and Wildlife and the Alaska Department of Fish and
Game, Juneau, Alaska).
In summer, the most abundant birds appear to be the procellariids,
mainly the slender-billed shearwater _(Puffinus tenuirostris)_ and
Pacific fulmar _(Fulmarus glacialis)_; the alcids, mainly the common
murre _(Uria aalge)_, thick-billed murre _(U. lomvia)_, tufted puffin
_(Lunda cirrhata)_, horned puffin _(Fratercula corniculata)_, and the
ancient murrelet _(Synthliboramphus antiquus)_; and the larids, mainly
the glaucous-winged gull _(Larus glaucescens)_ and the black-legged
kittiwake _(Rissa tridactyla)_.
In winter, the alcids and larids appear to be the most abundant
groups, the procellariids having been reduced by the departure of
the slender-billed shearwaters for breeding grounds in the southern
hemisphere. The selection of the types of food to be consumed by these
marine birds is a function of their morphological and physiological
adaptations and of the resultant feeding behavior. Ashmole (1971)
classified the feeding behavior of various genera of marine birds and
the relative importance of the kinds of food eaten by each group; this
information for some of the Bering Sea bird species occurring in the
genera listed by Ashmole (1971) is summarized in Fig. 5.
Fish and invertebrates are evidently of moderate to major importance in
the diet of these marine birds (Fig. 5). The extent to which a given
fish species is fed upon by or is in competition with marine birds
for food is determined by the life history of the fish. Most pelagic
and some demersal fish and shellfish are more subject to predation
by pursuit diving birds than by birds restricted to the near-surface
waters. Invertebrates appear to be equal to or more important than fish
in the diets of birds feeding in near-surface waters (Fig. 5).
Predation by Marine Birds
The literature contains numerous accounts of marine birds feeding
on marine fish and shellfish of commercial importance. Some studies
quantify the impact of some bird species on certain species of
commercial fish (Outram 1958; Shaefer 1970; Wiens and Scott 1976) and
shellfish (Glude 1967). Other studies have shown that in some regions
the value of guano produced by birds may exceed the value of the
commercial fish they consume (Jarvis 1970). Some fish of worldwide
commercial importance that are important in the diets of marine birds
are listed in Table 2.
Table 2. _Fish of worldwide commercial importance in the diets of
some marine birds._
--------------------------------------------------------
Fish Shearwaters Murres Puffins Fulmars Gulls
Anchovy X -- -- -- --
Sardines X -- -- -- --
Herring X X X X X
Sprat X -- -- -- --
Pilchard X -- -- -- --
Capelin -- X X -- X
Salmon -- X -- -- --
Mackerel -- X -- -- --
Pollock -- X -- X --
Haddock -- X -- -- --
Cod -- X -- -- --
--------------------------------------------------------
The significance of bird predation on pelagic or demersal fish and
shellfish (Fig. 5) depends on the feeding behavior of the birds and on
the life history of the fish (e.g., distribution, abundance, growth,
and adult size). Pursuit diving birds, such as murres and puffins,
can consume fish at greater depths than can birds that feed near the
surface, such as shearwaters, kittiwakes, fulmars, and gulls.
[Illustration: Fig. 5. Feeding behavior and relative importance of food
of some groups of marine birds that occur in the eastern Bering Sea.]
Aspects of the Life Histories of Fish Related to Predation by Marine
Birds
Fish that are pelagic during part of their lives, such as salmon and
herring, and forage fish like smelt, capelin, and sand lance, are
vulnerable to greater predation by a wider variety of marine birds than
are bottom-dwelling demersal fish, such as pollock, cod, sole, ocean
perch, and halibut, as well as king and snow crabs. Some species that
live on the bottom as adults have pelagic stages during which they are
vulnerable to predation by marine birds. Juveniles of some demersal
species (pollock, cod, halibut, some species of sole, and king crabs)
are sometimes found in shallow water where they might be subject to
predation by birds.
_Demersal Fish and Shellfish_
The early life histories of the commercially important demersal fish
of the eastern Bering Sea are quite different (Table 3). For example,
the eggs and larvae of Pacific halibut _(Hippoglossus stenolepis)_
generally occur at depths greater than 100 m (Hart 1973), whereas
those of pollock and yellowfin sole are found at or near the surface
(Musienko 1963, 1970). The eggs of Pacific cod are demersal, but the
larvae are oceanic (pelagic) and occur from 25-150 m (Mukhacheva and
Zviagina 1960).
In their juvenile stages, many demersal fish frequent the near-surface
waters (Table 3), where they become vulnerable to predation by
piscivorous marine birds. Juvenile pollock, for example, form into
small schools that usually move about close to the bottom but sometimes
move into areas as shallow as 3 m. Juvenile Pacific cod prefer the
warmer water close to shore and may be found within 10 m of the
surface (Moiseev 1953). The young of many species of flatfish, such as
yellowfin sole, rock sole _(Lepidopsetta bilineata)_, and flathead sole
_(Hippoglosoides elassodon)_, remain for a time in shallow warm water
after assuming a demersal existence. Yellowfin sole 2-2.5 cm in total
length may be found in abundance in areas as shallow as 5 m (Fadeev
1965; Moiseev 1953).
Table 3. _Informal listing of life history information on
selected species of commercial and forage fish and shellfish to
show vulnerability to predation by marine birds._ (? indicates no
information available.)
Fecundity Spawning season Source of data
Length Mean no. Total Peak
of female of eggs period period Yusa 1954
(cm)[54] Tanino et al. 1959
=Walleye pollock= 31-35 95,700 Feb.- April Kobayashi 1963
(_Theragra_ 46-50 324,400 June -May Musienko 1963, 1970
_chalcogramma_ Serobaba 1968
Pallas) Hart 1973[55]
Total Depth from Seasonal Duration of
Life length surface period of life stages
stage (cm)[56] (m) pelagic life (days)
Egg 0.1-0.2 0-10 Feb.-June { 12 at 6-7°C
{ 20.5 at 3.4°C[57]
Larval 0.4-0.9 10-25 March-? > 25 at 6-7°C
Larval 0.9-? 25-? ?-Sept. ?
Juvenile 2.2-4.1 0-?[58] Summer --
Juvenile 6.0-30.0 4-37 Summer --
Adult 30.0-70.0 0-386 -- --
Fecundity Spawning season Source of data
Length Mean no. Total Peak
of female of eggs period period Moiseev 1953
(cm)[54] Mukhacheva and
=Pacific cod= 60 1,200,000 Jan.- ? Zviagina 1960
(_Gadus_ 78 3,300,000 March Musienko 1970;
_macrocephalus_ Hart 1973[55]
Tilesius)
Total Depth from Seasonal Duration of
Life length surface period of life stages
stage (cm)[56] (m) pelagic life (days)
Egg 0.1-0.11 100-250 Demersal { 8-9 at 11°C
{ 17 at 5°C
{ 28 at 2°C
Larval 0.5-3.2 25-150 Feb.-Aug. ?
Juvenile ? 10-? Summer --
Adult 40.0-99.0 0-900 -- --
Fecundity Spawning season Source of data
Length Mean no. Total Peak
of female of eggs period period Stevenson 1962
(cm)[54] Musienko 1970
=Pacific herring= 20.5-22.0 26,600 May- Varies Rumyantsev and
(_Clupea_ 28.0-31.0 77,800 June Darda 1970
_harengus pallasi_ Reid 1972
Valenciennes) Hart 1973[55]
Total Depth from Seasonal Duration of
Life length surface period of life stages
stage (cm)[56] (m) pelagic life (days)
Egg 0.1-0.2 0-12 Demersal 10-20[57]
Larval 0.9 0.5-8 May-June }
Larval 1.3 0.5-8 June-July } 42-56
Larval 2.5 1-6 July-Aug. }
Juvenile 2.5-20.5 0-? March-Nov. --
Adult 20.5-31.0 0-140 March-Nov. --
Fecundity Spawning season Source of data
Length Mean no. Total Peak
of female of eggs period period
(cm)[54] Clemens and
=Capelin= ? 3,000 June- ? Wilby 1961
(_Mallotus_ ? 6,000 July Musienko 1970
_villosus_ 10.3 6,670 Hart 1973
(Muller)) ? 60,000
Total Depth from Seasonal Duration of
Life length surface period of life stages
stage (cm)[56] (m) pelagic life (days)
Egg 0.1 <20 Demersal 14-?
Larval 0.5-? ? June-? ?
Juvenile ? ? March-Nov.(est.) --
Adult ? 0-? March-Nov. --
Fecundity Spawning season Source of data
Length Mean no. Total Peak
of female of eggs period period Musienko 1963, 1970
(cm)[54] Kashkina 1970
=Pacific sand lance= -- ? June- [59] Hart 1973
(_Ammodytes_ Aug.
_hexapterus_ Pallas)
Total Depth from Seasonal Duration of
Life length surface period of life stages
stage (cm)[56] (m) pelagic life (days)
Egg ? ? Demersal ?
Larval 0.7-3.4 0-? June-Sept. ?
Juvenile 3.6-9.6 0-? ? --
Adult 26 0-? ? --
Fecundity Spawning season Source of data
Length Mean no. Total Peak
of female of eggs period period Paraketsov 1963
(cm)[54] Lisovenko 1965
=Pacific ocean perch= 26 10,000 March- ? Lyubimova 1965
(_Sebastes_ 44 180,000 May Kashkina 1970[60]
_alutus_ (Gilbert))
Total Depth from Seasonal Duration of
Life length surface period of life stages
stage (cm)[56] (m) pelagic life (days)
Egg[61] -- -- -- --
Larval[62] 0.6-? [62] March-Aug. ?
Juvenile 6.2 37-128 -- --
Juvenile 10.4 37-154 -- --
Juvenile 14.7-21.3 37-230 -- --
Adult 21.3-51.0 37-420 -- --
Fecundity Spawning season Source of data
Length Mean no. Total Peak
of female of eggs period period
(cm)[54] Novikov 1964
=Pacific halibut= 75 101,723 Oct.- ? Hart 1973
(_Hippoglossus_ 135 2,800,837 March
_stenolepis_
Schmidt) Total Depth from Seasonal Duration of
Life length surface period of life stages
stage (cm)[56] (m) pelagic life (days)
Egg 0.3-0.4 40-935 Oct.-March 48 at ?
Larval 0.8-1.5 >200 Nov.-May }
Larval 1.5-2.9 <100 May-Sept.} 70-98
Juvenile 3.4-4.2 7-43 -- --
Juvenile 19-25 7-45 -- --
Fecundity Spawning season Source of data
Length Mean no. Total Peak
of female of eggs period period Moiseev 1953
(cm)[54] Pertseva-Ostraumova
=Yellowfin sole= 1954; Musienko 1963;
(_Limanda_ 26.1-28.0 1,295,000 June- July Fadeev 1965;
_aspera_ 40.1-42.0 3,319,500 Aug. Kashkina 1965_a_,
(Pallas)) 1965_b_[55]
Total Depth from Seasonal Duration of
Life length surface period of life stages
stage (cm)[56] (m) pelagic life (days)
Egg 0.07-0.09 >0 June-Aug. 9.4 at 13.1°C[57]
Larval 0.2-1.2 >0 July-Oct. ?
Juvenile 2.1-2.5 5-15 -- --
Fecundity Spawning season Source of data
Length Mean no. Total Peak
of female of eggs period period
(cm)[54] Kurata 1960, 1964
=King crabs= 9.4 55,408 April- ? Korolev 1964
(_Paralithodes_ 17.1 444,651 June Rodin 1970
_camtschatica_ (Tilesius))
Total Depth from Seasonal Duration of
Life length surface period of life stages
stage (cm)[56] (m) pelagic life (days)
Egg -- 100-200[63] -- ?
Zoeal} 0.55-0.65 ? April-July {33 at 7-10°C
Zoeal} {23 at 12.3-12.5°C
Glaucothoeal 0.38x0.18 ? May-? ?
Juvenile ? 1-? -- ?
Fecundity Spawning season Source of data
Length Mean no. Total Peak
of female of eggs period period Haynes 1973[55]
(cm)[54] Jewett and
=Snow crabs= Haight[64]
(_Chionoecetes_ ? ? ?[65] ?
_bairdi_ Rathbun)
Total Depth from Seasonal Duration of
Life length surface period of life stages
stage (cm)[56] (m) pelagic life (days)
Egg 100[63] -- ?
Prezoeal 0.22-0.28 ? May-? 1-2 at 2.5°C
1st zoeal 0.50-0.56 ? Summer ?
2d zoeal ? 0-10 Summer ?
Megalopal 0.30-0.35x ? Summer --
0.18-0.21
Juvenile 0.44-0.48x ? -- --
0.32-0.35
Fecundity Spawning season Source of data
Length Mean no. Total Peak
of female of eggs period period Ito 1968; Kon 1970
(cm)[54] Haynes 1973;
=Snow crabs= Motoh 1973
(_Chionoecetes_ ? ? ?[65] ? Jewett and
_opilio_ Haight[64]
(O. Fabricius))
Total Depth from Seasonal Duration of
Life length surface period of life stages
stage (cm)[56] (m) pelagic life (days)
Egg ? 93[60] -- ?
Prezoeal -- ? May-? }
1st zoeal 0.48-0.54 ? Summer }
2d zoeal 0.62-0.71 ? Summer } 63-66 at 11-13°C
Megalopal 0.29-0.33 ? Summer }
0.19
Juvenile 4.4-4.8x ? -- --
3.2-3.5
The commercially important king and snow crabs of the eastern Bering
Sea also have larval stages that are pelagic (Table 3). Zoeae and
megalopa of snow crabs are found near the surface where they are
vulnerable to plankton-feeding marine birds. The eggs of king crabs are
attached to the abdomen of the female, but after hatching, the larvae
become pelagic and occur near the surface. They are planktonic through
five larval stages before settling to the bottom to take up demersal
residence (Kurata 1960, 1964). These larvae attain a length of 5.5-6.5
mm and spend 33 days or more in the plankton (Kurata 1960). Even
after the young king crabs have settled to the bottom, they may still
frequent water shallow enough to make them vulnerable to predation by
some marine birds. Juvenile king crabs 1 and 2 years of age appear to
prefer shallower water than do older crabs. In southeastern Alaska,
during the spring, small juvenile crabs have been observed in pods at
depths as little as 1 m below the low tide level.
The available life stages of king and snow crabs and commercially
important demersal fish (Table 3) represent an enormous food supply for
other fishes and marine birds. Predation by marine birds on pelagic
eggs and on the larval and juvenile stages of demersal fish is not well
documented, probably because the rapid digestion rate of birds makes
species identification of these stages difficult. Investigators must
often depend on the presence of the hard parts of fish (such as scales
and otoliths) in the stomachs of birds to identify the species eaten.
Because these hard parts have not yet formed in the larvae and most
juveniles, predation by marine birds on older fish is more apparent on
examination of stomach contents. Full understanding of predation by
marine birds on demersal fish and shellfish requires additional data on
when and where the egg, larval, and juvenile stages are present.
_Pelagic Fish_
Many fish, such as herring, capelin, smelt, and salmon, are pelagic
for part of their lives, particularly during the spring and summer
feeding periods. The extent of predation by marine birds on these
species depends primarily on the location of their spawning grounds,
their growth rates, and the size of the adults. The spawning location
determines the extent of predation on eggs, whereas growth rate and
adult size determine during how much of its lifetime a given fish
species is vulnerable to the wide variety of marine birds.
Herring spawn in intertidal and subtidal zones and spend most of
their post-larval lives in bays or estuaries near the coast. They
deposit their adhesive eggs primarily on vegetation, and the eggs are
particularly vulnerable to predation by a wide variety of marine and
terrestrial birds. Outram (1958) estimated that gulls alone accounted
for 39% of the egg loss on the spawning grounds at Vancouver Island,
British Columbia. When herring larvae hatch, they are between 0.7 and
0.8 cm long; when they metamorphose about 6-8 weeks later, they are
between 2.6 and 3.5 cm long. Thereafter, juvenile herring grow rapidly
and reach a length of about 7-10 cm before winter. Although herring
as old as 13 years and up to 38 cm long have been reported in Alaska,
they seldom exceed 30 cm and 11 years of age (Rounsefell 1929). During
spring and summer, herring are commonly within 10 m of the surface,
but in winter, they are in water 100-140 m deep. Although herring are
particularly vulnerable to predation in spring and summer, they are
available to marine birds during most of their life.
The life history of capelin is somewhat different than that of
herring--they live in the open sea near the surface and throughout the
water column most of their lives. Sometime in June or early July, they
migrate in large schools toward shore to spawn (Musienko 1970). In
British Columbia, capelin bury their eggs in coarse sand and gravel in
the intertidal and subtidal zones. The larvae are 0.5-0.7 cm long at
hatching and are carried by currents to the open sea where they develop
in the plankton. Capelin attain an age of 5 years and a maximum length
of about 22 cm; their small size makes them vulnerable to predation by
marine birds most of their lives, and they are an important pelagic
food fish for other commercial fish in the Bering Sea.
The sand lance reaches a maximum size of 20-26 cm and is vulnerable to
bird predation during most of its life. Little information is available
on the maximum age attained by this species in the Bering Sea, but
because of its size, it is an important forage fish for many commercial
fish species.
The five species of Pacific salmon of the eastern Bering Sea spawn
in fresh water, unlike herring, capelin, and sand lance. Their eggs
are not vulnerable to extensive predation by marine birds; gulls take
mainly salmon eggs which have been dislodged from the gravel and are
drifting or being rolled along the stream bottom by the current (Moyle
1966). After a few months to several years in fresh water, the juvenile
salmon (5-14 cm long) enter the Bering Sea during late spring or early
summer and migrate through these waters to feeding grounds, primarily
in the north Pacific Ocean. At maturity, the survivors return to their
home streams and rivers to spawn. It is during the seaward migratory
phase of their life cycle that salmon are most vulnerable to predation
by marine birds.
The sockeye salmon _(Oncorhynchus nerka)_ is the most abundant and
valuable species harvested by American fishermen in the waters adjacent
to the Bering Sea and, as a result, the one that has been most
extensively studied during early marine life. Juvenile sockeye salmon
are between 8 and 14 cm long when they enter the Bering Sea between
late May and early July. They are most abundant in the upper 1 m of
water at night and the upper 2 m during the day (Straty 1974)--well
within the regime that can be exploited by many species of marine birds.
The numbers of juvenile sockeye salmon migrating seaward from the
Bristol Bay region of the Bering Sea in a single year has ranged
between 46.3 and 370.4 million (H. Jaenicke, personal communication).
This is equivalent to between 409 and 3,267 metric tons (on the basis
of the mean weight of the juveniles when they enter the Bering Sea).
These large numbers of juvenile sockeye salmon, plus juvenile chinook
salmon _(O. tshawytscha)_, coho salmon _(O. kisutch)_, chum salmon _(O.
keta)_, and pink salmon _(O. gorbuscha)_ from all other rivers entering
the Bering Sea, represent a considerable input of energy from fresh
water in the form of prime forage fish for other fishes, marine birds,
and mammals. Young salmon enter the Bering Sea each year over a period
of only 6 to 8 weeks and may follow rather discrete coastal migration
routes through the Bering Sea (Fig. 6), with the result that predators
have access to an abundant but transient food supply.
[Illustration: Fig. 6. Distribution of juvenile sockeye salmon in
Bristol Bay and the eastern Bering Sea (adapted from Straty 1974).]
The only published account of predation by marine birds on juvenile
salmon in the Bering Sea is that of Ogi and Tsujita (1973). They found
juvenile sockeye salmon in the stomachs of murres captured in gill nets
in the eastern Bering Sea. The predation did not appear extensive, but
most of the birds were captured outside or on the fringes of the main
seaward migration route of the salmon. The foods of marine birds should
be studied in conjunction with studies of the migrations of juvenile
salmon.
Influence of Growth Rate and Adult Size of Fish on the Extent of
Predation
Incubation time for fish eggs, the length of the pelagic larval period
(Table 3), and the growth rate of juvenile fish are species-specific
and temperature-dependent. The extent to which a fish species is
subjected to predation by marine birds is directly related to the rate
at which development and growth occur. For example, the less time it
takes the pelagic eggs of demersal fish and shellfish to hatch and
complete pelagic larval life, the less is the time they will be preyed
on by marine birds. For fish species that are pelagic during their
entire life, the rate of growth will determine how long they remain
small enough for birds to eat. Some of the smaller pelagic fish, such
as herring, capelin, and smelt, are vulnerable to bird predation most
of their lives; larger pelagic species like salmon may be preyed on
for only a very short time. The maximum size fish that can be eaten
by marine birds is, therefore, important in evaluating predation on a
given species of fish.
The literature on the food habits of marine birds contains little on
the sizes of fish consumed. Tuck (1960) stated that murres probably
will take fish up to 18 cm long. Ogi and Tsujita (1973) estimated the
lengths of Pacific pollock in the stomachs of murres taken in the
eastern Bering Sea at 24 cm.
Herring in the eastern Bering Sea reach an age of 11 years and grow to
about 33 cm. Herring could, therefore, be taken during most of their
lives by murres but during only the first few years by smaller birds
such as fulmars and shearwaters. Capelin and some species of smelt
would be vulnerable to birds during all their lives. Although the size
of adult Pacific salmon varies with the species, they are all so large
that they are not preyed upon by marine birds. Once in the ocean,
juvenile salmon grow at such a rapid rate that they are probably not
very vulnerable to marine birds after their first 4 to 6 months at sea.
Limited studies on the growth of juvenile sockeye salmon in the eastern
Bering Sea (Straty 1974) indicate they may double their size in their
first 8 weeks at sea. A sockeye salmon that entered the Bering Sea at
12 cm in mid-June would be 24 cm long in August--the maximum size that
a murre could eat; the fish could be eaten by smaller marine birds for
much less time. Pink and chum salmon enter the sea at a smaller size
than sockeye salmon and would be vulnerable to predation both by a
greater variety of marine birds and for a longer period of time.
Competition Between Commercial Fish and Marine Birds
We do not know the importance of competition between marine birds and
commercial fish in the eastern Bering Sea. Only a few investigators
have even alluded to competition between marine birds and fish for
food. Ogi and Tsujita (1973) mentioned that competition seemed to exist
between murres and juvenile sockeye salmon for euphausiids in the
eastern Bering Sea. We have listed some of the types of forage fish
and invertebrates eaten by commercial fish (Table 4) and marine birds
(Table 5) in the eastern Bering Sea; comparison of these two tables
clearly indicates that competition could occur.
The principal factors determining the extent of competition between
marine birds and fish are the numbers of birds and fish, the length of
time that various life history stages of the fish are in association
with the birds, and the abundance of the preferred foods at these
times. The impact of competition depends on the adaptability of the
birds and fish to alternative types of food.
The types and sizes of food eaten by fish vary with the life history
stage--especially with size at each stage. For instance, very young
herring eat the eggs and nauplii of copepods or small copepodite stages
and barnacles. As herring grow, their diet includes small fish and
larger zooplankton, such as mature copepods, amphipods, euphausiids,
and pteropods. Pacific cod shorter than 9 cm feed on small crustaceans
(Moiseev 1953), whereas larger cod eat young crabs, shrimp, and
fish. Small juvenile sockeye salmon feed mainly on larval stages of
euphausiids (Straty 1974), but larger juveniles also eat the more
adult forms, which eventually make up a significant part of their diet
(Nishiyama 1974).
The change in the diet of fishes with growth results in competition
with a changing variety of marine birds. For example, deep-diving
birds may replace surface feeders as the major bird competitors of the
Pacific cod and pollock as these fish increase in size and seek deeper
waters. The diet of cod changes from small crustaceans in shallow water
to progressively larger food that eventually includes herring, sand
lance, shrimp, and crabs. The change to herring and sand lance, and
quite possibly small crabs, places the adult cod in competition with
both the surface feeders and pursuit diving birds, but adult cod do not
compete with birds for zooplankton.
Table 4. _Food items eaten by the adult stage of seven
commercially important species of fish in the eastern Bering Sea._
Pacific
Food Walleye Pacific ocean Yellowfin Pacific
item Herring Salmon pollock cod perch sole halibut
Invertebrates
Pteropods X X -- -- X -- --
Squid -- X -- X X -- X
Polychaetes X X X X -- X X
Copepods X X X -- -- -- --
Amphipods X X X X X X --
Euphausiids X X X -- X X --
Decapods X X X X X X X
Fish
Capelin X X X X -- X --
Sand lance -- X X X -- -- X
Table 5. _Forage fish and invertebrate foods eaten by seven
species of marine birds in the eastern Bering Sea._
Shear-
Food item waters Murres Puffins Murrelets Fulmars Kittiwakes Gulls
Forage fish
Sand lance X X X -- -- X X
Capelin -- -- X -- -- -- --
Invertebrates
Copepods -- -- -- -- -- X --
Euphausiids X X -- -- -- X --
Amphipods X X -- -- -- X --
Decapods X X -- -- -- X --
Pteropods -- X -- -- -- -- --
Chaetognaths -- -- -- -- -- -- --
Polychaetes -- X X -- -- X --
Squid X X -- -- X -- --
As pollock increase in size, they continue to feed mainly on
zooplankton, but they change from copepods near the surface to
euphausiids at mid-depths and near the bottom. Euphausiids are large
and abundant zooplankters which, for the most part, are available only
to deep-diving birds. Adult pollock also consume herring, sand lance,
capelin, and other small fish.
Both marine birds and fish are capable of exploiting a wide variety of
food, and often their stomach contents reflect the relative abundance
of food items in the area. Ogi and Tsujita (1973) illustrated the
differences in the food taken by murres captured at different locations
in the eastern Bering Sea. Carlson (1977) and Ogi and Tsujita (1973)
reported on differences in the diet of juvenile sockeye salmon captured
at various locations in Bristol Bay and the eastern Bering Sea. The
diets of many species of birds and fish, however, seem to be largely
determined by their physiological and morphological adaptations and
resultant feeding behavior. For instance, adult sockeye and pink salmon
have well-developed gill rakers and feed largely on zooplankton,
whereas chinook and coho salmon have poorly developed gill rakers
and feed almost entirely on fish. In the eastern Bering Sea, murres
appear to prefer the Pacific sand lance, whereas the slender-billed
shearwater consumes mainly euphausiids (Ogi and Tsujita 1973). Thus,
murres may be greater competitors with piscivorous fish than are
shearwaters. Shearwaters are probably more important as competitors
with zooplankton-eating fish that inhabit shallow water in juvenile
stages and with pelagic fish species (such as pollock, herring, salmon,
and capelin) that are heavily dependent on euphausiids.
Some species of marine birds may interact with fish as predators and
competitors. As an example, pursuit diving birds, such as murres
and puffins, may be important predators on juvenile salmon in the
eastern Bering Sea, but these same birds may compete for food with
adult salmon. Surface-feeding birds, such as fulmars, shearwaters,
kittiwakes, and gulls, may be important as both predators and
competitors with herring and capelin and some demersal fish.
Dependency of Marine Birds on Commercial Fish
The interactions of commercial fish and marine birds of the Bering Sea
can be determined only if we know their distribution, abundance, and
food habits, especially while they are associated with one another.
Information is particularly lacking for all life history stages of
commercial fish species and the seasonal movements of birds. We have
some knowledge of the distribution and abundance of the various life
history stages and the food habits of commercial fish in the Bering
Sea. Little is known of the abundance, seasonal movements, and food
habits of marine birds in this region, however, probably because
marine birds have had little direct commercial value in the northern
hemisphere. Food studies on marine birds are particularly difficult
because their rapid digestion soon destroys the identity of the food.
We can make a reasonable guess as to some bird-fish associations
for two regions of the Bering Sea where we have information on the
distribution of marine birds and the various life history stages of
commercial fish. For example, piscivorous birds, such as murres,
puffins, black-legged kittiwakes, and slender-billed shearwaters, are
extremely abundant in the summer along the seaward migration route of
juvenile sockeye salmon (Fig. 7); the juvenile salmon, kittiwakes,
and shearwaters all feed on plankton. Shuntov (1961) showed that
kittiwakes are most abundant along the edge of the continental shelf
in the Bering Sea in the summertime. This distribution coincides
with the distribution of the eggs and larvae of pollock, certain
flatfish, rockfish, sablefish, and several other species. These birds
both exploit the fish directly (predation) and compete with them for
plankton. Not enough information is available on the food habits of
birds at the time fish eggs and larvae are present to evaluate this
interaction.
Environmental Influence on Predation and Competition Between Marine
Birds and Commercial Fish
Because fish are cold-blooded animals, temperature, through its
influence on the rate of metabolism, is a major variable in determining
the amount of energy needed for maintenance and for performing such
essential activities as swimming and feeding--fish are less active,
feed less, and grow more slowly in cold waters. For example, growth
in young sockeye salmon is very slow at temperatures lower than 4°C
(Donaldson and Foster 1941), and temperature profoundly affects their
swimming speed (Brett et al. 1958). The rates of development of the
eggs of some flatfish are closely correlated with water temperature
(Ketchen 1956)--flatfish developed more rapidly at higher temperatures
(Fig. 8). At lower temperatures, the rate of growth is also slower and,
therefore, the duration of pelagic larval life is longer for demersal
fish and shellfish.
Variations in sea temperature should, therefore, influence the extent
to which fish are vulnerable to predation and competition. For example,
eggs would take a longer time to hatch in colder than in warmer sea
water. In both pelagic fish such as herring, whose eggs are laid in
the intertidal zone, and in demersal fish with pelagic eggs such as
the sole, the period of vulnerability of eggs to bird predation would
be extended. At lower temperatures the length of the pelagic life
of demersal fish and shellfish and their vulnerability to predation
would also be greater than at higher temperatures. For example, the
number of days between molts of the zoeal stages of snow crabs is
temperature-dependent--the warmer the water, the less the time between
molts (Kon 1970).
[Illustration: Fig. 7. Distribution and numbers of birds observed in
Bristol Bay along seaward migration route of sockeye salmon (from
Bartonek and Gibson 1972).]
Temperature, through its effects on swimming speed, feeding activity,
and growth of juvenile fish, might influence the magnitude of
predation by birds on pelagic fish in the following ways: (1) lower
sea temperatures would increase the vulnerability of juvenile fish to
bird predation because swimming speed would decrease, and the time the
fish are of a size that could be eaten by would-be predators would
increase; (2) lower sea temperatures would reduce the feeding by fish
and decrease the competition by fish for food exploited by birds; and
(3) higher sea temperatures would have the opposite effect--the feeding
by fish would increase consumption of the foods that birds feed on.
In the eastern Bering Sea, water temperatures may vary greatly between
years for the same month (Fig. 9). Such variation should result in
variation in the temperature-dependent activities of fish and, in
turn, in magnitude of marine bird predation and competition.
[Illustration: Fig. 8. The relation of temperature to the rate of
development to hatching of lemon sole, as compared with two European
flatfishes (Ketchen 1956).]
Possible Influences of Man on the Interaction of Marine Birds with
Commercial Fish
We have noted that the abundance and age and size composition of major
stocks of fish in the Bering Sea have been drastically reduced by
commercial fishing. This has resulted in the reduction in numbers of
fish at all life history stages, including those on which marine birds
and other fishes depend for food. What effect this reduction has had
on the abundance and distribution of marine birds in the Bering Sea is
unknown. It depends in part on the ability of birds to eat other fish
or increase their use of zooplankton or nekton.
We can hypothesize on probable changes in bird and fish abundance that
resulted from the heavy commercial harvest of fish but any such changes
cannot be documented or quantified. A reduction in stocks of a fish
species could result in a reduced supply of food for a species of bird
and cause a shift in the diet of this bird to other species of fish or
to more zooplankton. For a bird species with specific food preferences,
this could mean a reduction in its abundance to a level supportable by
the available food supply. For bird species with less specific food
requirements, a reduction in a species of fish could mean a reduction
in competition for food with that fish--which could increase survival
of the birds.
Man's intentional harvest of marine birds, such as the shearwater in
parts of the southern hemisphere, and his inadvertent harvest of other
bird species which are entangled or caught in fishing gear reduce
predation and competition by marine birds. This, in turn, may aid the
survival of the fish stocks in the Bering Sea.
The status of most stocks of commercial fish and shellfish in the
Bering Sea is such that reductions in harvest are warranted, have
been proposed, or are in effect. If the 200-mile (61-km) limit of
jurisdiction over the marine resources by adjacent coastal States is
implemented, either as a result of the Law of the Sea Conferences or
unilaterally by the United States, we can expect commercial fishing
in the eastern Bering Sea to be more tightly regulated. Such action
should result in a reduction in harvest of those fish species now in
a depleted condition, which, in turn, could influence the abundance
of marine birds. Now is an opportune time to implement the studies
required to increase our knowledge of the abundance, distribution, and
seasonal movements of marine birds and their relationship to commercial
fish resources of the eastern Bering Sea.
Conclusions
• The eastern Bering Sea is a region of high biological productivity;
it is one of the world's great producers of commercial fish and major
congregating areas for marine birds.
• The vulnerability of fish to predation by marine birds depends on
life history features, such as place of spawning, duration of larval
stages, growth rate, sea temperature, and adult size of fish, and on
the distribution, feeding behavior, and food habits of marine birds.
[Illustration: =Fig. 9.= Sea temperatures in Bristol Bay and
southeastern Bering Sea in mid-June and early July of 1967 and 1971
(from Straty 1974).]
• The most apparent predation by marine birds on fish is on fish large
or mature enough that some hard body parts persist and can be found in
the stomach samples of birds.
• Little is known of the extent of bird predation on the pelagic eggs
and larvae of demersal fish and shellfish in the Bering Sea because of
lack of investigation and the rapid digestion of eggs and larvae by
birds.
• Predation by marine birds on juvenile salmon is not well documented
because of the lack of investigation in areas where both birds and fish
are present.
• Marine birds and commercial fish eat similar zooplankton and fish in
the eastern Bering Sea. The food exploited by both generally reflects
the relative abundance of the types of food in the area, but food
preference is displayed by some species of fish and birds.
• More is known about the food habits of the commercial fish than of
the marine birds of the Bering Sea.
• Sea water temperature may be a major environmental factor in the
Bering Sea since it influences both the extent to which fish are
vulnerable to predation and the amount of competition with marine
birds. Sea temperatures may vary greatly from year to year in the
Bering Sea, and this may result in variations in the magnitude of
predation and competition between birds and fish.
• The distribution of marine birds and the various stages in the life
history of commercial fish are not well known for the eastern Bering
Sea. Where these have been studied, they are intimately related. Such
knowledge is required to gain some insight into even the potential
for predation and competition in the dynamics of the marine bird and
commercial fish populations of this region. In two instances, it is
known that the occurrence of marine birds and the early life history
stages of fish coincide so as to result in both potential predation on
the fish by the birds and competition for food between the fish and the
birds.
• The possibility exists that the commercial fish resources of the
eastern Bering Sea will eventually come under the jurisdiction of the
United States. This could mean reduced harvests of fish to restore
depleted stocks. Such action could result in changes in the abundance
of the marine birds of this region by creating an increased food supply
for some and decreased supply for others.
Acknowledgments
We thank J. C. Bartonek and H. R. Carlson, H. Jaenicke, H. Larkins, and
B. L. Wing for supplying various materials presented in this paper.
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Bering Sea. Part 5, pages 149-156 _in_ Soviet fisheries
investigations in the northeast Pacific Ocean. (Transl. from
Russian.) Israel Program for Scientific Translations, Jerusalem.
Rounsefell, G. A. 1929. Contribution to the biology of the Pacific
herring, _Clupea pallasii_, and the condition of the fishery in
Alaska. Bull. U.S. Bur. Fish. 45:227-320.
Rumyantsev, A. I., and M. A. Darda. 1970. Summer herring in the
eastern Bering Sea. Part 5, pages 409-441 _in_ Soviet fisheries
investigations in the northeastern Pacific Ocean. (Transl. from
Russian.) Israel Program for Scientific Translations, Jerusalem.
Sanger, G. A. 1972. Preliminary standing stock and biomass
estimates of seabirds in the subarctic Pacific region. Pages
499-611 _in_ A. Y. Takenouti, ed. Biological oceanography of the
northern north Pacific Ocean.
Serobaba, I. I. 1968. On the spawning of Alaska pollock _Theragra
chalcogramma_ (Pallas) in the northeastern part of the Bering
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Israel Program for Scientific Translations, Jerusalem.
Shaefer, M. B. 1970. Men, birds, and anchovies in the Peru
current--dynamic interactions. Trans. Am. Fish. Soc.
99(3):461-467.
Shuntov, V. P. 1961. Migration and distribution of marine birds in
the southeastern Bering Sea during spring-summer season. Zool.
Zh. 40(7):1058-1069. (In Russian, summary in English.)
Shuntov, V. P. 1966. Concerning wintering of birds in the far
eastern seas and in the northern part of the Pacific Ocean. Zool.
Zh. 45(11):698-711. (Transl. from Russian.) Can. Wildl. Serv.
Solomensen, F. 1965. The geographical variation of the fulmar
_(Fulmarus glacealis)_ and the zones of marine environment in the
North Atlantic. Auk 82:327-355.
Stevenson, J. C. 1962. Distribution and survival of herring larvae
(_Clupea pallasi_ Valenciennes) in British Columbia waters. J.
Fish. Res. Board Can. 19(5):735-810.
Straty, R. R. 1974. Ecology and behavior of juvenile sockeye salmon
_(Oncorhynchus nerka)_ in Bristol Bay and the eastern Bering Sea.
Inst. Mar. Sci., Univ. Alaska, Occas. Publ. 2:285-320.
Tanino, Y., H. Tsujisaki, K. Nakamichi, and K. Kyushin. 1959. On
the maturity of Alaska pollock, _Theragra chalcogramma_ (Pallas).
Bull. Hokkaido Reg. Fish. Res. Lab. 20:145-164.
Taylor, F. H. C. 1967. The relationship of midwater trawl catches
to sound scattering layers off the coast of northern British
Columbia. J. Fish. Res. Board Can. 25(3):457-472.
Tuck, L. M. 1960. The murres: their distribution, populations, and
biology, a study of the genus _Uria_. Can. Wildl. Ser. 1. 260 pp.
Wiens, J. A., and J. M. Scott. 1976. Model estimation of energy
flow in Oregon coastal seabird populations. Condor 77(4):439-452.
Yusa, T. 1954. On the normal development of the fish, _Theragra
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Res. Lab. 10. 15 pp.
FOOTNOTES:
[54] For crabs, this measurement is carapace width.
[55] Authors' data.
[56] For crabs, the measurements are total length for zoeal stages and
carapace length and width for postzoeal stages.
[57] The incubation period for an egg is temperature dependent. Embryo
development is faster at higher temperatures.
[58] Juvenile pollock have diurnal migrations.
[59] The peak period varies with latitude: to 55°N--June; to
55-60°N--July; to north of 60°N--August.
[60] H. R. Carlson and R. E. Haight (in preparation), Juvenile life
of Pacific ocean perch, _Sebastes alutus_, in coastal fiords of
southeastern Alaska: their environment, growth, food habits, and
schooling behavior.
[61] The genus _Sebastes_ is a live bearer.
[62] Rockfish larvae resemble each other quite closely, and complete
descriptions for the 10 species in the Bering Sea do not exist. The
following depth distribution for rockfish larvae may or may not include
_S. alutus_: 45-365 m (Taylor 1967) off British Columbia; 0-88 m
(Ahlstrom 1959, 1961) off California and Baja California.
[63] In crabs, the eggs are attached to the female.
[64] S. C. Jewett and R. E. Haight (in preparation), A description of
megalopa of the snow crab, _Chionoecetes bairdi_ Rathbun (Majidae,
subfamily Oregoniinae).
[65] Spawning occurs in May in the eastern Bering Sea, but the total
period is not known.
Interrelations Between Seabirds and Introduced Animals
by
Robert D. Jones, Jr.
U.S. Fish and Wildlife Service
1011 East Tudor Road
Anchorage, Alaska 99507
and
G. Vernon Byrd[66]
U.S. Fish and Wildlife Service
Aleutian Islands National Wildlife Refuge
Adak, Alaska
Abstract
Animals introduced to insular seabird habitats
are of both intentional and accidental origin.
The results of the introductions--particularly
of herbivores--cannot be predicted, but may
range from severely destructive to beneficial.
Herbivores are of both domestic and wild
stocks of ungulates, hares, and rabbits. Rats
are the most commonly introduced omnivore on
a worldwide basis. In Alaska the commonest
carnivore introduction has been the red fox
_(Vulpes fulva)_ and arctic fox _(Alopex
lagopus)_, and the first of these were made in
the early 19th century by the Russian-American
Company. These foxes nearly extirpated the
Aleutian Canada goose _(Branta canadensis
leucopareia)_ from its nesting grounds. Black
flies (Simuliidae), which are vectors of avian
blood parasites, have been introduced to three
of the Aleutian Islands.
The purpose of this paper is to discuss some influences of introduced
animals, primarily mammals, on seabirds and their nesting habitat, with
emphasis on the coasts of Washington, British Columbia, and Alaska.
Our discussion focuses on island introductions partly because a large
proportion of seabirds choose island nesting sites, and because islands
present ecosystems vulnerable to such introductions.
Flightless animals have no means of immigration, hence little
probability of colonizing islands. In these circumstances marine birds
evolve populations in relatively simple ecosystems (Carlquist 1965;
MacArthur and Wilson 1967), though the degree of simplicity depends
on several variables, including the island's size and its distance
from a source of immigrants. These systems have achieved ecological
homeostasis through reciprocal adaptation over an extended period.
Experience has shown that introductions to such systems result in
severe perturbations (Odum 1971:221).
The introductions can be categorized as being either intentional or
accidental events. Effects of such introductions have varied widely,
depending on the type of animal introduced, the types of birds present
and the habitat they occupy, the size and shape of the island, the type
of nesting area used by the birds, and the status of their populations
before the introduction. An example drawn from our Aleutian experience
with gallinaceous birds illustrates the interaction of these variables.
The dark phase of the arctic fox _(Alopex lagopus)_ was introduced to
Adak and Amchitka islands, both of which had native populations of the
rock ptarmigan, _Lagopus mutus_ (Gabrielson and Lincoln 1959). Foxes
were released on Adak in 1924, and on Amchitka in 1921. Adak has an
area of 751 km² and Amchitka 350 km². Adak is irregular in shape with
extensive precipitous shorelines, relatively few beaches, and a large,
central mountainous hinterland which foxes rarely penetrated. Amchitka,
on the other hand, presents a zone of marine planation on its eastern
two thirds, low mountains on the rest, shelving beaches around most
of the island, and a long, linear, narrow shape that foxes explored
completely. By 1949 ptarmigan were difficult to find on Amchitka, and
then only in the highest, steepest section of the mountains. They were
extirpated from the low, eastern two thirds of the island. The foxes
flourished on Amchitka, but did much less well on Adak, where the
ptarmigan population fluctuated in a normal cyclic manner, apparently
uninfluenced by the foxes. Then the foxes were eradicated on Amchitka
in the 1950's, and by 1962 the ptarmigan had spread over the whole of
the island and become one of the most conspicuous avian features of the
landscape.
Animal Introductions
_Non-predatory Animals_
Man has taken ungulates with him to many islands. Although numerous
records of livestock introductions are available, few provide
information relating to the effects of these animals on the habitat and
their fauna unless the impact has been severe.
A most noteworthy example of destruction by ungulates occurred on
Guadalupe Island off the coast of Baja California. Domestic goats
_(Capra hircus)_ were introduced in the unrecorded past with the
result that little of the once abundant vegetation remains. In its
place introduced species capable of withstanding heavy grazing are
abundant over most of the island. Several endemic avian species are now
considered extinct, including the Guadalupe storm-petrel, _Oceanodroma
macrodactyla_ (Howell and Cade 1954; Jehl 1972).
Sheep _(Ovis aries)_ have been introduced to seabird nesting islands
with varying results. In Bass Strait, Australia, Norman (1970) studied
the effects of introduced sheep on vegetation and birds. He cited
various papers attributing destruction of colonies of shearwaters
(_Puffinus_ sp.) to the activities of sheep, primarily their treading
on the burrows. He found, however, that on Big Green Island and Phillip
Island, sheep were not responsible for declines in shearwater breeding
success, nor did they prevent expansion of colonies.
Other authors have reported damage to seabird nesting areas by
sheep. One such example in the eastern North Pacific region concerns
Protection Island, Washington. According to Richardson (1961), 100 to
300 sheep grazed freely on the island since 1958. He reported damage
by grazing and frequent trampling of nesting areas of rhinoceros
auklets _(Cerorhinca monocerata)_. Landslides were initiated by these
activities, rendering the slopes unusable by auklets. Of the burrows
in his study area, 46% were buried by slides. He did not determine
mortality.
Other avian consequences may flow from sheep introductions. Husbandry
of these ungulates has been practiced with varying success for many
years in the Aleutian Islands, most notably on Umnak and Unalaska
islands, both of which have large native populations of bald eagles,
_Haliaeetus leucocephalus_ (Gabrielson and Lincoln 1959). Before the
introduction of sheep, these raptors were oriented to the sea, hunting
fish and seabirds. Sheep presented a new resource and presently the
industry found itself confronted by a formidable predator, and demanded
that eagles be destroyed (letter to William Egan, Governor of Alaska,
from James S. Bynum, Secretary-treasurer, Umnak Company, Inc.).
Other ungulates introduced on Alaska islands include cattle _(Bos
taurus)_ on Chernofski and Chernabura islands; caribou _(Rangifer
tarandus)_ on Adak; reindeer on St. Matthew, Nunivak, Atka, Umnak, St.
Paul, St. Lawrence, Hagemeister, and Kodiak as well as many interior
locations; deer _(Odocoileus hemionus)_ on Kodiak and Afognak; elk
_(Cervus canadensis)_ on Afognak; and musk oxen _(Ovibos moschatus)_
on Nunivak. All these animals have maintained populations on islands
for a time, and some appear likely to do so into the distant future.
Specific effects on seabirds is generally not known, but trampling of
grassy slopes such as that reported for sheep develops in some cases.
Bailey et al. (1933) speculated that nests of the snow goose _(Anser
caerulescens)_ were destroyed by reindeer or their herdsmen in the
Point Barrow area.
The destruction of vegetation by introduced rabbits and hares has been
documented for many areas in the world. This destruction has often
extended to seabirds. Perhaps the most dramatic example occurred on
Laysan Island in the Hawaiian archipelago, where rabbits of unknown
species were introduced in 1903. According to Warner (1963) it took
less than 20 years for the rabbits to remove every green plant but
three patches of _Sesuvium portulacastrum_. The Laysan duck _(Anas
laysanensis)_ was brought perilously close to extinction. The rabbits
were eliminated in the 1920's, and the population of ducks increased to
over 600 by 1963, a figure thought to approximate the pre-disturbance
population.
European hares _(Lepus europaeus)_ were introduced on Smith, San Juan,
and Long islands, in Washington. On Smith Island, these burrowing
animals apparently grazed nearly all the succulent vegetation close to
the ground. By 1924, their burrows riddled the bluffs, causing them
to cave into the ocean (Couch 1929). Couch found no seabirds nesting
on the island, but found numerous tufted puffins _(Lunda cirrhata)_
present on the bluffs, but not nesting. A removal campaign was directed
against the hares in 1924 and in a few years they were gone. Smith
Island now supports nesting pelagic birds (D. Manuwal, personal
communication).
Accounts of hare and rabbit introductions to islands are legion, but
not all such introductions have drastically affected seabirds. Manana
Island, Hawaii, is such a case. Tomich et al. (1968) believed that
introduced rabbits _(Oryctolagus cuniculas)_ were not even indirectly
detrimental to the nesting noddies _(Anous tolidus)_ and sooty terns
_(Sterna fuscata)_. In some situations, introduced lagomorphs have
been credited with benefiting seabirds. Lockley (1942) suggested that
rabbits helped to open new breeding colonies of manx shearwaters
_(Puffinus puffinus)_ at Skomer and in west Wales in general. In Alaska
rabbits were introduced to Middleton Island in 1952 (Rausch 1958) and
to Ananiuliak Island at an earlier unrecorded date. Both have developed
sustaining populations in the presence of large seabird populations
without measurable effect on the birds. On Ananiuliak glaucous-winged
gulls _(Larus glaucescens)_ have been observed feeding on rabbits (W.
S. Laughlin, personal communication).
Invertebrates have been introduced on three islands in the Aleutians.
The black fly (_Simulium_ sp.) reached Adak by 1958, Shemya by 1964,
and Amchitka in connection with activities of the Atomic Energy
Commission in 1968. Apparently the insects were transported on jet
aircraft. The pest appears well established on Adak, but its status
on the other two islands is uncertain. Like the mosquito, the female
black fly sucks blood from warm-blooded animals, and in the process
becomes the vector of a _Leucocytozoan_ blood parasite of birds. In
years of black fly abundance at Seney (Michigan) National Wildlife
Refuge the blood parasite has been responsible for reproductive failure
in Canada geese (_Branta canadensis_; Sherwood 1968). If black fly
problems reach such a scale in the Aleutians, the parasites might prove
limiting to pelagic birds as well as to waterfowl. Winds, for which the
Aleutian region is famous, constitute a limiting factor for obligate
blood-feeding Simuliids and may control the severity of this problem.
_Predatory Animals_
The list of introduced animals that prey on seabirds is extensive.
Often several animals have been introduced to the same island. For
example, in 1951 Amchitka Island in the Aleutians supported populations
of feral dogs _(Canis familiaris)_ and cats _(Felis catus)_, rats
_(Rattus norvegicus)_, and arctic fox. Their presence resulted
from three of the usual sources of predator introductions: escape
of pets, escape from visiting ships (and aircraft), and commercial
introductions. Add introductions to control pests, such as that of
the mongoose _(Herpestes auropunctatus)_ to the Hawaiian Islands, and
only one source remains--the desire of man to improve on nature. In
the Aleutians this impulse has taken the more innocuous form of fish
and plant introductions, such as rainbow trout _(Salmo gairdneri)_ on
Adak and Shemya, and trees (mostly Sitka spruce, _Picea sitkensis_) on
every military base in the "Chain."
Rats appear to be the most commonly introduced predators on a worldwide
scale. Ships furnish the traditional source of their introduction,
but one of us (R.D.J.) has observed them disembarking from a military
aircraft at Cold Bay on the Alaska Peninsula. These animals probably
entered the plane at Adak, which received rats from military ships
early in World War II.
Rats may be able to exploit a larger percentage of the seabird species
on a given island than other introduced predators because they can
enter crevices and burrows in search of the birds and their eggs and
young. They also destroy ground-nesters, and cliff-nesters may not be
altogether safe from them. Clayton M. White (personal communication)
found that _Rattus norvegicus_ had ravaged every one of 16 eyries of
the peregrine falcon _(Falco peregrinus)_ that he checked in 1971 at
Amchitka Island, Alaska. Only one egg had tooth marks, however. Kenyon
(1961) ascribed the disappearance of the song sparrow _(Melospiza
melodia maxima)_ and the winter wren _(Troglodytes troglodytes
kiskensis)_ from Amchitka to predation by rats.
Many authors have mentioned potential rat damage, but few have
quantitatively documented it. Imber (1974), however, provided
data concerning the magnitude of rat predation on diving petrels
and storm-petrels on some New Zealand islands. He found that rats
were taking between 10 and 35% of the chicks of gray-faced petrels
_(Pterodroma macroptera gouldi)_ on Whale Island in the parts of the
colonies where burrows were dense. On those parts of the island with a
very low density of petrel burrows, rats were believed to have killed
virtually every chick. Imber revealed that where Polynesian rats
_(Rattus exulans)_ occur, diving petrels and storm-petrels are rare
or absent, though they are widespread on neighboring islands. Imber
concluded from his studies of the ecology of petrels and Polynesian and
Norway rats that a petrel colony is endangered if invaded by a species
of rat whose maximum weight approaches or exceeds the mean adult weight
of the petrel. Harris (1970), who worked with dark-rumped petrels
_(Pterodroma phacopygia)_ on Santa Cruz in the Galapagos Islands,
indicated that black rats _(Rattus rattus)_ were responsible for the
extremely low nesting success of the petrels there.
In British Columbia, Campbell (1968) recorded predation by the
Alexandrian rat _(R. rattus)_ on ancient murrelets _(Synthliboramphus
antiquus)_ at Langara Island. The extent of damage to the murrelet
population is not known.
The animals most widely introduced in Alaska seabird habitat are the
red fox _(Vulpes fulva)_ and the arctic fox. The red fox is native
to the Alaska Peninsula and to the easternmost group of islands in
the Aleutians, known as the Lissii or Fox Islands (Berkh 1823; Murie
1959). At the other end of the archipelago, in the group known as the
Near Islands, Attu Island has a native population of the arctic fox
(Tikhmenev 1861; Bancroft 1886). Between Umnak Island, the westernmost
island of the Fox group, and Attu there are no native terrestrial
mammals, and substantial avian populations evolved an ecology in the
absence of mammalian predation (Murie 1959).
At the time of Russian contact with the Aleutians, both fox species
were dominantly dark phase, and the early introductions (about 1836)
by the Russian-American Company were of both species (Tikhmenev
1861). Initially both species were successful in developing insular
populations, but in the long run the arctic fox proved the more
successful. At Great Sitkin, Adak, and Kanaga, introduced red foxes
maintained populations that were eliminated in the 1920's to be
replaced by arctic foxes (unpublished records of the Aleutian Islands
National Wildlife Refuge). Differential harvest of the preferred dark
phase had in the meantime altered the genetic makeup of the population,
and the light phase had become dominant. In the arctic fox populations,
the dark phase remained generally dominant at about 95%, but in some
small islands with limited genetic stock (e.g., the Semichis) the
proportion approached one to one (unpublished records of the Aleutian
Islands National Wildlife Refuge).
By 1936, the Aleutian archipelago constituted a large-scale fox farm,
which in its 23 years of existence as a refuge had produced 25,641 fox
pelts with a value of $1,162,826. During the same period, and perhaps
earlier, arctic foxes were introduced on almost every island from
the Aleutians to Prince William Sound, and on some of the islands in
southeastern Alaska. The Aleutian Islands National Wildlife Refuge
maintained records from which the above figures are quoted, but though
records of other islands' use for fur farms exist in the archives of
the Alaska Game Commission, no record of the fur values was kept.
Murie (1959) assessed the influence of the foxes by examining 2,501 fox
droppings collected in 1936 and 1937 from 22 of the Aleutian Islands.
He reported 57.8% of the food items in these droppings was avian--48.9%
seabirds. The result of his investigations was the adoption of new
policies governing issuance of permits for fox farming in the Refuge.
The essential feature of these policies was the revocation of certain
existing permits, with a view to reserving the islands concerned for
wildlife use. The decision proved academic, for fur prices declined
until no market for Aleutian arctic fox pelts could be found. But the
foxes remained.
The most obvious damage has been the nearly complete extermination
of the Aleutian Canada goose _(Branta canadensis leucopareia)_. It
has vanished from its former nesting range in the Aleutian and Kuril
Islands, except for Buldir Island in the western Aleutians (Jones
1963). Clark (1910) described this goose as extremely abundant on
Agattu Island in 1909; however, foxes from Attu were introduced there
in 1923, 1925, and 1929. Murie (1959) found "probably less than six
pairs" in 4 days of traveling over the island in 1937.
In our main area of interest, cats appear to have been widely
introduced, but we found no record of extensive predation on marine
birds. Jehl (1972) attributed the extinction of the Guadalupe petrel to
predation by cats, in combination with the destruction of vegetation
by goats. Imber (1974) reported that "serious predation by cats upon a
colony of gray-faced petrels on Little Barrier Island, New Zealand was
observed in 1950. Since that time, the colony has become extinct."
Though feral dogs are reported present on islands in our area of
interest, they do not appear to have significant influence on seabirds.
On Attu Island, the pet dogs of personnel of the Coast Guard LORAN
station are reported to take common eiders _(Somateria mollissima)_.
Conclusions
Ecological consequences of animal introductions to islands are rarely
well documented. Usually no thought is devoted to such consequences
until redress becomes difficult or quite impossible. Many of the
introductions stem from a period before ecological understanding, and
the introduced animal has acquired the status of a native. The arctic
fox in the Aleutians fits all of these conditions. Until we conducted
a thorough search of the literature, some of it difficult to secure
and written in several languages, the original status of this animal
was not known. Its elimination, now under way on selected islands,
is difficult and expensive. Rapid recovery of some avian species,
including certain passerines, has been observed. However, ecological
homeostasis is the product of evolution, and restoration in the
Aleutians must follow that course. It is not likely to proceed rapidly
to a point thought desirable by man. The accidental introductions
of animals such as rats and black flies in the Aleutians constitute
particularly irksome events because they cannot be reversed. The new
ecology of Amchitka, from which the foxes have been removed, must
evolve in the presence of these species. Its face will look very
different than if they were not there. We would like to suggest a means
by which such introductions may be prevented, but it seems likely that
more, not less, can be expected.
Preventing the introduction of ungulates seems more likely to be
successful, especially if the islands lie within a National Wildlife
Refuge. Even this, however, becomes less certain with an expanding
human population and, with it, demands for more land on which to
produce food.
Legal restrictions have been suggested as a means to control or prevent
introductions, but in the northern islands, little enforcement is
likely. There is a phrase bearing on this, said to have governed human
behavior in the early years of Caucasoid occupation of the Aleutian
Islands, "Heaven is too high and the Czar too far away."
References
Bailey, A. M., C. D. Brower, and L. B. Bishop. 1933. Birds of the
region of Point Barrow, Alaska. Prog. Act. Chic. Acad. Sci.
4(2):14-40.
Bancroft, H. H. 1886. History of Alaska, 1730-1885. San Francisco.
Berkh, V. 1823. The chronological history of the discovery of the
Aleutian Islands or the exploits of the Russian merchants. N.
Grech., St. Petersburg.
Campbell, R. W. 1968. Alexandrian rat predation on ancient murrelet
eggs. Murrelet 49:38.
Carlquist, S. 1965. Island life: a natural history of the islands
of the world. Natural History Press, New York.
Clark, A. H. 1910. The birds collected and observed during the
cruises of the United States Fisheries Steamer "Albatross" in
the North Pacific Ocean and in the Bering, Okhotsk, Japan, and
Eastern seas from April to December 1906. Proc. U.S. Natl. Mus.
38:25-74.
Couch, L. K. 1929. Introduced European rabbits in the San Juan
Islands, Washington. J. Mammal. 10:334-336.
Gabrielson, I. N., and F. C. Lincoln. 1959. The birds of Alaska.
Stackpole Co. and Wildlife Management Institute, Washington, D.C.
Harris, M. P. 1970. The biology of an endangered species, the
dark-rumped petrel (_Pterodroma phacopygia)_ in the Galapagos
Islands. Condor 72:76-84.
Howell, T. R., and T. J. Cade. 1954. The birds of Guadalupe Island
in 1953. Condor 56:283-291.
Imber, M. J. 1974. The rare and endangered species of the New
Zealand region and the policies that exist for their management:
petrels and predators. Paper presented to the International
Council for Bird Preservation (XVI World Conference), Canberra.
Jehl, J. R. 1972. On the cold trail of an extinct petrel. Pac.
Discovery 25:24-28.
Jones, R. D. 1963. Buldir Island, site of a remnant breeding
population of Aleutian Canada geese. Wildfowl Trust Annu. Rep.
14:80-84.
Kenyon, K. W. 1961. Birds of Amchitka Island, Alaska. Auk
78(3):305-326.
Lockley, R. M. 1942. Shearwaters. Devin-Adair, New York.
MacArthur, R. H., and E. O. Wilson. 1967. The theory of island
biogeography. Princeton Univ. Press, Princeton, N.J.
Murie, O. J. 1959. Fauna of the Aleutian Islands and Alaska
Peninsula. U.S. Fish Wildl. Serv., N. Am. Fauna 61:1-364.
Norman, F. I. 1970. The effects of sheep on the breeding
success and habitat of the short-tailed shearwater _(Puffinus
tenuirostris)_ (Temminch). Aust. J. Zool. 18:215-242.
Odum, E. P. 1971. Fundamentals of ecology. W. B. Saunders Co.,
Philadelphia, Pa. 574 pp.
Rausch, R. 1958. The occurrence and distribution of birds on
Middleton Island, Alaska. Condor 60(4):227-242.
Richardson, F. 1961. Breeding biology of the rhinoceros auklet on
Protection Island. Condor 63(6):456-473.
Sherwood, G. A. 1968. Factors limiting production and expansion
of local populations of Canada geese. Pages 73-85 _in_ R. L.
Hine and C. Schoenfeld, eds. Canada goose management. Dembar
Educational Research Service, Madison, Wis.
Tikhmenev, P. 1861. Historical review of the origin of the
Russian-American Co. and its activity up to and the present time.
Edward Weimar, St. Petersburg.
Tomich, P. Q., N. Wilson, and C. H. Lamoureux. 1968. Ecological
factors on Manana Island, Hawaii. Pac. Sci. 12:352-368.
Warner, R. E. 1963. Recent history and ecology of the Laysan duck.
Condor 65(1):2-23.
FOOTNOTES:
[66] Present address: Hawaiian Islands National Wildlife Refuge,
Kilauea, Hawaii.
Oil Vulnerability Index for Marine Oriented Birds
by
James G. King
U.S. Fish and Wildlife Service
P. O. Box 1287
Juneau, Alaska 99802
and
Gerald A. Sanger
U.S. Fish and Wildlife Service
Anchorage, Alaska
Abstract
The 176 species of birds using marine habitats
of the Northeast Pacific are graded on the
basis of 20 factors that affect their survival.
A score of 0, 1, 3, or 5, respectively,
representing no, low, medium, or high
significance is assigned for each factor. The
total score is the Oil Vulnerability Index
(OVI). The OVI's range from 1 to 100, an index
of 100 indicating the greatest vulnerability.
Using this system, one can rank the avifauna
of different areas according to their
vulnerability to environmental hazards as an
aid in making management decisions.
Today's decision makers require an ever-increasing array of information
and planning documents. The Federal Government's requirement for
environmental impact statements under the National Environmental
Protection Act of 1969 is but one example of this trend. These
documents generally consider the effects of proposed actions on
waterfowl and a few other species of birds, but the bulk of the
avifauna is usually only listed, or sometimes ignored completely. A
simple system for evaluating and presenting avian data is badly needed
so that those interested in birds, whether technically trained or not,
can easily grasp the implications of proposed actions. It is incumbent
on biologists to devise new ways of presenting their knowledge so that
it can be easily and effectively used by decision makers, who are often
less informed. In short, biologists must do for the environmental
impact statement assessors what Roger Tory Peterson did for the bird
watchers by giving them a simple and comprehensible system.
The need for a system to evaluate relative vulnerabilities of bird
populations is particularly great for birds that are being increasingly
affected by marine oil pollution. The system needs to allow comparisons
of potential impacts to birds resulting from various oil development
projects in different locations and served by various modes of
transport. The Oil Vulnerability Index (OVI) is our attempt to fulfill
this informational need on the avifauna of the Northeast Pacific.
Insofar as we know, this approach to assessing a wildlife management
problem has been attempted only for ranking endangered species in a
numeric ranking system that identified where restoration efforts could
best be directed (Sparrowe and Wight 1975).
We are indebted to Gene Ruhr and Keith Schreiner for ideas generated in
their work with endangered species. Frank Pitelka, James Bartonek, Kent
Wohl, and Mary Lou King reviewed portions of the manuscript and offered
helpful suggestions. Jack Hodges helped prepare the OVI tables.
Methods
A list of 176 species of birds using marine habitats in or near the
States of Washington and Alaska and the Province of British Columbia
(Table 1, left column) was compiled from checklists by the American
Ornithologists' Union (AOU 1957) and Gibson (1970). Nomenclature is
from AOU (1957). The scientific names of three species of shorebirds
recently identified in the Aleutian Islands that were not listed by the
AOU (1957) came from Peterson et al. (1967).
Each bird was scored on 20 factors that affect its survival (Table
1). Point scores for most birds were either 0, 1, 3, or 5, indicating
no, low, medium, or high importance, respectively, in their biology
or habits as related to Northeast Pacific oil development. Rare or
accidental species were given only one point for occurrence, and
endangered species 99 points for population size plus 1 point for
occurrence. Thus the potential range of the OVI's is from 1 to 100.
The factors in Table are largely self-explanatory. The items under
"range" apply to the entire world population of the species.
"Productivity" is derived from a combination of clutch size and age
at first nesting. Specialization is used in the biological sense to
compare a versatile species like mallards (_Anas platyrhynchos)_ with a
less versatile species such as the trumpeter swan _(Olor buccinator)_.
Mortality under "history of oiling" is based on our knowledge that
some species (e.g., alcids) have been more involved than others such
as gulls. Exposure relates to the level of exposure within the Pacific
area in any season.
Information on many of the factors for many species is scanty at best,
and subjective appraisals were made by us when information was lacking.
Opinions as to appropriate scores will vary among experts. References
used, in part, in preparing Table 1 were: AOU 1957; Fay and Cade 1959;
Gabrielson and Lincoln 1959; Isleib and Kessel 1973; Kortright 1942;
Murie 1959; Palmer 1962; Robbins et al. 1966; Sanger 1972; and Stout et
al. 1967.
Results
The OVI for each of 176 bird species is listed in Table 1. The average
OVI for 22 avian families comprising 128 species that are neither rare
stragglers nor endangered ranged from 19 to 88, with a mean of 51
(Table 3).
Tables 4 and 5 show a possible use for the OVI by comparing impacts
in two large, widely separated areas. A species list from Southeast
Alaska (U.S. Forest Service and Alaska Department of Fish and Game
1970) is compared with a list from the Aleutian Islands (U.S. Fish
and Wildlife Service 1974). Only commonly occurring species are
included. These tables graphically display rather strong differences
in the vulnerability of the avifauna of each area. A person explaining
comparative impacts of projects might use the tables in the following
way:
• Column 1, with scores from 1 to 20 points, indicates birds with a low
level of project involvement, where damage or future costs would not be
expected. As this will normally be the longest list, as in Tables 4 and
5, one would expect an immediate rise of interest on the part of the
planning agency, which is probably eager to learn where problems will
be fewest.
• Column 2 (21 to 40 points) indicates birds for which there is a low
level of concern. Perhaps all that is needed is a review to determine
if special characteristics of the project might be detrimental to these
species.
• Column 3 (41 to 60 points) might be called "trial and error" species.
If some birds are adversely affected, it will not be catastrophic. As
the project develops it will be merely necessary to monitor these to
make sure their status is not adversely affected. If it is, there will
be time to develop conservation measures.
• Columns 4 and 5 (61 to 80 points and 81 to 100 points, respectively)
include the species where concern is high. It is for these species
that research money will be needed, where project modifications may be
required, where a contingency plan in case of disaster is needed, where
a conservation technology will be needed, and where periodic project
shutdown could be called for.
Table 1. _Oil Vulnerability Index (OVI) for waterbirds in the
Northeast Pacific Region._
Range
|Breeding range size
| |Migration length
| | |Winter range size
| | | |Marine orientation
| | | |
| | | | Population
| | | | |Population size
| | | | | |Productivity
| | | | | |
| | | | | | Habits
| | | | | | |Roosting
| | | | | | | |Foraging
| | | | | | | | |Escape
| | | | | | | | | |Flocking on water
| | | | | | | | | | |Nesting density
| | | | | | | | | | | |Specialization
| | | | | | | | | | | |
| | | | | | | | | | | | Mortality
| | | | | | | | | | | | |Hunted by man
| | | | | | | | | | | | | |Animal depredations
| | | | | | | | | | | | | | |Non-oil pollution
| | | | | | | | | | | | | | | |History of
| | | | | | | | | | | | | | | | oiling
| | | | | | | | | | | | | | | | |Annual
| | | | | | | | | | | | | | | | | exposure
| | | | | | | | | | | | | | | | |Spring
| | | | | | | | | | | | | | | | | |Summer
| | | | | | | | | | | | | | | | | | |Fall
| | | | | | | | | | | | | | | | | | | |Winter
| | | | | | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | |OVI
Family, common (AOU) name and | | | | | | | | | | | | | | | | | | | | |Total
scientific name | | | | | | | | | | | | | | | | | | | | |Points
-------------------------------------------------------------------------------
Gaviidae
Common loon _(Gavia immer)_ 1 3 3 3 1 5 5 5 5 1 1 3 1 1 3 3 1 0 1 1 47
Yellow-billed loon
_(G. adamsii)_ 3 3 5 3 5 5 5 5 5 1 1 3 1 1 0 3 5 1 5 5 65
Arctic loon _(G. arctica)_ 3 3 3 3 3 5 5 5 5 1 1 3 1 1 3 3 3 1 3 3 58
Red-throated loon
_(G. stellata)_ 1 3 3 5 1 5 5 5 5 1 1 3 1 1 3 3 1 0 1 1 49
Podicipedidae
Red-necked grebe (_Podiceps_
_grisegena_) 1 3 3 3 1 3 5 5 5 1 1 3 0 1 3 3 1 0 1 1 44
Horned grebe _(P. auritus)_ 1 3 3 3 1 3 5 5 5 3 1 3 0 3 3 3 1 0 1 1 48
Western grebe (_Aechmophorus_
_occidentalis_) 3 3 3 5 1 3 5 5 5 5 1 3 0 1 3 5 1 0 1 3 56
Diomedeidae
Short-tailed albatross
_(Diomedea albatrus)_ 99 1 100
Black-footed albatross
_(D. nigripes)_ 5 1 1 5 3 5 5 3 3 1 5 5 0 0 1 3 1 1 1 1 50
Laysan albatross
_(D. immutabilis)_ 5 1 1 5 3 5 5 3 3 1 5 5 0 0 1 3 1 1 1 3 52
Procellaridae
Fulmar _(Fulmarus glacialis)_ 3 3 1 5 1 5 5 3 3 3 5 3 0 1 1 3 3 3 3 3 57
Pink-footed shearwater
_(Puffinus creatopus)_ 3 1 1 5 1 5 5 3 3 3 5 3 0 1 1 3 1 1 1 1 47
Pale-footed shearwater
_(P. carneipes)_ 1 1
New Zealand shearwater
_(P. bulleri)_ 1 1
Sooty shearwater
_(P. griseus)_ 1 1 1 5 1 5 5 3 3 5 5 3 1 1 1 3 1 5 1 0 51
Slender-billed shearwater
_(P. tenuirostris)_ 1 1 3 5 1 5 5 3 3 5 5 3 1 1 1 3 1 5 1 0 53
Scaled petrel (_Pterodroma_
_inexpectata_) 1 1
Cooks petrel _(P. cookii)_ 1 1
Hydrobatidae
Fork-tailed storm-petrel
_(Oceanodroma furcata)_ 3 3 3 5 1 5 5 3 3 3 5 3 0 1 1 3 5 5 5 5 67
Leach's storm-petrel
_(O. leucorhoa)_ 1 3 1 5 1 5 5 3 3 3 5 3 0 1 1 3 5 5 5 5 63
Pelecanidae
Brown pelican
_(Pelecanus occidentalis)_ 1 1
Phalacrocoracidae
Double-crested cormorant
_(Phalacrocorax auritus)_ 1 3 3 3 3 3 1 5 3 1 3 3 0 1 3 5 3 3 5 52
Brandt's cormorant
_(P. penicillatus)_ 3 3 3 5 3 3 1 5 3 1 3 3 0 1 3 5 3 3 3 3 57
Pelagic cormorant
_(P. pelagicus)_ 3 3 3 5 3 3 1 5 3 3 3 3 0 1 3 5 5 1 5 5 63
Red-faced cormorant
_(P. urile)_ 5 3 3 5 3 3 1 5 3 3 3 3 0 1 1 5 5 5 3 3 63
Ardeidae
Great blue heron
_(Ardea herodias)_ 1 3 1 1 3 3 1 1 1 1 3 3 0 1 1 1 1 1 1 1 29
Anatidae
Whooper swan _(Olor cygnus)_ 1 1
Whistling swan
_(O. columbianus)_ 3 3 3 3 3 3 5 3 1 5 1 3 3 1 3 1 3 0 3 0 50
Trumpeter swan
_(O. buccinator)_ 5 5 3 3 5 3 5 5 1 5 1 5 1 1 3 3 3 0 3 3 63
Canada goose
_(Branta canadensis)_ 1 3 1 1 5 3 1 1 1 3 1 1 5 1 1 1 1 1 1 1 34
Black Brant _(B. nigricans)_ 3 3 3 5 3 3 5 5 3 5 3 3 5 1 3 5 3 1 5 3 70
Emperor goose
_(Philacte canagica)_ 3 5 5 5 3 3 3 3 3 3 3 3 3 1 1 5 5 3 5 5 70
White-fronted goose
_(Anser albifrons)_ 3 3 3 1 3 3 1 1 1 1 1 1 5 1 3 1 1 1 1 1 36
Snow goose
_(Chen hyperborea)_ 1 3 1 1 3 3 1 1 1 1 1 1 5 1 3 1 1 1 1 1 32
Mallard
_(Anas platyrhynchos)_ 1 3 1 1 1 1 1 3 3 3 1 1 5 3 3 1 1 1 1 1 36
Gadwall _(A. strepera)_ 3 3 1 1 1 1 1 3 3 3 1 1 5 3 3 1 1 1 1 1 38
Pintail _(A. acuta)_ 1 3 1 1 1 1 1 3 3 3 1 1 5 3 3 1 1 1 1 1 36
Common teal _(A. crecca)_ 1 1
Green-winged teal
_(A. carolinensis)_ 1 3 1 1 1 1 1 3 3 1 1 1 5 3 3 1 1 1 1 1 34
Blue-winged teal
_(A. discors)_ 1 1
Cinnamon teal
_(A. cyanoptera)_ 1 1
European wigeon
_(Mareca penelope)_ 1 1
American wigeon
_(M. americana)_ 1 3 1 1 1 1 1 3 3 3 1 1 5 3 3 1 1 1 1 1 36
Shoveler
_(Spatula clypeata)_ 1 3 1 1 1 1 1 3 3 1 1 1 5 3 3 1 1 1 1 1 34
Redhead
_(Aythya americana)_ 1 3 1 1 5 3 5 5 5 3 1 3 5 1 3 3 1 1 1 1 52
Ring-necked duck
_(A. collaris)_ 1 1
Canvasback
_(A. valisineria)_ 1 3 1 1 5 3 5 5 5 3 1 3 5 1 3 3 1 1 1 1 52
Greater scaup
_(A. marila)_ 1 3 1 5 1 3 5 5 5 3 1 3 5 1 3 3 1 1 1 1 52
Lesser scaup
_(A. affinis)_ 1 3 1 3 1 3 5 5 5 3 1 3 5 1 3 3 1 1 1 1 50
Common goldeneye
_(Bucephala clangula)_ 1 3 1 3 1 3 5 5 5 3 1 3 3 1 3 3 1 1 1 1 48
Barrow's goldeneye
_(B. islandica)_ 3 3 1 3 1 3 5 5 5 3 1 3 3 1 3 3 3 1 3 3 56
Bufflehead
_(B. albeola)_ 1 3 1 3 1 3 5 5 5 3 1 3 1 1 3 3 3 1 3 3 52
Oldsquaw
_(Clangula hyemalis)_ 1 3 1 5 1 3 5 5 5 5 1 3 3 1 1 5 5 3 5 5 66
Harlequin duck
_(Histrionicus
histrionicus)_ 3 5 1 5 1 3 1 3 3 3 1 3 1 1 1 5 5 5 5 5 60
Steller's eider
_(Polysticta stelleri)_ 3 3 5 5 1 3 5 5 5 5 1 3 3 1 1 5 5 3 5 5 72
Common eider
_(Somateria mollissima)_ 3 5 3 5 1 3 5 5 5 3 1 3 1 1 1 5 5 3 5 5 68
King eider
_(S. spectabilis)_ 3 5 3 5 1 3 5 5 5 5 1 3 1 1 1 5 5 3 5 5 70
Spectacled eider
_(Lampronetta fisheri)_ 5 5 5 5 3 3 5 5 5 5 3 3 1 1 1 5 5 3 5 5 78
White-winged scoter
_(Melanitta deglandi)_ 3 3 3 3 1 3 5 5 5 5 1 3 3 1 3 5 5 5 5 5 72
Surf scoter
_(M. perspicillata)_ 3 3 3 3 1 3 5 5 5 5 1 3 3 1 3 5 5 5 5 5 72
Common scoter
_(Oidemia nigra)_ 3 3 3 3 1 3 5 5 5 5 1 3 3 1 3 5 5 5 5 5 72
Ruddy duck
_(Oxyura jamaicensis)_ 1 3 1 3 1 1 5 5 5 5 1 5 5 3 3 3 1 0 1 3 55
Hooded merganser
_(Laphodytes cucullatus)_ 1 3 1 1 3 3 3 5 3 1 1 3 1 1 3 1 1 0 1 1 37
Common merganser
_(Mergus merganser)_ 1 3 3 3 1 3 3 5 5 3 1 3 3 1 3 3 3 3 3 3 56
Red-breasted merganser
_(M. serrator)_ 1 3 3 3 1 3 3 5 5 3 1 3 3 1 3 3 3 3 3 3 56
Accipitridae
Bald eagle
_(Haliaeetus leucocephalus)_ 1 5 3 3 5 5 0 1 1 0 1 5 0 0 5 3 5 5 5 5 58
Steller's sea eagle
_(H. pelagicus)_ 1 1
Marsh hawk _(Circus cyaneus)_ 1 3 1 1 1 3 1 1 1 0 1 1 0 0 1 1 1 0 1 0 19
Pandionidae
Osprey _(Pandion haliaetus)_ 1 3 1 1 5 5 0 1 1 0 1 5 3 1 5 1 1 1 1 0 37
Falconidae
Peregrine falcon
_(Falco peregrinus)_ 1 3 1 1 5 5 0 1 1 0 1 3 3 0 5 1 3 3 3 1 41
Gruidae
Sandhill crane
_(Grus canadensis)_ 1 3 1 1 1 3 1 1 1 0 1 1 3 1 1 1 1 1 1 0 24
Rallidae
American coot
_(Fulica americana)_ 1 3 1 1 1 1 3 3 1 3 1 1 3 3 3 1 1 0 1 1 33
Haematopodidae
Black oystercatcher
_(Haematopus bachmani)_ 5 5 5 5 3 5 1 1 1 1 1 5 0 1 3 3 5 5 5 5 65
Charadriidae
Ringed plover
_(Charadrius hiaticula)_ 1 1
Semipalmated plover
_(C. semipalmatus)_ 1 1 1 1 1 3 1 1 1 1 1 1 0 5 1 1 3 1 3 0 28
Mongolian plover
_(C. mongolus)_ 1 1
Killdeer _(C. vociferus)_ 1 3 1 1 1 3 1 1 1 1 1 1 0 5 1 1 1 1 1 0 26
Dotterel
_(Eudromias morinellus)_ 1 1
American golden plover
_(Pluvialis dominica)_ 1 1 1 3 3 3 3 1 1 3 1 3 3 5 0 1 1 0 1 0 35
Black-bellied plover
_(Squatarola squatarola)_ 1 1 1 5 3 3 1 1 1 3 1 3 3 5 1 3 3 1 3 0 43
Surfbird _(Aphriza virgata)_ 5 1 5 5 3 3 1 1 1 3 1 3 0 5 1 3 5 0 5 3 54
Ruddy turnstone
_(Arenaria interpres)_ 1 1 3 5 3 3 1 1 1 3 1 3 0 5 1 3 3 3 3 0 44
Black turnstone
_(A. melanocephala)_ 5 3 3 5 3 3 1 1 1 3 1 3 0 5 1 3 5 3 5 3 57
Scolopacidae
Common snipe
_(Capella gallinago)_ 1 1 1 1 1 3 1 1 1 1 1 1 5 5 1 1 1 1 1 0 29
Eurasian curlew
_(Numenius arquata)_ 1 1
Whimbrel _(N. phaeopus)_ 1 1 1 3 3 3 1 1 1 3 1 3 1 3 1 3 3 1 3 0 37
Bristle-thighed curlew
_(N. tahitiensis)_ 5 1 1 5 5 3 3 1 1 3 1 1 1 3 1 3 3 1 3 0 45
Eskimo curlew _(N. borealis)_ 99 1 100
Upland plover
_(Bartramia longicauda)_ 1 1 1 0 5 3 1 1 1 0 1 1 3 3 1 0 1 1 1 0 26
Spotted sandpiper
_(Actitis macularia)_ 1 3 1 1 1 3 1 1 1 1 1 1 0 3 1 1 1 1 1 0 24
Common sandpiper
_(Tringa hypoleucos)_ 1 1
Solitary sandpiper
_(T. solitaria)_ 1 1
Wood sandpiper
_(T. glareola)_ 1 1
Wandering tattler
_(Heteroscelus incanum)_ 5 1 1 5 5 3 1 1 1 3 1 3 1 3 1 3 5 0 5 0 48
Polynesian tattler
_(H. brevipes)_ 1 1
Willet
_(Catoptrophorus
semipalmatus)_ 1 1
Greater yellowlegs
_(Totanus melanoleucus)_ 1 5 1 1 3 3 1 1 1 1 1 1 3 3 1 1 1 0 1 0 30
Lesser yellowlegs
_(T. flavipes)_ 1 5 1 1 3 3 1 1 1 1 1 1 3 3 1 1 1 0 1 0 30
Spotted redshank
_(T. totanus)_ 1 1
Greenshank
_(Tringa nebularia)_ 1 1
Knot _(Calidris canutus)_ 1 1 1 5 5 3 1 1 1 3 1 1 1 3 1 3 3 3 1 0 39
Great knot
_(C. tenuirostris)_ 1 1
Rock sandpiper
_(Erolia ptilocnemis)_ 5 3 3 5 3 3 1 1 1 3 1 3 0 3 1 3 5 5 5 5 59
Sharp-tailed sandpiper
_(E. acuminata)_ 3 1 3 5 3 3 1 1 1 3 1 3 0 3 3 3 3 0 3 3 46
Pectoral sandpiper
_(E. melanotos)_ 1 1 3 1 3 3 1 1 1 1 1 1 0 3 1 1 3 3 3 0 32
White-rumped sandpiper
_(E. fuscicollis)_ 1 1
Baird sandpiper
_(E. bairdii)_ 1 3 3 1 3 3 1 1 1 1 1 1 0 3 1 1 3 3 3 0 34
Least sandpiper
_(E. minutilla)_ 1 3 3 3 1 3 1 1 1 1 1 1 0 3 1 1 3 3 3 0 34
Long-toed stint
_(E. subminuta)_ 1 1
Temminck's stint
_(Calidrus temminckii)_ 1 1
Rufous-necked sandpiper
_(E. ruficollis)_ 3 1 3 5 3 3 1 1 1 3 1 1 0 3 1 3 1 1 1 0 36
Curlew sandpiper
_(E. ferruginea)_ 1 1
Dunlin _(E. alpina)_ 1 3 1 5 1 3 1 1 1 1 1 1 0 3 3 3 3 3 3 3 41
Short-billed dowitcher
_(Limnodromus griseus)_ 3 3 3 3 3 3 1 1 1 1 1 3 3 3 1 3 3 3 3 0 45
Long-billed dowitcher
_(L. scolopaceus)_ 5 3 3 3 3 3 1 1 1 1 1 3 3 3 1 3 3 3 3 0 47
Stilt sandpiper
_(Micropalama himantopus)_ 1 1
Semipalmated sandpiper
_(Ereunetes pusillus)_ 1 3 1 3 1 3 1 1 1 1 1 1 0 3 1 1 3 5 3 0 34
Western sandpiper
_(E. mauri)_ 5 3 3 5 1 3 1 1 1 1 1 1 0 3 3 3 3 5 3 1 47
Buff-breasted sandpiper
_(Tryngites subruficollis)_ 1 1
Marbled godwit
_(Limosa fedoa)_ 1 1
Bar-tailed godwit
_(L. lapponica)_ 3 1 1 5 3 3 1 1 1 3 1 3 3 3 1 3 5 5 3 0 49
Hudsonian godwit
_(L. haemastica)_ 1 1
Black-tailed godwit
_(L. limosa)_ 1 1
Ruff _(Philomachus pugnax)_ 1 1
Sanderling _(Crocethia alba)_ 3 1 1 5 3 3 1 1 1 3 1 3 0 3 1 3 3 3 3 3 45
Spoon-billed sandpiper
_(Eurynorhynchus pygmeum)_ 1 1
Phalaropodidae
Red phalarope
_(Phalaropus fulicarius)_ 3 1 1 5 1 3 5 5 1 5 1 5 0 3 1 5 5 3 5 0 58
Wilson's phalarope
_(Steganopus tricolor)_ 1 1
Northern phalarope
_(Lobipes lobatus)_ 3 1 3 5 1 3 5 5 1 5 1 5 0 3 3 5 5 3 5 0 62
Stercorariidae
Pomarine jaeger
_(Stercorarius pomarinus)_ 1 1 1 5 1 3 3 3 1 3 1 3 1 1 1 3 3 3 3 0 41
Parasitic jaeger
_(S. parasiticus)_ 1 1 1 5 1 3 3 3 1 3 1 3 1 1 3 3 3 3 3 0 43
Long-tailed jaeger
_(S. longicaudus)_ 1 1 1 3 1 3 3 3 1 3 1 3 1 1 1 3 3 3 3 0 39
Skua _(Catharacta skua)_ 1 1
Laridae
Glaucous gull
_(Larus hyperboreus)_ 1 5 3 3 1 3 3 3 1 3 3 1 0 1 1 1 3 3 3 3 45
Glaucous-winged gull
_(L. glaucescens)_ 5 1 3 5 1 3 3 3 1 3 5 1 1 1 1 1 5 5 5 3 56
Slaty-backed gull
_(L. schistisagus)_ 1 1
Western gull
_(L. occidentalis)_ 3 1 3 5 1 3 3 3 1 3 5 1 1 1 1 1 3 3 3 3 48
Herring gull
_(L. argentatus)_ 1 3 1 3 1 3 1 3 1 3 1 1 1 1 1 1 3 3 3 3 38
Thayer's gull _(L. thayeri)_ 3 3 5 3 1 3 1 3 1 3 1 1 1 1 1 1 3 1 3 3 42
California gull
_(L. californicus)_ 3 5 3 3 1 3 3 3 1 3 1 1 1 1 1 1 1 1 1 1 38
Ring-billed gull
_(L. delawarensis)_ 1 5 3 3 1 3 3 3 1 3 1 1 1 1 1 1 1 1 1 1 36
Mew gull _(L. canus)_ 1 5 3 3 1 3 3 3 1 3 1 1 1 1 1 1 3 3 3 3 44
Black-headed gull
_(L. ridibundus)_ 1 1
Franklin's gull
_(L. pipixcan)_ 1 1
Bonaparte's gull _(L.
philadelphia)_ 1 5 3 3 1 3 3 3 1 3 1 1 1 1 1 1 3 1 3 1 40
Heerman's gull _(L. 1 1
heermanni)_
Ivory gull _(Pagophila 1 5 3 5 3 3 3 3 1 3 1 3 0 1 1 1 1 1 1 3 43
eburnea)_
Black-legged kittiwake 1 3 3 5 1 3 3 3 1 3 5 3 0 1 1 1 3 3 3 3 49
_(Rissa tridactyla)_
Red-legged kittiwake _(R. 5 5 5 5 3 3 3 3 1 3 5 3 0 1 0 1 5 5 5 5 66
brevirostris)_
Ross' gull _(Rhodostethia 5 5 3 5 3 3 3 3 1 3 5 5 0 1 0 1 3 1 3 3 56
rosea)_
Sabine's gull _(Xema sabini)_ 3 3 3 5 1 3 3 3 1 3 1 3 0 1 1 1 3 3 3 0 44
Common tern _(Sterna 1 1
hirundo)_
Arctic tern _(S. paradisaea)_ 1 1 1 3 1 3 3 3 1 3 1 1 0 1 1 1 3 1 3 0 32
Aleutian tern _(S. aleutica)_ 5 3 3 5 3 3 3 3 1 3 1 1 0 1 1 1 5 5 5 1 53
Caspian tern _(Hydroprogne 1 1
caspia)_
Black tern _(Chlidonias 1 1
niger)_
Alcidae
Common murre _(Uria aalge)_ 1 5 3 5 1 5 5 5 5 5 5 3 1 1 3 5 3 3 3 3 70
Thick-billed murre _(U. 1 5 3 5 1 5 5 5 5 5 5 3 1 1 3 5 3 3 3 3 70
lomvia)_
Dovekie _(Plautus alle)_ 1 1
Black guillemot _(Cepphus 1 5 3 5 3 5 5 5 5 3 5 5 1 1 1 5 3 3 3 3 70
grylle)_
Pigeon guillemot _(C. 5 5 3 5 3 5 5 5 5 3 5 5 1 1 3 5 5 5 5 3 82
columba)_
Marbled murrelet 5 5 3 5 1 5 5 5 5 3 5 5 1 3 3 5 5 5 5 5 84
_(Brachyramphus marmoratus)_
Kittlitz's murrelet _(B. 5 5 5 5 1 5 5 5 5 5 5 5 1 3 3 5 5 5 5 5 88
brevirostris)_
Xantus' murrelet 1 1
_(Endomychura hypoleuca)_
Ancient murrelet 3 3 3 5 1 5 5 5 5 5 5 5 1 3 3 5 3 3 3 3 74
_(Synthliboramphus antiquus)_
Cassin's auklet 5 3 5 5 1 5 5 5 5 5 5 5 1 3 3 5 5 5 5 3 84
_(Ptychoramphus aleutica)_
Parakeet auklet 3 3 3 5 1 5 5 5 5 5 5 5 1 3 3 5 5 5 5 3 80
_(Cyclorrhynchus psittacula)_
Crested auklet _(Aethia 3 3 3 5 1 5 5 5 5 5 5 5 1 3 1 5 5 3 5 3 76
cristatella)_
Least auklet _(A. pusilla)_ 3 3 3 5 1 5 5 5 5 5 5 5 1 3 3 5 5 5 5 3 80
Whiskered auklet _(A. 5 5 5 5 1 5 5 5 5 5 5 5 1 3 3 5 5 5 5 5 88
pygmaea)_
Rhinoceros auklet 3 3 3 5 1 5 5 5 5 5 5 5 1 3 3 5 3 3 3 3 74
_(Cerorhinca monocerata)_
Horned puffin _(Fratercula 3 5 3 5 1 5 5 5 5 3 5 5 1 3 1 5 3 3 3 3 72
corniculata)_
Tufted puffin _(Lunda 3 5 3 5 1 5 5 5 5 3 5 5 1 3 1 5 3 3 3 3 72
cirrhata)_
Alcedinidae
Belted kingfisher 1 1 3 1 1 1 1 5 1 0 1 3 0 3 1 1 1 1 1 1 28
_(Megaceryle alcyon)_
Corvidae
Common raven _(Corvus corax)_ 1 1 1 1 1 1 1 1 1 0 1 1 3 1 1 1 1 1 1 1 21
Northwestern crow _(C. 3 5 3 3 1 1 1 1 1 0 1 3 1 1 1 1 5 5 5 5 47
caurinus)_
Table 2. _Criteria and points used in calculating Oil
Vulnerability Index._
Point assignment
1 3 5
Range
Breeding Large Medium Small
Migration Long Medium Short
Winter Large Medium Small
Marine orientation Coastal zone Intertidal Open water
Population
Size Large Medium Small
Productivity Large Medium Small
Habits
Roosting Shore Drift Water
Foraging Walking Flying Swimming
Escape Leave area Fly Dive
Flocking Small Medium Large
Nesting density Low Medium High
Specialization Low Medium High
Mortality
Hunted by man Low Medium High
Animal depredations Low Medium High
Non-oil pollution Low Medium High
History of oiling Low Medium High
Exposure
Spring Low Medium High
Summer Low Medium High
Fall Low Medium High
Winter Low Medium High
With these points in mind it is immediately obvious that Southeast
Alaska (Table 4), which has only 9 high-score birds, offers far less
potential for bird problems than does the Aleutian area (Table 5),
which has 24 high-score species. The planning agency could make some
immediate decisions on site priorities and research funding based on
such information.
Discussion
We are convinced that the OVI principle expressed here will become a
useful management tool with all sorts of possible applications. We
recognize some difficulties with the present version, but believe it
is timely to present the system so that a broader range of thought,
improvements, and application can be applied to it.
Of prime importance is the system's simplicity. The use of four levels
of value for each factor, instead of five or more, is an attempt to
simplify. Ian McHarg (1969) has shown that extremely complex land-use
values can be graphically compared and displayed by using three levels
in a way that is useful to decision makers. The difficulty of using
more levels of value was indicated by Sparrowe and Wight (1975) who
used up to 10 levels, enormously complicating the problem of dealing
with low-quality information, which is often all that is available.
The use of scores of 0, 1, 3, 5 instead of 0, 1, 2, 3 for 20 factors
enabled us to use the convenient 100 points instead of 60 points as the
maximum potential total score for any species.
The 20 factors that were evaluated are admittedly arbitrary; with
refinement and more detailed data they could be adjusted to show better
separation between affected species. The decision to use 20 factors
instead of more or less again relates to simplicity. This appears to be
the minimum number that will assure species separation and that can be
neatly displayed.
Table 3. _Oil Vulnerability Index (OVI) for families of birds
of the Northeast Pacific marine habitats, excluding rare and
endangered species in the scoring._
OVI per species
Number of Total
Family species OVI Average Range
Loons--Gaviidae 4 219 55 47-65
Grebes--Podicipedidae 3 148 49 44-56
Albatrosses--Diomedeidae 2 102 51 50-52
Shearwaters--Procellaridae 4 208 52 47-57
Storm-petrels--Hydrobatidae 2 130 65 63-67
Cormorants--Phalacrocoracid 4 235 59 52-63
Herons--Ardeidae 1 29 29 29
Waterfowl--Anatidae 33 1,765 53 32-78
Eagles and Hawks--Accipitridae 2 77 39 19-58
Ospreys--Pandionidae 1 37 37 37
Falcons--Falconidae 1 41 41 41
Cranes--Gruidae 1 24 24 24
Rails and Coots--Rallidae 1 33 33 33
Oystercatchers--Haematopodidae 1 65 65 65
Plovers--Charadriidae 7 287 41 26-57
Sandpipers--Scolopacidae 22 857 39 24-59
Phalaropes--Phalaropodidae 2 120 60 58-62
Jaegers and Skuas--Stercorariidae 3 123 41 39-43
Gulls and Terns--Laridae 16 730 46 32-66
Auks--Alcidae 15 1,164 78 70-88
Kingfishers--Alcedinidae 1 28 28 28
Crows--Corvidae 2 68 34 21-47
Total and Mean 128 6,490 51 19-88
The system will be much more useful when it is expanded to the
subspecific level. Many Holarctic species are represented in the
Northeast Pacific by a single race that would have a much higher OVI
than the species as a whole. For example, the OVI for the Peale's
peregrine falcon _(Falco peregrinus pealei)_ confined to marine
habitats within the Pacific region would be high; and the endangered
Aleutian Canada goose _(Branta canadensis leucopareia)_ would score 100
points instead of the 34 we show for Canada geese _(B. c.)_. If Tables
4 and 5 showed subspecies, the differences in value would be more
marked.
Tables 4 and 5 are for broad geographical areas. A comparison between
smaller areas would probably show more dramatic differences.
Because the dearth of easily available, applicable information
poses a problem in evaluating the various factors, our scoring was
conservative. Experts on the various avian families can doubtless
refine the scoring. If this system proves useful, investigators will
begin to acquire the information needed for more precise evaluations.
Ultimate perfection may never be achieved; however, as with the field
guides, the fact of minor professional disagreement should not destroy
the system's utility.
We believe re-scoring of all birds on the basis of various projects
should be avoided because a standard against which individual projects
can be measured is needed. If everyone did their own scoring, there
would be no standard, and projects evaluated by different investigators
would not be comparable. If a species list for the project area and
standard point scores are used, the level of involvement for many
species and perhaps for most species will be properly identified. As
with any system, there will be exceptions and the assessor will need
to deal with these as appropriate. The result will still be to focus
attention on those species and impacting factors where it is most
needed.
Table 4. _Oil Vulnerability Index for 109 species of birds of
Southeast Alaska (Total Points--2,678)._
OVI 1-20 OVI 21-40 OVI 41-60
Marsh hawk 19 Great blue heron 29 Common loon 47
52 species, rare Canada goose 34 Arctic loon 58
or occasional
(one point each) 52 White-fronted goose 36 Red-throated loon 49
Snow goose 32 Red-necked grebe 44
Mallard 36 Horned grebe 48
Pintail 36 Whistling swan 50
Green-winged teal 34 Trumpeter swan 63
American wigeon 36 Greater scaup 52
Semipalmated plover 28 Lesser scaup 52
Killdeer 26 Common goldeneye 48
Common snipe 29 Barrow's goldeneye 56
Spotted sandpiper 24 Bufflehead 52
Greater yellowlegs 30 Harlequin duck 60
Lesser yellowlegs 30 Common merganser 56
Pectoral sandpiper 32 Red-breasted merganser 56
Least sandpiper 34 Bald eagle 58
Herring gull 38 Peregrine falcon 41
Bonaparte's gull 40 Black turnstone 57
Arctic tern 32 Rock sandpiper 59
Belted kingfisher 28 Dunlin 41
Common raven 21 Short-billed dowitcher 41
Western sandpiper 47
Glaucous-winged gull 56
Thayer's gull 42
Mew gull 44
Northwestern crow 47
Totals 71 665 1,324
OVI 61-80 OVI 81-100
Pelagic cormorant 63 Pigeon guillemot 82
Oldsquaw 66 Marbled murrelet 84
White-winged scoter 72
Surf scoter 72
Black oystercatcher 65
Northern phalarope 62
Common murre 70
Totals 470
Table 5. _Oil Vulnerability Index for 123 species of birds of the
Aleutian Islands_ (Total Points--2,689).
OVI 1-20 OVI 21-40 OVI 41-60
80 species, rare Canada goose 34 Fulmar 57
or occasional Least sandpiper 34 Slender-billed shearwater 53
(one point each) 80 Arctic tern 32 Greater scaup 52
Common raven 21 Common goldeneye 48
Bufflehead 52
Harlequin duck 60
Bald eagle 58
Peregrine falcon 41
Ruddy turnstone 44
Rock sandpiper 59
Western sandpiper 47
Red phalarope 58
Parasitic jaeger 43
Glaucous-winged gull 56
Black-legged kittiwake 49
Totals 80 121 777
OVI 61-80 OVI 81-100
Fork-tailed storm-petrel 67 Pigeon guillemot 82
Leach's storm-petrel 63 Whiskered auklet 88
Pelagic cormorant 63
Red-faced cormorant 63
Black Brant 70
Emperor goose 70
Oldsquaw 66
Steller's eider 72
Common eider 68
King eider 70
White-winged scoter 72
Common scoter 72
Black oystercatcher 65
Red-legged kittiwake 66
Common murre 70
Thick-billed murre 70
Ancient murrelet 74
Parakeet auklet 80
Crested auklet 76
Least auklet 80
Horned puffin 72
Tufted puffin 72
Totals 1,541 170
We have used our OVI system to show the vulnerability of birds to oil,
but it seems likely that the vulnerability index could be applied on
a much broader scale to help make decisions in other areas of human
activity and resource development. The vulnerability index system
could be applied to terrestrial as well as aquatic species by adding
or subtracting impacting factors, as appropriate. Indexes relating the
impact of man upon each North American species could have broad uses in
the field of conservation. Population explosions, as well as declines,
might be predictable. Human activity could be better adjusted to favor
or depress wildlife populations, as appropriate.
We believe that this vulnerability index system has promise for aiding
in the decision-making processes upon which future bird conservation
will depend.
References
American Ornithologists' Union. 1957. Check-list of North American
birds. 5th ed. Lord Baltimore Press, Baltimore, Maryland.
Fay, F. H., and T. J. Cade. 1959. An ecological analysis of the
avifauna of St. Lawrence Island, Alaska. Univ. Calif. Publ. Zool.
63(2):73-150.
Gabrielson, J. N., and F. C. Lincoln. 1959. The birds of Alaska.
The Stackpole Company, Harrisburg, Pa., and Wildlife Management
Institute, Washington, D.C. 922 pp.
Gibson, D. D. 1970. Check-list of the birds of Alaska. Univ. of
Alaska, Fairbanks. 2 pp.
Isleib, M. E., and B. Kessel. 1973. Birds of the North Gulf
Coast-Prince William Sound region, Alaska. Univ. of Alaska Biol.
Pap. 14. 149 pp.
Kortright, F. H. 1942. The ducks, geese and swans of North America.
Wildlife Management Institute, Washington, D.C.
McHarg, I. L. 1969. Design with nature. Natural History Press,
Garden City, N. Y. 197 pp.
Murie, O. J. 1959. Fauna of the Aleutian Islands and Alaska
Peninsula. U.S. Fish Wildl. Serv., N. Am. Fauna 61:1-364.
Palmer, R. S. 1962. Handbook of North American birds. Vol. 1. Yale
University Press, New Haven, Conn. 567 pp.
Peterson, R. T., G. Montfort, and P. H. D. Hallom. 1967. A field
guide to the birds of Britain and Europe. Houghton Mifflin Co.,
New York.
Robbins, D. S., B. Bruun, and H. S. Zimm. 1966. Birds of North
America, a guide to field identification. Golden Press, New York.
Sanger, G. A. 1972. Preliminary standing stock and biomass
estimates of seabirds in the subarctic Pacific region. Pages
589-611 _in_ A. Y. Takenouti et al., eds. Biological oceanography
of the North Pacific Ocean. Idemitsy Shoten, Tokyo.
Sparrowe, R. D., and H. M. Wight. 1975. Setting priorities for the
endangered species program. Proc. N. Am. Wildl. Nat. Resourc.
Conf. 40:142-156.
Stout, G. D., P. Matthiessen, V. R. Clem, and R. S. Palmer. 1967.
The shorebirds of North America. Viking Press, New York. 270 pp.
U.S. Fish and Wildlife Service. 1974. Birds of the Aleutian Islands
National Wildlife Refuge. Washington, D.C.
U.S. Forest Service and Alaska Department of Fish and Game. 1970.
Birds of Southeast Alaska, a check-list. The agencies, Juneau,
Alaska. 12 pp.
PROGRAMS AND AUTHORITIES RELATED TO MARINE BIRD CONSERVATION
Programs and Authorities Related to Marine Bird Conservation in
Washington State
by
Ralph W. Larson
Washington Department of Game
600 North Capitol Way
Olympia, Washington 98504
Abstract
Seabirds are one of the most visible biological
components of ecosystems, and yet little is
known about them. They could readily be used
as an index of marine environmental quality if
adequate studies were conducted to determine
populations, habitat needs, and causes of
fluctuations in abundance. The lack of adequate
funding at the State level has precluded
necessary studies to make these determinations
and to provide habitat protection and
preservation.
The State of Washington has developed a funding
source for protection, preservation, and
enhancement of nongame wildlife, which includes
seabirds. The sale of personalized license
plates for vehicles is now providing some
funds for nongame wildlife management--funds
which should increase as the popularity of
the licensing program increases. Outdoor
Recreation Bonds are providing funding for
habitat preservation. Authorities provided
the Washington Game Department are adequate
to manage and protect seabird species. Other
State laws offer additional protection to their
habitat--specifically the Shoreline Management
Act of 1971 and the State Environmental Act.
It has been often stated that seabirds are one of the most visible
biological components of ecosystems, and yet little is known about
them. Most studies to date have been on fish, and because of their
recreational and commercial value, the concern for maintaining the
marine environment has been primarily a result of the concern for
maintaining the fishery resource. The visible knowledge of the fishery
resource, however, becomes an "after-the-fact" knowledge since the
status of the stocks relates to the value and amount of the fishery--a
fishery resulting from survival under the surface in the marine
environment that can be very secretive about its quality until it is
too late to do something about it. Seabirds, however, are visible
above the surface, in numbers that can reflect changes in the marine
environment that occur below the surface, since many depend on the
subsurface quality that reflects populations of fish.
Studies in Oregon have indicated that consumption of pelagic fish by
murres (_Uria_ spp.), cormorants (_Phalacrocorax_ spp.), storm-petrels
(_Oceanodroma_ spp.), and shearwaters (_Puffinus_ spp.) account
for about 22% of the annual production of various species of these
fish. A decline in this food source will reflect a decline in the
seabird population. Why then should it be necessary to use only fish
populations as an index of marine environmental quality, when seabirds
can more readily be observed and can reflect the same changes that
occur?
As a public wildlife agency, the Washington Department of Game is
often attempting to justify the value of seabirds, and sometimes that
is not easy. When fishermen complain that the seabirds are eating
all of the food of our mighty salmon, and hunters indicate little
compassion because the birds have no value to sport hunting, one has
to think a little to explain their value. However, rhinoceros auklets
_(Cerorhinca monocerata)_ do drive herring into ball-shaped schools,
which attracts salmon in search of food--which in turn provides a
signal to fishermen that salmon may soon be in the area. Explaining
value to the hunter is a bit more difficult, but anyone who has taken
the time to go out on our marine waters and observe the many species
of seabirds and watch them flying and feeding cannot help but be
fascinated by them. The flight of thousands of murres skimming over the
water surface and somehow managing not to dash headlong into a wave is
a fascinating sight.
We who are in fish and wildlife work have had to readjust our thinking
and values during recent years. Our primary programs and concerns for
many years were with the fish, birds, and animals that were of value
to fishermen and hunters. Species of wildlife that we now classify as
nongame received incidental benefit from programs related to game fish,
game birds, and game animals, but we did not do badly in maintaining
and enhancing these incidental wildlife species, mostly by indirection.
However, in the last few years our Department, at least, has taken on a
new responsibility and a new look as related to nongame wildlife.
Our first positive step in this direction was to develop a funding
source for nongame wildlife programs. Our funding attempt charted its
way through stormy waters, but finally ended up being voted on by
the citizens of the State. Our citizens passed Referendum 33, which
provided funds to the Department for nongame wildlife programs from the
sale of personalized license plates. Although the funds have not been
adequate, they are a step in the right direction and have permitted the
Department to engage in a modest program of research and management.
We have placed one person in charge of our program to do the planning
and programming so necessary for developing an effective, growing
program. During the 1st year of operation, we contracted studies on the
rhinoceros auklet, the tufted puffin _(Lunda cirrhata)_, and the black
oystercatcher _(Haematopus bachmani)_. These studies have provided a
basic knowledge of some of the problems facing these seabird species.
As funds increase, additional studies will be made to provide more
information on these birds and others.
During the 1975 legislative session we were successful in amending
the personalized license program to include automobiles other than
passenger cars--a step which should further enhance our funding. We
anticipate that funding will increase from the sale of these license
plates each year. They serve as their own advertisement, and as more
plates are sold, the exposure to the public increases. We anticipate
that within the next few years the funding should reach $150,000 per
year--a modest sum to be sure, but nevertheless adequate to establish a
viable program.
We have been involved in studies funded through other agencies that
involve seabirds. The principal reasons for the studies are not
seabirds, but they become an integral part of any analysis that must be
made of our saltwater environs. One such study involves a comprehensive
status survey of the marine shoreline fauna of Washington. The
Department of Ecology has provided the funding as a part of their
analysis of resources that may be adversely affected by oil spills and
economic development of our shorelines. This study will be the first
one designed to comprehensively identify wildlife species associated
with our shorelines and will determine the species, their status,
location, and habitat. This study will provide a basis for readily
identifying visually the results of oil spills and of the economic
development of critical habitat areas, and provide sound basic data for
use in combating destructive projects in the marine environment.
We are finding that you cannot separate functions of other governmental
agencies that deal with marine waters from seabird analysis. Pollution
responsibilities, shoreline management, coastal zone management, clam
dredging, channel dredging, erosion control, housing development,
industrial expansion, shipping port development--to name a few--all
must have some effect on our seabird species. Therefore, we must
concentrate on obtaining an adequate data base to insure the
perpetuation of these valuable marine species.
As I indicated earlier, the Department of Game has not had a special
program to manage seabirds in the past, but this should not indicate
that we have not assisted in maintaining the seabird resource. Our
basic land acquisition program designed for waterfowl enhancement has
benefited seabirds. We now own some 15,500 acres of lands, tideland,
and marshes bordering the marine waters (including our Skagit and
Nisqually holdings) which provide habitat and protection for many
seabirds. We also recently acquired 48 acres on Protection Island,
designed to protect the nesting area of the rhinoceros auklet. This
purchase was an excellent example of how combined efforts of several
groups accomplished a nearly impossible goal.
Protection Island had been subdivided for summer home development and
many lots had been sold. The developer, however, got caught in the
requirements of our Shoreline Management Act with his last subdivision.
The uproar caused due to the use of this subdivision by auklets created
an atmosphere that made subdivision a real conservation issue. The
outspoken critics of the project from the Audubon Society, Fish and
Wildlife Service, independent conservationists, and our Department
enlisted the aid of Nature Conservancy to negotiate for purchase
of this subdivision, and after lengthy negotiations the option was
obtained, and the Department purchased the land from the Nature
Conservancy with funds provided by the Interagency Committee for
Outdoor Recreation. The area now is destined to be a seabird sanctuary,
with limited public viewing and incidental recreation use. This
project is an excellent example of the power of cooperative efforts by
conservationists to protect a resource.
The State of Washington now has a reasonably good legislative base to
insure constructive programs for management of our seabird resource.
Our legislative authority lies in State statutes under Title 77. These
authorities first provide that the wild birds, wild animals, and game
fish of the State are the property of the State and that they shall be
preserved, protected, and perpetuated. Any regulations for taking shall
be designed so as to not "impair the supply thereof."
The commission also has the authority to classify wild birds. Seabirds,
other than hunted species, fall into the category of nongame birds.
We also have the authority to regulate the propagation and protection
of wild birds, develop rules and regulations for taking them (or to
prohibit taking them), and to create game reserves and closed areas
where necessary to protect various species. Our authorities also
include the obligation to enforce the laws, rules, and regulations
pertaining to the protection of all wild birds.
The Department may also acquire land for habitat and for sanctuaries
for nongame birds and may exchange lands for these purposes. We may
also enter into agreements with the Federal Government, persons,
and municipal subdivisions of the State for all matters relating to
propagation, protection, and conservation of all wild birds, and may
lease State lands for this purpose.
We believe our authorities are now totally adequate to satisfactorily
manage the State's marine bird resources.
In addition to our personalized license plate legislation, which
earmarks funds for nongame wildlife, other State laws and programs
assist in protection of this resource. One program that has assisted
materially in providing funds for habitat acquisition is a bond issue
passed by citizens of the State designed to acquire and develop
recreational land in the State for public use. Our Interagency
Committee for Outdoor Recreation provides the necessary mechanism for
funding of projects, using these bond monies to match Federal funds.
Although recreation is a key factor in obtaining funding, it is still
possible to acquire key habitat for wildlife and develop a people-use
program around the primary purpose for acquisition.
The purchase of a portion of Protection Island was accomplished by
use of these funds, as I indicated earlier, and we are now working
again with Nature Conservancy to acquire key bald eagle habitat on the
Skagit River in northwestern Washington. The bond issues total some $50
million, of which this Department receives about 15%. The State now
is in its third bond issue, and we hope the citizens will continue to
support this program.
One of the newer laws is the Shoreline Management Act of 1971. This act
provides for development of comprehensive shoreline management programs
designed to control the development of these areas to insure protection
of the public interest, while still recognizing and protecting private
property rights consistent with this public interest. These plans
must be developed with citizen involvement. Shoreline classification
generally falls into four categories--natural, conservancy, rural, and
urban. The natural classification can accomplish the most substantial
benefit for marine birds. Provisions are also made for protection of
"shorelines of statewide significance." Plans for these areas must give
preference to uses favoring the public and long-range goals. These
shorelines cover the areas between low and high tide levels on inland
waters and high water and the western boundary of the State on our
Pacific Ocean coast.
Our State Environmental Policy Act, which requires that environmental
impact statements be prepared for various programs and developments,
gives our Department an opportunity to insure that our valuable
wildlife resources are given consideration during the planning phase of
the proposed project.
The Department feels that our authorities at this time are adequate
to protect marine bird populations and their habitat. The one lacking
factor, as usual, is the funding for both adequate management programs
and habitat protection. Our marine habitat is rapidly being developed
for recreational homesites and public use which can eliminate key
habitat use. A greater public awareness of the needs of marine birds
can be a help in preventing destruction of their habitat; however,
money talks the loudest. The acquisition of these key habitats is the
most positive means of insuring their retention. We have no solution
at this time to the funding problem and only hope that someone smarter
than we are can provide an acceptable solution before all of our
efforts become too little and too late.
Programs and Authorities of the Province of British Columbia Related to
Marine Bird Conservation
by
W. T. Munro
British Columbia Fish and Wildlife Branch
300-1019 Wharf Street
Victoria, British Columbia, Canada V8W 2Z1
and
R. Wayne Campbell
British Columbia Provincial Museum
Victoria, British Columbia, Canada
Abstract
British Columbia Provincial agencies are given
authority for protecting marine birds and their
habitats by the Provincial Wildlife Act, the
Parks Act, and the Ecological Reserves Act. The
Provincial Museum Act accommodates research
on marine birds. The Fish and Wildlife branch
has protected over 30,000 ha of intertidal
estuarine habitat in the form of reserves and
has conducted limited inventories of birds
on the Queen Charlotte Islands and northern
mainland coast. The Provincial Museum has
conducted inventories and life-history studies
of marine birds and maintains a repository for
information on seabirds, including a catalog
of colonies. Pollution from oil and chemicals,
improper logging practices, and disturbance by
boating recreationists are the most apparent
threats to the well-being of birds. Additional
inventories and the determination of seasonal
distribution are among the information needed
to better protect the marine birds of British
Columbia.
Most marine-associated birds in Canada are covered by the Migratory
Birds Convention Act and are therefore federally protected. In British
Columbia additional protection is provided by the Provincial Wildlife
Act. Several other provincial acts provide authorities related to
seabirds. The Provincial Museum Act permits research related to natural
history; the Parks Act and Ecological Reserves Act provide for the
protection of habitat and prohibit harassment of wildlife within park
and reserve boundaries; and the Firearms Act permits the closure of
areas frequented by selected wildlife to the discharge of firearms. The
fact that several authorities for the protection and conservation of
marine birds are available does not mean that they have been used to
full advantage.
British Columbia's irregular shores provide thousands of kilometers
of coastline, much of which is used by marine birds for nesting
and wintering as well as during migration. Through legislation of
different types, some of the more ecologically important and unique
sites have been protected. Twelve "ecological reserves," which are
basically inviolate preserve areas, provide habitat for and protection
to a number of major breeding colonies. Over 30,000 ha of intertidal
estuarine habitat has been protected by the provincial Fish and
Wildlife Branch in the form of reserves. Less than half of the total
area is in Order-in-Council reserves (passed by the Provincial
Cabinet), which afford strong protection; the rest is in departmental
map reserves, which merely means other agencies must inform the branch
before they disturb them; they are hardly secure. Provincial Parks
Branch protects other areas used by marine birds by incorporating them
within parks.
Research and conservation of seabirds in British Columbia have not
been a high priority in the Fish and Wildlife Branch, basically
because seabirds are not consumed by people. Our primary interest
in seabirds has been in their role as a life support system for the
peregrine falcon _(Falco peregrinus)_. Most Fish and Wildlife Branch
reserves have been established to protect estuarine habitat for fishes,
waterfowl, and shorebirds rather than for true seabirds. That situation
is not likely to change in the near future unless additional funds
become available to the Branch. About the most we can expect to do is
designate key areas as sanctuaries or wildlife management reserves.
Under the folio and referral systems now operational among resource
agencies in British Columbia, we have the opportunity to advise other
disciplines against approving practices that would adversely affect
wildlife. By those methods we are attempting to protect critical
seabird habitat. It must be stressed, however, that we can only advise;
we cannot force other agencies to follow procedures we suggest.
The only significant work relating to seabirds in which the Fish and
Wildlife Branch is presently engaged involves inventory of specific
sites on the Queen Charlotte Islands and the northwest mainland coast.
Those areas are ones on which we expect to find seabird colonies and
where applications for logging are pending. To enable us to advise the
Forest Service on the wildlife values of those sites, we began field
work in the summer of 1975.
The Federal Government, in comparison to what it has done on the
east coast and in the north of Canada, has been negligent in its
support of seabird conservation on the west coast. By far the most
seabird research by a government agency in British Columbia has been
accomplished by the staff at the Provincial Museum in Victoria. In
the past, beginning in the 1940's, museum personnel (mainly C. J.
Guiguet) explored and inventoried seabird colonies along the British
Columbia coast. Most work then was exploratory, and little quantitative
information was gathered. More recently, precise counts have been
obtained of seabirds nesting in the Strait of Georgia, Juan de Fuca
Strait, the central west coast of Vancouver Island, the northern
mainland coast, and the east coast of the Queen Charlotte Islands. That
information, along with quantitative data gathered in the summer of
1975, will be used to update the "Catalogue of British Columbia Seabird
Colonies" published in 1961 by the museum.
The museum has a number of programs under way.
• A cooperative survey with Washington State of colonies of the
double-crested cormorant _(Phalacrocorax auritus)_ in the Pacific
Northwest. To limit disturbance, that survey is to be conducted at
5-year intervals beginning in the summer of 1975.
• A survey of all islands, whether or not they are supporting seabirds,
in the Strait of Georgia and Juan de Fuca Strait in 1980, to detect
changes in populations after 1974.
• Monitoring changes in seabird populations along the west coast of
Vancouver Island, gathering data for all islands there. Permanent
quadrats will be established on ecological reserves in the area to help
detect such changes. As a result of such quadrats having been set up in
1967 on Cleland Island and being re-examined in 1974, we can document a
significant decrease in Leach's storm-petrel _(Oceanodroma leucorhoa)_
and a corresponding increase in rhinoceros auklet _(Cerorhinca
monocerata)_.
• Mapping vegetation substrate as it relates to seabird populations on
selected islands in the Province.
• Investigating differences in eggshell thickness between eggs within
clutches of glaucous-winged gulls _(Larus glaucescens)_ near Victoria.
• A saturation banding program for cormorants (_Phalacrocorax
penicillatus_, _P. pelagicus_, and _P. auritus_) on south-coast
colonies.
• Continued banding of select colonies of glaucous-winged gulls which
began in the 1960's. Life tables, survivorship curves, and dispersal
patterns should result.
The museum also acts as a repository for information on seabirds in
British Columbia and maintains files on the history of seabird islands
as well as references to literature published on all seabirds in the
Province. The references include unpublished theses and reports. This
information is easily retrievable--not a small contribution in today's
paper-producing society.
Future programs planned by the Provincial Museum, in addition to the
continuance of some of those already mentioned, include a system of
monitoring colonies every 5 to 10 years, depending on the sensitivity
of the species involved, to detect changes in population numbers and
distribution. It is also hoped that the first complete provincial
census, with cooperation from Federal and provincial agencies,
naturalist groups, and the like, can be budgeted and arranged for
in the summer of 1980. That census could conceivably be expanded to
include the entire Pacific coast of North America.
Some research on the breeding biology of seabirds has been conducted
by universities, notably the University of British Columbia under
the guidance of R. H. Drent and M. Udvardy. We expect that graduates
returning to coastal universities will continue that work. The section
of government dealing with ecological reserves has just recently
received funding to permit field studies on reserves harboring marine
birds. J. B. Foster, Coordinator of Ecological Reserves, emphasizes
that research by other agencies is encouraged under permit on
ecological reserves.
There are a number of threats to seabirds in British Columbia. Along
with the chemical pollutants in their environment and food, logging,
and the specter of huge oil tankers plying the west coast, we are
greatly concerned by the potential threat of boating enthusiasts and
recreationists. Well-meaning but uninformed vacationers and boaters
stopping to visit or picnic at seabird islands can do serious damage
to nesting seabirds. The possibility of loss of habitat to seabirds
from people searching for island summer homes poses a threat, and
indeed some seabird islands have already been lost to speculators. With
increased leisure time and travel the potential of unintentionally
introducing predators, such as rats (_Rattus_ spp.) and snakes, to
seabird islands is great. Intentional or accidental introduction of
mammals, such as mink _(Mustella vison)_, rabbit (_Sylvilagus_ spp.),
fox (_Vulpes fulva)_, and raccoon _(Procyon lotor)_, to islands is
another serious threat to the future existence of seabird populations.
The recent unauthorized and apparently unsuccessful introduction of
mink on the Queen Charlotte Islands could have resulted in the eventual
devastation of seabird colonies there and on adjacent islands. The
destruction of habitat by logging near colonies on large islands and
complete logging on small offshore islands will no doubt adversely
affect some seabird populations. Competition between increasing
numbers of gulls (_Larus_ spp.) and certain species of seabirds (e.g.,
storm-petrels and cormorants) may result in reduced numbers of the
seabirds.
What types of programs are needed? About 80% of all known seabird
colonies in British Columbia have been investigated to date, and a
modest program to monitor changes has been established. We do, however,
require exploratory work along the west coast of the Queen Charlotte
Islands and northern mainland coast. We need to know more about the
breeding biology and reproductive potential of each of the species
nesting in the Province, as well as about their adaptability to
different habitats. Will some burrow-nesting alcids use man-made tubes
erected in otherwise marginal habitat? Can and should more man-made
habitat be created for cormorants that have been displaced from
ancestral breeding grounds?
Of immediate urgency is exploratory work involving seasonal
distribution, abundance, and flight lanes of pelagic seabirds along the
coast of British Columbia--especially the northern portion. We lack
the base-line data which could help influence routes of oil tankers to
lessen the potential danger of spills to marine birds. We know little
about the winter distribution of marine birds, especially alcids.
As a general rule, offshore islands of less than 100 ha should be
protected completely from logging, and the larger ones supporting major
seabird colonies should have some protection from development. We must
also consider the possibility of preserving some islands which may act
as buffer areas and provide potential alternate habitat to seabirds.
Another concern is the effect of commercial and sport fishing in the
Province on food supplies for seabirds, and what damage, if any,
gillnetting may have on diving seabirds. Perhaps we should discourage
fishing by nets in areas where large numbers of seabirds aggregate to
feed.
We also need to know more about the effects of chemical pollutants on
individual species and on their reproduction. Of paramount importance,
and one which biologists tend to neglect, is communication among all
disciplines interested in seabirds. For example, a comprehensive file
of the history of seabird colonies in British Columbia is established
at the Provincial Museum. It would be a waste of time and money to
duplicate that file and have three or four scattered across the
country. We would be better advised to tackle another phase of work yet
to be accomplished. Communication assures that seabirds benefit and are
not unduly harassed.
Annual meetings, both local and international, of persons interested in
marine birds should be arranged so that problems relating to seabirds
can be discussed. For example, populations of glaucous-winged gulls in
British Columbia have increased exponentially in the past 10 years. If
they are a threat to the existence of other seabirds (e.g., Leach's
storm-petrel, double-crested cormorants), should they be controlled,
and, if so, how? Such meetings would also help develop a pattern of
universal census methods and techniques that could be put to use along
the Pacific Coast to provide comparable data from different areas.
Finally, in today's world, natural resource agencies must operate
on limited funding. How can one convince administrators to divert a
significant portion of those funds to the investigation of species that
are widely regarded as having little social importance?
A detailed bibliography of seabirds of British Columbia is available
from either of us.
We thank D. F. Hatler, J. B. Foster, and A. L. Allen for comments on
the manuscript.
Petroleum Industry's Role in Marine Bird Conservation
by
Keith G. Hay
American Petroleum Institute
2101 L Street NW
Washington, D.C. 20037
Abstract
Despite improved safety practices, engineering,
and navigational skills, marine tanker
transportation will not be 100% accident
free. The industry seeks to mitigate wildlife
losses through improved technology, research
in the rehabilitation of species exposed to
oil, and the development of oil spill/wildlife
contingency plans.
Oil spills and marine birds not only constitute a deadly mix but have
proved to be one of our toughest environmental problems to solve. The
rehabilitation of these tragic victims is plagued with controversy,
emotion, apathy, and biological unknowns. The costs have been high
and the survival rates low. During the last 10 years, a few dedicated
people working here and in Europe have reversed this trend. They have,
in addition, taken steps to develop contingency plans and conducted
research to reduce seabird mortalities from oil spills. I present a
brief status report on their progress and the melange of problems
involved.
The unfortunate encounter between spilled oil and marine birds is
not new. It goes back at least to the turn of the century, when
coal-burning steamships and sailing clippers were replaced by
oil-fueled vessels. Since then thousands of marine birds have succumbed
to floating oil, especially during World Wars I and II (Blanks 1942)
and in recent spills here and off the coast of Europe (Clark 1969).
With the current and projected demands for energy in the United States
and with expanded tanker traffic and accelerated development of
offshore petroleum reserves, the oil-contaminated ("oiled") bird is not
going to go away. Periodically, this ugly problem will arise, despite
the efforts of the petroleum industry to improve its safety practices,
engineering, and navigational skills. Unfortunately, the problem is the
product of the inherent fallibility of man and his imperfect machines.
We cannot ignore the situation. We must here, as elsewhere, improve our
technology and mitigate the impact.
A study of more than 100 spills that occurred throughout the world
between 1960 and 1971 revealed that about 1 in 5 spills (20%) involved
50 or more birds (Ottway 1971). Nearshore spills have a far greater
effect on waterfowl than do spills occurring several miles or more
offshore.
In the 1967 _Torrey Canyon_ tanker spill, some 8,000 oiled birds were
rescued. About 6,000 were picked up alive in England and about 2,000 in
France, at a cost estimated at $160,000 (Clark 1969; Bourne 1970). Less
than 5% of those treated by British authorities survived for release
some months later. The survival rate of those rescued in France is
unknown.
In 1969 the Santa Barbara spill resulted in the treatment of 1,575
marine birds, of which 169 were eventually released. Many of those
released were found dead within a short time (Smail 1971).
In 1970 the tanker _Delian Apollon_ was responsible for a spill in
Tampa Bay, Florida. Thousands of seabirds were lost. No exact count
was taken, but hundreds of birds were cleaned and farmed out for
rehabilitation. Reports show that many of the birds were returned dead
within a few days (Smithsonian Institution 1971).
In 1971, when two tankers collided under the Golden Gate Bridge at the
mouth of San Francisco Bay, the resulting spill involved some 4,686
oiled birds taken to cleaning centers (Lassen 1972). Eight months
later the last of 200 survivors (less than 5%) were released at a cost
estimated at $900 per bird (Smith 1975).
The most vulnerable species involved in spills have been the oceanic
birds such as the alcids--murres (_Uria_ spp.), auks (_Pinguinus_
spp., _Alca_ spp.), puffins (_Fratercula_ spp., _Lunda_ spp.), and
guillemots (_Cepphus_ spp.). Other species less affected included
ruddy ducks _(Oxyura jamaicensis)_, scaup (_Aythya marila_, _A.
affinis_), scoters (_Melanitta_ spp.), mergansers (_Lophodytes_ spp.),
oldsquaws (_Clangula_ spp.), and goldeneyes (_Bucephala_ spp.). Grebes
(_Podiceps_ spp.), eiders (_Polysticta_ spp.), loons (_Gavia_ spp.),
and cormorants (_Phalacrocorax_ spp.) are also frequently involved.
Ruddy ducks and scaup are particularly vulnerable during winter on
large river systems with heavy oil transport traffic. Fortunately, none
of the above species have been reported in jeopardy as a result of
spills in American waters.
In Europe and South Africa, however, it is believed that oil pollution
is responsible for a steady decline in seabird colonies. For example,
in known oil-dumping areas in the Baltic Sea, where some mortality
of oldsquaws has been associated with surface oil, their population
has dropped to about one-tenth of the pre-World War II level (Bergman
1961). Other authors report that oil spills have reduced the number
of scoters in the Baltic and off southeast England (Atkinson-Willes
1963). The auk populations off the coast of England have been reported
to be substantially decreased by oil pollution (Parslow 1967). Tankers
traversing South Africa's Cape of Good Hope are said to be responsible
for the reduction of jackass penguins, _Spheniscus demersus_ (Rowan
1968). Oil pollution, especially sustained pollution, has thus been
cited as a limiting factor on certain seabird populations.
Estimates of seabird mortalities from an oil spill are imprecise; they
may differ by thousands of birds. It is believed that only a small
fraction of the birds killed in a spill wash up on the shore. Some
authors have even speculated that the death rate at sea could range
from 6 to 25 times the number washed ashore (Tanis and Mörzer-Bruyns
1968).
In contrast to terrestrial birds and semiaquatic species (e.g., ducks;
geese; coots, _Fulica_ spp.; or gulls, _Larus_ spp.), totally seaborne
species have a restricted reproductive potential. Many, such as the
alcids, do not breed until they are 3 or more years old, and lay only
one egg per year. Only one in five survives to go to sea.
Until about 5 years ago we knew little about seabirds. They are not
game species (they taste fishy) and thus do not constitute an important
economic resource. They have never been the subject of intensive
waterfowl management or research by either State or Federal governments.
During the last 5 years a small group of people here and in England
have been studying marine birds--their distribution, population status,
physiology, diseases, and husbandry in captivity. Four organizations
have primarily been involved: The American Petroleum Institute (API);
the Wildlife Rehabilitation Center at Upton, Massachusetts; England's
Advisory Committee on Oil Pollution of the Sea; and the International
Bird Rescue Research Center in Berkeley, California. They have
encountered many common biological and people problems, some of which I
discuss here.
Biological Problems
The recuperation record for oiled seabirds in the past has admittedly
been dismal. A few birds have been returned to nature, but only after a
long and costly period of care. In the process, semidomestication often
takes place. The percentage of cleaned birds that actually survive
after release is even smaller. One should not infer from this small
percentage that rehabilitated birds cannot readjust to life in the
wild. Several successful reintroductions have been documented. U.S.
Fish and Wildlife Service bands were returned from two western grebes
that were cleaned and released after the 1971 San Francisco spill. One
bird was picked up a year later near Treasure Island, California, and
the second after almost 2 years, in the State of Washington (Fletcher
1973).
Survival rates have zoomed with recent strides in cleaning technology
and husbandry. The International Bird Rescue Research Center reported
a survival rate of 41%, based on hundreds of birds and about 20
different species over a 2-year period (Smith 1975). In South Africa,
where powdered clay was used as a cleaning agent on jackass penguins,
nearly 50% survived, although exact percentages have not been published
(Edwards 1963; Holmes 1973). Rapid retrieval, the relatively small
groups of birds treated, and expert cleaning and husbandry techniques
are largely responsible for high success ratios. Rehabilitation success
is measured not only in terms of percent survival but also in terms of
median length of captivity and average cost per bird.
Rescued oiled birds arrive at cleaning centers under a wide range of
physical conditions. Before capture they may have spent hours or days
in water, during which their energy has been continuously drained. The
oil destroys the bird's protective insulation, and metabolic rate must
be increased to sustain body temperature. Constant preening also takes
energy. Food demands increase, but feeding attempts, especially for
diving birds, are thwarted by oil-fouled plumage. A bird may arrive
at the cleaning center under stress, chilled, exhausted, dehydrated,
starved, and ill from ingested oil. Cold weather accentuates these
conditions. Often such birds are jammed together with other species,
hauled long distances, and immediately put through a series of cleaning
processes that would leave even a healthy bird weak and in a state of
shock. One marvels at the stamina of the survivors.
In most past spills, every bird found was routinely cleaned regardless
of its condition. Instead of attempting to reclaim all birds, a
selective judgment should be made. If a bird's physical condition makes
its chances of survival nearly impossible, it should be humanely killed
(except for rare or endangered species). This would enable workers
to devote more time and care to birds having a reasonable chance at
survival.
Fletcher (1973) stated that many variables affect bird survival:
weather conditions, the type and amount of oil in and on the bird, the
species, the distance of the spill from the shore, the time lag from
initial fouling until initial treatment, the degree of stress a bird is
subjected to, the husbandry techniques used, the time of release (the
sooner released, the higher the apparent survival), the number of birds
being cared for (the fewer birds being handled, the higher the survival
rate), the quality of the facilities available, and the training and
experience of the people handling the birds.
Many of the above biological problems are under study here and in
Europe, including the following.
• The effect of ingested oil on the mucosal transport mechanism of
marine birds. To use seawater, birds must be able to transport sodium
ions through the gut and expel the excess salt through the nasal
passages. Oil can block the mucosal ion transport mechanism, resulting
in dehydration and eventual death.
• The development of a successful program of hormonal and electrolyte
therapy to restore osmotic balance and the functioning of the salt
glands in contaminated seabirds.
• Treatment and prevention of aspergillosis (fungus infection); septic
arthritis or "bumble-foot" (joint capsule infections); breast sores
(especially in seabirds confined on hard surfaces); eye lesions (caused
by ammonia fumes from unsanitary pens); dehydration and hypoglycemia;
lipid pneumonia; and bacterial infections.
• Treatment of stress after capture, including perfection of handling
and cleaning techniques, administration of proper steroids, crowding,
light, temperature, noise levels, and so on.
• Development of proper nutritional regimes for certain species and
feeding techniques to eliminate forced feeding.
• The establishment of criteria for confident recognition of terminal
pathological conditions in oiled birds.
• Determination of optimum density of confined birds to insure healthy
conditions and adequate room for preening.
• Determination of proper time and conditions for reintroduction of the
birds into their native habitat.
People Problems
Handling an over-responsive and emotional army of bird-cleaning
volunteers and training them to play constructive roles is a major
undertaking. Planning, cooperation, understanding, patience, and clear
direction must be developed. In the absence of these virtues, chaos can
and has prevailed.
The San Francisco Bay oil spill of 1971 was a classic example. There
was virtually no State or Federal coordination. Splinter groups of
volunteers established their own "treatment centers" and jealously
guarded their patients. Some actually absconded with their pet patients
to seek better care elsewhere. Long hours, fatigue, and frustrations
led to dissension and bitter quarrels. Antiestablishment sentiment was
rampant.
Instant experts on bird cleaning, avian medicine, and nutrition
appeared or developed overnight. Veterinarians volunteered their
services, but their knowledge of oiled-bird treatment was limited. A
wide variety of food (from canned dog food to live shrimp) was given
the birds. Forced feeding was routine. Medications and vitamins of all
kinds were also administered. Needless to say, the states of the art
in treating oiled birds and handling volunteers were both in their
infancy. For both, the success ratio was near zero.
To prevent such fruitless efforts and the frantic, unorganized response
that prevailed, a well-designed contingency plan for wildlife involved
in an oil spill is needed.
Contingency Planning
It is only prudent to take reasonable measures to prepare for
oiled-bird emergencies. This is especially true in regions where
bird concentrations and oil shipment traffic converge. Almost equal
attention must be devoted to handling volunteers as to handling birds.
Safety is a major consideration. The sharp beaks of birds can be very
dangerous.
A model State contingency plan should include the following:
• A list of State and Federal agencies to be alerted, including 24-h,
7-day-a-week telephone numbers, and names of individuals to contact.
• Clarification of the roles of State and Federal agencies under the
Regional Response Plan of the National Oil and Hazardous Substances
Pollution Contingency Plan.
• A list of State and Federal laws pertaining to possession of birds
and mammals.
• An updated roster should be maintained of team members, assignments,
and responsibilities for inland and marine spills, including discovery
and notification, record keeping, public information, containment and
counter-measures, wildlife protection, and cleanup, restoration and
evaluation of effects on the biota.
• A list of individuals or organizations that possess skills and
experience in treatment of oiled birds (locally and nationally).
• Location of emergency wildlife reception and treatment centers.
• A list of the necessary supplies, equipment, and holding facilities
for cleaning, treating, drying, and post-care operations. Such
information can be obtained from:
--California Department of Fish and Game, Oil and Hazardous
Materials Contingency Plan (July 1974)
--International Bird Rescue Research Center, Aquatic Park,
Berkeley, California 94710
--American Petroleum Institute, 2101 L Street, Northwest,
Washington, D.C. 20037
--Wildlife Rehabilitation Center, 84 Grove Street, Upton,
Massachusetts 01568
• An organizational plan which includes assignments of duties and
responsibilities for personnel manning a bird-cleaning center. In
addition to bird cleaning and husbandry, assignments must be made for
record keeping, internal communications, public relations, logistics
(supplies), security, sanitation, safety, and meals.
• A slide lecture or film to instruct volunteers in the correct
techniques for handling, cleaning, and post-care of oiled birds.
• A selected bibliography of key references on oiled-bird cleaning and
care.
• Appendices to the plan should include maps of the major coastal oil
terminals, bays, and estuarine areas with heavy oil transport traffic.
Map overlays would depict the location of resident species and the
migratory patterns, species composition, relative abundance, and winter
concentration areas of migrants. Additional overlays would locate
commercially important demersal seafood areas (e.g., oyster and abalone
beds, lobster and crabbing locales) and marine mammal habitats. Further
refinement of an atlas could include information on tides, prevailing
winds, ocean currents, and water mass movements to assist in predicting
the path of spilled oil.
What Has Been Accomplished
The petroleum industry, through the API, took prompt steps to mitigate
the problem after the first seabird mortalities were reported from
Santa Barbara in 1969. They commissioned a young aviculturist, Philip
Stanton, who has extensive experience working with wild waterfowl, to
start a research program on cleaning and caring for oiled birds. At
his Wildlife Rehabilitation Center at Upton, Massachusetts. Stanton,
with the help of API, has been conducting research on oiled birds
for 7 years. He is also an assistant professor of biology at nearby
Framingham State College. Stanton's studies (unpublished) include
investigations on food shape and color preferences in wild ducks, the
effects of lengthened photoperiods on breeding of arctic geese, and
the effects of diets of varying protein concentrations on growth and
development of the common eider duck.
As a result of his research on cleaning techniques and agents,
Stanton has recommended a nontoxic liquid cleaner called Polycomplex
A-11. Although not perfect, it is one of several cleaning agents
being successfully used today. He has authored a "how to" guide
for oiled-bird treatment entitled "Operation Rescue" and prepared
a companion bibliography (Stanton 1972). These booklets have been
distributed throughout the United States to State and Federal agencies
and conservation organizations. He has provided consulting services at
numerous spills and has worked to establish oiled-wildlife treatment
centers in coastal States.
Since 1972 the API has sponsored an avian physiology study at the
University of California at Santa Barbara. Under the direction of W. N.
Holmes, the studies are directed at the effects of ingested crude oil
and petroleum products on marine birds. Holmes has revealed that small
quantities of crude oil introduced into the gut of a saltwater-adapted
bird can affect the mucosal transport and extra-renal excretory
mechanisms, resulting in acute dehydration and eventual death. Dr.
Holmes is also examining the effects of the various distillation
fractions derived from crude oil and the long-term effects of ingested
oil in mature birds. Incidentally, Alaska North Slope oil was found to
be almost innocuous when administered to ducklings in amounts similar
to the effective doses of other oils (Holmes and Cronshaw 1975).
Refined products (diesel oil, No. 2 fuel oil, and Bunker "C") are known
to be more toxic than crude oil. For example, the relatively small
spills of Bunker "C" at Tampa, Florida, in 1970 and in San Francisco
in 1971 caused approximate mortalities of 90 and 20 birds per ton of
spilled product, respectively. The crude oil spills of the _Torrey
Canyon_ and at Santa Barbara, however, resulted in mortalities of only
0.5 and 0.6 bird per ton of oil (Clark 1973).
Dr. Holmes is now testing measured amounts of the above refined oils
on adult birds. He is determining the degree of dehydration incurred,
the resulting pathological changes, and the replacement (hormonal and
electrolyte) therapy necessary to rehabilitate the birds.
It is obviously important to keep as many birds away from an oil
slick as possible. This was the objective of an API contract with the
Av-Alarm Corporation of Santa Maria, California. Their objective was to
determine the feasibility of repelling aquatic birds from an area by
using an acoustical jamming device as the stimulus.
The flocking instinct in birds provides mutual protection through their
almost constant communication with one another. When this (audio)
communication is prevented by jamming with high-frequency sounds,
the birds immediately leave the area to seek relief. This harmless
technique has been used successfully for years to repel agricultural
pest birds.
The Av-Alarm device was tested on waterfowl at the Grizzly Island Game
Refuge some 48 km north of San Francisco Bay and in the bay itself
over a 2-year period (1972-73). Using a single, fixed-location system
covering a three-quarter square mile (1.21 km²) area Crummett (1973)
repelled 82% of the ducks and 92% of the shorebirds on the Refuge. The
intrepid coot, however, was found to be relatively indifferent to the
sounds. Immediately upon activation, there was a sudden drop in the
bird count, which was followed by a continual decline in numbers.
In tests of the device from a cruising boat in ocean and bay waters,
the degree of effectiveness varied by species. Ducks were repelled
100%; pelicans (_Pelecanus_ spp.) 92%; great egrets _(Casmerodius
albus)_ 85%; gulls 42%; cormorants 75%; shearwaters (_Adamastor_ spp.)
29%; and murres, 51%.
Grebes and murres dived away from the stimulus, then surfaced and dived
again if the threat was still present. To prevent driving the diving
species deeper into the center of a slick, investigators recommended
that buoyed repelling equipment be placed within the spill area. When
the alarm system was used in conjunction with the occasional firing
of a rocket or shellcracker, an even greater percentage of birds was
repelled.
The International Bird Rescue Research Center, a nonprofit corporation
in Berkeley, California, was an outgrowth of the Richmond Bird Care
Center that played an active role in the 1971 San Francisco Bay spill.
Since that time, a small group of individuals has continued research on
bird-cleaning techniques, testing cleaning agents, perfecting husbandry
methods, and alleviating stress. Their 41% survival rate speaks for
itself. A paper describing their work is being presented at this
conference (Smith 1975).
Under a grant from the API, the center is currently evaluating various
cleaning agents, and testing the pressurized jet versus serial baths
and the re-establishment of feather waterproofing. The center is also
perfecting an audio-visual slide presentation that will illustrate
how to select the proper cleaning agent, together with the latest
bird-cleaning and care procedures.
About 5 years ago, England's Advisory Committee on Oil Pollution of the
Sea established a research unit in the Department of Zoology at the
University of Newcastle-Upon-Tyne. It was funded by a grant from the
Royal Society for Prevention of Cruelty to Animals, the Royal Society
for the Preservation of Birds, the World Wildlife Fund Seabird Appeal,
and the British Institute of Petroleum.
Their efforts have also led to high survival rates. Focusing primarily
on the efficiency of various detergents, they have found that the
loss of waterproofing is largely due to soap and oil residues and
the disturbance of the feather structure in the cleaning process.
Consequently, they have devoted their efforts to selecting detergents
that can be completely removed with a minimum disturbance of plumage
(Seabird Research Unit 1971).
In May 1974, the API in cooperation with the U.S. Fish and Wildlife
Service convened a seminar on Oil Spill Wildlife Response Planning.
The 2-day workshop was held at the Patuxent Wildlife Research Center
at Laurel, Maryland. Some 70 State and Federal government personnel in
charge of oil spill response plans involving wildlife participated.
The program addressed itself to fish and wildlife considerations
and the role of regional response teams under the National Oil and
Hazardous Substances Pollution Contingency Plan. The actions of State
wildlife departments, U.S. Fish and Wildlife Service, Environmental
Protection Agency, U.S. Coast Guard, and the oil industry in handling
spills involving wildlife were examined. The latest oil spill cleanup
technology was reviewed, and the workshop ended with demonstrations of
the cleaning of oiled waterfowl. Similar seminars were planned for the
Gulf of Mexico and the West Coast.
It was obvious from this seminar that the most comprehensive
wildlife oil spill contingency plan had been developed by the State
of California. Copies of this plan (Oil and Hazardous Materials
Contingency Plan, California Department of Fish and Game, July 1974)
were later distributed to all coastal States as a prototype or model
plan by API.
The U.S. Fish and Wildlife Service has been conducting experiments on
various bird-cleaning agents and techniques at its Migratory Bird
and Habitat Research Laboratory near Laurel, Maryland. The Fish and
Wildlife Service is also working with the API in developing information
on migratory patterns and winter waterfowl concentration areas on
the East Coast as they relate to petroleum transport traffic and oil
terminals.
In Canada, the Petroleum Association for Conservation of the Canadian
Environment (PACCE) employed the services of a consulting firm to make
a comprehensive review of dispersal and rehabilitation of waterfowl
associated with oil spills. The resulting PACCE report (LGL Ltd. 1974)
codified what was known about the problem, identified research needs,
and developed effective wildlife oil-spill contingency plans for
critical areas on Canada's east and west coasts, the Great Lakes, and
the Arctic.
The Florida Game and Fresh Water Fish Commission has initiated a
program for the rehabilitation and treatment of oiled birds. It is
being organized by veterinarian Harold F. Albers of St. Petersburg.
He is working in cooperation with the Florida Associated Marine
Institutes, the Shell Oil Company, Clean Gulf Associates, and the API.
The Standard Oil Company of California provided a grant to James
Naviaux of Pleasant Hill, California, to develop bird-cleaning
technology, including the testing of various cleaners. Dr. Naviaux
had treated birds from the 1971 San Francisco spill. A publication
on the after-care of oil-covered birds (Naviaux 1972) resulted from
the collaboration with Alan Pittman, research chemist of the U.S.
Department of Agriculture's Western Research Laboratory.
In 1971, the API in cooperation with the National Wildlife Federation
(NWF) initiated an NWF/API Fellowship program. One of the first grants
under this program was to Charles W. Kirkpatrick, Professor of Wildlife
Management at Purdue University. He and assistants studied for 4 years
the nesting ecology and productivity of the emperor goose _(Philacte
canagica)_ in the Igiak Bay area of the Yukon Delta in Alaska
(Eisenhauer and Kirkpatrick 1977).
An extensive program of marine bird research was initiated on the North
Slope of Alaska by the Atlantic Richfield Company in 1969. It has
been continued ever since and includes the acquisition of extensive
base-line data on all waterfowl, including June surveys of breeding
pair counts and August surveys for brood counts. The results of these
surveys for 1969-73 are presented by Gavin (1975).
Base-line data on marine birds of the Gulf of Alaska are currently
being collected and compiled through grants to various universities
and institutions by the American petroleum industry. These data will
constitute elements of a report on the environmental status of the Gulf
of Alaska. Such information is essential prior to development of the
Gulf's offshore petroleum resources.
Marine Mammals
Most sea mammals are relatively resistant to oil slicks and tend to
avoid contaminated waters. As a result, little research has been
conducted on cleaning and treatment techniques except for experiments
on live beavers and on the carcasses and pelts of sea otters and
beavers.
No sea otter or seal has ever been oiled and subsequently cleaned in an
oil spill situation. It is possible, however, that a spill could have
significant adverse effects on sea otters and fur seals, especially at
a rookery during the pupping season. These animals depend on an air
blanket trapped in their dense underfur for warmth and buoyancy. Any
form of pollutant, especially oil, could penetrate the outer guard
hairs and underfur and allow water to reach the skin, with disastrous
effects.
Seals and otters are powerful animals, and the larger males and females
can be quite aggressive and dangerous. Only professional wildlife
specialists and consulting veterinarians should be permitted to handle
and treat them. A guide to cleaning and care of oiled sea otters can be
found in the California Oil and Hazardous Materials Contingency Plan.
Conclusions
This status report has revealed that substantial efforts and progress
have been made in oiled-wildlife research. New techniques being
developed are leading to higher survival rates. Preventive measures
are being devised to keep birds from entering a spill area. Wild life
contingency plans are being developed and materials to handle future
emergencies are being stockpiled. Basic research is being continued on
the difficult problems inherent in achieving high survival levels and a
rapid return to the wild, at a reasonable cost.
Much more must be done, but these pioneering efforts both within and
outside of industry reflect a difficult problem yielding to the time
and attention of dedicated men and women.
References
Advisory Committee on Oil Pollution of the Sea. 1972. Research unit
on the rehabilitation of oiled seabirds. Committee, Dep. Zool.,
Univ. of Newcastle-Upon-Tyne, England, Annu. Rep. 2. 33 pp.
Atkinson-Willes, C. 1963. Wildfowl in Great Britain. Nat. Conserv.
Monogr. 3. 368 pp.
Bergman, G. 1961. The migrating populations of the long-tailed duck
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Bourne, W. R. P. 1970. Special review--after the _Torrey Canyon_
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Clark, R. B. 1969. Oil pollution and the conservation of seabirds.
Proc. Int. Conf. on Oil Pollut. of the Sea 1968:76-112.
Clark, R. B. 1973. Impact of chronic and acute oil pollution of
seabirds. Page 634 _in_ Background papers for a workshop on
inputs, fates and effects of petroleum in the marine environment,
Vol. 11. Ocean Board National Academy of Science, Washington, D.C.
Crummett, J. G. 1973. Bird dispersal techniques for use in oil
spills. Final report. American Petroleum Institute, Washington,
D.C.
Edwards, R. A. 1963. Treatment of washed up penguins. Bokmakierie
15(1):8.
Eisenhauer, D. I., and C. M. Kirkpatrick. 1977. Ecology of the
emperor goose in Alaska. Wildl. Monogr. 57. 62 pp.
Fletcher, A. 1973. Why save oiled birds? University of California,
College of Forestry, Berkeley. 26 pp. (Unpublished report)
Gavin, A. 1975. Wildlife of the North Slope, a five year study,
1969-73. Atlantic Richfield Co., Anchorage, Alaska. 63 pp.
Holmes, M. 1973. Oil and penguins don't mix. Natl. Geogr. Mag.
143(3):384-397.
Holmes, W. N., and J. Cronshaw. 1975. Final progress report on
studies completed, 1972-75, on the effects of petroleum on marine
birds. American Petroleum Institute, Washington, D.C. 77 pp.
(Unpublished report)
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mortalities associated with oil spills. Petroleum Association for
Conservation of the Canadian Environment Rep. 75-4. 50 pp.
Lassen, R. W. 1972. Waterbirds and the San Francisco oil spill.
Proc. Cal-Nev Wildl. 1972:20-24.
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Ottway, S. M. 1971. A review of world oil spillages, 1960-1971. Oil
Pollut. Res. Unit, Orielton Field Centre, Pembroke, Wales.
Parslow, J. L. F. 1967. Changes in status among breeding birds in
Britain and Ireland. Br. Birds 60:2-47, 97-122, 177-202.
Rowan, M. K. 1968. Oiling of marine birds in South Africa. Pages
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the Sea Research Unit on the Rehabilitation of Oiled Seabirds.
Second annual report. Dep. Zool., Univ. of Newcastle-Upon-Tyne,
England. 33 pp.
Smail, John. 1971. The oil spill in retrospect. Point Reyes Bird
Observatory News 18:1-2.
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Stanton, P. B. 1972. Operation rescue. American Petroleum
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oil-pollution on seabirds in Europe. Proc. Int. Conf. on Oil
Pollut. of the Sea. 1968:67-76.
CONSERVATION OF MARINE BIRDS IN OTHER LANDS
Conservation of Marine Birds in New Zealand
by
Gordon R. Williams
New Zealand Wildlife Service
Department of Internal Affairs
Wellington, New Zealand
Abstract
Marine species (pelagic birds and those of
exposed coasts) make up about 48% of New
Zealand's native avifauna, excluding stragglers
and antarctic species. The biological history
that has led to the present status of marine
birds in this archipelago of some 700 islands
is outlined, methods of conservation are
briefly described, and some illustrative case
histories of management programs are given. In
spite of the major environmental changes that
have occurred in New Zealand during 200 years
of European occupation, only one marine species
has become extinct, although five such endemic
species are currently regarded as threatened
as are a few subspecies of widely distributed
forms.
New Zealand, which lies some 2,000 km southeast of Australia, has
been a changing archipelago for many millions of years. It has been
separated from any major landmass (first, Gondwanaland and later,
Australia) for at least 80 million years.
Before the arrival of man, probably between 1,000 and 1,500 years ago,
New Zealand was free of any land mammals except two species of bats,
and there were few avian predators. These, among a number of other
biological peculiarities, reflect the archipelago's considerable and
long-standing isolation.
There are nearly 700 islands 0.5 ha or more in area in the New Zealand
region; and, if North, South, and Stewart islands are regarded
collectively as the mainland, about 650 of these islands lie within
50 km of the coast and 30 beyond that limit, to about 850 km offshore
(Atkinson and Bell 1973). The archipelago extends from about 30° to
52°S lat. (over a distance of about 2,400 km)--that is, from the
subtropical to the subAntarctic--and from about 166° to 176°W long.
(Fig. 1).
Pelagic and coastal birds must obviously be an important part of the
avifauna and, in fact, aside from stragglers, antarctic species, and
established introduced species, they make up about 48% of the 173 in
the New Zealand Checklist (Kinsky 1970). Of the 83 species I have
regarded as marine, 48 (28%) are pelagic and 35 (20%) shorebirds of
exposed coasts. Ten of the 48 pelagics (21%) and 12 (34%) of the 35
shorebirds are endemic.
More than a thousand years of occupation by Polynesian man with his
commensal Polynesian rats _(Rattus exulans)_ and a peculiar breed
of domesticated and feral dog (now extinct), did little damage to
pelagic and open coast species, even though many, if not most, were
used as food--especially the petrels, and particularly those belonging
to the genera _Puffinus_, _Procellaria_, and _Pterodroma_. However,
the Europeans, who arrived about 200 years ago, brought with them a
menagerie of mammals and birds, and 33 species of each have become
established and are now feral (Gibb and Flux 1973; Williams 1973). They
also put into practice, on a large scale, European methods of land use
that had unfortunate effects on almost the entire native avifauna.
Although terrestrial, freshwater, and estuarine species suffered most,
marine species suffered also. However, reduction in numbers and range
rather than extinction was the rule, except locally.
Apart from habitat destruction by man and the various mammalian
browsers and grazers, the most inimical agents have been black rats
_(Rattus rattus)_, Norway rats _(R. norvegicus)_, feral cats, and feral
pigs. One would expect the inhospitality or inaccessibility of an
island to be a marine species' best protection, and so it has generally
proved-the greatest losses have occurred on the two major mainland
islands (North Island and South Island). Bourne (1967) suggested that
Polynesians in pre-European times may have caused the extinction of
numerous petrels in the Chatham Islands. There are still a few islands
on which no exotic mammals occur, but modern transport, allied with
human curiosity and cupidity, are stripping all but the most wild and
remote of these of the protection against invasion they have had so
far. Cruises by nature-hungry but sometimes environmentally illiterate
tourists are beginning to be a local problem.
[Illustration: Fig. 1. New Zealand and its main offshore and outlying
islands (from Atkinson and Bell 1973).]
The matter of conservation of marine species in New Zealand has
stemmed mainly from the recognition of the value of certain islands as
refuges for whole ecosystems, as convenient areas for study, and as
arks for the rescue of the threatened species that can be successfully
established on them--an often highly hazardous and uncomfortable
procedure for men as well as birds.
Conservation Measures
By statute, all feral species of birds in New Zealand are automatically
protected unless specifically legislated for otherwise. (About
50 of our grand total of 285 species have been so legislated
for.) One fortunate consequence of this provision is that all new
arrivals--vagrants or new discoveries--are also fully protected. The
legislation also states that it is illegal to have in one's possession
the nests, eggs, feathers, skins, or bones of any fully protected
species unless one has been issued a permit for this purpose. This
restriction may apply to institutions as well as to persons.
After this good start and the setting aside of conservation reserves of
various kinds, active conservation measures depend on making careful
and comprehensive surveys of the species and its ecosystem--often none
too easy a task in the New Zealand region because of the rough seas,
the relative inaccessibility of many of the important islands and their
ruggedness, and the near-impenetrability of some of the vegetation
types they support. Having decided that positive action is necessary,
the next step is to use all available media to inform the public (local
as well as national, if the island is inhabited) of the situation and
the proposals for remedying it. As in most other countries, uninformed
emotionalism is one of the most pervasive and serious obstacles to
effective conservation because of the political pressure it can
generate.
Apart from formal ecological studies, the New Zealand Wildlife Service
uses three main methods to support threatened species (other than the
attempts we are making to breed certain freshwater and terrestrial
species in captivity):
• The translocation and founding of new colonies in promising or
unmodified habitat. Such habitats are not common in New Zealand because
of the ubiquity of the introduced mammalian browsers, grazers, and
predators (Williams 1977).
• The destruction, or at least the reduction, of such browsers,
grazers, and predators by physical, chemical, or biological methods, or
combinations of these.
• The exertion of social influences to promote changes in methods
of land use or in traditional harvest for food (the latter can be
particularly important as far as the Polynesian [Maori] population is
concerned, as nowadays the taking of birds for food is predominantly a
cultural rather than an economic matter).
Translocation has been a valuable technique for increasing the numbers
and ranges of a few threatened terrestrial species. The very nature of
most marine species, however, limits its application as far as they
are concerned. Nevertheless, we have considered it worth trying for
one nonmigrant wader; and no doubt it could be tried under similar
circumstances elsewhere.
Convincing local experiences have shown that predator or competitor
destruction is likely to be practical only on small, not-too-rugged
islands, usually no larger than about 500 ha. However, special
circumstances have prompted us to attempt destruction, or at least
control, on much larger and more difficult islands. It is implicit that
the predators or competitors are exotic, not indigenous. Recently, on
those rare islands that are inhabited but still free of either black
or Norway rats, we have set up permanent bait stations (at which
sodium fluoroacetate--"1080"--is used as the poison) on wharves and
jetties in the hope that such a precaution will, with the addition of
a propaganda campaign calling for the regular fumigation of visiting
vessels, prolong the charmed lives that these fortunate islands have so
far enjoyed. It goes without saying that we ask that the greatest care
be taken when expeditions land stores on uninhabited, rat-free islands
which, if by "rat-free" we mean also free of _R. exulans_, are even
rarer in our seas.
The sociolegal approach is effective only when ecosystems or
communities have not been seriously modified, otherwise it is no
substitute for either of the other two measures discussed.
Some Case Histories
Translocation
Last century, an endemic monotypic genus of wader--the New Zealand
shore plover _(Thinornis novaeseelandiae)_--was widespread and
occasionally very common around the coasts of the North and South
islands and the Chatham Islands. As a result of European settlement
and the accompanying predation by feral cats and rats, the species now
occurs only on South East Island in the Chatham group (860 km east of
the mainland), where it at present seems safe, since there are no rats
on the island and it is now a reserve. However, the population numbers
only about 120 individuals. Because calamities can always occur (for
example, ship rats recently reached shore on three important islets off
the southwest coast of Stewart Island), the Wildlife Service is anxious
to spread the shore plover to other suitable islands, if they can be
found. The species is not a migrant and is rather sedentary. The first
translocation attempts failed, probably because mainly adult birds were
used, and we are now continuing our studies of the species with the
thought in mind, among others, that success may come if young birds are
used instead; the question is--how young?
As is widely known, the New Zealand Wildlife Service has been
remarkably successful in recent years in translocating one species
of the endemic wattlebird family--the forest-dwelling saddleback
_(Philesturnus carunculatus)_--to other islands than the four small
ones it had been reduced to by the early 1960's; three of these islands
were the ones recently invaded by ship rats, referred to above.
Predator Control
Some 25 km off the North Island's east coast lies the 3,000-ha, very
rugged and forested Little Barrier Island, which has now been a reserve
for the protection of flora and fauna for about 80 years. Before that,
it had been almost continually occupied by Maoris since their arrival
in New Zealand, and about one-third of its forest was felled or burnt,
especially after European settlement of the adjoining New Zealand
mainland began.
Most unusually, Little Barrier is now free of any grazing or browsing
mammals, and has only the Polynesian rat (a reminder of the Maori
occupation) and feral cats (a European legacy) to impair its extreme
importance as a reserve. The rats have been unmolested by man because,
rightly or wrongly, they are considered ineffective predators
generally; however, their impact has probably been under-rated. More
than half a century of trapping and hunting of cats by successive
caretakers on the island has not effectively reduced that population.
Among its other important attributes, Little Barrier supports two
birds endemic to New Zealand--the rare black petrel _(Procellaria
parkinsoni)_, and one endemic honey-eater, the stitchbird _(Notiomystis
cincta)_, which was once widespread on the North Island but is now
found only on Little Barrier in moderate numbers, and apparently in
no immediate danger. The impact of feral cats on stitchbirds has not
been determined, but it is known that cats are seriously affecting the
black petrel especially: they kill at least 90% of the chicks and some
adults annually. Their impact on a locally remnant population of Cook's
petrels _(P. cookii)_ is apparently less severe.
In 1968-69 the Wildlife Service, with veterinary advice and assistance,
added an attempt at biological control to the campaign of poisoning
("1080" in fish was the poison and bait used), trapping, and shooting.
The very specific viral disease--feline enteritis--was introduced by
trapping island cats, infecting them, and then releasing them. Some
estimates of the resulting mortality from the combined techniques were
as high as 90%; but there has been a recovery since, and the campaign
is expensive in both time and man-power. And, oddly enough, the control
effort has met with some opposition. Nevertheless, another campaign is
planned.
Habitat Rehabilitation by Destruction of Mammals
The Kermadecs are a group of small islands about 800 km north-northeast
of the North Island. Their biological significance, insofar as this
symposium is concerned, is that they are the southernmost breeding
area in New Zealand seas for many elements of the Pacific tropic and
subtropical marine avifauna. Unfortunately, goats were liberated on the
two largest islands--Raoul (3,000 ha) and Macauley (300 ha)--almost
150 years ago and Macauley Island was burnt over; such forest cover as
it had was severely damaged or destroyed, probably at about the same
time. The goats were to be an emergency food supply for whalers and
shipwrecked mariners. Cats, too, became feral on Raoul Island during
one of its fitful periods of occupation. The New Zealand Wildlife
Service, in spite of the distance and difficulties involved, has
undertaken pest destruction campaigns on both islands, but I offer here
only an account of the simpler, and more successful, Macauley operation.
In 1966, a 5-week expedition to this waterless and almost treeless
island resulted in the shooting of what was then thought to be all
of its 3,000-odd goats (a density of about 15/ha). Four years later,
a follow-up expedition found and destroyed another 17 goats (a later
brief inspection suggested that these were indeed the last), and
rehabilitation of the island is well under way. Now that the short turf
is disappearing, erosion of the soft volcanic soils is reduced. With
compaction no longer occurring, it will be interesting to see what the
effect will be on birds breeding on the island--six breeding species of
petrels, three breeding species of terns, and other marine species.
Sociolegal Conservation
The taking of petrels and other procellariiform birds for food has
always been part of the Polynesian economy and culture throughout the
Pacific. In New Zealand, the practice now has only minor economic
importance, but it is still an essential part of Maori culture and
tradition. The most commonly taken species are the sooty shearwater
_(Puffinus griseus)_ and, until recently, the gray-faced petrel
_(Pterodroma macroptera)_. Although no formal study of the impact of
the annual harvest of chicks on the population has yet been made, all
the indications are that it is not significant. Nevertheless, the
Maoris willingly accepted the limited amount of legislation that has
been passed to afford the two principal exploited species at least
token protection. However, on the Chatham Islands, where there is a
strong tradition of taking some of the albatrosses, this tradition has
persisted, even though all albatrosses are fully protected throughout
New Zealand.
Enforcement of legislation in small and isolated communities is not
always easy and sometimes may not be wholly politic. However, the
Maoris of the Chathams have been specially informed of the conservation
issues at stake, and a "gentleman's agreement" has been reached: If
a planned survey shows that full protection of albatrosses in the
Chathams is indeed essential, the Maoris will honor the legislation to
the letter; on the other hand, if limited exploitation seems justified,
the Wildlife Service has agreed that it will be allowed.
Conclusions
Insofar as conservation measures of a passive type are concerned, it
is fortunate that the offshore and outlying islands not yet occupied,
farmed, or set aside as reserves, are likely to remain unexploited,
either because they are too remote for exploitation to be economical
or because they are too inhospitable, or both. In any event, public
opinion is now such that unmodified or otherwise biologically important
islands not already reserved would be proclaimed as reserves if threat
of exploitation arose unexpectedly, unless they were found to be major
sites for oil or minerals. Even so, legislation exists that offers the
possibility of protection even from this threat, and has already been
used to exempt some important mainland areas from prospecting and the
granting of mining rights.
It is gratifying to realize that, although some endemic marine
subspecies (generally not very different from neighboring subspecies)
are endangered to varying degrees, there are very few whose
disappearance would result in the disappearance of the species itself
from the New Zealand area. Only one endemic marine species has become
extinct in recent times, the Auckland Island merganser _(Mergus
australis)_ in about 1905, and only six are currently in any real
danger: the Chatham Island taiko _(Pterodroma magentae)_, the black
petrel, Hutton's shearwater _(Puffinus huttoni)_, the Westland black
petrel (_Procellaria westlandica)_, the shore plover, and the Chatham
Island oystercatcher _(Haematopus chathamensis)_. However, a list
of this kind is often a matter of some controversy. Something is at
present being done to help all but the first and last of these. The
Chatham Island taiko had not been positively identified for about 50
years, until 1977 when this species was "rediscovered" on the main
island of the Chatham group; though its numerical status is unknown,
it is rare. The Chatham Island oystercatcher, although certainly
"threatened" (only about 50 are known to exist), does occur on four
islands, two of which are reserves. Although this species has not been
actively studied until now, it is soon to be the subject of a full
ecological survey.
A few words about the hunting of marine species: Mutton-birding
aside--that is, apart from the taking by Maoris of the young of the
sooty shearwater and the gray-faced petrel--there has been no legal
hunting of any marine birds in New Zealand for 35 years now, nor is
there likely to be. This situation reflects the consistently increasing
weight of informed public opinion in favor of, let alone scientific
concern for, transoceanic migrants. The pro-hunting lobby for some
species of waders, in particular the eastern bar-tailed godwit _(Limosa
lapponica baueri)_, is a small one, the numbers of which decrease
yearly. However, small-scale poaching occasionally occurs; it is
punished when discovered.
Protection for marine species extends only to the 3-mile limit of New
Zealand's territorial waters, but it would be extended further should
New Zealand follow the present trend of including as territorial waters
all those that cover the continental shelf or beyond. [This extension
occurred in 1977; the marine fishing zone for New Zealand waters has
been extended to 200 miles (360 km) around all coasts.]
Only three marine species are not afforded full protection under
the Wildlife Act: two, the black-backed or Dominican gull _(Larus
dominicanus)_ and the black shag _(Phalacrocorax carbo)_, are
totally unprotected--the first because of its predation on some rare
shorebirds during the breeding season and for its attacks on sheep and
lambs at a similar time, and the second because of its depredations
(seldom serious) on the introduced trout and salmon, mainly in fresh
waters--the third species, the southern skua _(Stercorarius skua
lonnbergi)_, may be destroyed only when it is actually attacking
sheep or lambs, an occasional event confined to the Chatham Islands.
Destruction of these three common species is not encouraged by the
Wildlife Service except when black-backed gulls become too active among
colonies of, say, the fairy tern _(Sterna nereis)_, which is very rare
in New Zealand but not elsewhere in its range. Otherwise, control
of the species is left in the hands of those most affected by their
depredations but whose judgment is usually reasonable.
Marine birds, therefore, are generally satisfactorily protected by
law or managed for conservation in New Zealand--especially when one
considers the remarkable changes that have occurred in the New Zealand
archipelago over the last 200 years. Although the situation could be
better, it would certainly have been worse if the Wildlife Service (and
other conservation organizations) had not been untiring in keeping the
general public and the legislature aware of the issues at stake and
seen to it that as much as possible of the necessary conservation work
was done--and done before it was too late.
Acknowledgments
I thank my Wildlife Service colleagues, B. D. Bell, M. J. Imber, D. V.
Merton, and C. J. R. Robertson, for valuable comments and advice on the
preparation of this paper.
References
Atkinson, I. A. E., and B. D. Bell. 1973. Offshore and outlying
islands. Pages 372-392 _in_ G. R. Williams, ed. The natural
history of New Zealand. A. H. & A. W. Reed, Wellington.
Bourne, W. R. P. 1967. Subfossil petrel bones from the Chatham
Islands. Ibis 109:1-7.
Kinsky, F. C. 1970. Annotated checklist of the birds of New
Zealand. A. H. & A. W. Reed, Wellington.
Gibb, J. A., and J. E. C. Flux. 1973. Mammals. Pages 334-371 _in_
G. R. Williams, ed. The natural history of New Zealand. A. H. &
A. W. Reed, Wellington.
Williams, G. R. 1973. Birds. Pages 304-333 _in_ G. R. Williams,
ed. The natural history of New Zealand. A. H. & A. W. Reed,
Wellington.
Williams, G. R. 1977. Marooning--a technique for saving threatened
species from extinction. Int. Zoo Yearb. 17:102-106.
Marine Birds in the Danish Monarchy and Their Conservation
by
Finn Salomonsen
Chief Curator of Birds
The Zoological Museum
University of Copenhagen
Copenhagen, Denmark
Abstract
Most species of seabirds that regularly breed
in Denmark are declining, for a variety of
reasons: shooting; oil pollution; toxic
chemicals; reclamation of land; collecting
of eggs; disturbance at breeding sites
by visitors, motorboats, camping, etc.;
destruction by predators; and others. On the
other hand, the numbers of certain other
species are increasing as a result of climatic
changes (six species), protection (three
species), and increase in food supply (three
species of gulls). In addition to breeding
birds, a total of about 3 million birds occur
in Danish waters as passage migrants or winter
visitors. More than half of the European winter
populations of a number of marine waterfowl
species winter in Denmark. Large numbers of
seabirds spend the summer in Danish waters,
including several hundred thousand immature
gulls and just as many molting waterfowl.
The seabird fauna of the Faroe Islands is
very rich, the immense number of birds
being attracted by the local abundance
of macroplankton and fish. The seabirds
are harvested by man, formerly by fowling
(capturing and shooting), now primarily by
shooting. Until about 1910, more than 400,000
birds were taken annually by fowling. The
Faroese game act is now very restrictive, and
most seabird populations appear to be almost
stable. However, a census in 1972 indicated
that common murres _(Uria aalge)_ have declined
by about 20% to a population of about 600,000.
Shooting and snaring appear to be the primary
causes of the decline; oil pollution and toxic
chemicals do not seem to be contributing to the
population decrease.
In Greenland seabirds provide an important
source of human food; however, because of the
increase in human population and in the use
of guns and speedboats for hunting, and the
absence of a game act, serious overshooting
of seabirds is taking place. A new game act
passed in 1977 should largely alleviate
this overharvest. Oil pollution and toxic
chemicals do not yet play an important part
in influencing the number of seabirds, though
offshore oil drilling is being initiated in
West Greenland. A recently established gigantic
national park, covering 200,000 km² of ice-free
land, is the largest nature reserve in the
world.
The Danish Monarchy consists of three parts far removed from each
other, scattered in the North Atlantic--namely Denmark proper, the
Faroe Islands, and Greenland. They differ so much from each other in
climate and in bird life that they must be treated separately in this
paper. The Faroes possess a provincial government and also a sort
of home rule. Greenland also has a provincial government, but all
statutory provisions, including acts concerning hunting or wildlife
protection, must be passed by Danish authorities, usually by the
Ministry of Greenland.
Insofar as seabirds are concerned, it is important that Greenland is
an arctic country, whereas the Faroes and Denmark are boreal. In both
Greenland and the Faroes the breeding birds are most significant, from
an ecological point of view, whereas in Denmark the passage migrants
and winter visitors are far more important.
There are other differences as well. In Greenland and the Faroes the
seabirds mostly breed in colonies on high and steep cliffs, and the
structure of these breeding places is not disturbed by man. In Denmark,
on the other hand, the seabirds usually breed on glacial deposits, now
forming meadows, low islets, salt marshes, etc., and these habitats
have unfortunately been largely changed in the last hundred years by
draining and reclamation. This practice has taken place in Denmark on a
much larger scale than in most other countries and has, therefore, to a
high degree diminished the life conditions of seabirds.
Seabirds in Denmark
Denmark is situated on the continental shelf of western Europe; all
seas surrounding the country are shallow (less than 100 m deep), apart
from the Skagerrak, north of Jutland, which is much deeper. The shallow
depth, combined with the rapid flow of water between the Baltic and the
North seas causes much upwelling, which forms excellent life conditions
for plants and animals. It is well known that the fishery in Danish
waters, especially in the North Sea, is very rich. This richness of the
seas provides suitable conditions for a high diversity of seabirds and
ecological types.
Seabirds regularly breeding in Denmark include five species of terns
(common tern, _Sterna hirundo_; arctic tern, _S. paradisaea_; least
tern, _S. albifrons_; Sandwich tern, _S. sandvicensis_; and gull-billed
tern, _Gelochelidon nilota_); seven species of gulls (black-headed
gull, _Larus ridibundus_; herring gull, _L. argentatus_; lesser
black-backed gull, _L. fuscus_; great black-backed gull, _L. marinus_;
mew gull, _L. canus_; little gull, _L. minutus_; and black-legged
kittiwake, _Rissa tridactyla_); four species of geese, swans, and
ducks (mute swan, _Cygnus olor_; greylag goose, _Anser anser_; common
eider, _Somateria mollissima_; common merganser, _Mergus merganser_;
and red-breasted merganser, _M. serrator_); three species of auks
(black guillemot, _Cepphus grylle_; common murre, _Uria aalge_;
and razorbill, _Alca torda_); and one species of cormorant (great
cormorant, _Phalacrocorax carbo_). Shorebirds have not been included
in this review. Some of the species mentioned are partly freshwater
birds--for example, the black-headed gull, little gull, mute swan,
greylag goose, and the two species of mergansers. The gull-billed tern
forages in terrestrial habitats, but nests along the coast with the
other seabirds. It is often difficult, therefore, to make a clear-cut
distinction between seabirds and freshwater birds.
Among the auks, the black guillemot breeds in the Cattegat area in the
huge heaps of boulders on small raised islets, or in holes (mostly
formed by starlings, _Sturnus vulgaris_) on steep clayey slopes or
promontories. The common murre and razorbill are restricted to the
islet Graesholm in the Christiansø Archipelago, about 24 km east of
Bornholm Island in the Baltic, where they breed on small cliffs of
Precambrian granite rock.
The estimated number of seabirds of different species that breed
in Denmark is shown in Table 1. Species like the mergansers, mute
swan, and greylag goose, which breed partly or mostly in freshwater
localities, are not included. Overall, the number of breeding seabirds
is slowly declining, probably due to many factors which are discussed
below. There are two exceptions, however, to this general decrease--the
herring gull (and to a lesser degree the other big gull species) and
common eider. Both species have increased during the last 50 years.
Since they breed in the same habitat, usually mixed together, the
eider is probably dependent on herring gulls for protection against
predators. When the ducklings are fledged, the herring gull acts as
a successful predator itself, but the eider nevertheless maintains a
close association with herring gulls.
Table 1. _Estimated average number of breeding pairs of seabirds
in Denmark, based on a census in 1970-72._ (Data for terns from
Mardal 1974, and for other species from Sten Asbirk and N. O.
Preuss, personal communications.)
Number of
breeding
Species pairs
_Sterna paradisaea_ 5,750
_S. hirundo_ 900
_S. sandvicensis_ 4,000
_S. albifrons_ 600
_Gelochelidon nilotica_ 105
_Larus marinus_ 300
_L. argentatus_ 60,000
_L. fuscus_ 2,000
_L. canus_ 28,500
_L. ridibundus_ 135,000
_L. minutus_ 25
_Rissa tridactyla_ 125
_Phalacrocorax carbo_ 600
_Somateria mollissima_ 3,800
_Cepphus grylle_ 325
_Alca torda_ 400
_Uria aalge_ 1,100
Total 243,530
More than 90% of the herring gull population breeds on small islands,
and a large proportion occurs in a few large colonies. It never breeds
in freshwater localities, but is exclusively found as a breeding
bird in coastal habitats. The population has particularly increased
in the last 5 decades, some colonies reaching their maximum size in
the 1960's. Others are still expanding and occupying new breeding
grounds. Today the largest colonies are found on the following islands:
Saltholm, 20,000-40,000 pairs; Christiansø 9,000 pairs; Hirsholmene,
2,500 pairs; Jordsand, 1,800 pairs; Samsø, 2,000 pairs; Hjelm, 1,500
pairs; and the archipelago south of Funen, a total of 3,500 pairs in
several colonies.
Attempts have been made to reduce the breeding population of herring
gulls at Hirsholmene and Christiansø sanctuaries (in 1973 and 1974,
respectively), to improve conditions for other nesting seabirds. In
1969 the Bird Strike Committee of the Royal Danish Airforce also
initiated a program to reduce the number of herring gulls breeding
on Saltholm Island, which is near the Kastrup airport in Copenhagen.
Nests were sprayed with a formaldehyde oil dye, which resulted in a
33% reduction in population. In Christiansø and Hirsholmene, where the
adult breeding birds were poisoned, the effect is not yet known.
The total number of seabirds occurring in the Danish waters as
passage migrants and winter visitors is substantially larger than the
breeding population, because Denmark is situated on a very important
fall migration route for seabirds from Scandinavia, the Baltic
countries, northern Russia, and northwestern Siberia. Furthermore, the
shallow waters of the Danish seas (less than 10 m deep) that occupy
extensive regions bordering the coasts are important feeding grounds
for diving ducks. Birds frequenting the seas outside the breeding
season include hundreds of thousands, or probably millions, of gulls;
numerous ducks (especially diving ducks); swans and brants, _Branta
bernicla_; jaegers, _Stercorarius_ spp. (four species); loons, _Gavia_
spp. (four species); grebes, _Podiceps_ spp. (four or five species);
gannet, _Morus bassanus_; great cormorant; northern fulmar, _Fulmarus
glacialis_; common murre; razorbill; and other species of alcids.
To these should be added a number of species of various seabirds,
especially gulls, tubenoses, phalaropes, and others which appear as
casual or accidental visitors and which are not further mentioned in
this paper.
Table 2. _Total numbers of ducks, swans, and coots recorded in
Denmark during a winter census in January 1973 (based on ground
counts and aerial surveys), compared with estimated flyway
populations wintering in western Europe and annual bird harvest
in Denmark (after Joensen 1974:23, 155, 168)._
Estimated winter Average
Census, populations of the annual bag
Species January 1973 Western Europe Flyway in Denmark
_Anas platyrhynchos_ 127,000 1,550,000 380,000
_A. crecca_ 500 260,000 76,000
_A. querquedula_ 11 [67] [68]
_A. acuta_ 100 70,000 13,000
_A. strepera_ 5 [67] [69]
_A. penelope_ 3,000 485,000 44,000
_A. clypeata_ 17 63,000 9,000
_Tadorna tadorna_ 13,000 105,000 [69]
_Aythya ferina_ 7,100 235,000 5,000
_A. fuligula_ 94,700 530,000 35,000
_A. marila_ 80,900 145,000 8,000
_Clangula hyemalis_ 11,000 [67] 11,000
_Melanitta nigra_ 148,100 [67] 18,000
_M. fusca_ 6,700 [67] 9,000
_Somateria mollissima_ 450,800 [67] 136,000
_Bucephala clangula_ 67,000 142,000 25,000
_Mergus serrator_ 11,700 40,000 8,000
_M. merganser_ 23,200 75,000 6,000
_M. albellus_ 206 5,000 [69]
_Cygnus olor_ 48,900 120,000 [69]
_C. cygnus_ 5,700 17,000 [69]
_C. bewickii_ 1,113 6,000 [69]
_Fulica atra_ 142,500 [67] 70,000
Totals 1,243,252 3,848,000 853,000
A comprehensive investigation of the nonbreeding waterfowl in Danish
waters was recently undertaken by the Game Biology Station Kalø
(Joensen 1974). Aerial surveys of marine ducks indicate that a large
percentage of the ducks that winter in European waters do so in the
shallow areas of the Danish seas. A census in January 1973 indicated
a total of more than 1.2 million birds (Table 2). In a number of
other countrywide surveys, undertaken in all winters since 1967,
usually 1.0-1.5 million birds have been recorded. Since such censuses
usually give minimum numbers, and certain species-especially marine
ducks--generally go unrecorded, the normal winter population (November
to February) of ducks, swans, and coots in Danish waters can scarcely
be less than 2 million birds (Joensen 1974:156). In Table 2, bird
numbers in Denmark are compared with the estimated winter populations
in western Europe, based on the investigation of Atkinson-Willes
(1972). When all the winter censuses in Denmark are compared with
those for Europe, as was done by Joensen (1974:156), it is evident
that Danish waters support about half of all greater scaup _(Aythya
marila)_, common goldeneye _(Bucephala clangula)_, red-breasted
merganser, mute, whooper _(Cygnus cygnus)_, and tundra swans _(C.
bewickii)_ wintering in Europe; about one-third of the population of
tufted duck _(Aythya fuligula)_ and common merganser; and probably also
one-third of the population of common eider and coot _(Fulica atra)_.
The wintering population of common eider is very large. According to
banding records it makes up the greater part of Baltic breeding birds;
however, it is not possible to calculate its percentage contribution
to the total European winter population since its size is unknown in
most European countries. Although most of the surface-feeding ducks
disappear from Denmark waters in winter, extremely large numbers occur
there during the fall migration period. For example, it has been
estimated that for species like common teal _(Anas crecca)_ and wigeon
_(A. penelope)_ about one-third of the West European Flyway population
passes Denmark in the fall. Possibly some of the surface-feeding ducks
listed in Table 2 for January 1973 were recorded in fresh water and not
from the seas, but at the time the census was taken most freshwater
lakes were frozen and, therefore, unavailable for water birds.
These breeding seabirds and the off-season visitors do not constitute
the total population in Danish waters. Large numbers also occur in
summer as nonbreeding birds; most are in two categories: (1) several
hundred thousand pre-adult (up to 4-5 years of age) gulls (mostly great
black-backed, herring, and lesser black-backed gulls), which feed
inshore or at the coast, and (2) large concentrations of waterfowl that
carry out a molt migration in Danish waters, particularly in shallow
areas. Black scoter _(Melanitta nigra)_, velvet scoter _(M. fusca)_,
common eider, and whooper swan are especially numerous, totaling
hundreds of thousands of individuals, and probably constituting the
majority of the European molting populations of these species. Less
numerous, but still totaling thousands of molting birds, are sheld-duck
_(Tadorna tadorna)_, common goldeneye, red-breasted merganser, and
possibly some other diving ducks. About 3,000 surface-feeding ducks of
various species, most of which undoubtedly are local breeding birds
undergo wing molt in Danish waters. Comprehensive descriptions of the
molt migration, particularly in Denmark, were published by Salomonsen
(1968) and Joensen (1973_a_, 1974).
It may then be concluded that very large numbers of seabirds are found
in Danish waters in all periods of the year; most feed in the inshore
zone and some offshore, but none in the pelagic zone.
_Increase of Seabirds_
Seabirds are affected by several factors related to human activities,
most of which pose a threat to them and will eventually reduce their
numbers. Some factors, however, tend to increase bird numbers, like
climatic changes which, as reported by Salomonsen (1963), have given
rise to the immigration to Denmark of great cormorant (in 1938); eared
grebe, _Podiceps nigricollis_ (about 1870); red-crested pochard, _Netta
rufina_ (1940); common pochard, _Aythya ferina_ (about 1860); tufted
duck (about 1900); and common murre (1929). They all still breed in
Denmark, having more or less increased in number.
Another reason for increases of certain species is legal protection.
Among protected seabirds are the sheld-duck, which has been completely
protected since 1931, and particularly the mute swan, of which only 2
or 3 pairs were breeding in Denmark when the species was completely
protected in 1926. Since then, mute swans have increased enormously,
reaching at least 2,740 pairs in 1966 (Bloch 1971:43), of which large
numbers were breeding colonially on small islets of boulders or on sand
reefs off the coast (Bloch 1970:152). The gannet has also increased
considerably as a fall visitor since about 1945, apparently due to
protection in England and other countries.
Finally, some gull populations have increased in size because of an
increase in the food supply, consisting especially of wastes from
commercial fisheries and garbage dumps. In Denmark, this unnatural food
source has caused an enormous increase since about 1925 in herring
gulls (from less than 500 pairs to 60,000 pairs), lesser black-backed
gulls (all three subspecies, _fuscus_, _intermedius_, and _graelsii_
have immigrated to Denmark), and great black-backed gulls (immigrated
to Denmark in 1930). Improved waste disposal practices in recent years
have not yet offset the rate of growth of these gull populations.
The increase of common eiders, which also started in about 1925, is
probably related to the increases in the larger gulls.
_Decrease of Seabirds_
A variety of factors tend to reduce the numbers of seabirds. The most
important ones are outlined below, with comments on what has been done
or what is expected to be done to reduce the impact of these activities
on seabirds and protect this endangered resource.
Shooting of Seabirds
The shooting of seabirds in Denmark is considerable, because the
seabirds are extraordinarily numerous, and the number of sportsmen is
very large, amounting to about 135,000 (a larger number per capita than
in any other country).
The Danish game statistics are excellent--well known to be much more
accurate than in most other countries (see Salomonsen 1954; Strandgaard
1964). According to Danish bag records, almost one million ducks,
geese, and coots (Joensen 1974:31) and about 100,000-200,000 gulls
(Salomonsen 1954:125) are shot each year. The average annual bag of
each species of wildfowl is given in Table 2 and the open season for
each species of seabirds in Table 3. The open season for dabbling ducks
is long, extending from 16 August to 31 December, which means that
local birds are persecuted almost as soon as birds-of-the-year are able
to fly. This has resulted in a dabbling duck breeding population that
is much smaller than what the available food supply could support, and
in the large-scale development of artificial rearing of mallards for
later shooting. A 5-month hunting season on specialized birds like
loons, grebes, and various auks is not good management practice and
should be carefully reviewed.
Four other important facts about the shooting of seabirds in Denmark
merit inclusion here: (1) there is no bag-limit for any species; (2)
in general, all marine areas within territorial limits are open to
all Danish sportsmen, and the admission is free; (3) motorboats with
a maximum speed of 10 knots are allowed for shooting in the period 1
October-30 April; and (4) the shooting of seabirds is permissible from
1.5 h before sunrise to 1.5 h (in December 1 h) after sunset, whereas
for most other birds shooting is prohibited between sunset and sunrise.
Shooting is a national tradition in Denmark, and the large number of
sportsmen has considerable political power. Too much influence is given
to the representatives of the hunters' organizations, which have the
decisive force in game committees dealing with protective measures. It
is difficult, therefore, to change the existing system.
Table 3. _Open hunting seasons for seabirds in Denmark, according
to the Game Act of 1967. Species not given in the table are fully
protected._
Hunting period and species
1 August-31 December
_Anser anser_
_A. fabalis_
_A. brachyrhynchus_
_A. albifrons_
_Branta bernicla_[70]
_B. canadensis_
1 August-30 April
_Phalacrocorax carbo_
16 August-31 December
_Anas platyrhynchos_
_A. crecca_
_A. querquedula_
_A. acuta_
_A. penelope_
_A. clypeata_
16 August-29 February
_Aythya ferina_
_Fulica atra_
_Larus ridibundus_
_L. canus_
16 August-30 April
_L. fuscus_
_L. argentatus_
_L. marinus_
1 October-29 February
_Aythya fuligula_
_A. marila_
_Clangula hyemalis_
_Melanitta nigra_
_M. fusca_
_Somateria mollissima_
_Bucephala clangula_
_Mergus serrator_
_M. merganser_
_Gavia stellata_
_G. arctica_
_G. immer_
_Podiceps cristatus_
_Uria aalge_
_U. lomvia_
_Alca torda_
Shooting of seabirds, especially various waterfowl, is popular and
intensive. The number of ducks taken by Danish sportsmen is probably
in the order of 10-15% of the total kill on the West European Flyway
(Joensen 1974:171). Excessive duck shooting can, in some cases, be
controlled by banding in the breeding areas; the ensuing results then
give rise to strong protests from the Scandinavian countries against
the extensive persecution. As stated above, Denmark has (in relation to
its size) the largest number of sportsmen of any nation in the world
and the most intensive shooting. The number of sportsmen shooting
ducks and shorebirds per 100 km² is 278 in Denmark, 28 in Sweden, 37
in Finland, 10 in Poland, 83 in Holland, 164 in Britain, and 129 in
Western Germany; the number of ducks shot per 100 km² is 1,856 in
Denmark, 39 in Sweden, 68 in Finland, and 129 in Western Germany (Nowak
1973). This shooting is undoubtedly of importance to dabbling duck
populations, which are popular as shooting objects everywhere in Europe.
Insofar as marine ducks are concerned, it can be seen in Table 2 that
appreciable numbers are shot in Denmark. The same is true for other
Scandinavian countries, whereas shooting on the high seas is rather
modest in most other European countries. The Danish bag undoubtedly
makes up a significant proportion of the total number of marine ducks
killed each year, but when the total number of ducks in European waters
is considered, the shooting pressure in Denmark appears to be of only
minor importance. However, the shooting, particularly when undertaken
from motorboats, is so noisy and makes such a disturbance over large
areas that the time for seabirds to rest and forage is significantly
reduced. It must also be noted that the number of pleasure craft is
steadily increasing in the present period of prosperity, and that
increasing numbers of sportsmen will probably make use of the free
shooting in territorial waters, since it is becoming more and more
expensive to lease hunting areas.
To restrict seabird shooting, the Danish Ornithological Society has
recently (1975) submitted a proposal to the Danish Government, of which
the following points are relevant:
• The open season for dabbling ducks and geese should begin 15
September except for pintail _(Anas strepera)_, shoveler _(A.
clypeata)_, wigeon, and pochard--species which should not be hunted
until 1 October;
• the open season for all diving ducks, as well as for coot, should end
31 December;
• the open season for the great cormorant should be restricted to the
period between 15 September and 31 October;
• murres, razorbill, great-crested grebe _(Podiceps cristatus)_, and
all species of loon should be fully protected;
• it should be prohibited to shoot from motorboats less than 1 km from
the shoreline, as well as in certain narrow sounds and fjords;
• it should be prohibited to shoot from shooting-punts less than 100 m
from the shoreline;
• it should be prohibited to sell waterfowl and shorebirds shot, except
for eider ducks and mallards _(Anas platyrhynchos)_; and
• no shooting should be allowed between sunset and one hour before
sunrise.
Oil Pollution
Oil pollution incidents constitute one of the greatest dangers to
seabird populations in Danish waters. The enormous masses of seabirds
present in these waters throughout the year, combined with the fact
that Danish waters contain some of the heaviest shipping traffic in the
world would give rise to anxiety for oil disasters. The majority of all
tanker traffic from the Atlantic and the North Sea to the Baltic passes
through the Cattegat and the narrow straits of the Sound, the Great
Belt, and the Little Belt, to supply a population of about 100 million
people. Up to 100,000 ships pass through these waters each year, half
through the Sound.
There have been severe oil pollution disasters every year since about
1935, accompanied by enormous mortalities of seabirds, particularly
marine ducks. The Danish Game Biology Station, which has studied these
disasters (Joensen 1972_a_, 1972_b_, 1973_b_), has noticed that the
number of seabirds involved has increased in recent years, in spite of
increased control by Danish authorities.
Unfortunately, it appears that small amounts of oil in the sea,
originating from cleaning the tanks of vessels, or from the release
of a few tons of oil, are enough to create mass mortality of seabirds
when large concentrations of birds are present in the vicinity. Such
incidents have passed unnoticed in spite of control measures. In no
case has the source of the pollution been traced (Joensen 1972_b_:27).
There has not yet been a real "oil disaster" in the Danish waters
similar to the _Torrey Canyon_ catastrophe. If such a disaster takes
place, the destruction of seabirds will be enormous and immeasurable.
Table 4. _Species composition of 8,304 birds killed by oil and
examined in connection with five pollution disasters in the
Cattegat, 1969-71._ (After Joensen 1972:12.)
Oil incident no.
Species 1 2 3 4 5 Totals
_Gavia stellata_ 1 9 1 4 15
_G. arctica_ 2 2 4 8 16
_Gavia sp._ 4 1 5
_Podiceps grisegena_ 4 1 8 8 21
_P. cristatus_ 1 1
_Phalacrocorax carbo_ 20 20
_Anas platyrhynchos_ 2 2 4
_A. clypeata_ 2 2
_Aythya marila_ 6 2 8
_Clangula hyemalis_ 35 2 26 6 4 73
_Melanitta nigra_ 387 241 521 262 77 1,488
_M. fusca_ 197 33 417 223 119 989
_Somateria mollissima_ 1,683 1,081 947 1,713 19 5,443
_Bucephala clangula_ 3 3 13 9 28
_Mergus serrator_ 48 28 28 2 106
_Cygnus olor_ 10 17 1 28
_C. Cygnus_ 1 1
_Fulica atra_ 1 1 2 5 9
_Larus sp._ 13 13
_Alca torda_ 1 12 1 14
_Uria aalge_ 1 1
_Cepphus grylle_ 1 2 16 19
Total birds examined 2,380 1,362 1,996 2,324 242 8,304
Estimated minimum number
of birds killed 10,000 5,000 12,000 15,000 1,500 43,500
Percent of total birds contributed
by three species[71] 95.3 99.5 94.4 94.6 88.8 95.4
As a result of five of the major oil pollution incidents in the
Cattegat from 1969-71, a total of 43,500 birds were killed, of which
8,304 were examined and enumerated (Table 4). Altogether, 21 or 22
species were involved, but 95% of all birds examined were diving ducks:
common eider and black and velvet scoters. At present, it has not
been possible to identify any decrease in the number of these ducks
in Danish waters due to oil pollution. However, if these disasters
continue, it can be expected that duck populations of northern Europe
and the Baltic area will be severely reduced, and that an overall
decline will take place from which the birds may not be able to recover.
A particularly disastrous year was 1972, when large numbers of ducks
were killed as a result of rather small oil spills. A tanker disaster
in March 1972 off the eastern coast of Jutland, in the northern
Cattegat, and another in December 1972 in the Danish Waddensea, both
took place in areas critical to major concentrations of sea ducks.
A total of more than 60,000 birds were killed, of which about 95%
consisted of the same three species of diving ducks mentioned above.
These tragic events represent a further increase in the annual
mortality of birds caused by oil, and there is reason to believe that a
critical upper limit is rapidly being approached.
It appears, however, that the measures taken by pollution control and
naval authorities have greatly improved in recent years. In January
1973, when a Polish merchant vessel collided with a Swedish tanker in
the Sound, about 300 tons of heavy fuel oil were released into the sea.
Several Danish and Swedish ships working in cooperation succeeded in
dispersing the oil, and no serious effect on seabird populations took
place (Joensen 1973_b_:118). It seems that the best way of cleaning up
such oil disasters is through a mechanical removal of the oil, but this
is a very expensive and difficult procedure.
Pollution by Toxic Chemicals
Chemical pollution is probably the most ominous threat to seabirds
at present. Since all toxic chemicals used in agriculture ultimately
end up in the sea, and many large factories release their industrial
wastes directly into the sea, the effects of this pollution on marine
organisms is attracting a growing interest. Many students have worked
on these problems, and the results that concern birds were summarized
by Bourne (1972:205). It is known that organochlorine residues have
been found in seabirds in all the oceans of the world, including
Antarctic waters and Arctic seas (Bogan and Bourne 1972:358). The
chemicals most often found in birds are DDE (a metabolite of DDT)
and PCB's (polychlorinated biphenyls), a mixture of related chemical
compounds often originating from industrial wastes. In addition, some
mercury will always be found, sometimes in increased concentrations.
The present restrictions on the use of DDT and PCB in Denmark have
not yet resulted in a corresponding decrease in the amount of these
pesticides in birds.
It is well known that marine pollution reaches a peak in the Baltic.
This high level of pollution is reflected in seabirds. For example,
analyses have shown that eggs from the colony of common murres on
Christiansø in the Baltic contain about 100 times as much DDE and 50
times as much PCB as eggs of murres from the Faroe Islands in the
Atlantic Ocean (Dyck 1975).
A similar difference exists in the mercury content in birds examined
in the two areas. Feathers of a large sample of black guillemots and
murres from the Cattegat and the Baltic had higher mercury levels than
those from the Faroe Islands and Greenland. It is interesting that
this difference existed over a hundred years ago, as evidenced by the
analysis of feathers in museum specimens. The Baltic populations of
both species show very significant increases in the mercury content
in 1965-70, as compared with the values earlier in this century.
Since 1970 there has been a sharp decrease in mercury content, and
in 1973 the level was almost as low as it was early in the century.
These results indicate that the strict control of mercury discharges
enforced in Sweden has resulted in a quick recovery of nearly normal
conditions in the Baltic (Somer and Appelquist 1974). However, recent
studies by Koeman et al. (1975:286) appear to show that mercury does
not accumulate to the same extent in seabirds as it does in seals.
High concentrations of chlorinated hydrocarbon residues accumulate in
carnivorous birds and upset the normal breeding behavior by making the
eggshells too thin and fragile to survive (Peakall 1970:73; Mueller
and Leach 1974:289). In Denmark, shells of herring gull eggs from the
Baltic population were thinner, lighter, and more heavily contaminated
with DDE and PCB than were shells of eggs from other colonies
(Jørgensen and Kraul 1974:173). This further emphasizes the pollution
of the Baltic Sea.
Massive mortalities of common murres, such as the one reported in the
Irish Sea in the fall of 1969 which was apparently caused partly by
malnutrition and PCB poisoning (Parslow and Jefferies 1973:87), are
unknown in Danish waters.
It should be added that the pollution of seawater with cadmium, so very
dangerous for man, has been high in recent years owing to the increased
use of this element in industry, but no analysis of its importance for
seabirds in Danish waters has yet been made.
It should also be mentioned that pollution of fresh water in lagoons
or lakes near the sea can often cause serious declines in numbers of
certain seabirds. This is well illustrated by recent events in the
sanctuary Nakskov Indrefjord on the island of Lolland. This landlocked
fjord once supported numerous breeding populations of ducks, grebes,
and terns, but in recent years a number of species (e.g., eared grebe;
common teal; garganey, _Anas querquedula_; pintail; and black tern,
_Chlidonias nigra_) have failed to breed and practically all other
species have declined in numbers. The main reason for these changes is
a severe pollution from the admission of raw sewage from tributaries
(Bloch et al. 1972). After several outbreaks of botulism in recent
years, procedures to improve conditions are now being developed.
Other Threats to Seabirds
The most dangerous threats to seabirds are those discussed above.
Authorities are aware of these dangers and attempts are being made
to improve conditions. Some results have been achieved in the combat
against oil pollution, and the control of shooting is reaching an
acceptable level. Game management agencies in Denmark and other
Scandinavian countries (Norway, Sweden, and Finland) are cooperating on
the request of the parliamentary body of the Nordic Council. If game
biologists in these countries could agree on proposed changes in the
game acts, owing to the marked decline of a number of bird species, the
parliamentary basis for such a legal step would be absolutely certain.
However, it must be admitted that the impact of man on the environment
is enormous, especially in a country like Denmark, which possesses
no raw materials, and where agriculture has transformed the whole
country. In such a country, the birds have to "face the music," and by
this sharing of resources with man, they will inevitably decrease in
number. It is the responsibility of biologists and politicians, without
emotional biases, to find the balance between the requirements of the
two spheres of interest.
Many other dangers that threaten seabirds, some of which are unrelated
to human activities, are listed here.
• Land reclamation.--Reclamation of land has reduced extensive areas of
shallow water, lagoons, marsh land, etc., from seabirds for foraging
or breeding places. Draining and diking of coastlands, estuaries, and
saltings have had the same effect. This activity is now almost stopped,
as these projects are no longer subsidized by the government.
• Egg-collecting.--According to the present game act, collecting gull
eggs is permitted until 24 May. This creates much disturbance on the
breeding grounds, and eggs of terns and shorebirds are also taken.
This practice should be halted. The "Bird Island Group" of the Danish
Ornithological Society, in a symposium in 1972, prepared some rules
for the protection of seabirds, among which is a proposal to stop
egg-collecting.
• Common property.--The Nature Conservancy Act regards all land not
fenced in, even small uninhabited islets, as common property. People
have free access to such areas with the result that seabirds breeding
in colonies, or separately on islands, are disturbed by visitors
arriving by boat. At the same time, noisy motorboats, bathing parties,
or camping visitors frighten the birds, making successful breeding
almost impossible. Even ornithologists, bird-banding teams, and bird
photographers add to the destruction. The "Bird Island Group" of the
Danish Ornithological Society has proposed a general prohibition
against visitors on important bird islands from 1 March to 15 July to
protect the breeding seabirds.
• Destruction by predators.--Fox, ermine, and stone-marten do not play
an essential role. Rats are more important, even on small islands, and
have caused destruction of tern and gull colonies. Rat numbers do not
decline until a severe winter with much ice occurs, or until high tide
kills them all. Large gulls also cause a great deal of destruction, but
crows and magpies are unimportant as predators in seabird colonies.
Numbers of nonbreeding mute swans or greylag geese may sometimes be a
nuisance, trampling eggs and nestlings in seabird colonies.
• Forestry practices.--The prevailing practice of the forestry industry
in Denmark of not preserving old trees with holes has considerably
diminished the breeding habitat of hole-nesting species like the common
merganser. Artificial nest-boxes have now been established in several
areas.
• Sea conditions.--During high water, or rough sea, salt water may
flood colonies of breeding seabirds nesting on low islets, often
reducing the production of young.
• Aircraft disturbance.--Disturbances are also caused by noise from jet
aircraft flying low, especially in military training areas where air
traffic may be heavy.
• Commercial fisheries.--Modern commercial fisheries are depleting
so-called industrially important fish stocks such as sand eels
_(Ammodytes)_, herrings, and other small fish over large areas of the
sea for the production of fish meal. This fishing has undoubtedly been
the main reason for the decline in the number of terns--especially
sandwich terns which depend on these small fish species for food.
• Unknown factors at sea.--Large numbers of pelagic seabirds,
particularly fulmars, kittiwakes, and gannets, are washed up on
the western coast of Jutland in certain years (e.g., 1959, Joensen
1961:212). These birds died at sea, for unknown reasons, and apparently
as a result of food shortages or oil pollution.
_Conservation_
The threats to seabirds mentioned above are all well known to
conservationists, who are attempting to reduce the impact of these
factors on seabirds where possible. Insofar as legal protection is
concerned, it must be admitted that there are no marine sanctuaries
in Denmark, although several discussions have taken place reviewing
the possibility of establishing some in critical areas. There are,
however, a number of sanctuaries on islands where seabirds breed. In
the Sanctuary Act of 1936 these areas were called "Scientific Reserves"
because they were the site of scientific investigations of bird life.
All admission was forbidden, at least during the breeding season, and
all shooting was prohibited, with few exceptions. These sanctuaries
were administered by the government's Nature Conservancy.
The following Scientific Reserves are important for seabirds:
Hirsholmene Islands (in Cattegat off Frederikshavn), Knotterne Islands
(small islets east of Laesø Island), Vejlerne (diked in, landlocked
fjords, densely covered with vegetation, at the Lim Fjord), Tipperne
Peninsula and Klaegbanken Island (in Ringkøbing Fjord, western
Jutland), Varsø Island (Horsens Fjord, eastern Jutland), and Græholm
Island (Christiansø Archipelago, in the Baltic off Bornholm). A
detailed description of these sites and their erection, bird life, and
ornithological value was given by Salomonsen (1945). More recently, two
additional Scientific Reserves have been established: Aegholm Islet
(south of Sealand), and Hesselø Island in the southern part of Cattegat.
In addition to these scientific sanctuaries, there are game reserves
and governmental forest reserves in Denmark. The game reserves are
administered by the Ministry of Agriculture, which is also responsible
for hunting legislation. The purpose of game reserves is to support and
protect the stock of game, which includes migrating birds. Shooting is
usually prohibited, but a restricted shooting season is allowed at some
reserves. More than 50 game reserves are now present and functioning.
Regulations differ widely from reserve to reserve, but entry to some of
them is not allowed in the breeding season. Many reserves are important
for breeding or migrating waterfowl and some seabirds. In fact, a total
of 26 game reserves contain seabirds, the most important of which are
the following: Ulvedybet (landlocked fjord at the Lim Fjord), Hjarbaek
Fjord (landlocked fjord with brackish water at the Lim Fjord), Felsted
Kog (landlocked fjord at Nissum Fjord), Jordsand (large stretches,
almost 11,000 ha, of the Danish Waddensea), Stavns Fjord (at Samsø
Island), Esrum Lake (in northern Sealand), and Kalvebod Beach (at
Amager Island, near Copenhagen).
In the Nature Conservancy Act of 1969, differences between scientific
and game reserves were abolished, although regulatory provisions
that were in force for the scientific sanctuaries were maintained.
Unfortunately, the amalgamation of the two types of reserve has
given more power to the hunters' associations, which constitute the
majority of the administrative body of the reserves, the so-called
Game Commission ("Vildtnævnet"). However, any change in status of the
original scientific reserves will not be tolerated by conservationists
and other environmental groups in Denmark.
The Faroe Islands
The number of seabirds in the Faroe Islands is greater than in any
other region of the North Atlantic, and is closely related to the
extraordinary richness of the plankton. The high phytoplankton
production is due to a strong vertical mixing of the water in the
northeast Atlantic, especially at the slopes of the submarine ridges,
where both tidal currents and oceanic currents are usually strong.
The resulting upwelling enriches the upper layers of water with large
quantities of nutrient salts for the phytoplankton, and this, in turn,
produces a teeming life of macroplankton and fish on which the seabirds
are dependent (Salomonsen 1955).
The enormous seabird population of the Faroes is apparent from the
first description of the islands, "De mensura orbis terrae," a document
written in the year 825 by the Irish monk Dicuilus, who described the
most characteristic feature of the Faroes as being the fact that "the
islands were full of various kinds of marine birds." This richness
has remained to the present, and has provided an important source of
food for the resident human population, particularly in former times.
There are few, if any, countries in the world in which wild-fowling and
other exploitations of birdlife have played such a major role as in the
Faroes. A number of elaborate and varied bird-catching methods were
invented, and these have remained essentially the same for at least the
last 500 years. Bird-fowling at great heights on precipitous sea-cliffs
was a dangerous venture, and each year lives were lost. The main thing,
however, was that food obtained from fowling meant life and death
for local inhabitants and so was undertaken in such a well-balanced
way that the seabird populations did not decrease or disappear. Some
fowling still takes place, but on a reduced scale, since most men are
now engaged in the fishery during the summer. Shooting is now of much
greater importance than in former times.
The Faroese game acts (from 1897, 1928, and 1954) are very severe and
show a broad consideration for birdlife. Practically all terrestrial
birds, including shorebirds, are protected, and existing regulations
permit people to catch or shoot only common murres, razorbills,
puffins, shags _(Phalacrocorax aristotelis)_, fulmars, gannets,
parasitic jaegers _(Stercorarius parasiticus)_, and gulls, as well
as a few "pest" species like crows _(Corvus corone)_ and ravens _(C.
corax)_. The legal right of fowling on a "fowling cliff" belongs to the
registered owner of the land on which the cliff is situated. There are
some sound restrictive laws for these cliffs. For example, shooting
within 3.2 km of any seabird colony is prohibited.
Table 5. _Number of seabirds caught by fowling each year in the
Faroe Islands in the early 1900's._ (From Salomonsen 1935.)
--------------------------------------
Number of birds
Species caught per year
--------------------------------------
_Uria aalge_ 60,000
_Fratercula arctica_ 270,000
_Puffinus puffinus_ 1,500
_Fulmarus glacialis_ 80,000
_Morus bassanus_ 1,300
Total 412,800
--------------------------------------
The annual number of seabirds caught by fowling in the early 1900's
(summarized in Table 5) were reported in Salomonsen (1935). This large
harvest of birds, taken by fowling year after year for centuries,
did not appear to influence the seabird populations, as bird numbers
remained stable. However, in recent years, shooting and a special form
of snaring of murres have increased dramatically and seem to have
endangered the murre population. The annual number of murres killed is
estimated to be about 120,000, of which 70,000 are snared and at least
50,000 shot (estimates of birds shot range from 50,000 to 100,000).
This total is almost double the number of birds caught during fowling,
and because of an apparent decline in murre numbers the provincial
government decided to investigate the matter, and in 1972 the Danish
Ornithological Society agreed to conduct the study. Figures from the
1972 census of murres (Table 6) show that almost 600,000 birds were
counted, from which an estimate of more than 393,000 breeding pairs was
calculated (Dyck and Meltofte 1975). In spite of this large number,
Dyck and Meltofte (1975) concluded that the Faroese murre population
has declined by about 20% during the last 10-15 years. Investigations
are under way to monitor further changes in murre numbers, and to
determine the trend, and whether reductions in shooting and snaring are
necessary to maintain the population.
Oil pollution is practically unknown in Faroese waters, but since
drilling for oil will probably take place in the near future, the
importance of oil to birds in this region may change. Toxic chemicals
do not appear to be involved in the decline in murres. Investigations
of concentrations of chemical pollutants in their eggs show that levels
of DDE (mean 1.1 ppm), PCB (mean 2.0 ppm), and mercury (mean 0.2 ppm)
(Dyck and Meltofte 1975) are relatively low and unlikely to affect
reproduction (Dyck and Meltofte 1975). Levels are much smaller than
those found in seabirds in Britain, the Baltic, or in albatrosses in
the Pacific (Fisher 1973).
Table 6. _Colonies of the common murre,_ Uria aalge, _on the
Faroe Islands, based on a census conducted in 1972._ (After Dyck
and Meltofte 1975.)
----------------------------------------------
Number of
birds Number of
Colony observed pairs[72]
----------------------------------------------
Suderoy 73,945 49,500
Lítla Dímun 13,220 8,800
Stóra Dímun 68,050 45,600
Sandoy 101,710 68,100
Hestur 17,290 11,600
Mykines 14,500 9,700
Vágar 4,224 2,800
Streymoy 27,214 18,200
Eysturoy 10,520 7,000
Kalsoy 14,150 9,500
Vidoy 5,980 4,000
Fugloy 22,730 15,200
------- -------
Totals 587,333 393,200[72]
----------------------------------------------
Greenland
Greenland, which has an area of 2,175,600 km² and extends for a
distance of 2,670 km from the northernmost to the southernmost point
of the country, is almost a continent by itself. The range of the
different species of seabirds, therefore, is greatly varied, and it
is necessary to classify them according to the relation between their
distributions and the marine zones. A description of the zones of
the marine environment in the North Atlantic was given by Salomonsen
(1965), and the breeding distributions of seabirds in Greenland
based on this system are given in Table 7. The terrestrial area of
southernmost West Greenland belongs to the subarctic zone of the boreal
province, and one boreal bird species, the black-headed gull, has bred
there in recent years. It is, however, as much a freshwater bird as a
marine one.
Table 7. _Distributions of seabirds breeding in Greenland in
relation to marine zones._
Marine zone and species[73]
Boreo-panarctic
_Fulmarus glacialis_
_Somateria mollissima_
_Stercorarius parasiticus_
_Rissa tridactyla_
_Sterna paradisaea_
_Cepphus grylle_
_Fratercula arctica_
Panarctic
_Larus hyperboreus_
_Uria lomvia_
_Clangula hyemalis_
_Gavia stellata_
High arctic
_Somateria spectabilis_
_Branta bernicla_ _(hrota)_
_Stercorarius longicaudus_
_Xema sabini_
_Larus thayeri_
_Pagophila eburnea_
_Cepphus grylle_ (_mandti_ group)
_Plautus alle_
_Fratercula arctica_ _(naumanni)_
_Phalaropus fulicarius_
Low arctic
_Larus glaucoides_
_Phalaropus lobatus_
Boreo low arctic
_Mergus serrator_
_Phalacrocorax carbo_ _(carbo)_
_Larus marinus_
_Alca torda_
_Uria aalge_
_Cepphus grylle_ (_grylle_ group)
_Fratercula arctica_ _(arctica)_
Boreal
_Larus ridibundus_
[Illustration: Fig. 1. Breeding range in Greenland of four
boreo-panarctic seabirds, _Fulmarus glacialis_, _Somateria mollissima_,
_Rissa tridactyla_, and _Fratercula arctica_.]
[Illustration: Fig. 2. Breeding range in Greenland of three
boreo-panarctic seabirds, _Sterna paradisaea_, _Cepphus grylle_, and
_Stercorarius parasiticus_, and one low arctic species, _Phalaropus
lobatus_.]
[Illustration: Fig. 3. Breeding range in Greenland of three panarctic
seabirds, _Uria lomvia_, _Larus hyperboreus_, and _Clangula hyemalis_,
and one high arctic species, _Stercorarius longicaudus_.]
[Illustration: Fig. 4. Breeding range in Greenland of three boreo-low
arctic seabirds, _Mergus serrator_, _Larus marinus_, and _Phalacrocorax
carbo_, and one high arctic species, _Plautus alle_.]
The widely differing ranges of Greenland seabirds are shown in Figs.
1-4 and are based on my new and previously unpublished data. The
borderline between the high arctic and low arctic zones is situated in
Melville Bay on the west coast, and just south of Scoresby Sound on the
east coast; the innermost parts of Scoresby Sound belong to the low
arctic zone.
In the low arctic Pacific region the number of seabirds is said to be
about 51 million in summer and 8 million in winter (Sowl and Bartonek
1974). No similar estimate is available for low arctic West Greenland,
but I suggest that it is much lower in summer and slightly higher in
winter.
The human population of Greenland, now numbering about 50,000
individuals, is restricted to the seashore, where all cities and
minor outposts are situated. Although shooting seabirds is an ancient
tradition in Greenland, the true land-birds, which are few in number,
are usually left alone. Seabirds collected by shooting provide an
important source of food that the Greenlanders could not do without.
Since special shooting and hunting regulations have not been developed
in Greenland, these activities often resemble a sort of slaughter
rather than true hunting. There is no game act in Greenland, and
practically all birds can be shot. This condition is similar to that
in Canada, where according to Section 5(7) of the Migratory Birds
Regulations (Canadian Wildlife Service, Ottawa 1973) "an Indian or Inuk
may at any time, without a permit, take auks, auklets, guillemots,
murres, puffins and scoters and their eggs for human food and
clothing." Much the same sort of hunting privileges exist for native
peoples of Alaska. What is still worse, however, is the enormous
illegal shooting of ducks, geese, swans, and cranes that is known to
take place in arctic North America, but is largely ignored by police
and game authorities. Bartonek et al. (1971) described this situation
very well for Alaska. In Greenland, it is not possible any more to
distinguish between "native Eskimos" and Greenlanders (including Danes
working in the country), but the attitude toward animals among the
inhabitants is the same as it has always been--a food source to hunt
and kill.
With a rapidly growing human population, and a readily available
supply of guns and speedboats for hunting, the whole natural ecosystem
is beginning to break down, and it cannot be permitted to continue.
The provincial government is aware of this fact, and various legal
enactments have been issued from both the government and the local
magistrates. However, since the size of the police force (mostly
Greenlanders) is small, it is of little help for the preservation of
wildlife, and sometimes even the policemen themselves do not know
the local ordinances. The result has been that seabirds, previously
profusely flourishing, have considerably decreased in number in West
Greenland.
I have previously described the shooting and hunting of seabirds in
Greenland and the statutory provisions issued to protect them (see
Salomonsen 1970). At present, the following seabirds and their eggs
are totally protected: whooper swan; common puffin, _Fratercula
arctica_; and harlequin duck, _Histrionicus histrionicus_. Some other
species have a closed season or are protected in certain parts of the
country: snow goose, _Anser caerulescens_; common eider; king eider,
_Somateria spectabilis_; great cormorant; dovekie, _Plautus alle_;
black guillemot; and thick-billed murre, _Uria lomvia_. Furthermore,
all catching and hunting of birds within 2 km of breeding colonies of
murres and kittiwakes is prohibited. Bird sanctuaries where hunting,
catching, and collecting of eggs and down are prohibited are Avsigsut,
Nunatsiaq, and Satuarssunguit islands, which are scattered in Disko
Bay, and Tasiussarssuaq Fjord (the inner part of Arfersiorfik Fjord,
south of Egedesminde).
However, the Greenland Provincial Council has been alarmed by the
serious decline in the numbers of seabirds due to increases in human
persecution, and it has decided to introduce a game law similar to
those in Denmark and other European countries. The preparation of this
legislation was left to me, and a draft of this Greenland game act has
been issued (Salomonsen 1974); the new law was passed in parliament in
1977 and went into force on 1 January 1978.
It is not possible to review in detail the different parts of the new
law, but certain important points should be mentioned. In northern
parts of West Greenland (north of Egedesminde) the sea is ice-covered
for 7-8 months a year, and seabird hunting is therefore not possible
outside the breeding season. Because of this, it was necessary to allow
some hunting of murres, eiders, and immature gulls during the breeding
period, but away from nesting locations. Consumption of seabirds is to
be limited to local residents, and sales to canneries for shipment to
other cities is to cease. Previously, canneries in northwest Greenland
exported large numbers of thick-billed murres to South Greenland--e.g.,
25,606 birds in 1971; and 30,029 in 1972 (Anonymous 1974:64). This
marketing of murres will end.
Other parts of the proposal important for seabirds include:
• A general closed season extending from 15 June to 15 August.
• Prohibition of shooting at breeding colonies of seabirds, as is in
force at present (cf. above).
• Eggs of terns and gulls can be collected for food in southwest
Greenland to 1 July, and in northwest Greenland to 10 July; fulmar and
murre eggs can also be collected in northwest Greenland.
• Each hunter is allowed to shoot or catch 50 birds per day, but the
entire bag must be used for human consumption.
• All shooting from speedboats, aircraft, and motor vehicles is
prohibited.
• Catching flightless common eiders, king eiders, and oldsquaws
_(Clangula hyemalis)_ is prohibited.
• Practically all seabirds and shorebirds can be shot; all other birds
(except rock ptarmigan and raven) are totally protected.
The principles of this radical new act must be taught to the population
by all possible means of communication, including radio, public
meetings, schools, etc.
* * * * *
Another matter of great concern to seabirds in Greenland is the
Atlantic salmon fishery off the west coast by Danish, Greenlandic
and foreign fishermen. It is well known that many birds are killed
in the fishing gear, and a serious political controversy has arisen,
especially between the governments of the United States and Denmark.
The fact that a large number of thick-billed murres were drowned in
salmon gill nets during their southward swimming migration along the
Greenland coast was significant. In a resolution sent by the XV World
Conference of the International Council for Bird Preservation in Texel
to the Danish Government, it was stated that the annual incidental
drowning of murres probably involved about 250,000 individuals--a
figure exceeding the reproductive capacity of the species. This
estimate was doubted by Danish fishery biologists, but recent
investigations carried out by the Canadian Wildlife Service and the
Fisheries Research Board of Canada have shown that the figure is even
greater, and that the total kill amounts to about half a million murres
annually (Tull et al. 1972).
Because of this mortality of murres, an agreement was reached between
the American and Danish governments, namely that:
From 1 January 1976, all salmon fisheries outside the 12-mile
boundary shall totally stop. In the years 1972-75 the fishery
carried out by Danish and Faroese fishermen shall be reduced
gradually from 800 to 300 tons of fish, and shall terminate on 31
December 1975. The fish quota by Greenland fishermen must amount
to no more than 1,100 tons annually, but from 1976 onwards, the
fishery shall be restricted to areas within the 12-mile limit.
This agreement, which has drastically reduced the number of murres
caught, was discussed at a meeting of the International Committee of
North Atlantic Fisheries in May 1972, and was ratified by the countries
involved in July 1972.
Oil pollution has never occurred in Greenland, but concessions for
offshore oil drilling along the West Greenland coast have just been
granted by the Danish Government, and this new development gives rise
for concern. However, it is clearly stated in the concession that the
Ministry for Greenland can lay down rules for protection against oil
pollution and other damage to human or animal life, and can adopt
measures to fight pollution which has already taken place (section
5(9)). It is up to the concessionary to oversee industrial developments
in the area and see that marine pollution is avoided (section 11).
Toxic chemicals have been found in Greenland seabirds, as everywhere
else in the world, but it must be emphasized that no pesticides
whatsoever are in use in Greenland itself. Investigations by Somer
and Appelquist (1974) indicated that the mercury content in black
guillemots in Greenland has doubled over the last 20 years, and has now
reached 2 ppm, which is, however, a relatively low figure. Levels of
DDE, PCB, and aldrin in Greenland birds were investigated by Braestrup
et al. (1974). Common eider, king eider, harlequin duck, and oldsquaw,
as well as thick-billed murre and great cormorant, were examined; all
were found to be contaminated with pesticides, although to varying
degrees. Highest concentrations occurred in the cormorant, which
contained 6.5-15 ppm of DDE and 14.1-46.7 ppm of PCB. These specific
differences appear to show that the pesticide level in the different
species of seabirds is influenced more by the position of the bird in
the food chain than by its migratory habits.
And finally, I wish to mention a more happy event. On 9 May 1974 a
new law of nature protection in Greenland was passed by the Danish
Parliament. According to this law, a National Park is to be established
covering almost the entire northeast and north regions of Greenland,
from the Thule District in northern West Greenland around the entire
north coast of Greenland and south along the east coast to the northern
inner parts of Scoresby Sound. All hunting, fishing, egg-collecting,
and disturbances to the environment are forbidden in this enormous
area. This is by far the greatest National Park in the world, covering
about 800,000 km². Of this total area, the greater part is a lifeless
icecap, to be sure, but about 200,000 km² is ice-free land and suitable
habitat for numerous high-arctic birds.
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Salomonsen, F. 1974. Forslag til vedtægt om jagt på fuglene i
Grønland. Diskussionsoplæg til kommunalbestyrelserne udarbejdet
på opfordring af Det grønlandske Landsråd. Tidsskr. Grønland
1974(5):155-172.
Somer, E., and H. Appelquist. 1974. Changes and differences in
mercury level in the Baltic and Kattegat compared to the North
Atlantic using _Uria_ sp. (guillemot sp.) and _Cepphus grylle_
(black guillemot) as indicators. 9th Conf. of the Baltic
Oceanographers, Kiel. 12 pp. Danish Isotope Centre, Copenhagen.
Sowl, L. W., and J. C. Bartonek. 1974. Seabirds--Alaska's most
neglected resource. Trans. N. Am. Wildl. Nat. Resour. Conf.
39:117-126.
Strandgaard, H. 1964. The Danish bag record. I. Studies in game
geography based on the Danish bag record for the years 1956-57
and 1957-58. Dan. Rev. Game Biol. 4(2):1-116.
Tull, C. E., P. Germain, and A. W. May. 1972. Mortality of
thick-billed murres in the West Greenland salmon fishery. Nature
(Lond.) 237(5349):42-44.
FOOTNOTES:
[67] Not counted.
[68] No estimate, but number insignificant.
[69] Species totally protected.
[70] _Branta bernicla_ is fully protected since 1972.
[71] _Somateria mollissima_, _Melanitta nigra_, and _M. fusca_.
[72] The "number of pairs" is calculated by multiplying the number of
birds observed by 0.67 (Dyck and Meltofte 1975).
[73] A few species breed near freshwater lakes, but are marine during
the nonbreeding season.
Present Status and Trends in Population of Seabirds in Norway
by
Einar Brun[74]
University of Tromsø
Tromsø, Norway
Abstract
The most numerous seabird in Norway is the
puffin _(Fratercula arctica)_, but its current
breeding population of 1.25 million pairs
is slowly declining. The kittiwake _(Rissa
tridactyla)_, however, is increasing and
establishing new colonies; its population now
stands at 510,000 pairs. The population of
the common murre _(Uria aalge)_, the seabird
species most vulnerable to human activity,
was about 160,000 breeding pairs in 1964 but
is now decreasing at a rate of nearly 5% per
year. Of the other alcids, the razorbill
_(Alca torda)_ and thick-billed murre _(Uria
lomvia)_ show similar declines, and the black
guillemot _(Cepphus grylle)_ is maintaining
a stable population. The fulmar _(Fulmarus
glacialis)_ and the gannet _(Sula bassana)_
have both spread from the British Isles and
have established a number of breeding colonies
in Norway during this century. Evidently
immigration of gannets is still occurring,
since the observed rate of increase far exceeds
the population's intrinsic rate of increase.
The impact of human activity on bird mortality
varies from species to species. The two most
serious factors are coastal oil pollution
and the use of fishing gear; direct hunting
pressure accelerates the decline of murres and
razorbills. Persistent toxic chemicals are not
yet a serious problem in Norway.
Norway, with a coastline of more than 20,000 km, an abundance of
islands, and areas of offshore upwelling, provides good conditions
for a rich seabird fauna. A regional study of this seabird fauna has
been undertaken as a sideline of basic marine research. Although the
ultimate aim has been to evaluate the importance of seabirds in the
energy flow of a marine ecosystem, a more realistic problem (given
priority so far) has been to study yearly production and the dynamics
behind changes in the breeding populations.
Good population estimates are of fundamental importance to studies of
population dynamics. Because the available censuses of seabirds in
Norway were few and largely inadequate, a long-term program was started
in 1961. In the beginning, resources and assistance were very limited,
and the work was concentrated on cliff-breeding seabirds, particularly
the gannet _(Sula bassana)_, fulmar _(Fulmarus glacialis)_, kittiwake
_(Rissa tridactyla)_, razorbill _(Alca torda)_, common murre _(Uria
aalge)_, thick-billed murre _(U. lomvia)_, and puffin _(Fratercula
arctica)_. Until 1970, the study involved making annual censuses in the
approximately 20 major colonies of cliff-breeding seabirds and mapping
the distribution of the quantitatively less important colonies.
Since 1970, the Norwegian seabird program has also involved more
detailed studies in some selected colonies. In these colonies, emphasis
has been on investigation of yearly production and of the factors
limiting this production, and evaluation of the effects of human
activity on the population growth.
Material and Methods
The logistics of census operations have gradually improved from the use
of slow, local transportation to the use of fast pneumatic boats and,
in more recent years, seaplanes. Various census methods have been used,
depending on species and circumstances.
For puffins, a method based on measurement of feeding frequency
and on the number of puffins per time unit that pass a particular
observation post when they return from the feeding ground was used
(Brun 1971_a_). Kittiwakes and gannets were readily censused by a
combination of photographic methods and detailed counts in sample areas
(Brun 1971_b_). Direct counting is by far the most accurate method
for razorbills, murres, and fulmars; but in the larger colonies of
common murre, lack of time permitted accurate counts for only a limited
proportion of the cliff. Direct counts of individuals, the egg/chick
ratio, and estimates of the relative size of the censused population
were used to estimate the total population of the colony.
In a colony of kittiwakes near Tromsø, environmental factors that limit
breeding success, such as temperature and wind exposure, were monitored
throughout the breeding season on a data recorder, and detailed
measurements of temperatures on and inside the eggs have been recorded.
For further information about the influence of environmental parameters
on incubation rhythm and nest attendance, the presence of the male and
female at a particular nest was recorded by using radioactive bands and
a Geiger-Muller tube connected to a pen recorder.
In a study of the effects of human activity, egg samples of selected
species were analyzed for mercury, PCB, and DDT derivates. An effort
was also made to obtain figures for the mortality caused by oil
pollution and fishing gear as well as by direct hunting pressure.
Results
_Status and Trends of Cliff-breeding Species_
Puffin _(Fratercula arctica)_
By far the most numerous seabird in Norway is the puffin (Fig. 1),
which is the only species with a breeding population of more than 1
million breeding pairs (Tables 1, 2). In a 1964 census (Brun 1966) the
total breeding population was put at 1.5 million pairs. The current
figure of 1.25 million pairs includes several newly discovered colonies
and some not censused in 1964; it is more accurate than the previous
census for most of the 15 largest colonies which make up 99.9% of the
total population. The puffin population is concentrated in Troms and
Nordland (94%), with only about 3% in Finnmark.
[Illustration: Fig. 1. Distribution of the puffin _(Fratercula
arctica)_ in Norway. Numbers refer to localities listed in Table 2.]
Kittiwake _(Rissa tridactyla)_
The second most numerous seabird species in Norway is the kittiwake,
which dominates in a number of the larger cliff colonies. Its
distribution pattern differs from that of the puffin--the main
occurrence of the kittiwake population (about 63%) is in Finnmark
(Table 3).
Table 1. _Estimate of the numbers of seabirds breeding on the
coast of Norway 1970-1974. Species are listed in descending order
of breeding population size._
Thousands of Increase (+) or
Species pairs[75] decline (-)
_Fratercula arctica_ 1250 -
_Rissa tridactyla_ 510 +
_Larus argentatus_ (260)[76] +
_L. canus_ (150)[76] +
_Uria aalge_ 100 -
_L. marinus_ (40)[76] +
_Phalacrocorax aristotelis_ 33 +
_Alca torda_ 30 -
_Cepphus grylle_ 22 0
_Sterna paradisaea_ (21)[76] -
_S. hirundo_ (13)[76] -
_Phalacrocorax carbo_ 12 +
_L. fuscus_ 9[76] +
_Stercorarius parasiticus_ (8) 0
_L. ridibundus_ 4[76] +
_Fulmarus glacialis_ 1.1 +
_U. lomvia_ 1.0 -
_Hydrobates pelagicus_ ? ?
_Sula bassana_ 0.76 +
_Oceanodroma leucorrhoa_ ? ?
The annual production of kittiwakes shows enormous variation, both
throughout the coastline and in different years; however, at our sample
stations in north Norway, the mean production in 1974 (Table 4) was
more stable and was near the minimum value necessary to maintain zero
population growth.
This minimum production, mₓ (number of females produced per breeding
female), can be computed from survival rates
mₓ = (1-P)/1ₓ = 0.13/0.57 = 0.23
where P is annual adult survival and 1ₓ is survival of fledged chicks
up to first breeding. Data on survival are taken from Coulson and White
(1959) and from Norwegian banding recoveries.
The kittiwake has, however, established a number of new colonies,
and although the local increase in some of these is spectacular, the
long-term change during the last 15 years is only about 1% increase per
year in northern Norwegian colonies (E. Brun, unpublished data). In
southern Norway, the population has increased much more rapidly (Brun
1971_c_).
Common murre _(Uria aalge)_
The common murre (Fig. 2) has shown a considerable decrease. The most
spectacular decrease is at Sør-Fugløy, where a colony of 10,000 pairs
in 1940 was reduced to 4,000 pairs in 1961, to 1,100 pairs in 1966, and
to only about 10 breeding pairs in 1974 (Table 5). Most of the census
work was done in 1964 and 1974. The general trend in population change,
as expressed by the yearly decrease or increase, has been extrapolated
forward to 1974 or back to 1964 for those colonies where censuses were
missing for either of these years, to enable a better comparison (Table
6). The overall decrease in Norwegian colonies of the common murre is,
thus, near 5% per year; the few cases with a positive trend are based
either on very small figures or on extrapolation from old, inadequate
censuses.
Thick-billed Murre _(Uria lomvia)_
The thick-billed murre (Fig. 3) was first proved to breed in Norwegian
colonies in 1964; it was then found at three localities and has since
been found breeding at eight localities (Table 7). It is now fairly
certain that the thick-billed murre is not a newcomer but has remained
unnoticed among the common murre for generations, possibly since the
original immigration of the _Uria_ species after the last glacial
period. Data are not sufficient to show whether this small population
of thick-billed murres is decreasing at the same rate as the common
murre.
Table 2. _Status of the puffin_ (Fratercula arctica) _in Norway
(cf. Fig. 1)_.
Year of Number of Percent of
Locality census pairs population
1. Kjør 1975 80 <0.1
2. Heglane 1970 4 <0.1
3. Ferkingstadøyene 1970 5 <0.1
4. Utsira 1970 2 <0.1
5. Utvær 1970 200 <0.1
6. Ryggsteinen 1970 2 <0.1
7. Veststeinen 1970 1,500 0.1
8. Einevarden 1970 1,500 0.1
9. Svinøy 1970 100 <0.1
10. Runde 1974 30,000 2.4
11. Saløy 1970 2 0.1
12. Sklinna 1974 2,000 0.2
13. Lovunden 1968 60,000 4.8
14. Fugløy i Gildeskål 1968 800 0.1
15. Røst 1964 700,000 55.7
16. Værøy 1974 70,000 5.6
17. Nykvåg 1967 40,000 3.2
18. Frugga 1975 5,000 0.4
19. Anda 1970 10,000 0.8
20. Bleik 1968 40,000 3.2
21. Sør-Fugløy 1968 40,000 3.2
22. Nord-Fugløy 1967 218,000 17.3
23. Loppa 1968 180 <0.1
24. Hjelmsøy 1964 20,000 1.6
25. Gjesværstappen 1973 18,000 1.4
26. Kongsøy 1966 30 <0.1
27. Syltefjord 1966 100 <0.1
28. Hornøy 1967 160 <0.1
29. Reinøy 1967 40 <0.1
Total 1,257,705 100.0
Razorbill _(Alca torda)_
Another colonial cliff-breeding alcid, the razorbill (Fig. 4), has a
distribution pattern very similar to that of the common murre, but the
individual colonies (Table 8) are, with one exception, smaller. The
total breeding population was estimated at 36,000 pairs in 1966-69
(Brun 1969_b_); some more recent censuses show a definite decline,
but data are not sufficient to estimate the overall decline in the
Norwegian population. At most, the current breeding population is
30,000 pairs.
Fulmar _(Fulmarus glacialis)_
The fulmar is one of two species of seabirds that have spread from
colonies in the British Isles and established themselves as breeding
birds in Norway during this century (the other is the gannet).
[Illustration: =Fig. 2.= Distribution of the common murre _(Uria
aalge)_ in Norway. Numbers refer to localities listed in Tables 5 and
6.]
[Illustration: =Fig. 3.= Distribution of the thick-billed murre _(Uria
lomvia)_ in Norway. Numbers refer to localities listed in Table 7.]
Table 3. _Status of the kittiwake_ (Rissa tridactyla) _in Norway,
and a comparison of distribution with that of the puffin_
(Fratercula arctica).
-------------------------------------------------------------
Breeding pairs
-------------------------------------------
_Rissa_ _Fratercula_
-------------------- --------------------
Number Number
County (thousands) Percent (thousands) Percent
-------------------------------------------------------------
Finnmark 321 62.9 38 3.0
Troms 9 1.8 258 20.5
Nordland 72 14.1 928 73.7
Trøndelag (S, N) 1 0.2 2 0.2
Møre and Romsdal 105 20.6 30 2.4
Sogn and Fjordane 1.9 0.4 3 0.2
Rogaland 0.1 -- <0.1 --
Total 510 100.0 1,259 100.0
-------------------------------------------------------------
The fulmar began nesting in the early 1920's on Runde, the only
sizeable seabird colony in south Norway, off Alesund. Further
immigration of birds from the British Isles probably occurred in the
first 25 years, when the population increased about 10% annually to
about 350 pairs in 1947 (Valeur 1947). Since then the population
increase has slowed down to about 3% annually, and the population on
Runde in 1971 was about 700 pairs (Table 9). From Runde, fulmars have
spread not only to a number of islands in the same region, but also
much farther afield--south to Utsira (59°18'N, 4°55'E) and north to
Bleik (69°3'N, 15°42'E). The total Norwegian population of fulmars in
1971 was estimated at 1,100 pairs.
[Illustration: =Fig. 4.= Distribution of the razorbill _(Alta torda)_
in Norway. Numbers refer to localities listed in Table 8.]
[Illustration: =Fig. 5.= Distribution of the gannet _(Sula bassana)_ in
Norway. Numbers refer to localities listed in Table 10.]
Table 4. _Annual production, mₓ, of the kittiwake_ (Rissa
tridactyla) _at some North Norwegian coastal localities (mₓ =
number of females produced per female)_.
-------------------------------------------
Sample size
Locality Year (number) mₓ
-------------------------------------------
Vedøy, Røst 1972 852 0.21
Hekkingen, Troms 1974 264 0.46
Hjelmsøy 1974 357 0.18
Jarfjord 1974 146 0.31
Total 1,619 0.25
-----------------------------------------
Gannet _(Sula bassana)_
The gannet (Fig. 5), the most recently established and least numerous
of the cliff-breeding seabirds, has the best-known population change.
Like the fulmar, it was established in 1946 on Runde, and the first
individuals were undoubtedly of British origin. During its entire
breeding history on Runde, and also in two of the three new colonies
in northern Norway established in the 1960's, the yearly increase has
far exceeded the intrinsic rate of increase (Table 10); for gannets
with a 50% breeding success, adult mortality of 6%, and 35% survival
up to first breeding, the intrinsic rate of increase is about 2% per
year. The Runde and Syltefjord colonies are naturally protected by
their inaccessibility, but the colonies at Mosken and Nordmjele, which
are on small islets, are both easily accessible. The Nordmjele colony,
however, has been effectively protected from its start, whereas the
Mosken colony has been open to visitors; this difference is probably
reflected in their different breeding success and annual growth rate
(Table 11). The breeding success necessary to maintain a stable
population with the mortality figures given above is 34%:
mₓ = (1-P)/1ₓ = 0.66/0.35 = 0.17
For equal sex ratio, breeding success is 2 times mₓ = 0.34.
A British ringed gannet from Ailsa Craig (55°12'N, 5°07'W) was found
nesting when 4 years old in the Nordmjele colony in 1970 (Brun 1972),
giving direct evidence that immigration from colonies in Great Britain
(Scotland) still takes place.
Table 5. _Status of the common murre_ (Uria aalge) _in Norway
(cf. Fig. 2)_.
Last census Previous census
No. of No. of
breeding breeding
Locality Year pairs Year pairs Reference
1. Utsira 1970 1 1950 10 Holgersen 1951
2. Utvær 1970 17 1948 55 Willgohs 1952
3. Veststeinen 1970 29 1950 40 Willgohs 1952
4. Klovningen 1970 35 1950 20 Willgohs 1952
5. Einevarden 1970 30 1952 25 Willgohs 1955
6. Runde 1974 6,000 1963 7,600 Brun 1969_a_
7. Storholmen 1970 8 -- --
8. Røst 1974 6,800 1964 9,700 Brun 1969_a_
9. Værøy 1974 1,750 1964 2,400 Brun 1969_a_
10. Nykvåg 1974 350 1966 430 Brun 1969_a_
11. Bleik 1974 60 1952 90 Regnell 1957
1964 75 Brun 1969_a_
12. Sør-Fugløy 1974 10 1940 10,000 Soot-Ryen 1941
1961 4,000 Brun 1963
1966 1,100 Brun 1969_a_
13. Nord-Fugløy 1967 9,000 1963 15,000 Lütken 1965
14. Loppa 1974 500 1966 800 Brun 1969_a_
15. Hjelmsøy 1974 70,000 1964 110,000 Brun 1965
1967 95,000 Brun 1969_a_
16. Gjesværstappene 1973 580 1967 750 Brun 1969_a_
17. Sværholtklubben 1973 20 1966 25 Brun 1969_a_
18. Omgangsstauran 1973 70 1967 85 Brun 1969_a_
19. Syltefjorden 1974 9,000 1966 12,300 Brun 1969_a_
20. Hornøy 1974 500 1964 730 Brun 1969_a_
21. Reinøy 1974 110 1964 160 Brun 1969_a_
22. Kjøfjord 1970 21 -- --
23. Skogerøy 1970 8 1967 6 Brun 1969_a_
24. Sagfjord 1970 9 1967 12 Brun 1969_a_
25. Kobbholmfjorden 1970 2 1967 1 Brun 1969_a_
_Estimates of Total Seabird Population in Norway_
In addition to the more detailed censuses of the cliff-breeding species
dealt with so far, notes have been made on all seabirds observed during
numerous flights along the Norwegian coast. Although a first attempt
at putting a figure to all seabird species in Norway may be somewhat
premature, it is believed that even an extrapolation combined with an
educated guess is of some value until more accurate censuses covering
the whole coast can be made. Although the data (Table 1) are arranged
in the same way as the results from "Operation Seafarer" in the British
Isles (Cramp et al. 1974), it must be stressed that the accuracy of the
Norwegian figures, at least for the non-cliff-breeding birds, is far
inferior to the very fine British data. The table includes data for two
petrels (_Hydrobates pelagicus_, _Oceanodroma leucorrhoa_), which in
Norway breed on Røst (well north of the Arctic Circle), where they have
adapted to a delayed breeding season with egg laying in August because
of the conflict of their nocturnal habits with the continuous daylight
due to the midnight sun. Of the present population trends that are
given for each species in Table 1, all auks except the black guillemot
_(Cepphus grylle)_ are decreasing, whereas the gulls, the gannets, and
the fulmars are increasing.
Table 6. _Population trends in colonies of the common murre_
(Uria aalge) _in Norway. Numbers for 1964 and 1974 are, when not
censused those years, extrapolated from present trends, using
estimated yearly decrease or increase from all available census
figures._
Number of Percentage yearly
breeding pairs[77] decrease (-) or
Locality 1964 1974 increase (+)
1. Utsira 2 1 -12.2
2. Utvær 23 14 -5.5
3. Veststeinen 32 27 -1.6
4. Klovningen 30 39 +2.8
5. Einevarden 28 31 +1.0
6. Runde 7,438 _6,000_ -2.2
7. Storholmen 9 7 (-2.2)[b],[c]
8. Røst _9,700_ _6,800_ -3.6
9. Værøy _2,400_ _1,750_ -3.2
10. Nykvåg 453 _350_ -2.6
11. Bleik _75_ _60_ -2.3
12. Sør-Fugløy 1,844 _10_ -68.5
13. Nord-Fugløy 13,201 3,681 -13.6
14. Loppa 900 _500_ -6.1
15. Hjelmsøy _110,000_ _70,000_ -4.6
16. Gjesværstappen 853 556 -4.4
17. Sværholtklubben 27 19 -3.2
18. Omgangsstauran 94 68 -3.3
19. Syltefjorden 13,299 _9,000_ -4.0
20. Hornøy _730_ _500_ -3.9
21. Reinøy _160_ _110_ -3.8
22. Kjøfjord 21 20 (-0.4)[78],[79]
23. Skogerøy 5 12 +10.1
24. Sagfjord 16 6 -10.1
25. Kobbholmfjord 1 5 +26.0
Total 161,341 99,566 -4.9
Table 7. _Status of the thick-billed murre_ (Uria lomvia) _in
Norway (cf. Fig. 3)_.
No. of Percentage of
breeding total _Uria_
Locality Year pairs population
1. Vedøy, Røst 1974 15 0.3
2. Værøy 1966 20 0.9
3. Hjelmsøy 1974 850 1.2
4. Gjesværstappene 1973 25 4.3
5. Syltefjord 1970 90 0.9
6. Hornøy 1966 55 8.1
7. Reinøy 1964 1 0.6
8. Kjøfjord 1970 1 4.8
Estimated number, Norway, 1974 >1,000 ca. 1.0
Table 8. _Status of the razorbill_ (Alca torda) _in Norway (cf.
Fig. 4)_.
--------------------------------------------------
No. of
Locality Year breeding pairs Percent
--------------------------------------------------
1. Kjør 1970 1 <0.1
2. Utsira 1970 25 0.1
3. Utvær 1970 16 0.1
4. Veststeinen 1970 22 0.1
5. Klovningen 1970 12 <0.1
6. Einevarden 1970 45 0.2
7. Runde 1974 2,800 9.5
8. Sklinna 1974 15 0.1
9. Lovunden 1968 8 <0.1
10. Røst 1974 3,900 13.2
11. Værøy 1974 800 2.7
12. Nykvåg 1966 250 0.8
13. Bleik 1968 28 0.1
14. Sør-Fugløy 1974 15 0.1
15. Nord-Fugløy 1967 10,000 33.8
16. Loppa 1969 750 2.5
17. Hjelmsøy 1974 7,000 23.7
18. Gjesvær 1973 2,500 8.5
19. Sværholtklubben 1973 18 0.1
20. Omgangsstauran 1973 6 <0.1
21. Kongsøy 1966 8 <0.1
22. Syltefjorden 1966 1,200 4.1
23. Hornøy 1967 65 0.2
24. Reinøy 1967 55 0.2
25. Kjøfjord 1970 9 <0.1
26. Skogerøy 1970 4 <0.1
27. Jarfjordnes 1970 3 <0.1
Total ca. 30,000
--------------------------------------------------
Since the coastline of Norway is about the same length as the
coastline of Great Britain and Ireland, it is interesting to compare
the population figures (Table 12), although the accuracy is very
different. Populations of auks and gulls are similar in both areas,
but the species composition is different. There are more terns in the
British Isles, but skuas _(Catharacta skua)_, shags _(Phalacrocorax
aristotelis)_, and great cormorants _(P. carbo)_ are present in similar
numbers. The most striking difference is the very small number of
procelli-forms and gannets in Norway compared to Britain and Ireland,
where they are almost as numerous as the gulls and the auks.
Table 9. _Status of the fulmar_ (Fulmarus glacialis) _in Norway_.
---------------------------------------
Number of
Number of breeding
County localities pairs
---------------------------------------
Nordland 6 140
Møre and Romsdal 7 945
Sogn and Fjordane 2 11
Rogaland 2 2
Total 17 1,098
---------------------------------------
Table 10. _Population increase of the gannet_ (Sula bassana) _in
Norway (cf. Fig. 5)_.
----------------------------------------------------------------------------
Mean yearly No. of breeding pairs
Year growth rate ----------------------------------
Colony established 1969-1974 (%) 1969 1970 1971 1972 1973 1974
----------------------------------------------------------------------------
1. Runde 1946 8.4 330 331 383 422 450 494
2. Mosken ca. 1960 5.4 50 83 77 60 62 65
3. Nordmjele 1967 83.3 7 36 65 103 127 145
4. Syltefjord 1961 14.5 28 29 44 48 51 55
Total 12.8 415 479 569 633 690 759
Yearly growth
rate (%) 15.4 18.8 11.2 9.0 10.0
----------------------------------------------------------------------------
Discussion
_Impact of Human Activity_
Direct Exploitation
According to Norwegian laws, all seabirds, with the exception (for some
odd reason) of the gannet and fulmar, can be hunted from 21 August
to 1 March. However, only the two species of murre and the razorbill
are still regularly hunted and, although no statistics support it, an
estimate based on interviews with some of the hunters reveals that
murres and razorbills are shot in the ratio of about 50:1. One man can
shoot as many as 380 murres and razorbills during a winter season as a
sideline to fishing. Although not many hunt on this scale, an absolute
minimum of 5,000 murres and razorbills are killed this way each season.
A new law based on modern principles of conservation has been under
consideration for several years, and this will mean an improvement.
However, the speed of the decline of the auks, particularly the
murres, makes it imperative to stop this hunting immediately, and it
is of very little economic importance to the few who take part. Some
illegal "fishing" for auks still takes place at Røst and Vaerøy, where
fishnets are anchored over wooden frames outside the auk colonies at
the beginning of the nesting season. At Vedøy on Røst in 1972, up to 80
murres were taken daily. Thus an estimated total of 500-700 murres were
taken that year--about 5% of the breeding population on this island.
Egg collecting was important during World War II, but in these more
affluent times and because of the relative inaccessibility of the auks'
nests, egg collecting is now both less attractive and less important.
Human disturbance of the breeding colonies, however, is gradually
becoming a more serious factor.
Table 11. _Comparison of annual growth rate and breeding success
in two colonies of gannets_ (Sula bassana).
----------------------------------------------
Mosken Nordmjele
---------------- ----------------
Annual Breeding Annual Breeding
growth success growth success
rate (%) rate (%)
----------------------------------------------
1969 62 --
1.66 5.14
1970 51 61
0.93 1.81
1971 36 46
0.78 1.58
1972 33 62
1.03 1.23
1973 50 35
1.05 1.14
1974 12 39
1969-1974 1.05 40 1.83 46
----------------------------------------------
Fishing Gear
Although on a scale different from that in western Greenland, drift-net
and longline fishing for Atlantic salmon _(Salmo salar)_ outside the
19-km (12-mile) limit off the northern Norwegian coast present a
serious mortality hazard to some seabirds. Reliable data exist only
for the longline fisheries. In the 1969 season (with 75 effective days
from mid-March to mid-June), one boat using 1,040 hooks per day caught
294 birds: 52 fulmars, 3 gannets, 43 kittiwakes, 107 murres, and 89
puffins. No razorbills were identified, but they may have been included
in the murre figure. If this sample is representative, the 100 or so
Norwegian boats using longlines plus about 20 Danish boats (which used
4,000-6,000 hooks per day and consequently caught more birds) would
have caught roughly 10,000 fulmars, 600 gannets, 9,000 kittiwakes,
21,000 murres, and 18,000 puffins in the 1969 season. The drift-nets in
Norwegian waters are reported to be less damaging to seabirds than are
the longlines, but even without adding the figures from the drift-nets,
the numbers are substantial in view of the size of the Norwegian
breeding populations.
Table 12. _Comparison of the number of seabirds breeding on the
coasts of Great Britain and Ireland (Cramp et al. 1974) and on
the coast of Norway._
Number of breeding pairs[80]
Species Great Britain and Ireland Norway
_Fulmarus glacialis_ 306,000 1,100
_Puffinus puffinus_ > 175,000 --
_Hydrobates pelagicus_ 10⁵ or 10⁶ 10³ or 10⁴
_Oceanodroma leucorrhoa_ 10⁴ 10²
_Sula bassana_ 138,000 760
_Phalacrocorax carbo_ 8,100 12,000
_P. aristotelis_ 31,000 33,000
_Stercorarius skua_ 3,100 1[81]
_S. parasiticus_ 1,100 8,000
_Larus ridibundus_ 74,000 4,000[82]
_L. canus_ 12,000 (150,000)[82]
_L. fuscus_ 47,000 9,000[82]
_L. argentatus_ 333,000 (260,000)[82]
_L. marinus_ 22,000 (40,000)[82]
_Rissa tridactyla_ 470,000 510,000
_Sterna sandvicensis_ 12,000 --
_S. dougalli_ 2,300 --
_S. hirundo_ 14,000 (13,000)[82]
_S. paradisaea_ (31,000) (21,000)[82]
_S. albifrons_ 1,800 --
_Alca torda_ (144,000) 30,000
_Uria aalge_ (577,000) 100,000
_U. lomvia_ -- 1,000
_Cepphus grylle_ 8,300 22,000
_Fratercula arctica_ (490,000) 1,250,000
Total ca. 3,000,000 ca. 2,500,000
Use of fishing gear close inshore, especially pound nets set near
colonies of diving seabirds, can take a heavy toll under special
weather conditions. In 1969 at Runde, 85 birds, mainly auks, shags,
and some diving ducks, were caught in one net in 24 hours; this is
an exceptionally high figure. The total loss of diving seabirds in
pound nets per year in Norway (about 6,000 nets fishing for 40 days)
was estimated to be at least 40,000 birds in 1969. The data are too
unreliable to give species composition, however, since fishermen rarely
make note of this.
Amounts of fish offal from offshore trawlers, drift-netters, and
longline fishing boats have increased in recent years, and some
seabirds, particularly kittiwakes, fulmars, and gannets make use of
this new and readily available food source. Thus, although the use of
fishing gear is a serious threat to seabird survival, fish waste from
the same boats provides an abundant food supply for the more pelagic
species.
Pollution
No quantitative investigation similar to those made in Great Britain,
Netherlands, and Belgium (Tanis and Bruyns 1968) has been carried out
on the impact of oil pollution on seabirds in Norway. The northern
Norwegian population of the most threatened species, murres and
razorbills, winter in North Sea coastal areas where oil pollution and
oiled birds have most frequently been found. It is possible that whole
populations winter every year in the same area, and if they happen to
be in a heavily polluted area, a particular population may be seriously
affected. Such an occurrence is believed to have caused the dramatic
decline in the Sør Fugløy population (cf. Table 5).
Although not yet serious, pollution by persistent toxic chemicals such
as organochlorines and mercury is a problem even in northern Norway,
because the northbound coastal current brings water masses, plankton,
and nekton from areas with industrial wastes. Analysis of the eggs of
herring gull _(Larus argentatus)_, murre, razorbill, and kittiwake in
1972 showed relatively low levels of mercury; the only species with
a relatively high level of mercury (mean 0.58 ppm) was the gannet
(Fimreite et al. 1974). This elevated toxic burden may have caused a
reduced breeding success for the gannet. Analysis of concentrations of
PCB's and DDT/DDE showed that the levels of these organochlorines were
generally also lower in Norwegian seabirds than in those of Britain
(Fimreite et al. 1977).
Protection and Necessary Conservation Measures
Total protection of some of the important seabird colonies (including
the surrounding nearshore waters) has proven very effective, especially
when the protection is so strict that landing is prohibited for a
specified period during incubation and fledging. However, to reduce the
rapid decrease of some species, a total hunting prohibition of those
species must be instigated, oil pollution must be reduced, and the
fisheries must be regulated to reduce the mortality caused by fishing
gear.
_Natural Factors Influencing Breeding Success_
The factors discussed so far are all results of human activities which
directly or indirectly influence seabird mortality. Yearly production
or breeding success is, however, also influenced by a number of
natural factors such as food supply, availability of suitable nest
sites, predation, climate (weather), and population-dependent factors
(age, breeding experience, population density). For the gannet, whose
breeding success has been studied in some detail (Brun 1974), it was
concluded that the differences in exposure (to severe weather) and in
breeding experience were the most important factors responsible for
annual fluctuation in breeding success. For such species as murres,
razorbills, and puffins, food supply is an important limiting factor.
If the spawning of the fish species that constitute their main food
items fails 1 year for some reason, it may be very difficult for the
seabirds to find an adequate alternative food supply and most of the
chicks starve to death. To a lesser degree, food supply is limiting
for the kittiwake, which seems to be more influenced by bad weather
(Norderhaug et al. 1977).
Conclusion
Two opposite population trends have been observed--the decline of the
coastal-bound murres and razorbills and the increase and spread of
the more pelagic gannets, fulmars, and kittiwakes. These changes are
attributed to a number of factors, which include the following:
• The diving murres and razorbills spend a major part of their time
swimming on the surface and are thus more susceptible to surface oil
pollution than are the pelagic species.
• The coastal-bound murres and razorbills are quite heavily hunted,
whereas there is no regular hunting of the pelagic species.
• The pelagic species are mainly surface feeders and do not swim under
water, and are thus less affected by the drift-nets than are diving
birds.
• The pelagic species are the principal beneficiaries of recently
increased supply of fish offal from trawlers.
Acknowledgments
The program was originally sponsored by Tromsø Museum, later University
of Tromsø, and has been financially supported by the Norwegian Research
Council for Science and Humanities and the Norwegian Game Fund. The
research grants are gratefully acknowledged. I also thank my field
assistants and the many local people at the breeding sites who have
been most helpful.
References
Brun, E. 1963. Ornithological features of Nord-Fugløy and
Sør-Fugløy. Astarte 1(22):1-13.
Brun, E. 1965. Brunnich's Guillemot, _Uria lomvia_ (L.), as a
breeding bird in Norway. (In Norwegian, English summary.) Sterna
6:229-250.
Brun, E. 1966. The breeding population of puffins _(Fratercula
arctica)_ in Norway. (In Norwegian, English summary.) Sterna
7:1-17.
Brun, E. 1969_a_. The breeding distribution and population of
guillemots _(Uria aalge)_ in Norway. (In Norwegian, English
summary.) Sterna 8:209-224.
Brun, E. 1969_b_. The breeding distribution and population of
razorbills _(Alca torda)_ in Norway. (In Norwegian, English
summary.) Sterna 8:345-359.
Brun, E. 1971_a_. Census of Puffins _(Fratercula arctica)_ on
Nord-Fugløy, Troms. Astarte 4:41-45.
Brun, E. 1971_b_. Breeding distribution and population of
cliff-breeding seabirds in Sør-Varanger, north Norway. Astarte
4:53-60.
Brun, E. 1971_c_. Population changes of some seabirds in south
Norway. (In Norwegian, English summary.) Sterna 10:35-56.
Brun, E. 1972. Establishment and population increase of the gannet
_Sula bassana_ in Norway. Ornis Scand. 3:27-38.
Brun, E. 1974. Breeding success of gannets _Sula bassana_ at
Nordmjele, Andøya, north Norway. Astarte 7:77-89.
Coulson, J. C., and E. White. 1959. The post-fledging mortality of
the kittiwake. Bird Study 6:97-102.
Cramp, S., W. R. P. Bourne, and D. Saunders. 1974. The seabirds of
Britain and Ireland. Collins, London. 287 pp.
Fimreite, N., J. E. Bjerk, N. Kveseth, and E. Brun. 1977. DDE and
PCBs in eggs of Norwegian seabirds. Astarte 10:15-20.
Fimreite, N., E. Brun, A. Frøslie, P. Frederichsen, and N.
Gundersen. 1974. Mercury in eggs of Norwegian seabirds. Astarte
7:71-75.
Holgersen, H. 1951. Investigations of seabirds in Rogaland
1949-1950. (In Norwegian, English summary.) Stavanger Mus. Arb.
1950:61-76.
Lütken, E. 1965. The breeding birds on Nord-Fugløy, north Norway,
their distribution and numbers. (In Danish, English summary.)
Dansk Orn. For. Tidsskr. 58:166-193.
Norderhaug, M., E. Brun, and G. U. Møllen. 1977. Barentshavets
sjøfuglressurser. Forhold i tilknytning til status,
miljøproblemer of forshningsoppgave. Medd. Norsk Polar Inst.
104:1-119.
Regnell, S. 1957. Fran det nordnorska fåggelberget Bleiksøya. Fauna
Flora, Upps. 52:199-202.
Soot-Ryen, T. 1941. The seabird rookeries of Troms county. (In
Norwegian, English summary.) Tromsø Mus. Aarsh. 62(1):1-112.
Tanis, J. J. C., and M. F. M. Bruyns. 1968. The impact of oil
pollution on seabirds in Europe. Proc. Int. Conf. Oil Pollution
of the Sea 1968:67-74.
Valeur, P. 1947. Havhesten og havsula på Rundøy. Naturen 70:370-379.
Willgohs, J. F. 1952. On the distribution of some seabirds in
western Norway. Univ. Bergen Årb. 1951 Naturvit. Rekke (9):1-20.
Willgohs, J. F. 1955. Om forekomsten av endel kyst-og sjøfugl på
Vestlandet. Fauna, Oslo 8:16-27.
FOOTNOTES:
[74] Deceased.
[75] Numbers in parentheses are not based on a complete census of the
coast.
[76] In addition, an unknown number of pairs breeding inland.
[77] Numbers in italics were censused from 1964 and 1974.
[78] Estimated values from trends in neighboring colonies.
[79] Numbers in parentheses are not based on a complete census of the
whole coast.
[80] Numbers in parentheses are not based on a complete census of the
whole coast.
[81] New in 1975 (Wim Vader, personal communication).
[82] In addition, an unknown number of pairs breeding inland.
SYMPOSIUM SUMMARY
Conservation of Marine Birds of Northern North America--A Summary
by
Ian C. T. Nisbet
Massachusetts Audubon Society
Lincoln, Massachusetts 01773
This is not going to be a straightforward summary of the conference
because it is my view that a number of important topics have not been
addressed. In particular, what was supposed to be the main theme of the
conference--the need for _conservation_ of marine birds of northern
North America--has been taken for granted by many speakers and has
been treated by others in what may be a misleadingly brief way. So
instead of simply summarizing the information that has been presented
in the papers, I want to give my own views about how we should use
this information to make a case for the conservation of marine birds.
I feel strongly that we can make a good case for conserving them, and
that we know enough to start doing so. The task of making a case for
conservation and of proposing priorities for action has been left to me
as the conference summarizer.
Particularly in the first half of this conference, we heard a long
series of accounts of the birds of the area which stressed our
ignorance--large amounts of information that was not known and large
amounts of research that needed to be done. Now, I have an unexpected
advantage over most of these speakers in that I have very little direct
experience in the area. What I learned from their papers, not having
any very clear picture of the islands, the birds, their habits, or
the food that they eat, is that we already know quite a lot about the
marine birds of northern North America. We certainly know enough to
decide what we ought to do next and how to take the basic steps in
conserving them.
After listening to the presentations, reading the abstracts, and
studying the maps posted in the conference hall, I drew up a list of 10
points that I will first list and then elaborate on.
• We know that we are discussing a very important biological resource
which has been neglected for a long time.
• We know roughly what this resource consists of and which aspects of
it are biologically important.
• We know why this resource is in its present condition, and we know
something about the ways in which it is related to other resources.
• We know a certain number of things that the birds do which make them
vulnerable to changes in the environment.
• We know that the resource has already been disturbed in the past,
both by human-induced and by natural changes, and we know that it has
already been damaged.
• We can identify at least some of the major threats that the resource
will face in the next few years.
• We know that the resource can be conserved, at least to a modest and
partial extent.
• We have a fairly good idea of what we ought to do now to start
conserving the resource.
• We have some ideas--so far rather rough and ill-formulated--about why
we should conserve the resource.
• We know--or so I believe--that it is practicable and economically
feasible to conserve the resource.
I am sure that there will be some disagreements with some of these
assertions, especially with the last two, so I will give reasons why I
believe that we should conserve these birds and that we can afford to
do so.
Magnitude and Importance of the Resource
The papers in the first half of the conference which reviewed the
abundance and distribution of the birds in the northern North Pacific
Ocean, the Bering Sea, and adjacent seas suggested that we are dealing
with numbers of birds of the order of 100 million. That is 100 million
birds at sea plus some unknown number of millions of birds along the
shore. We do not have to take these numbers literally--I am sure
that the persons who produced them did not mean them to be taken
literally--but certainly we are talking about something on the order of
tens of millions and not much more than some hundreds of millions. At
least, it is on the order of a hundred million rather than ten million
or a billion. I do not think it an exaggeration to say that this is one
of the great neglected biological resources of the world.
Characteristics of the Resource
Three important aspects of this resource have not been identified
clearly in the papers delivered at the conference, in part because the
papers summarizing the biological surveys did not include much of the
detail that was available in the maps posted in the conference hall.
[Maps in this volume do not show the detail of those posted.] These are
the numerical abundance of the birds, their diversity, and their unique
characteristics.
As to abundance, figures have been mentioned on the order of 50 million
for shearwaters (_Puffinus_ spp.) and 25 million for murres (_Uria_
spp.). For other species the quoted numbers have been less specific,
but I would estimate from what I have read and heard that the total
population must run into millions for eiders (_Somateria_ spp.),
kittiwakes _(Rissea brevirostris)_, and fulmars _(Fulmarus glacialis)_,
and doubtless for other species. The numbers of the smaller alcids, in
particular, must be very great.
As to diversity, there is an impressive number of species and a wide
variety of habitats. We have been shown in the photographs some
spectacular island colonies, particularly in the Bering Sea and the
Aleutian Islands, some of which have a remarkable variety of species.
Several different definitions of "seabird" have been used at this
conference, but certainly there are dozens, and probably scores, of
genuine marine species that either breed in the area or use it as a
major nonbreeding area. The collection of birds in the area of the
North Pacific and the Bering seas seems more impressive in terms of
both abundance and diversity than anything in the north Atlantic Ocean,
which has been so much more fully studied.
As to the uniqueness, there has been almost no mention of the endemic
species at the conference. It is therefore important to emphasize
in this summary that a significant group of marine or coastal
birds is endemic to this area. These birds include the red-legged
kittiwake (_Rissa_ spp.), the Aleutian tern _(Sterna aleutica)_, the
spectacled eider _(Somateria fischeri)_, the emperor goose _(Philacte
canagica)_, and the red-faced cormorant _(Phalacrocorax urile)_; a
number of alcids, including the whiskered _(Aethia pygmaea)_, parakeet
_(Cyclorrhynchus psittacula)_, crested _(A. cristatella)_, and least
auklets _(A. pusilla)_; the horned puffin _(Fratercula corniculata)_;
and Kittlitz's murrelet _(Brachyramphus brevirostris)_. In addition, we
should not forget some migrants that make exclusive use of this area
in their nonbreeding season. These include the short-tailed albatross
_(Diomedea albatrus)_, the scaled petrel _(Pterodroma inexpectata)_,
and I believe also Cook's petrel _(P. cookii)_, which has not
previously been mentioned. From the little we know about its off-season
distribution, the short-tailed albatross appears to use these waters
exclusively; hence it has as much claim to be regarded as an endangered
species of the United States as the whooping crane _(Grus americana)_.
Perusal of the lists of species presented at the conference brings out
one important point. Although we are meeting in the United States and
have been looking at the birds from a United States-Canadian viewpoint,
this is truly an international resource in almost every respect that I
have mentioned. The most abundant species, in terms of both numbers and
biomass, is probably the short-tailed shearwater, a migrant from the
southern hemisphere. The rarest species, and the most endangered, is
the short-tailed albatross, which breeds only on one island in Japan.
There are migrants in large numbers from Chile, Australia, New Zealand,
and especially the Soviet Union. All of these use the area of ocean
and shallow sea that we have been considering as a major area for a
substantial part of their annual cycle.
What more do we need to know about the extent of this resource? In my
opinion we should not place high priority on determining the exact
numbers of the birds--whether there are 25 million or 26 million
murres, for example. It would be difficult, if not impossible, to
determine such numbers in the kind of geographical and climatic area we
are considering. Moreover, even if we were to measure the populations
with great accuracy and to determine in a few years that they had
changed by 10%, we would not be able to draw any conclusions about the
reasons for the change or what should be done about it.
To set priorities for further exploration, I think it is more important
to survey in greater detail the general distribution of the breeding
colonies. So far, we know the location of only the largest colonies;
we know almost nothing about the colonies of a mere 10,000 pairs or
less. So I think future surveys should concentrate on locating the
medium-sized colonies and getting some impression of roughly how many
smaller colonies there are. It is important to locate and be sure that
we know of all the major colonies that have a considerable number of
species; these large, diverse colonies should be given priority for
conservation. Most important of all, we need to locate and survey the
endemic species with some precision. This need is especially great for
the species that we suspect are limited to small areas or that may
otherwise be particularly vulnerable.
If we are to measure population changes over the next few decades, it
is of course essential to have a good base-line survey. However, I do
not think it is either practicable or desirable to try to inventory
the entire population of breeding seabirds with great accuracy. A
more realistic and worthwhile program would be to select some sample
colonies and to catalogue these sample areas in some detail, preferably
with a photographic record, so that they can be resurveyed in later
years to determine whether substantial population changes have taken
place. Criteria for selection of sample colonies for inclusion in this
base-line survey should include not only numerical size and species
diversity but also ease of access, ease of observation, and the
practicability of obtaining good photographic records.
Ecology and Functioning of the Resource
In the opening session of this conference, several speakers reviewed
our general knowledge of the ecology of seabirds; others summarized
our specific knowledge of the birds of the North Pacific, Bering, and
adjacent seas, and their relation to physical and biological factors
in the environment. There is no need to summarize these reviews again
here except to point out that information on the relation between the
birds and the marine environment is being generated very rapidly. We
are beginning to understand the factors that control the breeding
distribution of the individual species, their foraging strategies, and
their dispersion at sea, at least in summer. However, it is clear from
what has been said at this conference that we know much less about
their ecology and distribution in winter. This lack of information
is important because conflicting opinions have been expressed as to
whether factors operating in the winter range or at the breeding
colonies are more critical in limiting population size.
It is evident from what was said in the opening session that the
distribution of the birds is very closely related to the distribution
of marine resources. It is clearly no accident that the distribution
of large numbers of many species of birds coincides with that of the
major fisheries. Similarly, it is no accident that there is a relation
between the distribution of birds and the extent of the continental
shelf. These coincidences, which reflect the fundamental dependence
of both birds and fish upon marine productivity, set the stage for
existing and further conflicts between conservation of the birds and
human exploitation of other resources of the area.
Perhaps the most significant gap in our knowledge of North Pacific
seabirds is in the area of productivity and demography. As far as
I can judge, we know almost nothing about the breeding success of
these birds, their post-fledging survival, their longevity, their
age at first breeding, the age structure of their populations, the
fluctuations in their breeding performance, or their survival from year
to year. For most species, we lack even the most basic life history and
life table information.
If we can argue by analogy from studies made in other parts of
the world, including the North Atlantic, we can make some basic
generalizations that we would expect to apply to the birds of our area.
We know that as a class seabirds have some peculiar characteristics
which make them difficult to manage and cause some of the problems we
have in conserving them. In general, they are long-lived and breed
slowly, most lay small clutches, and the historical experience is that
they take a very long time to recover from depletion of population.
Many have an irregular breeding performance; some have long series of
bad years interspersed with occasional years of good breeding success.
Many seabird populations have traditionally fluctuated, as exemplified
by those of the North Atlantic, whose fluctuations were described by W.
H. Drury and W. R. P. Bourne.
Some species of seabirds are conservative, staying in the same colonies
for many years or generations. Others are volatile, dispersing freely
from one site to another and forming new colonies in an unpredictable
way. Seabirds exhibit a wide range of ecological adaptations; some are
highly specialized, others are highly generalized and adaptable. These
differences can be very important when their environment changes, as
D. N. Nettleship's film "Puffins, predators, and pirates" graphically
illustrated.
As M. T. Myres pointed out on the 1st day of the conference, seabird
populations exhibit both short-and long-term fluctuations. Long-term
fluctuations are those that take place over times comparable to the
generation time of the species, which may be many years or even decades
for some seabirds. By surveying populations and measuring changes in
them, we usually obtain information only about long-term population
trends, reflecting long-term changes in the environment. Short-term
perturbations in the environment are usually not reflected quickly
by changes in total population--certainly not by changes that we can
measure with the accuracy of our present-day census techniques. Many of
the man-made changes we are concerned about are short-term. To identify
their effects we should look not for changes in total population but
rather for changes in biological parameters, such as the first-year
survival rate or the number of young raised. I therefore suggest that
some of the most critical parameters to be measured are changes in age
structure of populations. We should therefore select as biological
monitors species that can readily be aged--for example, gulls, which
have a sequence of distinguishable immature plumages.
In specifying gaps in our knowledge of the ecology of birds, we should
set clear priorities rather than compile a long "shopping list" of
research projects. On the basis of the foregoing survey, I would
suggest the following as priority items for further study. First, we
need to know a lot more about winter distribution, not only of the
marine birds, but also of inshore and coastal species. Second, we
need to study in greater detail the relation between the day-to-day
distribution of birds and the local patchiness of the resources on
which they depend. Evidence that seabirds are able to locate and
use fluctuating and shifting food sources has been given by several
speakers at the conference. We need to understand how birds locate
these resources and what relation this has to their survival and
vulnerability to human activities. There is a special need to study the
ecology of endemic species because their conservation is of special
importance. We need to learn more about the relation of the birds to
the commercial fisheries, both to resolve existing or alleged conflicts
and to avert future problems.
However, I believe that the highest research priority should be given
to obtaining basic information on reproductive success and life table
data for some representative species. Clearly, we cannot study many
species in detail, but in selecting key species for such studies we
should pick a variety of ecological types--for example, at least one
generalist species and one specialist, one sedentary species and one
migrant, one species at a high trophic level and one at a low trophic
level.
For the purpose for which we convened this symposium--conservation--I
do not think that we need detailed knowledge of the factors which
regulate populations. Such knowledge is, of course, of immense
biological interest and will ultimately be needed for effective
long-term management. However, it does not have immediate or even
medium-term relevance to the urgent problems of conservation that we
now face. What we do need to do is to set up some long-term studies of
a few carefully selected species--preferably long-lived species--so
that we can trace the effect of environmental fluctuations on their
performance for a long period.
Vulnerability of the Resource
We already understand a number of factors that make some of these bird
populations particularly vulnerable to the kind of human activities
which we can envisage in the next decade or two. Most of the breeding
birds concentrate on islands where they are vulnerable to predators
and to human disturbance. Many of them concentrate in flocks on human
fishing grounds and over other areas of the continental shelf which
are likely to be the focus of human activity in the near future.
In particular, some of the birds are known to concentrate in the
passes through the Aleutian Islands, where they will be particularly
vulnerable to future oil spills. In all these ways the birds are
concentrated in areas where they are likely to receive disproportionate
impacts from human activity and exploitation.
One point that has been barely mentioned in this symposium is the
effect of molting on the vulnerability of some of these populations.
The eiders, for example, concentrate on molting grounds in the Arctic.
The exact location of these molting grounds may not be fully known,
but we certainly know that the birds molt somewhere in an area where
they will be vulnerable to oil spills (and also to human hunting if
the people who move to the Arctic choose to hunt them). Nor are eiders
the only species that are flightless when they molt. Some alcids and
loons are also flightless for short periods and, hence, particularly
vulnerable to oil spills during molt.
Past Damage to the Resource
In the speech opening the symposium, Assistant Secretary Reed referred
to this biological resource as still relatively unspoiled. While
"relatively" may be an appropriate word, we do have spectacular
evidence of changes and damage to these bird populations. The use of
the Aleutian Islands for fox farming seems to me a quite horrifying
situation. We know also that the early whalers and sealers exploited
seabird populations. Although I know of little specific information
about the effects of such exploitation on birds in the northern North
Pacific, D. G. Ainley in his survey of historical records from the
Farallon Islands has shown very clearly the massive effects of human
exploitation of birds, starting early in the 19th century. In our area
of discussion alone, one species (the spectacled cormorant) is extinct
and another (the short-tailed albatross) became virtually extinct and
is still very rare. I believe that one or two southern hemisphere
species, which must have been substantial elements in the northern
summer bird population, have also been seriously depleted as a result
of human activity on their breeding grounds.
Several speakers emphasized the importance of long-term fluctuations
in bird populations resulting from natural causes, including some
examples from the North Pacific. Other types of human activity must
also have had some indirect effects on the birds. For example, whaling
and sealing in the 19th century must have provided large amounts of
food for scavenging birds and eliminated important competitors for the
larger fish-eating birds. A similar experiment is now in progress as
the predatory fish are being overfished.
Major Threats to the Bird Populations
We now know enough about the distribution and ecology of the seabirds
to identify the major threats to them that are likely to be posed by
the projected increase in human activity in the coming decades. The
relative importance of these threats clearly varies from species to
species and from area to area. However, I think that few of us would
disagree that the largest single threat in the area as a whole is posed
by oil, not only by the prospect of large-scale drilling for oil on
the Alaskan continental shelf but also by prospective spills during
transportation and deliberate dumping from ships.
My guess is that the second most important threat to the seabirds of
the northern North Pacific is the presence of introduced predators,
especially foxes and rats, at the breeding colonies. Much of the damage
inflicted by these predators may already have been done, but I think
their continuing presence is likely to have as great a negative effect
on the bird populations as anything else discussed at the conference.
The relative importance of the other identifiable threats to the birds
is even more conjectural. Drowning of diving birds in fishnets is
obviously of great potential impact, but its importance depends greatly
on the rapidly changing practices of fishermen. This problem must be
kept under close surveillance, and the establishment and enforcement of
international agreements will be critical.
Mineral development has not been mentioned much. It is my understanding
that there are prospects for substantial onshore, and perhaps offshore,
developments of heavy metal minerals. These are likely to lead to local
disturbance in the coastal zone, and the tailings in particular may
well pose a threat to coastal and inshore birds.
Ocean dumping has not been mentioned. I do not expect that there will
be much dumping of toxic chemicals from Alaskan industries, but we
must remember that this area is downstream from Japan and the Soviet
Union. I do not know the current practices of these countries, but the
unregulated dumping of toxic substances from some European countries
apparently has led to large-scale pollution problems in the North
Atlantic.
On present evidence, persistent pesticides and polychlorinated
biphenyls (PCB's) do not seem to pose a significant threat to north
Pacific seabirds, although high levels of PCB's have been reported in
shearwaters off the California coast. In my judgment, we have probably
turned the corner in regulating these chemicals, at least in the
northern hemisphere, and their impact will probably not be allowed to
get worse.
Human disturbance is obviously going to get very much worse, both
from the influx of new human populations who will be involved in more
industrialized activities in Alaska and from the likely increase in
tourism. A matter of particular concern is the prospective influx of
natural history tours, which can have major adverse effects if not
carefully regulated.
Finally, we should not forget the impact of natural phenomena,
including climatic changes and vulcanism. Bearing in mind the
experience of Katmai, we might expect a natural disaster to strike a
major bird colony at any moment.
Practicability of Conservation
Experience from other countries, as related in various papers at this
conference, has shown that conservation of seabirds is possible and
practicable, even in remote and inaccessible areas. We have heard today
particularly about conservation programs and achievements in Europe
and New Zealand. W. H. Drury spoke briefly about experience in eastern
North America and F. Salomonsen told us how the bird populations of the
Faeroes Islands have been managed for sustained yield.
At least in the North Atlantic, where the history of the bird
populations is much better known, the conservation situation has been,
and probably still is, very much worse than that now prevailing in the
North Pacific. Looking back on 200 years in the North Atlantic, we find
that two major marine species have been extinguished, at least one and
probably two or three others became endangered, and almost all the
seabirds were drastically reduced in numbers (at least in temperate
latitudes). Starting in the late 19th century when many species first
received effective protection, most showed impressive recoveries, but
some have declined again in the last 30 years.
We can learn several lessons from that experience. One is that we
can do great damage to seabird populations in a very short time if
we do things that cause substantial adult mortality. A second is
that seabird populations can recover well with protection and modest
management--although most of them, being slow breeders, recover slowly.
A third lesson is that in the last 30 years we have caused substantial
damage through oil spills, human disturbance at the breeding colonies,
chemical pollution, and indirectly by promoting the spread of gulls.
Much has been said at the conference about these present-day human
impacts. However, with the sole exception of the oil spills which have
affected alcids and sea ducks in parts of northwest Europe, it seems
to me that the damage caused by human activity in the past 30 years is
considerably less than that in the last 30 years of the 19th century.
Another lesson we can learn from the recent experience in other
areas is that it is possible to ameliorate some of these adverse
human impacts with local, small-scale, and even rather amateurish
management activities--for example, protecting seabird colonies from
gulls, regulating human visits, and controlling the use of the most
toxic chemicals. Our most conspicuous failure is in controlling oil
pollution. Although safety precautions imposed on offshore drilling
rigs and at shipping terminals have proved reasonably effective in
averting major damage to seabirds, attempts to control oil pollution
during transportation have been essentially fruitless. Tanker accidents
and deliberate discharges from vessels remain the major threat to
seabird populations.
Another lesson from other areas is that public education has been
very effective in putting pressure behind conservation measures, and
is doing so increasingly. At the same time, however, it is resulting
in an increase of the disturbances that the birds suffer at their
breeding grounds from casual visitors, photographers, and sometimes,
well-meaning naturalists.
Finally, in very recent years, there have been encouraging developments
in rehabilitating oiled birds, captive breeding, and reintroduction
into areas from which they have been depleted. Restoration of seabird
populations no longer seems an impossible goal.
Conservation Needs for North Pacific Seabirds
We now know enough about the seabirds of the northern North Pacific
to specify in principle what should be done immediately to conserve
them. I will not address the institutional arrangements needed for
conservation; R. E. LeResche's paper presented a very clear picture of
the institutional problems involved in protecting and managing seabirds
on an interregional and international basis. I will simply endorse
his principal recommendation: that we should try to bring the various
responsible agencies together to formulate comprehensive management
plans.
On the level at which we as individuals and as a group of biologists
can work, we can already make some positive recommendations. The most
important is that since prevention of damage is a lot better than cure,
measures to avert damage should have the highest priority. We have
heard a great deal from the oil industry about the "inevitability" of
accidents. One speaker mentioned the "inherent fallibility of man."
Well, we are all fallible, but the experience of the last 50 years is
that some people are more fallible than others. No oil company has a
perfect record, but some have 10 times as many accidents as the best,
and some, I believe, have considerably more than 10 times as many. This
means, very simply, that it is possible to eliminate most--not all,
but most--of the major threats to the seabirds, merely by upgrading
the safety performance of the entire industry to that already achieved
by its best segments. I suggest that our major challenge in the coming
years is to work for effective regulation of the industry: to achieve
regulations which will decisively penalize bad performance and as
decisively reward care.
Perhaps the second priority in conservation is to protect and manage
the existing breeding colonies. In most cases protection is legally
feasible if we have the will. Most of the major colonies are in
remote areas or in public ownership where development and disturbance
can be controlled. Management of the breeding populations is less
straightforward, however, because we do not know enough about the
functioning of this complex biological resource. Seabird populations
fluctuate and they have a very long response time, the environment
is not constant, we do not understand the dynamics of multispecies
communities, and we do not know how they respond either to external
changes or to our attempts to manage them. Management will have to be
improvisatory for a very long time. We must recognize that effective
conservation of a bird population with a 20-year generation time will
take at least 20 years to show results.
Another priority task is to control predators. I have been impressed
by the evidence we have for major effects of predators on the seabird
populations here. I would regard control of predators and management of
habitats on some of the major seabird islands as an extremely urgent
task.
A longer-term but no less important program is public education. This
program has several important aspects: one is to increase public
support for political actions and effective regulations to protect
seabirds; another is to educate the public about the vulnerability of
seabirds and to prevent disturbance or deliberate human destruction.
Another aspect of public education is to develop public interest
by making some of the birds more visible. The great problem with
this biological resource we have been talking about is that no one
knows it is there. Probably half of us did not know how substantial
and important a resource it is even 5 years ago. In setting up a
large-scale conservation program, we should not make the mistake of
basing it only on the most remote and inaccessible colonies, even
if these are the most important numerically. Many of the smaller
colonies are locally very important, both biologically and for human
interest and education. One example given at this conference was the
State of Washington's program for conserving what are, by northern
Pacific standards, quite small colonies. This program is important
and impressive because it is conserving bird populations near people
who want to see the birds. We have the same sort of situation in
Massachusetts and Maine, where effective protection programs have been
established for extremely small seabird colonies. We have learned
from these programs that a few hundred birds, or even a few dozen if
properly managed, can be of immense educational importance. If human
access is carefully managed so that people can see the birds without
disturbing them, these programs can generate support for conservation
of larger bird populations that may be thousands of miles away where
people may never see them.
A Rationale for Conservation
As I have tried to show, we know something about the importance of
this biological resource, and we know in outline what we should do
to conserve it. But why should we? Almost no one knows the birds are
there. We ourselves do not know whether there are 50 million or 250
million birds in the north Pacific Ocean. Who cares if 10 million
disappear? If we cannot give a good answer to this question, we might
as well go home and study chickadees instead.
To justify spending money on conserving marine birds--or any other
natural resources--we must establish their value. Some of the arguments
made in this conference for assigning economic values to seabirds have
been dangerously weak. The annual value of "muttonbirds" _(Puffinus
tenuirostris)_ in the New Zealand markets is about $70,000. Some
speakers have tried to argue that seabirds might play some subtle role
that we do not yet understand in regulating marine communities--perhaps
they weed out the sick fish. The direct economic values that we have
specified for seabirds are really not very impressive, even in terms of
the costs involved in conserving and studying them. The biggest number
we have heard for the value of these seabirds is the amount of money we
are spending on surveys.
However, this is not the real issue. In judging the costs and benefits
of a conservation program, we should not look just at the value of the
birds as meat, or oil, or indicators of pollution. The real issue here,
as in all economic problems, is the rational allocation of resources.
H. Boyd posed the rhetorical question: "Why should we waste public
money on conserving birds when there are so many other things to spend
it on?" The question is more properly posed in reverse: "Why should the
government waste so much public money on unproductive projects when
only a small amount of money can achieve conservation of these birds
which some people think are important?"
The fact is that we already know why we should allocate resources to
conservation. I believe that we have just been evading the answer.
We ought to conserve these birds because many people want them to be
conserved.
This is not, as one speaker said, an elite interest. The public, as
we well know, is already willing to spend money to conserve natural
resources and is increasingly demonstrating that willingness. The
public, in fact, is ahead of the administrators and bureaucrats. To
appreciate this, we need only look at some of the laws already on the
books. The Congress of the United States, in the National Environmental
Policy Act of 1969, declared that it was the national policy to
"create and maintain conditions under which man and nature can exist
in productive harmony, and fulfill the social, economic, and other
requirements of present and future generations of Americans." The
Marine Mammal Protection Act of 1972 found that "marine mammals have
proven themselves to be resources of great international significance,
esthetic and recreational as well as economic, and it is the sense of
Congress that they should be protected and encouraged to the greatest
extent feasible commensurate with sound policies of resource management
and that the primary object of their management should be to maintain
the health and stability of the marine ecosystem." As these laws have
been enacted, their language has become progressively stronger. The
Endangered Species Act of 1973 declares as the policy of Congress "that
all federal departments and agencies shall seek to conserve endangered
species and threatened species and shall use their authorities in
furtherance of the purposes of this Act" (P.L. 93-205). It further
directs all Federal departments and agencies to carry out conservation
programs for the conservation of endangered or threatened species and
to insure that their actions do not jeopardize the continued existence
of these species or destroy or modify critical habitat.
These references are not only to Federal laws passed by remote
politicians who can vote with only a modest responsibility to their
constituents. As we have heard, there are many State laws and local
ordinances which specify the same kind of thing. All these laws are on
the books for a powerful reason: public opinion was behind them. The
fact that they have not been enforced and implemented fully means that
we have not been doing our job.
In fact, there is no philosophical problem in justifying conservation.
What we face is an institutional problem. There is both a public
determination that natural resources should be conserved and a public
apathy and bureaucratic resistance toward doing it. As concerned
biologists, we should be combating this apathy by pointing out that
conservation represents a rational allocation of public resources.
Those who do not learn the lessons of history are destined to repeat
it. If we study the history of conservation, we find that it developed
most rapidly in those countries which mismanaged their natural
resources earliest. Within the developed countries there has been a
progressive historical trend toward rational use and conservation
of natural resources. Conservation of natural resources, in fact,
represents the future and, as biologists, it is our duty to promote it.
Economic Feasibility of Conservation
Conservation is cheap. Most of us are accustomed to working on what
are essentially shoestring budgets--on the order of $100,000, $10,000,
or even $1,000 per year. When we hear of a million dollars as the cost
of doing something, we tend to think of it as a lot of money. H. Boyd
mentioned a situation on Baffin Island, where it would cost about a
million dollars to dispose of mine tailings on shore instead of dumping
them into the ocean under a fulmar colony. I do not think a million
dollars is very much--certainly not in comparison with the cost of
restoring a colony of half a million fulmars.
We heard this morning about the acquisition of Protection Island at
a cost of several hundred thousand dollars. It was pointed out that
it could have been acquired much more cheaply only a few years ago.
Acquisition of habitat is cheap if we do it now compared with what it
will cost in a few years or a few decades. Management is cheap. None of
us gets paid very much, but each of us could manage several colonies
with a couple of students to help us. Wardens are cheap. Surveys are
cheap. The cost of conserving seabirds is minuscule in comparison with
the amount spent on the exploitation of resources that threatens them,
and it is minuscule in relation to the cost of restoring a seabird
population after it has been depleted.
It is far cheaper to avoid oiling birds than it is to rehabilitate
them and to reestablish them in breeding colonies in the wild. It
costs nothing at all to award leases to companies that have a good
safety record and to refuse leases to companies with bad records. It
costs a little more to maintain good safety practices in drilling
and transportation. It does cost more to transport oil in small,
double-bottomed tankers with well-trained crews than to transport it
in big ships flying flags of convenience, but the cost differential is
very small compared to the value of the shipment.
In considering the economics of conservation, we have to weigh
the costs of conservation against the value of the resource being
exploited. Full-scale development of oil reserves on the Alaskan
continental shelf would generate economic values on the order of
ten billion dollars per year. Of this total, 0.1% would support a
reasonably sized management program for the threatened resources. About
1% of the total, or 12¢ per barrel of oil, would not only support an
ample management program but also permit management of many other
coastal zone resources. Yet the experience of the last few years
has shown that an increase in oil prices of 1% is barely noticed by
consumers.
The point I am trying to make is that extracting oil carefully does not
cost significantly more than extracting it carelessly. If we can solve
the institutional problems--and I do not underestimate the difficulty
of doing so--we are not talking about an irrational use of resources.
Conservation is feasible; it is worthwhile; it is not expensive; and
there is a public demand for it.
Conclusions
Practical conservation is an adaptive process. It is not at present a
process that is firmly based in ecological theory. It is one in which
we have to start by doing something, see whether it works, and then
change our program in accordance with our early experience. I do not
believe that we can wait for detailed knowledge of population sizes, or
ecology, or demography, or trophic importance, or any other biological
attribute of these birds before we start conservation and management.
As scientists we do, of course, find it interesting and important to
study these things. We should do so; we need to do so; but we should
not use our ignorance of detail as an excuse for delaying action. If
this seabird resource is worth conserving, we should start now.
Summary
The marine birds of the northern North Pacific Ocean, Bering Sea,
and adjacent seas constitute one of the great neglected biological
resources of the world.
This resource is impressive in terms of both total numbers (probably
of the order of 100 million birds) and species diversity. A number of
species are endemic to the area and hence of special interest.
The resource is international in that it includes major populations of
migrants from Chile, New Zealand, Australia, Japan, the Soviet Union,
and other countries. Several migrant species appear to use this area
exclusively in their nonbreeding season and should be included in the
list of endemics.
The general relation between the distribution and abundance of seabirds
and other marine resources is beginning to be understood. However,
comparatively little is known about the distribution of seabirds in
winter, and there is a serious dearth of information about breeding
success, survival, and demography.
Seabirds in the north Pacific Ocean and adjacent seas are concentrated
over the continental shelf and in areas of high biological
productivity. Hence they are especially vulnerable to human
exploitation.
Seabirds of the northern Pacific Ocean have already been damaged by
human activities in the past and present. Experience in other areas
shows that seabirds are extremely vulnerable to human activities and
their populations are often very slow to recover.
The most important threats to the seabird resource are oil drilling
and transportation and introduced predators, especially foxes. Other
identifiable threats include mineral exploitation, fishing, ocean
dumping of toxic chemicals, and human disturbance, including both
hunting and tourism.
Experience in other parts of the world, especially in the North
Atlantic, has shown that seabird populations can be protected and
restored through modest programs of management and public education.
The principal exception has been the failure to regulate discharges of
oil at sea, which continue to cause major damage to seabird populations
in many areas.
In the North Pacific and Bering Sea areas, the most urgent conservation
needs are effective regulation of prospective oil exploitation, control
of introduced predators, and public education. Regional management
plans should be developed. Public access to bird colonies should be
managed carefully to combine protection with public education.
Conservation programs for seabirds can be justified as a response to
increasing public demand for rational management of natural resources.
Conservation programs are inexpensive in relation to the economic
values generated by oil and mineral development. They represent a
rational allocation of economic resources.
The following priorities for further study are suggested:
• Study of productivity and demography in a few carefully selected
species to provide basic life table data that will permit rapid
identification of future changes.
• A base-line census of some carefully selected breeding colonies,
including precise photographic surveys that can be used to measure
future population changes.
• Surveys of the distribution of seabirds of the North Pacific and
Bering Sea in winter, with special emphasis on areas close to shore
where birds may be vulnerable to oil pollution.
• Special studies of endemic species.
• Studies of the way in which seabirds locate and use patchily
distributed food resources.
The following conservation measures are suggested:
• Adoption of regulations governing exploitation and transportation
of oil which would provide strong incentives for safe performance and
severe penalties for safety violations.
• A conservation tax of a few cents per barrel of oil to cover the
costs of managing the major seabird colonies and to establish a trust
fund for restoring depleted populations.
• Equivalent measures for mining and other exploitative industries in
the coastal zone with a prospective impact on marine resources.
• Prohibition of dumping of toxic chemicals in biologically productive
waters.
• A program to eliminate introduced predators from the Aleutian Islands
and from important bird colonies elsewhere.
• Promulgation of effective regulations to protect birds under the
Migratory Bird Treaty with Japan.
• Negotiation of migratory bird treaties with other affected countries,
including the Soviet Union, Australia, New Zealand, and Chile.
• Acquisition of major unprotected seabird colonies into the national
wildlife refuge or other federal landholding systems.
• Formulation of regional and international management plans for
localized species, especially endemic species of the Bering Sea.
• Regulation of public access to major seabird colonies.
APPENDIX
Papers and Oral Summaries Presented at the Symposium but Which Do Not
Appear in this Publication
Conservation of marine birds of northern North America--the
symposium theme, by Nathaniel P. Reed
The marine environment of birds: an overview, by N. Philip Ashmole
Environmental hazards to birds from petroleum development in the
Beaufort Sea, by Kees Vermeer [in lieu of a paper on the status
of birds in the Beaufort Sea]
Birds of the marine habitat off northwestern North America, by
Gerald A. Sanger and James G. King
The pelagic and nearshore birds of the Beaufort and Chukchi Seas,
by George J. Divoky and George E. Watson
Dispersal and migratory movements, by George E. Watson, George M.
Jonkel, and F. Graham Cooch
Summary of the session "Status of Marine Bird Populations," by
David N. Nettleship
Breeding habitat of marine birds, by Gerald A. Bertrand
Exposure of marine birds to environmental pollutants, by Harry M.
Ohlendorf, Robert W. Risebrough, and Kees Vermeer[83]
Summary of the session "The Biology and Ecology of Marine Birds in
the North," by Hugh Boyd
Summary of the session "Conflicts Between the Conservation of
Marine Birds and Uses of Other Resources," by Joseph P. Linduska
Programs and authorities of the United States Government related to
marine bird conservation, by Omar Halvorson
Programs and authorities related to marine bird conservation:
Canadian Government, by Hugh Boyd
Programs and authorities of the State of Alaska related to marine
bird conservation, by Robert E. LeResche
Seabird programs of private organizations, by C. Eugene Knoder
Summary of the session "Programs and Authorities Related to Marine
Bird Conservation," by William H. Drury
Conservation of marine birds in Antarctica, by William J. L. Sladen
Seabirds and their conservation in Western Europe, by W. R. P.
Bourne
Summary of the session, "Conservation of Marine Birds in Other
Lands," by Joseph J. Hickey
FOOTNOTES:
[83] This paper, because of its length, was published separately as
_Wildlife Research Report 9_.
U.S. GOVERNMENT PRINTING OFFICE: 1979-681-016/29
TRANSCRIBER'S NOTES
P. 228 the sentence "The factors in Table are largely
self-explanatory" was missing the table reference.
Silently corrected simple spelling, grammar, and typographical
errors.
Retained anachronistic and non-standard spellings as printed.
Enclosed italics markup in _underscores_.
Enclosed bold markup in =equals=.
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