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Title: Birds in Flight
Author: Pycraft, W. P.
Language: English
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BIRDS IN FLIGHT
[Illustration: _Kingfisher and Young_]
BIRDS IN FLIGHT
BY
W. P. PYCRAFT
Zoological Department, British Museum (Natural History).
Fellow of the Zoological Society of London.
Hon. Member of the American Ornithologists' Union.
Associate of the Linnean Society.
Member of the Marine Biological Association of the United Kingdom.
Member of the Royal Anthropological Institute.
Author of "A History of Birds," "The Infancy of Animals," "The
Courtship of Animals," "The Sea-shore," Etc., Etc., Etc.
_Illustrated by_
ROLAND GREEN, F.Z.S.
LONDON
GAY & HANCOCK LIMITED
34 HENRIETTA STREET, COVENT GARDEN, W.C.2.
1922
_All Rights Reserved._
CONTENTS.
CHAPTER PAGE
I. Concerning Wings 1
What a wing is--The quill feathers and their function--The
skeleton of the wing--The muscles of the wing--The
great air-chambers of the body--The Bat's wing--The
wing of flying Dragons--The wings of Dragon-flies
and beetles.
II. The First Bird 15
The ancestors of birds--The first known bird and its
many remarkable features--The gradual evolution of the
birds of to-day.
III. The Sizes and Shapes of Wings and
their relation to Flight 21
The evasiveness of flight--The size of the wing in relation
to that of the body--Noisy flight--"Muffled" flight--The
swoop of the sparrow-hawk--The "flighting" of
ducks--The autumn gatherings of starlings and swallows--"Soaring"
flights of storks and vultures--The wonderful
"sailing" feats of the albatross--The "soaring" of the
skylark--The "plunging" flight of the gannet, tern, and
kingfisher.
IV. Modes of Flight 35
The movements of the wing in flight--Marey's
experiments--Stopping and turning
movements--Alighting--"Taking off"--Hovering--The use of the
tail in flight--The carriage of the neck in flight--And of the
legs--The flight of petrels--The speed of flight--The height
at which birds fly--Flight with burdens--Experiments on the
sizes of the wing in relation to flight--Flight in "troops."
V. Courtship Flights 53
The wing-play of black-game and grouse--The "musical
ride" of the snipe--The "roding" of the woodcock--The
musical flights of redshank and curlew--The "tumbling"
of the lapwing--The raven's somersaults--The
courting flight of the wood pigeon--The mannikin's
"castanets"--Wings as lures--The strange pose of the
sun-bittern--The "wooing" of the chaffinch and the
grasshopper-warbler--Darwin and wing-displays--The
wonderful wings of the argus-pheasant.
VI. How to tell Birds on the Wing 71
The small perching-birds and the difficulty of distinguishing
them--The wagtails--The finches--The buntings--The
redstart-wheatear, Stonechat--The thrushes--The
warblers--The tit-mice--The nuthatch, and tree-creeper--The
spotted flycatcher--The red-backed shrike--Swallows,
martins, and swifts--The night-jar--Owls--Woodpeckers.
VII. How to tell Birds on the Wing 97
(_continued_)
Falcons--Golden eagle--Harriers and sparrow-hawk--The
heron--The cormorant, shag, and gannet--The petrels--Guillemots,
razor-bills, and puffins--The ducks--The
great crested grebe and dabchick--The pigeons--The
"plover tribe"--The gulls and terns--The game birds.
VIII. The Wings of Nestling Birds 117
The wing of the unhatched bird--Of the coots and water-hen--The
hoatzin's wings--The wing of Archæopteryx--Moulting--The
nestling game-birds and ducks--Teaching
the young to fly.
IX. Flightless Birds 127
The steamer duck--The owl parrot--The flightless grebe
of Titicaca--The dodo and solitaire--The ostrich tribe--The
penguin's wings.
ILLUSTRATIONS
Coloured Plates
Kingfisher and Young _Frontispiece_
Jays _Facing Page_ 6
Pheasants " " 22
Brown Owl " " 30
Wild Duck " " 38
Woodcock carrying Young " " 54
Herons " " 64
Chaffinch and Young " " 76
Gold-crested Wrens " " 86
Great Spotted Woodpeckers " " 92
Some Types of Wings and Tails " " 102
Grouse " " 118
Black and White Plates
Swans, Heron, Geese _Facing Page_ 4
Black-game " " 26
Ducks " " 42
Lapwings " " 58
Some Common Birds _Facing Page_ 72
Some Types of Birds in Flight " " 80
Birds of Prey " " 106
Flightless Birds " " 130
Line Illustrations
Wings _Page_ 13
Archæopteryx and Pterodactyles " 19
Bat, Beetle, Dragon Fly, etc. " 33
Peregrine chasing Duck " 51
Sunbittern Displaying " 69
Drumming Snipe " 95
Buzzard Soaring " 115
Gulls " 125
Vultures " 133
Preface.
There are hosts of people who have a genuine
love of our native birds without yearning to possess their skins, or
desiring to acquire the reputation of being "Ornithologists." They
would call them all by name if they could, but seek, alas! in vain, for
some book wherein they will find some magic phrase which will enable
them to identify every bird they meet by the wayside.
Most of our native birds have learnt that "discretion is the better
part of valour," when in the neighbourhood of Man. Hence one gets but
too often no more than a fleeting glance at their retreating forms,
which, from frequent encounters, have become familiar, yet they leave
no more than a vague image in the memory. "What bird _was_ that? I have
often seen it but have never succeeded in taking it unawares." This is
a question, and its comment, often put to me.
Those who are in this quandary, and they are many, are always hoping to
find some book which will enable them to correctly name the retreating
forms. That book will never be written. In the following pages an
attempt is made to aid such enquirers, and at the same time the
difficulties of the task are pointed out.
It is hoped, however, that this attempt will find a welcome among
those for whom it is made. If it helps them to understand something,
at least, of the absorbing and fascinating problems which the study of
flight in the animal kingdom presents, it will at least have served
some useful purpose.
The pursuit of the flying bird will inevitably stimulate a desire
to know more about the bewildering changes of plumage presented at
different seasons of the year, as well as by the striking differences
which often distinguish the two sexes, and the immature birds. The
endeavour to satisfy this desire will open up a new world. Those
who would pass to this knowledge should possess themselves of the
"Practical Handbook of British Birds." Though most severely practical,
and designed for the serious student alone, even the beginner will find
interest in the description of these several plumages, and much else
beside that it is essential to know.
Now that the study of flight is so much to the fore, some may turn to
these pages in the hope of gaining useful information on the theme of
mechanical flight. Some help they may find. But it was not for this
that they were written. The flight of an aeroplane and the flight of a
bird have little in common--at present; though something may be learned
by the study of gliding flight and soaring, which of course have their
place in this book. But anatomical details and mechanical formulæ,
necessary to the serious student of flight, would have been entirely
out of place here, and they have been omitted.
My task has been by no means easy. But it has been enormously helped
by the extremely skilful and beautiful work of the artist, Mr. Roland
Green. Where birds are concerned, few artists in the past, and very few
in the present, have shown any ability to combine accuracy in drawing
with ingenuity of composition and faithfulness in colouring. Mr. Green
has shown this rare combination; his coloured plates and line-drawings
speak for themselves.
W. P. PYCRAFT.
_London_,
_September, 1922_
CHAPTER I.
Concerning Wings.
"Divinity within them breeding wings
wherewith to scorn the earth."--_Milton._
What a wing is--The quill feathers and their function--The skeleton
of the wing--The muscles of the wing--The great air-chambers of
the body--The Bat's wing--The wing of flying Dragons--The wings of
Dragon-flies and beetles.
The flight of birds has always aroused man's
envy and stirred his imagination. David longed for the wings of a dove:
the writer of the Book of Proverbs tells us that "the way of an eagle"
surpasses his understanding. Icarus, spurred on by dire necessity,
actually, we are told, contrived to fly--but his maiden effort ended in
disaster! To-day we have, in a sense, succeeded where he failed. But
only because we have given up the idea of flight by personal effort,
and make our aerial journeys in a flying machine.
That we owe much of our success to a study of the flight of birds is
common knowledge, but the machine which has evolved as a consequence
of this study pursues its way through the air after a very different
fashion from that of the birds, for its vast body is thrust, or drawn,
through the air by means of a propeller, driven at incredible speed,
its immobile wings sustaining the weight. The wings of the bird, on the
other hand, not only lift the body from the earth, but they sustain it
in the air by their marvellously complex movements. And this is true,
in varying degrees of bird, and bat, and butterfly: of dragon-fly and
beetle.
Even they who must perforce dwell in crowded cities see daily the
miracle of flight performed. For even here sparrows and pigeons, at
least, are everywhere, and it is just because this is so, just because
they have become so "common-place," that their very presence escapes
notice. Yet the wonder of their movements in the air might become a
never-ending source of delight if only we went about our business with
open eyes and minds alert.
Watch the wary sparrow spring from the ground and dart across the road,
or up to the nearest house-top. How is it done with such incredible
speed and accuracy?
To understand even the broad principles of flight, it is necessary to
realize, at the very beginning, that the wing, in the case of the bird,
or the bat, is a specially modified fore-leg. So also is the human arm
and hand. But its transformation has not been so drastic as that of the
bird, or the bat. Wherein the hand has been, as it were, completely
re-modelled to fulfil the peculiar and complex functions demanded of
it.
How should one describe the wing of a bird, as one sees it in flight?
The Dictionary, obscure and inaccurate as Dictionaries usually are,
defines a wing as "the organ of a bird, or other animal, or insect,
by which it flies--any side-piece." Might not the impression one
gathers of a wing, during flight, be defined as of a lateral extension
of the body, presenting a relatively large surface, but having no
appreciable thickness? That surface, examined in a dead bird, is seen
to be formed, for the most part, of a series of parallel, tapering,
elastic rods, fringed with an innumerable series of smaller, similar,
but much shorter rods, closely packed, and linked together by some
invisible means to form an elastic web? These we call the "quill,"
or "flight-feathers." The rest of the wing, and the body itself, is
clothed with precisely similar structures, differing only in their
smaller size. We call them "feathers" commonly, without realizing that
they are the "Hall-mark" of the bird, for no other creature has ever
been similarly clothed.
These quill-feathers play such a tremendously important part in flight
that their arrangement, and relation to the underlying skeleton must
be carefully examined by all who would understand the flight of birds.
To begin with, then, note that they are so arranged as to overlap one
another, the free edges of the quills facing the outer edge of the
wing. Only by this arrangement would flight be possible, for on the
upstroke of the wing through the air the quills act like the shutters
of the sails of a windmill, allowing the wind to pass between them and
so relieving pressure on the uplifting wing-stroke. On the down-stroke,
the opposite effect is produced. The full force of the stroke is
conserved, because, owing to the overlap, the several feathers are now
pressed closely together to form an impervious sheet.
How are they fixed to the skeleton? To see this all the smaller
feathers and the muscles, or "flesh" of the wing must be removed.
It will then be found that the flight-feathers are divisible into
two series. One, widely spaced, runs along the upper surface of the
fore-arm: the other, closely packed, along what answers to the back
of the hand. In effect this is but a single rod of bone, but it is
composed of three elements, answering to three of the digits of the
human hand--the thumb and the first and second fingers. But they are
scarcely recognizable as such, for the thumb is reduced to a mere
stump, while the two fingers have become welded together. The third
finger, indeed, has become reduced to the palm-bone, and a short stump
answering to the first finger joint. To this frame-work, which can be
folded up into the shape of a Z when the bird is at rest, the quills
are fixed by their base by means of slender, but very strong elastic
tendons. In birds which have a long upper arm bone, like the Albatross,
Gull, or Heron, there is a third series of long, almost "quill-like"
feathers running from the elbow to the body, thus closing up what would
otherwise be a gap between the wing surface and the body, rendering
flight impossible.
[Illustration:
Swans.
Heron.
Geese.
]
The most important muscles of the wing are those which have to provide
the power for the down-stroke of the wing. And these are the "pectoral"
or "breast-muscles"--which form such dainty meat in a roast fowl.
Owing to their great bulk the breast-bone itself would be insufficient
to afford them attachment. This is furnished by the development of a
deep, median keel, so that the breast-bone of a bird, such as a pigeon,
bears a fanciful resemblance, when seen in profile, to the hull of a
ship--unusually shallow--with a very deep keel. The front end of the
breast-bone supports two slender rods of bone, and these in their turn
support the long, sword-like blade-bone, and the "merry-thought."
The general appearance of this frame-work for the support of the wing
and its muscles can be seen in the adjoining illustrations. But it
must be remembered that in their relative sizes and disposition these
various parts present a very considerable range of differences. That
these differences are correllated with different forms of flight goes
without saying, but, be it noted, no one, as yet, has attempted to
discover in what way they are related. Some of the readers of this book
may, perhaps, be tempted to try and solve the problems which these
differences present. To begin with, a collection of breast bones of
different species of birds with their attached shoulder-girdles should
be made, and these should be studied together with careful observations
of the flight of the living bird. So far only a few comparisons of this
kind have been made.
It must not be supposed that the whole secret of flight in birds
is concentrated in the skeleton of the breast-bone and its
shoulder-girdle, and the muscles attached thereto. But those who would
investigate the modifications of the rest of the body which have taken
place in harmony with the requirements of flight, must turn to more
learned treatises. There is, however, one point which demands notice
here. And this is the popular belief that birds have the power of
materially reducing their weight when on the wing by drawing air into
their lungs, and storing it in large air-chambers enclosed within the
body. These chambers are indeed concerned with the needs of flight. But
the precise part they play is yet to be discovered. They certainly have
no effect of rendering the body lighter. So far as our knowledge goes
it would seem that they act as regulators of the temperature and as
reservoirs of breathing air, during the strenuous efforts of flight.
[Illustration: _Jays_]
It is a mistake to suppose that it is unnecessary to consider other
kinds of flight when studying that of birds. Even those who are not
interested in the abstruse problems of the mechanism of bird's flight,
will find that comparisons made between birds, bats, butterflies and
beetles when on the wing, are immensely interesting, and help to bring
out the peculiarities of each.
During the twilight hours of a still summer evening one may compare,
with advantage, the rushing swoop of the screaming swift, borne with
lightning speed upon long, ribbon-like pinions, with the curiously
erratic flight of the woolly bat with beaded eyes, who has ventured
abroad for his evening meal. One cannot but feel astonishment at the
marvellous dexterity with which he twists and turns, now shooting up
into the sky, now darting downward. What bird can beat him, or even
match him, in the art of doubling back on his tracks? And one can put
his skill at lightning turns to the test if one attempts to catch him
in a butterfly net. Often indeed have I attempted this feat, but never
yet with success.
In the glare of noon-day this aerial athlete may perhaps be found in a
deep slumber, hanging head downwards behind the shutters of a cottage
window, or in some crevice of a barn-roof. Gently seize him and as
gently stretch out his wing. The moment one opens it one sees that it
is constructed upon a totally different plan from that of a bird. In
the first place a thin membrane, or fold of skin is seen to take the
place of the series of quill-feathers found in the wing of the bird. In
the second it will be found that this membrane is stretched between
a series of long and very slender bony rods. These are excessively
attenuated fingers. And if the hinder border of the wing-membrane be
traced inwards it will be found to be attached to the hind limb. In
some species it will be found that this membrane passes backwards
beyond the leg to attach itself to the tail. Here, then, is a wing
as efficient for its purpose as that of a bird, but constructed on a
totally different plan.
Ages ago, before even the birds or the beasts had appeared on the
earth, the winged dragons, which the Men of Science call Pterodactyles,
held the proud position of being, not only the first, but the only
creatures blessed with a backbone that could fly. Their wings
resembled those of the bats, but differed in this, that instead of the
wing-membrane being stretched between all the fingers, leaving only
the thumb free, it was attached only to the fifth finger, leaving the
remaining fingers free, and these were reduced to mere vestiges. As
with the birds, the breast-bone was very broad and was furnished with a
keel, while in the bats it takes the form of a jointed rod, down which
no more than a slight keel is ever developed.
But millions of years before the Flying-dragons, birds, and bats came
into being, the stupendous problem of flight had been solved. Far away
in the distant Devonian Epoch, when the distribution of land and water
over the earth's surface was totally different from that of to-day,
dragon-flies and caddis-flies disported themselves in the summer sun,
amid landscapes that would seem strange to our eyes. For there were no
trees and flowering plants, such as we know.
* * * * *
The dragon-flies of that remote epoch were very like those of to-day,
whose dancing flights and graceful, swooping movements are such a
delight to watch by reed-fringed pools, or river-banks, during the
sweltering days of summer. This flight is very different from that of
a bird, though it would be hard to say precisely in what it differs.
But we have no such difficulty in regard to the broad outlines of the
mechanism of such flight. To begin with there are two pairs of wings,
and these appear to be fashioned out of some curiously gauze-like
material, a sort of mesh-work tissue, often strikingly coloured. And
they are obviously driven after a very different fashion from those
of the bird. For in the bird they are moved by quivering muscles,
attached to a bony, internal skeleton. In the dragon-fly--as with all
insects--the hard skeleton, composed of a material known as "chitin,"
forms the outside of the body and encloses the muscles. Finally, for we
may not dwell very long over this aspect of flight, it is clear that
the wings cannot have been derived from modified fore-legs, like those
of the bat, or the bird. Rather, it would seem, they have developed out
of plate-like breathing organs.
The restful twilight hours of summer tempt not only bats from their
hiding places, but a host of other winged creatures which are rarely
to be seen, or heard, during the glare of noon. Among these is the
lumbering dor-beetle, who, with lazy drone steers clear of solid
objects only with difficulty. Many, indeed, are his failures. He and
his kin are no match for bats and owls, who find them juicy morsels! On
the next opportunity catch one and examine him. His wings are curiously
interesting. There are the usual two pairs: but the fore-wings have
been changed to serve as covers for the hind-wings. During flight they
are spread outwards, and indirectly, no doubt, assist flight. But the
hind-wings are the real propellers. And it will be noticed that when
not in use they can be folded up in a perfectly wonderful manner, so as
to lie completely underneath the fore-wings, or "elytra," so that when
the creature is crawling it appears to be wingless.
Now compare these with the transparent wings of the bee, or the
gorgeously scale-covered wings of the butterfly. It is well worth
while. If this examination be done very carefully, and with the aid
of a magnifying glass, it will be found that the fore and hind wings
are yoked together in the wing of the bee, by a delicate mechanism
of hooks. In the moths, but not in the butterflies, a bristle, or
sometimes two or three bristles, serve the same purpose. Further, in
the case of the bee it will be found that the fore-wing, when at rest,
is folded longitudinally back upon itself.
Finally, turn to the flies. Herein it will be seen that there is but
a single pair of wings, the hind pair having become reduced to mere
stumps, known as "balancers."
Much, very much more, might have been said of these wings: but our
conversation is of birds. We cannot, however, properly appreciate
either the essential characters of their wings, or their flight,
without some such standards of comparison as is afforded by the wings
of other creatures.
[Illustration:
A Primaries. B Secondaries. C Tectrices. D Bastard Wing.
The upper figure shows the under side of wing with the coverts removed
to show attachment of flight feathers to skeleton.
The lower figure shows the quill or flight feathers and the coverts in
their natural condition.]
CHAPTER II
The First Bird.
"And let Fowl fly above the earth; with wings
Displayed in the open firmanent of heaven."--_Milton._
The ancestors of birds--The first known bird and its many remarkable
features--The gradual evolution of the birds of to-day.
Sooner or later all bird-lovers find
themselves pondering over the problem of the origin of birds: how they
evolved their peculiar covering of feathers: what was the fashion of
the original arm and hand out of which the wing was fashioned: and
finally, whence have the birds been derived?
Since these pages are avowedly devoted to the subject of Flight, any
attempt to summarize the state of our knowledge on these aspects of the
history of birds would be in the nature of a trespass on the space, of
necessity limited, which even a cursory survey of flight demands.
Let it suffice, then, to say, that birds are descended from reptiles.
The skeleton of modern birds bears undubitable testimony of this. For
we have the evidence furnished us by the remains of two remarkable
skeletons, belonging to that very wonderful reptile-like bird,
Archæopteryx.
Only two skeletons of this wonderful bird are known, and they were
obtained, many years ago, from the Solenhofen, or Lithographic slates
of Bavaria. The wing and tail-feathers are as perfectly developed as
in modern birds. But these precious fossils present two characters
which have long since been lost by birds. The first of these is the
presence of well developed teeth in the jaws. The birds of to-day have
horny beaks. The teeth bespeak the reptile. The second is the long,
tapering tail, which is composed of a series of cylindrical bones,
forming a lizard-like appendage. But each bone, be it noted, supported
a pair of stiff, tail-quills, so that the tail of this ancient bird,
in its general appearance, differs in a very striking way from that of
a modern bird, wherein these feathers seem all to spring from a common
base, fan-wise. But as a matter of fact this appearance is deceptive,
for the large bone, or "pygostyle" which supports the tail feathers
of the adult, is found, in the embryo, to be made up of a series of
separate pieces, agreeing in number with those of the tail of the
fossil ancestor, Archæopteryx. Each of these separate bones has, in
fact, in the course of the ages, been shortened up to the condition of
mere discs; and this "telescoping" of the vertebræ has brought the once
separated feathers close up, so that their bases lie packed in like the
spokes of a fan. As a result, a much more efficient tail for the needs
of flight has come into being. And the tail, it must be remembered,
plays, especially in some birds, an important part. But this is not
all. We have now to consider the wing. In all essentials this agrees
with that of living birds. And this agreement is strikingly close when
it is compared with the embryonic and early nestling stages. A detailed
account of these resemblances, and differences, would be out of place
here. Suffice it to say that its closest modern counterparts are to
be found in the wing of the nestling of that strange South American
bird, the Hoatzin, and the "Game-birds," such as of a young pheasant,
or a young fowl. The evidence these can furnish in this matter of the
evolution of the birds wing will be found in Chapter VI. For the moment
it will be more profitable to discuss the broad outlines of the origin
of flight, so far as this is possible.
On this theme there are, as might be supposed, many opinions--some of
them bearing little relation to fact.
The feet of Archæopteryx, it is important to remember, bear a very
extraordinary likeness to the feet of a "perching" bird, say that of a
crow. They are without any semblance of doubt, the feet of a bird which
lived in trees. Archæopteryx, then, was an arboreal bird. And this
being so, the most reasonable hypothesis of the origin of flight is
that it developed out of "gliding" movements, made for the purpose of
passing from the topmost branches of one tree to the lower branches of
another, after the mode of the "flying-squirrels," and "flying-lemur"
of to-day. The wing, at this primitive stage of its evolution, was
even then, probably, a three-fingered limb, provided with a broad
fringe of incipient feathers along its hinder border. At this stage
the body would have been less bird-like than that of Archæopteryx, and
have been still more like that of the ancestral reptilian stock from
which the birds have sprung. That feathers are, so to speak, glorified
reptilian scales cannot be certainly demonstrated, but men of Science
are generally agreed that this was their origin.
By the time that Archæopteryx had come into being, true flight had been
arrived at, though probably it could not have been long sustained.
As these primitive birds increased in numbers, and spread from the
woodlands to the open country, life became more strenuous. New
enemies had to be evaded, longer journeys had to be made for food.
Only the very best performers on the wing could survive, and thus,
in each generation, the failures would be speedily weeded out, while
competition among the survivors would raise the standard. We see the
result of this "struggle for existence" in the many and varied types of
wings, and of flight, which are presented in this book.
[Illustration: Archæopteryx.
Pterodactyles.]
CHAPTER III.
The Sizes and Shapes of Wings and their relation to Flight.
"... the fowls of heaven have wings,
And blasts of heaven will aid their flight:
* * * * *
Chains tie us down by land and sea."--_Wordsworth._
The evasiveness of flight--The size of the wing in relation to
that of the body--Noisy flight--"Muffled" flight--The swoop of the
sparrow-hawk--The "flighting" of ducks--The autumn gatherings of
starlings and swallows--"Soaring" flights of storks and vultures--The
wonderful "sailing" feats of the albatross--The "soaring" of the
skylark--The "plunging" flight of the gannet, tern, and kingfisher.
Who needs to be told that birds fly? So
common-place has this fact become that the many, and varied forms of
wings, and the peculiarities of flight which are associated with these
differences, are rarely perceived. Even sculptors, and artists show a
hopeless unfamiliarity with the shapes of wings, and their meanings, at
any rate, as a general rule. Look at their attempts to display birds in
flight, or in the fanciful use of wings which convention has ascribed
to angels. For the most part these superbly beautiful appendages are
atrociously rendered.
Yet it must be confessed that any attempt to explain exactly how birds
fly must fail. We can do no more than state the more obvious factors
which are indispensable to flight, and the nature of its mechanism. The
subtleties, and delicate adjustments of actual flight evade us.
Our appreciation, however, of this supreme mode of locomotion will be
materially quickened, if we make a point of studying the varied forms
of flight as opportunities present themselves.
To begin with, it is worth noting that the size of the wing decreases
with the weight of the body to be lifted--up to a certain point, of
course. This, perhaps, may seem strange a statement to make. But it
can be readily verified. Compare, for example, the size of the body in
relation to the wings, in the case of the butterfly and the dragon-fly,
on the one hand, and the partridge and the crow, on the other. The two
first named, by comparison, have enormous wings.
Birds, it will be noticed, which haunt woods, or thickets, have short,
rounded wings, like the wren, the pheasant, or the tawny owl. Such, on
the other hand, as live in the open, like the gull, and the swallow,
have long, pointed wings. The reason for this is fairly plain. Birds
which must steer their course through the intricate mazes of a wood, or
thicket, would find their flight seriously hampered by long wings.
[Illustration: _Pheasants_]
These general principles once realized, a foundation is laid on which
one may base observations on the peculiarities of flight distinguishing
different types of birds.
Most of us, probably, at one time or another, in taking a walk through
the woods, have been startled, almost out of our wits, by a sudden
"whirr" of wings at our very feet; made by some crouching pheasant,
waiting till the very last moment before revealing himself, by taking
flight. This alarming noise is due to the shortness and stiffness of
the quill, or flight-feathers. With pinions moving with incredible
speed, the bird is off like a rocket. Not seldom, probably, it owes
its life to this ability to disconcert its enemies, till it has put a
safe distance between itself and danger. By way of contrast, let us
take the absolutely silent, easy movements of the owl, stealing forth
in the twilight of a summer's evening, seeking whom he may devour.
Here, again, we have a meaning in the mode of flight. Here silence is
more than golden: it means life itself. Nimble-footed, sharp-eared
mice and rats, must be snatched up before even the breath of suspicion
can reach them. The uncanny silence of this approach is rendered
possible, only by what may be called a "muffling" of the wings. For the
flight-feathers are not only of great breadth, but they are covered,
as it were, with velvet-pile, the "barbules" of the wing-quills, which
form the agents by which the "web" of the quill is held together,
having their upper spurs produced into long, thread-like processes,
which extinguishes any possibility of a warning "swish."
John Bright, in one of his magnificent perorations, caused his
spell-bound listeners to catch their breath, when, conjuring up a
vision of the Angel of Death, he remarked "we can almost hear the
rustle of his wings." One realizes the vividness of that imagery, when
one hears, as on rare occasions one may, the awe-inspiring rustle of
the death-dealing swoop of the falcon, or the sparrow-hawk, as he
strikes down his victim.
But the swish, and whistle of wings often stirs the blood with
delicious excitement, as, when one is out on some cold, dark night,
"flighting." That is to say, awaiting mallard passing overhead on the
way to their feeding ground, or in watching the hordes of starlings, or
swallows, settling down to roost in a reed-bed. No words can describe
these sounds, but those to whom they are familiar know well the thrill
of enjoyment they beget. There is no need, here, to muffle the sound of
the wing-beat. The falcon vies with the lightning in his speed, escape
is well nigh hopeless: neither have the swallows need for silence;
indeed, on these occasions, they add, to the music of their wings, the
enchantment of their twittering.
So much for flight in its more general aspects. Let us turn now to a
survey of some of the more remarkable forms of flight, beginning with
that known as "soaring."
This but few birds have mastered, and to-day it is rarely to be seen in
our islands, for eagles, falcons, and buzzards are, unfortunately, only
to be found in a few favoured localities. Happily, however, one may
yet realize the delight of watching a soaring buzzard, or raven, among
the hills of Westmorland, or in parts of Cornwall and Wales. But to
see the past-masters in the art, one must seek the haunts of pelicans,
vultures, and adjutant storks. The last-named is perhaps the finest
performer of them all. For the first hundred feet or so he rises by
rapid and powerful strokes of the wings, and then, apparently without
the slightest effort, or the suspicion of a wing-beat, he sweeps round
in great spirals, gaining some ten or twenty feet with each gyration,
the wings and tail all the while being fully extended and the primary
feathers widely separated at their tips. During the first part of
every turn he is flying slightly downward: at the end of the descent
he sweeps round and faces the wind, which carries him upward. Round,
round, he goes, mounting ever higher and higher, until at last he
attains a height of perhaps two miles.
The adjutant thus goes aloft apparently for the mere delight the
movement affords him. But not so with the vulture, who is a close rival
in this art. He soars for his very existence, for dead bodies are not
to be found everywhere. Possessing powers of sight infinitely greater
than ours, he mounts aloft for the purpose of taking observations. If
nothing "toothsome" can be seen from his vast range, he turns his
attention to the movements of such of his fellows as may be up on
the same errand miles away. Should he see one swooping earthwards he
instantly tracks him down, and is soon at the feast. This accounts for
the mysterious way in which vultures will gather together to the feast,
in a place where an hour ago not one was to be seen. A caravan of
camels, perchance, is making its toilsome way across a burning desert.
One falls by the way. In a few hours its bones will be picked clean by
a horde of these ravenous birds.
Longfellow sang the song of the vultures hunting in stately verse:--
"Never stoops the soaring vulture
On his quarry in the desert,
On the sick or wounded bison,
But another vulture, watching
From his high aerial look-out,
Sees the downward plunge and follows,
And a third pursues the second,
Coming from the invisible ether,
First a speck, and then a vulture,
Till the air is thick with pinions."
[Illustration: Black-game.]
Darwin, in his wonderful "Journal of a Voyage Round the World" gives a
marvellously vivid word-picture of the largest, and most interesting of
all the vultures, the Condor of the Andes--one of the largest of flying
birds, having a wing-span of something over nine feet:--
"When the condors are wheeling in a flock round and round any spot,
their flight is beautiful. Except when rising from the ground, I do
not recollect ever having seen one of these birds flap its wings.
Near Lima, I watched several for nearly half an hour, without once
taking off my eyes; they moved in large curves, sweeping in circles,
descending and ascending without giving a single flap. As they glided
close over my head, I intently watched, from an oblique position, the
outlines of the separate and great terminal feathers of each wing;
and these separate feathers, if there had been the least vibratory
movement, would have appeared as if blended together; but they were
seen distinctly against the blue sky. The head and neck were moved
frequently, and, apparently, with force, and the extended wings seemed
to form the fulcrum on which the movements of the neck, body, and the
tail acted. If the bird wished to descend, the wings for a moment
collapsed; and then again expanded with an altered inclination, the
momentum gained by the rapid descent seemed to urge the bird upwards
with the even and steady movement of a paper kite. In the case of
any bird _soaring_, its motion must be sufficiently rapid, so that
the action of the inclined surface of its body on the atmosphere may
counterbalance its gravity. The force to keep up the momentum of a
body moving in a horizontal plane in the air (in which there is so
little friction) cannot be great, and this force is all that is wanted.
The movement of the neck and body of the condor, we must suppose, is
sufficient for this. However this may be, it is truly wonderful and
beautiful to see so great a bird, hour after hour, without apparent
exertion, wheeling and gliding over mountain and river."
Those who "go down to the sea in ships" have to face many perils, but
the "wonders of the great deep" are for them a lure. One of these is
to watch the marvellous "sailing" flights of the wandering albatross.
His wings have, when expanded, a peculiarly "ribbon-like" form,
and measure from tip to tip, over eleven feet--thus exceeding that
of the condor, which, however, is the heavier bird of the two. The
"ribbon-like" form of the wings is due to the extreme shortness of the
flight-quills--the primaries and secondaries, and the great length of
the arm and fore-arm. And it may be to these structural peculiarities
that the "sailing" flight just alluded to is due. Resembling soaring in
many of its aspects, yet it differs materially in that it is performed
low down, not at immense heights. The most graphic description of
these movements is surely that of Mr. Froude: "The albatross," he
tells us, "wheels in circles round and round, and for ever round the
ship--now far behind, now sweeping past in a long rapid curve, like a
perfect skater on a perfect field of ice. There is no effort; watch
as closely as you will, you will rarely see, or never see, a stroke
of the mighty pinion. The flight is generally near the water, often
close to it. You lose sight of the bird as he disappears in the hollow
between the waves, and catch him again as he rises over the crest;
but how he rises, and whence comes the propelling force, is, to the
eye, inexplicable; he alters merely the angle at which the wings are
inclined; usually they are parallel to the water and horizontal; but
when he turns to ascend, or makes a change in his direction, the wings
then point at an angle, one to the sky, the other to the water."
One sometimes hears the skylark described as "soaring" upwards, when
performing that wonderful musical ride which has made him so famous.
But as, spell-bound, one listens to his rapturous strains, and watches
his spiral ascent, one cannot help noticing that his wings are never
still, they seem almost to be "beating time" to his music. In true
soaring they are scarcely ever moved.
The upward progress of a bird when soaring is, of necessity,
comparatively slow. But in what we may call "plunging" flight the case
is very different, for here the velocity of the descent is great.
The frigate-birds of tropical seas, and the gannet of our own, display
this mode of flight to perfection. It is worth going far to see a
gannet dive. Travelling at a relatively considerable height, and
eagerly scanning the surface of the water for signs of a shoal of
fish, this amazing bird dives with the speed of lightning, and with
half-spread wings disappears with a terrific plunge beneath the
surface, to emerge, an instant later, with his prey. One can measure
the force of such a plunge by the cruel trick, sometimes played by
fishermen, of fastening a herring to a board, and setting it adrift
where gannets are about. The unsuspecting victim descends as usual
upon his prey, only to meet instant death by the shock of his impact
with the board. Those who talk glibly of identifying birds by their
flight may point to this wonderful diver as a case in point. But while
one may often see the gannet on the wing, it is by no means so often
that one will have the good fortune to see him dive, for he is not
always hungry. His white body, pointed tail, and black quill-feathers
would then enable the novice to name him at once. But--in his immature
plumage, he would, at a little distance, appear black, and unless he
were fishing, the chances of recognition would be by no means great.
Close at hand he would appear speckled with white.
[Illustration: _Brown Owl_]
But this by the way. There are two other birds which dive from a
height on the wing. One of these is the kingfisher: the other is the
tern. The term "tern" is here used collectively, for there are several
species, but all have this habit of diving from a height. During the
summer months one may be quite sure of an opportunity of watching the
graceful, easy flight of at least three species. For they haunt the
sea-shore, river, and lake with equal impartiality. Those who are on
the look-out for terns, for the first time, will easily recognise
them. For, in the first place they look like miniature gulls, but
with longer and more pointed wings, and forked tails. Further, all
have a characteristic black cap. They travel in small parties, as if
for company, keeping no more than a yard or two from the surface of
the water, and scanning it eagerly in search of shoals of small fish,
or crustacea. As these are found one will note a quickening of the
wing-beat, and a sudden dive, like that of the gannet, with half-closed
wings. And sometimes, too, the impetus will take them completely under
water.
[Illustration:
1 Bat
2 Butterfly
3 Beetle
4 Dragon-Fly
5 Bone of Birds Wing, Showing the three Divisions,
Arm--Fore-arm--Hand.
6 Breast Bone of Swan
7 " " " Pigeon
8 " " " Pelican
9 & 10 Apteryx, Cassowary (degenerate wings).
]
CHAPTER IV.
Modes of Flight.
"The soaring lark is blest as proud
When at Heaven's gate she sings:
The roving bee proclaims aloud
Her flight by vocal wings."--_Wordsworth._
The movements of the wing in flight--Marey's experiments--Stopping
and turning movements--Alighting--"Taking off"--Hovering--The use of
the tail in flight--The carriage of the neck in flight--And of the
legs--The flight of petrels--The speed of flight--The height at which
birds fly--Flight with burdens--Experiments on the sizes of the wing
in relation to flight--Flight in "troops."
While it is possible to show that certain
kinds of flight are to be associated with such and such peculiarities
of the skeleton, and the muscles attached thereto, there are many
"eccentricities" which cannot be measured, and explained, in terms of
mechanism.
The very disconcerting, twisting, flight of the snipe is one of these.
The sportsman knows it well: and he knows that the twisting, during
which the bird turns the body half over--that is with, say, the
left wing pointing directly downwards, and the right wing directly
upwards--is only the preliminary to getting fully on the way, and that,
presently, it will pursue a straight course, with arrow-like speed.
Yet its cousin, the jack-snipe, never twists.
Why does the woodcock invariably drop after a charge of shot, even
though not a pellet has touched it, while a snipe pursues its way?
These differences are not merely differences of "habit": they indicate
subtle differences in nervous response to the same kind of stimulus,
and in structural details yet to be unravelled.
Some day the cinematograph will reveal to us all the phases of flight
and the movements to which they are due. Even now, thanks to the modern
camera, we have learned a great deal. We have learned, for example,
that the flight of a bird is not effected merely by rapid up and down
movements of the fully extended wings, or with flexed wings--that is
to say, half closed, as in "gliding" flight when a bird is descending,
or in the swoop of, say, the sparrow-hawk. Only in one of these two
positions do we ever seem to see the wings when we have to trust to our
eyes alone, as the bird hurries past us. The impression that we have
seen aright is confirmed when we stand on the deck of a steamer, and
watch the gulls following in its wake. For incredibly long distances
they will travel without a perceptible wing-beat. The albatross is the
finest of all performers in regard to this kind of flight, which is
due, apparently, to air currents created by stiff breezes, or gales.
Some birds seem to make their way against a head-wind with the minimum
of effort, by partly flexing the wings and gliding downwards: at the
end of the descent, by turning the body sharply upwards, and spreading
the wings to the fullest extent, they are lifted up, and driven
forward, like a kite.
Marey and Pettigrew, long ago, showed conclusively, by means of
photography, that our conception of the movement of the wing during
flight was far from correct.
To avoid a long and tedious description, and many technicalities, it
must suffice to say that the wing of a bird possesses very considerable
freedom and range of movement at the shoulder joint. Certainly, during
some phases of flight, the wings are thrust forward and extended to
their fullest extent, so that the outer margins of the wings come to
lie almost parallel with the long axis of the body, as may be seen in
the spirited illustration showing the goshawk in flight. As they sweep
downwards, and backwards, they lift the body and drive it forwards.
At the end of the "sweep" they are "flexed," that is to say, bent at
the elbow and wrist-joints, while at the same time they are raised and
brought forward above the body for a repetition of the stroke. These
movements are too quick for the eye to follow, but they have been fixed
for us by the camera.
Marey devised an ingenious experiment in his endeavour to discover the
movements of the bird's wing during flight. He fastened a small piece
of paper to the tip of a crows wing, and as the bird flew in front of
a perfectly black screen he took a photograph of this moving speck of
white, while, of course, no image of the crow appeared on the plate.
The resultant picture gave a series of "figure of 8 loops" as one would
make this figure with a pen, contriving to make the lower loop very
small, and the upper loop very large. But as the wing-beat increased in
speed the lower loop gradually faded out.
These movements of the wing, however, are descriptive rather of what
takes place during very vigorous flight, as when the bird is getting
up "steam." When he is well under way there is no need for these long
and very tiring strokes, except in the case of birds like the pheasant
or the duck. A gull, when in full career does not, apparently, raise
the wings very high, nor depresses them very low, nor does it flex the
wings at the wrist-joints.
Stopping and turning movements are generally extremely difficult to
follow, because they are performed so quickly. They can be seen fairly
easily in the case of some of the larger birds. Ducks, as is well shown
in one of our coloured Plates, draw the head backwards, tilt the body
upward, thrust the feet forward, and spread the tail, at the same time
turning it forwards. Gulls and pigeons too may be watched with profit.
[Illustration: _Wild Duck_]
In turning, the body is tilted sideways, so that the tip of one wing
points skywards, the other earthwards, as in the case of the goshawk
illustrated in this book. The pigeon, and some other birds seem further
to spread out the long, stiff quills borne by the thumb, which form
what is known as the "bastard-wing." This turning movement is well
shown, again, in the very realistic coloured picture of the woodcock
turning in mid-air, and bearing too the burden of one of its nestlings.
If it is difficult to satisfy oneself as to the way in which a bird
alights, it is no less so to detect its movements in taking wing.
Most of us must have seen sparrows making this effort from the road,
thousands of times. But ask of anyone, How is it done? The act takes
place so quickly that the eye cannot follow its execution. And what is
true of the sparrow is true of most birds. But there are some where
this is not the case. Many water-birds, the cormorant, for example,
get under way but slowly, and with evident effort. They flap along
the surface for some distance before they gain sufficient impetus to
lift them into the air. And there are many long-winged, short-legged
birds which can rise from a level surface only with great difficulty,
or not at all. The swift is one of these, for its legs are excessively
short. The albatross is another: and this is true, indeed, of many of
the petrel-tribe. The puffin, again, seems unable to rise on the wing
from the ground. It appears invariably to run along until it reaches
the edge of cliff which lodges its burrow, and then, as it were,
throw itself over the edge. The heron, when springing into the air,
stretches his long neck out to its fullest extent, and presents a pair
of dangling legs, well shown in one of our coloured Plates, but when
once fully on the way its pose entirely changes, the neck being drawn
in and the legs thrust out backwards.
Flight does not always mean progress through the air. Most birds can,
at need, arrest their course, and hang, as it were, suspended in the
air. In the beautiful coloured plate, representing the chaffinch
hovering over its half-fledged young, and in that of the kingfisher
and its young, this form of "hovering" flight can be seen. But the
greatest of all exponents in the art of hovering is the kestrel, known
also, for this very reason, as the "windhover." It is most fascinating
to watch this bird hang, as it were, from the clouds, motionless,
yet with quivering wings, as he scans the ground below in his search
for some unsuspecting mouse. It is hard, indeed, to say which is the
more wonderful, this power of remaining stationary for comparatively
long periods in the air, or the surprising powers of sight which this
bird possesses. During these hovering movements, always head to wind,
it will be noted, the tail plays a very important part, being spread
to its extremest limit, and at the same time thrust forward beneath
the body. In some birds this forward movement is more marked than in
others. And this because such birds possess a somewhat more flexible
spine, there being a certain amount of "play" where the vertebræ of the
loins join the welded mass of vertebræ which lie between the bones of
the hip-girdle.
But the tail feathers are not indispensable. This much is shown in the
case of birds like the kingfisher, the water-hen, and the land-rail,
which contrive to fly well, and at a great pace, though they have but
the merest apology for a tail. More than this, the grebes have no
tail at all. But it is to be noted that they are by no means adept at
turning movements; owing to the lack of this appendage the body, when
in mid-air, has a curiously truncated appearance, as may be seen in
the illustration. Further, it is significant that in the contemptible
"sport" of pigeon-shooting from traps, the birds are deprived of their
tails to prevent them from making turning movements.
The carriage of the head and neck, and of the legs, during flight
presents some interesting, and some instructing contrasts.
Ducks, geese, and swans, flamingoes, storks, and cormorants always fly
with the head and neck stretched out to their fullest extent. Herons
and pelicans, though also long-necked birds, draw the head back till it
rests almost on the shoulders. Most birds, indeed, fly with the head
drawn back towards the body. The appearance of some of these birds on
the wing can be seen at a glance on turning to the page illustrating
this aspect of flight.
Not so very long ago a great controversy was waged as to what birds did
with their legs during flight. Many of the older artists invariably
depicted them drawn up under the breast. But as a matter of fact,
this method seems to be confined to the Passerine birds--the "perching
birds," such as crows and finches and their kin. It has yet to be
settled what obtains among what are known as the "Picarian" birds, such
as kingfishers, bee-eaters, woodpeckers, and so on. The legs and feet
of these birds are so small, and their flight is so rapid, that the
matter is by no means an easy one to settle. But all other birds carry
the legs and toes bent backwards, under the tail. In the gulls, this
can easily be seen, and easier still in the case of the common heron,
where they are, as it were, trailed out behind--owing to the shortness
of the tail and the great length of the leg. The puffin carries them
"splayed" out on each side of his tail, and so also do his kinsmen, the
razor-bills, and guillemots.
The legs, as a rule, take no part in flight. True, they can be seen
thrust out just before alighting, but this is solely for the purpose
of effecting a safe landing. But where gulls can be watched at close
quarters, as in harbours, round a ship, or in such favoured spots as
are to be found about the bridges of London during the winter, careful
watch will show that the legs are frequently used when efforts are
being made to turn, or check the speed of flight.
Some of the smaller petrels--like the storm-petrel, or "Mother Carey's
chickens," will patter over the water with their feet as they fly just
over the surface of the waves.
[Illustration: _Sketches of Ducks in flight 1922_
1. }
} Scaup.
1a. }
2. Goldeneye.
3. }
} Pochard.
4. }
5. }
to } Mallard.
10. }
]
Whether the legs are carried drawn close up beneath the breast, or
thrust backwards under the tail, the purpose of this disposal is the
same--to prevent any interference with the "stream-lines" of the body
which would impede flight.
On the matter of the speed of flight there seems to be much
misconception. Gätke, the German ornithologist, gravely asserted that
the little Arctic blue-throat--one of our rarer British birds--could
leave its winter resort in Africa in the dusk of evening, and arrive at
Heligoland--where he spent so many years studying bird migration--nine
hours later. That is to say it could travel 1,600 geographical miles
in a single night, at the astounding velocity of 180 miles an hour!
According to another estimate of his, curlews, godwits, and plovers
crossed from Heligoland to the oyster-beds lying to the eastward, a
known distance of rather more than four English miles, in one minute;
or at the rate of over 240 miles an hour. Against such extravagant
estimates it is hardly necessary to bring rebutting evidence. But if
any be demanded it may be furnished by the carrier pigeon, which has
been known to maintain a speed of 55 miles an hour for four hours in
succession: and it is extremely unlikely that this is much, if at all,
exceeded by any wild bird during long-distance flights.
That our spring and autumn migrants must possess wonderful powers of
endurance is beyond question. And it is equally certain that thousands
must perish by the way. By this means is the standard of flight
maintained--the weak perish. Even the minimum standard of efficiency
for the survival of such an ordeal must be a high one.
Few of us see anything of these marvellous migration flights. For, in
the first place, they are generally performed at night, and at a great
height, often beyond the range of human vision. Only as they approach
land, and their destination, do they descend. American naturalists
have made some interesting observations by directing a telescope
against the sky. Thus, Mr. Frank Chapman, by turning his instrument
towards the full moon, has seen birds passing at night at an altitude,
according to his computation, of five miles: while the late Mr. W.
E. D. Scott saw, through an astronomical telescope at Princeton,
New Jersey, great numbers of birds passing across the face of the
moon--warblers, finches, and woodpeckers among them. Mr. Chapman again,
on another occasion, saw no less than 262 birds pass over the field of
his telescope at a height of from 1,500 to 15,000 feet: and the most
remarkable thing of all was the fact that the lowest birds were flying
upwards, as if they had risen from the immediate neighbourhood and were
seeking the proper elevation to continue their flight.
As has already been remarked, when nearing their destination migrating
birds descend, though still many miles from land. Should a gale be
raging they fly so low that they barely top the waves. And this,
apparently, to escape, so far as is possible, the force of the wind.
Larks, starlings, thrushes, and other small birds, can sometimes be
seen during daylight crossing the North Sea in their thousands. At such
times many will often afford themselves a brief rest in the rigging
of ships, homeward bound, but the main host hurry on. The beautiful
golden crested wren, our smallest British migrant, is one of these. A
glance at our charming coloured plate will show at once that the wing
is not that of a bird of strong flight. There is no more interesting
experience to the bird-lover than that of watching the tired travellers
drop earthwards, as they leave the dreadful sea behind them.
With all birds yet retaining the power of flight there is always a
liberal "margin of safety" in regard to the wing area. That is to
say this is always in excess of the minimum area necessary to make
flight possible. This much, indeed, is manifest from the fact that the
eagle can bear off a victim equalling himself in weight. Should he
miscalculate, he can always drop his burden, or lessen its weight by
eating part of it on the spot. Not so the osprey, or the sea-eagle,
which have been known to plunge down and drive their talons into
fishes too large to be raised. Unable to release their grip, death, by
drowning, has inevitably followed.
Sometimes the burden is a passenger, instead of a victim. One of
the most striking of the coloured plates in this volume is that of a
woodcock carrying one of its nestlings to a distant feeding place. This
habit is well known. It is not often that the necessity arises, but
there are occasions where suitable nesting and feeding grounds cannot
be found together, or when, as during prolonged drought, the normal
feeding area dries up. Then, instinctively, the parent will surmount
the dangers of starvation for their offspring, by conveying them to a
land of plenty, returning again to the shelter of the wood as soon as
the meal is over. The weight of a newly-hatched nestling, it is true,
could scarcely be called a "burden." But they are carried about thus
until they are strong enough to perform the journey for themselves.
Thus, then, towards the end of the nursing period the weight to be
carried is by no means a light one.
But it was shown, long since, by direct experiment, that the area of
a bird's wing is considerably in excess of what is required for the
purpose of flight. Dr. J. Bell Pettigrew, more than fifty years ago,
to test this matter, cut off more than half of the secondary wing
feathers of a sparrow, parallel with the long axis of the wing. He
first clipped one, then both wings, and found that in both cases flight
was apparently unimpaired. He then removed a fourth of the primary
feathers--the outermost quills--and still the flight was unimpaired. At
any rate the bird flew upwards of thirty yards, rose to a considerable
height and alighted in a tree. Thirty yards, however, is a short
flight even for a sparrow. But it is enough to show that flight, if not
_sustained_ flight, was possible after this mutilation. Not until more
than one-third of the quills along the whole length of the wing were
removed, did the flight become obviously laboured. And he found that
what was true of the sparrow, was equally true of the wings of insects.
Though these experiments demonstrate, in a very unmistakable manner,
that flight with a greatly reduced wing area is possible, we have no
evidence that this reduction would make no difference to the length of
time the bird could remain on the wing. And this is a very important
matter.
An aspect of flight which has now to be considered is that of birds
which fly in troops. Some species always travel thus, others only on
occasions. Rooks and gulls afford instances of this, when, during windy
weather, or for other reasons, they congregate and fly round and round
in great circles, at a considerable height. Small wading-birds, like
ringed plovers and dunlin, commonly fly in "bunches." The last named
furnish a singularly interesting sight when thus travelling; for their
evolutions are so amazingly timed. As if at a given signal every bird
in the troop will change its course at the same moment, and in the
same direction, so that now one sees a flickering mesh-work of grey,
and now a shimmering as of snow-flakes, as first the grey backs, and
then the white breasts are turned towards one. But flights such as this
are to be seen only during the autumn and winter months. For during
the breeding season these little flocks are broken up and distributed
far and wide. But there is yet another reason. They wear a totally
different dress--the courtship or breeding plumage. Herein the upper
parts are of a rich chestnut hue, streaked with black, while the under
parts are black. Even more fascinating to watch are the autumn troops
of starlings on the way to their roosting places. Hundreds at a time,
not to say thousands, take part in these flights. Now they rush onward,
in one great far-flung sheet, and now they close up into a great,
almost ball-like, mass: and now they thin out till they look like a
trail of smoke. But always they wheel and turn and rise and descend,
not as separate bodies, but as one. How are such wonderful evolutions
timed. The movements of an army on review-day are not more precise,
or more perfectly carried out. During the whole flight not a sound,
save the swishing of their wings can be heard. The marvel of it all is
beyond the range of words, nor can one express the peculiar delight
such a sight affords.
Why is it that ducks and geese commonly fly either in Indian file, or
in a roughly V-shaped formation, with the apex of the V forward? Why do
they not fly all abreast? One cannot say, but they never do.
Some mention must be made here of the surprising numbers in which
geese, of some species, congregate. Writing of the Brent goose, in his
"Bird Life of the Borders," Mr. Abel Chapman--and there are few men who
can write with such authority on the subject--tells us:--"Just at dark
the whole host rise on the wing together, and make for the open sea. In
the morning they have come in by companies and battalions, but at night
they go out in one solid army; and a fine sight it is to witness their
departure. The whole host, perhaps ten thousand strong, here massed in
dense phalanxes, elsewhere in columns tailing off into long skeins, V's
or rectilineal formations of every conceivable shape, (but always with
a certain formation)--out they go, full one hundred yards high, while
their loud clanging, defiance--"honk, honk,--torrock, torrock," and its
running accompaniment of lower croaks and shrill bi-tones, resounds for
miles around."
[Illustration: Peregrine chasing Duck.]
CHAPTER V.
Courtship Flights
"A pair of falcons wheeling on the wing,
In clamourous agitation ..."--_Wordsworth._
The wing-play of black-game and grouse--The "musical ride" of
the snipe--The "roding" of the woodcock--The musical flights of
redshank and curlew--The "tumbling" of the lapwing--The raven's
somersaults--The courting flight of the wood pigeon--The mannikin's
"castanets"--Wings as lures--The strange pose of the sun-bittern--The
"wooing" of the chaffinch and the grasshopper-warbler--Darwin and
wing-displays--The wonderful wings of the argus-pheasant.
One of the most striking features of
bird-life is surely its restless activity. This is always apparent,
but it attains to a state of almost feverish excitement as the spring
advances, and the parental instincts re-awaken. As they gather
strength, so they manifest themselves, in outbursts of song--often of
exquisite beauty--strange antics, or wonderful evolutions in mid-air.
It is with these last that we are chiefly concerned here. As might
be supposed, they present a wide variety in the matter of their form
and duration. Black-game furnish an example of a very simple form of
courtship flight, but it is associated with curious antics on the
ground. And these, it is to be noted, are only to be witnessed soon
after sunrise. Two blackcocks will approach one another and stand as
if prepared to ward off a very vigorous onslaught; reminding one of two
barn-door cockerels. With lowered head and neck they face one another,
the beautiful lyrate tail spread fan-wise, and arched so that the
curled, outer, feathers touch the ground, while the wings are trailed
like those of the turkey-cock. Then one will at last rush forward,
and seizing his adversary by the scruff of the neck, will administer
a sound beating with his wings. The victor celebrates his triumph by
a loud, and most unmusical screech, which has been likened, by that
accomplished observer and sportsman-artist, Mr. J. G. Millais, to the
call of cats on the house-tops at mid-night. But presently a grey-hen
makes her appearance. Hostilities cease at once, on all sides; and
intense excitement prevails amongst the whole assembly--for a large
number of cocks will gather together at these sparring matches. Her
approach has been observed by a single bird, who, unintentionally,
gives the signal by suddenly drawing himself up to a rigid position of
attention, till he is sure she is really coming, then he throws himself
into the air and flutters up a few feet, uttering at the same time, a
peculiar hoarse note of exultation. Immediately all the others follow
suit; each seeming to strive to outdo his neighbour in a series of
absurd pirouettings. Here we have a "Love-flight," of exceedingly brief
duration, associated with terrestrial combats and frantic prancings.
[Illustration: _Woodcock carrying Young_]
The grouse pursues a different method. He strives to incite his mate
to amourous moods by chasing her about. But she is "coy," and will
tolerate this for hours at a time, apparently intent on nothing more
than seeking something interesting to eat, she seems to affect to
be quite unaware of the presence of her importunate mate; though
her behaviour is belied by the fact that she keeps up a continuous
"cheeping" note, heard only at this time of the year. Every now and
then he will vary his tactics by leaping up into the air and taking
an upward flight of from twenty to thirty feet, crowing vociferously.
On alighting he will commence his addresses again. Then, perhaps, she
herself will take to flight, darting off and twisting like a snipe,
evidently enjoying her tantalizing tactics. He follows in close
pursuit, in the hope, doubtless, of satisfying his desires, when she
shall come to rest. Here is a "courtship" flight of longer duration, in
which both sexes participate.
The "musical ride" of the snipe is of a much more imposing character:
and in this, again, both sexes take a part. During this performance,
which affords some thrilling moments to the bird-lover, the bird
ascends to a great height, and then plunges earthwards in a terrific
"nose-dive" accompanied by a weird bleating noise, comparable to the
bleat of a goat. For long years discussion waged furiously as to the
source of this sound. Some held that it was produced by the voice:
others by the tremulous motion of the wing-feathers: others, again,
contended that it was caused by the tail feathers. This was first
mooted by the Danish naturalist, Meeves, and he produced some very
striking and curious evidence to prove his view. He showed that the
outermost tail-feathers had peculiarly thickened shafts, which were
also bent in a very striking way. By removing these feathers, and
sticking them into a cork, he was enabled, by twirling the cork rapidly
round at the end of a string, to reproduce the "bleat" exactly. Many
years later Dr. Philip Bahr revived this experiment, for the purpose
of finally setting the matter at rest--for there were still many who
remained unconverted to the Meeves interpretation. Dr. Bahr left no
room for further doubt. He showed, too, that during the production
of this sound these tail-feathers were extended laterally, so as
to separate them from the rest of the tail, and so give the air
rushing past them during the earthward plunge, full play on these
sound-producing structures. He too, applied the test first instituted
by Meeves, and so clinched his arguments. One may hear this strange
music as early as February, and even, though rarely, as late as July.
But it is essentially a breeding-season, or rather a "Courtship"
performance sound, though it may be evoked by a sitting bird suddenly
surprised, when she will "bleat" as she leaves her eggs, possibly to
distract the intruder on her vigil.
The woodcock has a "love-flight" but of a quite different character,
known by sportsmen as "roding." It takes the form of short flights
up and down the "ride," or space selected for the nesting site.
But while the female is sitting the male will still continue these
flights, choosing the early morning and evenings. As he goes he utters
strange cries, which have been compared, by some, to the words "more
rain to-morrow" and by others to, "Cro-ho, cro-ho," varied by a note
sounding like, "whee-e-cap." These flights are varied by strange little
displays upon the ground, when he will strut about before his mate with
wings drooped and trailing on the ground, the tail spread, and the
feathers of the head and neck standing on end. This gives him a very
odd appearance, to human eyes, but it serves its purpose--which is to
arouse his mate to amourous moods.
Redshank, curlew, and dunlin--cousins of the snipe and woodcock--are
all accomplished performers in the art of wooing on the wing. The male
redshank, uttering flute-like notes, Mr. Farren tells us, soars up to a
moderate height, and remains, for a brief space, "hanging in the wind"
with the tips of his curved wings rapidly vibrating. He then descends,
pipit-like, earthwards, while the song, which has been uttered slowly,
now quickens, reaching its climax as the bird, raising its wings above
its back for an instant, finally alights on the ground. But he has yet
other wiles, which are not used in mid-air. Approaching his mate with
his head erect and body drawn up to its full height, he raises his
wings for an instant high above his head: then allowing them gradually
to droop, he vibrates them, at the same time rapidly moving his legs
like a soldier "marking time."
The curlew seems to prefer the evening for his best efforts. Rising
from the ground with rapid wing-beats, he will "check" suddenly when
near the summit of his ascent; so suddenly as almost to throw himself
backwards. Then, recovering, he will hang poised, kestrel-like, in
mid-air, and pour forth a joyous thrilling, or jodelling, song. Rising
and falling, on quivering wings, or sweeping round in great circles,
and hovering again, he will remain for some considerable time pouring
forth this joyful ripple of song.
The courtship flight of the lapwing is even, if possible, more
interesting. Rising from the ground with slow heavy flaps of his broad
wings--which, it is to be noted, present a remarkable difference
from those of the female, in that the primaries are much longer, so
as to give this portion of the extended wing a conspicuously broader
appearance--as though he had difficulty in getting under way, he
speedily dissipates this impression by a sudden upward rush, an
effortless turn, apparently; and then follows a downward swoop, or
fall, with half-closed wings. To this swoop there succeeds a surprising
change. In an instant the wing-beat is increased to an incredible
speed, causing the body to turn a half, and sometimes even a complete
somersault. But the next instant he is up and away over the ground
with musical wing-beats, tilting and swaying from side to side with
wonderful buoyancy.
[Illustration: Lapwings.]
Throughout, this delightful performance is accompanied by a wild
and joyous song, which seems to be attuned to the somewhat bleak
surroundings. It thrills one even to remember it in later days: and
it defies one to express it in human fashion. It has been as nearly
rendered as any version I have ever seen--and I have seen many--by
Mr. Brock. It is not a whistle, nor is it like any sound that can
be faithfully rendered by the human voice, yet it seems to say
"_whey-willuchooee-willuch-willuch-cooee_." It suffers a break, remarks
Mr. Farren, commenting on this theme, during the flutter of the wings
at the end of the fall, but is picked up at once with a triumphant
"coo-whee, coo-ee," as the bird dashes off at the end of the somersault.
The lapwing is very intolerant of any trespass on his breeding
territory on the part of his neighbours. As soon as the intruder is
sighted, the owner of the territory charges. And the two then mount up
into the air, often to a great height, each striving to get above the
other for a downward swoop. As the one "stoops" at the other, the lower
bird dodges, and so rapidly are the wings moved that they are often
brought smartly together over the back, producing a clapping noise.
Even the black, forbidding raven has his amorous moods. And at such
times he will even outdo the more lively, though irascible lapwing in
the art of aerial somersaults; if somersaults they can be called. For
in the middle of an ordinary spell of flying he will suddenly fold up
his wings and bring them close up to the body, at the same time turning
completely round, as though he were turned on a spit; the body being
held horizontal as the turn is made. For a moment or two there he is
suspended, as it were, between earth and sky, with his back towards
earth, and his breast towards the heavens. Lest he should forget the
manner of the trick, it would seem, he will practice it at times,
during the stern work of chasing intruders from his territory; for he
will brook no competitors on his ground.
The woodpigeon, during the courtship season, makes frequent sallies
into the air for the purpose, apparently, of giving vent to his
exuberant feelings. During such flights he will dart up from the
tree-tops and sail round, high above, in great circles, rising and
falling as he goes, with out-spread wings, every now and then bringing
them over his back with a resounding snap. During such displays the
white bar across the wing is most conspicuous, serving at once to
identify the performer.
Among our native birds, the only other species which habitually, and
especially during the courting season, produce characteristic sounds
during flight, by bringing the wings smartly together over the back,
is the night-jar. But there are certain small passerine birds, known
as mannikins, inhabiting the forests of South America, which have the
shafts of the quill-feathers of the fore-arm enormously thickened. By
means of these transformed and translated "castenets," at will, the
bird can produce a sound which has been likened to the crack of a whip.
So far this discourse has been concerned solely with "courtship"
flights, or flights associated with peculiar sounds, dependent on rapid
movements of the wing in mid-air for their production. And with the
mention of these instances this Chapter might, quite legitimately,
be brought to an end. But it must not. And this, because there are a
number of birds which put their wings, during Courtship season, to very
different purposes. Spectacular flights and evolutions in mid-air do
not appeal to them. They use their wings instead as lures, as a means
of adding intensity to strange poses and pirouettings; whereby they
desire to give expression to the amorous feelings which possess them,
in the hope--if for the moment, we may accord to them human standards
of intention--of arousing kindred emotions in their mates.
Darwin was the first to draw attention to these curious displays.
Which, on the evidence then available, seemed always to be made, and
only to be made, by birds having wings conspicuously coloured. It
seemed as though the possessors of such wings were conscious of their
beauty, and so displayed them that nothing of their glory should be
missed.
The sun-bittern affords a case in point. This bird, a native of
Brazil, is soberly, but very beautifully coloured when at rest; its
plumage presenting an indescribable mixture of black, grey, brown,
bay, and white; blended in the form of spots, bars, and mottlings. But
during times of sexual excitement it will spread out its wings in the
form of a great fan, encircling the long, slender, neck. And in this
position they present a very conspicuous appearance, taking the form
of beautifully graded bands of black, white, and bright grey, forming
patterns which vanish the moment the primaries fall into their place
behind the quills of the fore-arm. But when thus spread the bird seems
to find the greatest delight in displaying their chaste splendour
before his mate. He seems to spread his wings just because he is
conscious of their beauty when thus opened out.
But we need not travel so far as Brazil to find examples of displays
of this kind. Among the birds of our own Islands we can find many
close parallels. The chaffinch and the goldfinch, when seeking to
arouse the sympathy of their mates make much play with their wings, not
only in short "nuptial flights," designed, apparently, to display the
conspicuous and brilliant colouring of the plumage as a whole, but when
perched on some convenient spray. At such times the wing is more or
less completely spread out, as if to reveal, to the fullest possible
advantage, the bright bars and splashes of colour which this extension
alone can bring into being.
Since these gaily coloured vestments seemed always to be associated
with striking, stilted, attitudes, sometimes bordering on the
grotesque, and always to be paraded in the presence of the female,
Darwin drew the inference that they were the outcome of female choice
persistently exercised during long generations. That is to say he
held that, far back in the history of the race, these performers were
soberly clad, as their mates commonly are. Then certain of the males of
these now resplendent species began to develop patches of colour, small
at first, but gradually increasing, generation by generation, in area
and intensity. This progressive splendour, he believed, was due to the
"selective" action of the females, which, from the very first, chose
from among their suitors those who stood out among their fellows by
reason of their brighter plumage. Thus the duller coloured males died
without offspring. On this assumption each succeeding generation would
be, in some slight degree, brighter than the last, until the process of
transformation ended in the glorified creatures we so admire to-day.
It would be foreign to the purpose of this book to pursue this theme at
length. Let it suffice to say that while the "Sexual Selection" theory
still holds good, it has, so to speak, changed its complexion. And this
largely owing to the accumulation of new facts. For the most important
of these we are indebted to the singularly exact and laborious
observations analysed, clarified, and interpreted with remarkable
insight and sagacity of Mr. H. Eliot Howard, one of the keenest
Ornithologists of our time. He has set forth his case, and interpreted
his facts with masterly skill, and there seems no escape from his
conclusions. Briefly, he has shown that birds of quite sober coloration
like the warblers, which formed the basis of his investigations, engage
in displays quite as remarkable, and of precisely the same character
as in birds of gaily coloured plumage. From this it is clear that this
wing-play is not prompted by a more or less conscious desire to display
conspicuously coloured patches of colour, for of colour there is none
save that of the general hue of varying shades of brown, as in the case
of the grasshopper warbler, for example. Nor is the display, apart
from colour, to be regarded as a performance slowly perfected through
long generations through the selection of females, coy and hard to
please. We must regard these "Nuptial flights" and wing-displays, as
the outward and visible signs of a state of ecstatic amorousness on the
part of the males which, by their persistence and frequent recurrence,
at last arouse sympathetic response in the females. They play the
part of an aphrodisiac. Without them there would be no mating. In my
"Courtship of Animals" those who will may pursue this subject further.
[Illustration: _Herons_]
Before closing this Chapter mention must be made of the most remarkable
wing-display to be found among birds, and of the equally remarkable
uses to which they are put. The possessor of these wonderful
appendages, for they are wonderful, is the argus pheasant of the Malay
Peninsula and Borneo. Though efficient for short flights in jungles,
all that is ever required of them, they would be quite useless in
open country where an extended journey had to be made, or escape
attempted from some vigorous enemy. And this because the secondary
wing-quills--the quills attached to the fore-arm--are of enormous
length, making, as we have remarked, sustained flight impossible. They
have, indeed, come dangerously near losing their normal functions
altogether. And this because they have passed over into the category of
specialised "secondary sexual characters." But for the fact that this
bird lives in an environment where food is abundant all the year round,
and can be obtained without any undue exertion, and that there are no
serious enemies to be evaded, it would long since have become extinct.
For this exuberant growth of quill-feathers must be borne all the year
round, though they are not required to function in their later role,
save during the period of courtship.
Their great length is not their only striking feature, or even their
chief feature. This, indeed, is represented by their extraordinary
coloration. For each feather bears along its outer web a series of
"ocelli," so coloured as to look like a series of dull gold balls
lying within a deep cup. Outside the ocelli run numerous pale yellow
longitudinal stripes on a nearly black background. The inner web is
of a delicate greyish brown hue, shading into white and relieved by
innumerable black spots, while the tips of the quills have white spots
bordered with black. The primaries, too, are most exquisitely coloured,
though in the matter of size they are not very exceptional. These,
indeed, are the only true flight feathers.
The full beauty and significance of the coloration of these feathers
can only be appreciated during periods of display. Then the two wings,
in some indescribable manner, are opened out so as to form a huge
circular screen, concealing the whole of the rest of the body. The
effect produced from the human standpoint is one of great beauty, after
the first burst of astonishment has spent itself. His mate is less
easily moved. Perchance "familiarity breeds contempt." At any rate it
is only after persistent and frequent attempts to charm her to his will
that success rewards him.
Those who have the good fortune to be able to make frequent visits to
the Zoological Gardens in London may, with great good fortune, and at
rare intervals, have an opportunity of witnessing such a display, and
of studying in detail these wonderful wings. They are wonderful, not
merely because of the manner of their display, or of their colouring,
but also because in them we see ornament pushed to its furthest limit
since, as wings, they have become well nigh useless, and therefore
almost dangerous to the well-being of their possessors.
[Illustration: Sunbittern Displaying.]
CHAPTER VI.
How to tell Birds on the Wing.
"I can tell a hawk from a hernshaw."--_Shakespeare._
The small perching-birds and the difficulty of distinguishing
them--The wagtails--The finches--The buntings--The redstart-wheatear,
Stonechat--The thrushes--The warblers--The tit-mice--The nuthatch, and
tree-creeper--The spotted-flycatcher--The red-backed shrike--swallows,
martins, and swifts--The night-jar--owls--Woodpeckers.
The experienced ornithologist apart, there
are hosts of people who are interested, at least, in our native birds:
who would fain call them all by name; yet who can distinguish no more
than a very few of our commonest species. They are constantly hoping
to find some book which will give, in a word, the "Hall-mark" of every
bird they may meet in a day's march. But that book will never be
written. For some species present no outstanding features by which they
may be certainly identified, when no more than a momentary examination
is possible, and this at a distance. And it is often extremely
difficult to set down in words, exactly, what are the reasons for
deciding that some rapidly retreating form belongs to this, or that,
species.
And then, too, there are difficulties due to seasonal changes of
plumage--often striking--sex, and age; since immature birds often
differ totally from the adults in appearance. The young robin and the
starling afford instances in point.
The adult starling, as everybody knows, is "black" with a yellow beak
and reddish legs. But seen close at hand his feathers gleam with a
wonderful metallic sheen reflecting changing hues of violet, green,
and purple. The young bird, in the early summer, is of a pale brown
colour. In the autumn the plumage is changed for a "black dress,"
like that of the adult, but heavily spotted with white. As the winter
wears on the white spots become abraded, and disappear. The robin
needs no description. But the young bird, in its first plumage, is
commonly mistaken for the female, which, of course, is practically
indistinguishable from the male. It is certainly unlike one's notion of
a "cock-robin," being of a yellowish brown colour, with pale spots, a
type of plumage characteristic of the young of the "thrush tribe."
In some nearly related species, again, the males are strikingly
different, the females barely distinguishable.
But nevertheless, a very considerable number of our British birds can
be more or less easily distinguished during flight--sometimes by the
manner of that flight, sometimes by characteristic markings, sometimes
by the notes they utter; and these are briefly summarised in this
Chapter.
[Illustration:
1. Swallow.
2. House Martin.
3. Swift.
4. Sand Martin.
5. Pied Wagtail.
6. Grey Wagtail.
7. Yellow Wagtail.
8. Chaffinch.
9. Goldfinch.
10. Linnet.
11. Greenfinch.
12. Bullfinch.
]
When it is realized that no less than 475 species, and sub-species, of
British birds are now recognized, it will be apparent that it would be
impossible to do more than briefly epitomise the commoner species, and
some of these, like the robin, and the wren, need no interpreter.
The aim of this Chapter is primarily to give, as far as possible, the
salient features of our commoner native birds, as seen during flight.
But some species merely "flit," from one place to another, and that so
rapidly that no details of coloration can be distinguished. They can
only be examined at favourable, and often fleeting moments, when at
rest, and clear of foliage. Only such as are frequently encountered are
included here. To attempt more would be to lead to confusion. Enough,
it is hoped, will be said to help the beginner. Experience will soon
lead to an ever increasing proficiency--and with this will come an
ever increasing conviction that the identification of birds, during
flight, is an extremely difficult task. Whoever essays it should,
whenever possible, supplement his efforts by the aid of a pair of good
field-glasses. These, indeed, are indispensable.
The small perching birds are, perhaps, the most difficult to name at
sight, and this because their flight presents so little to distinguish
one species from another. All fly with rapid wing-beats, alternating
with a period during which the wings are practically closed, causing
the body to travel forward on a rapidly descending curve in the
interval between the wing-beats. This gives rise to what is known as
an "undulating" flight. But the large passerines, like the crows,
differ conspicuously in their method of progress. With them the wing
beats relatively slowly, so that its shape can be readily seen; and
their course is direct--hence the familiar saying "straight as the
crow flies." Further, the inner webs of the outer primary quills
are, what is called "emarginate," that is to say, the width of the
web is suddenly reduced towards the tip of the feather, so that the
outstretched wing has a conspicuously fringed appearance, as may be
seen at a glance at the beautiful pen-and-ink sketches on another page.
The eagles and falcons have similar emarginations.
But to return for a moment to the smaller passerines. There are very
few of our native species which could be distinguished in the field by
their flight alone. For the most part one has to rely on this and clues
afforded by characteristic markings: while a further aid is afforded
by at least a slight knowledge of the haunts of birds. One would not
expect to find a wheatear in a wood, or a wren in a reed-bed.
The wagtails are among the easiest of the "undulating" fliers to
distinguish, if only because of the great length of the tail. The
pied-wagtail, with its black and white plumage--or black, grey, and
white in the winter--can be identified at a glance. And so too, may the
yellow, and the grey wagtails. The last named has the longest tail
of all, and is further marked by his beautiful grey back and bright
sulphur abdomen and under tail coverts. All have white feathers in the
tail. The pipits and skylark, like the wagtails, have very long inner
secondaries, but they can never be confused on this account. They can
never be mistaken for wagtails, but on the other hand, the several
species can be distinguished, when on the wing, only by long practice.
The chaffinch, greenfinch, and goldfinch are with us all the year
round, keeping each to his favourite haunts. Most people know them
well. But one meets even people living in the heart of the country, who
cannot call them by name! The cock chaffinch can be distinguished at
once by its white "shoulders," and white bars across the wing, apart
from the bright hues of the body, so well shown in the adjoining Plate.
The hen has similar wing-marks, but lacks the bright colours of her
lord. His cousin, the brambling--who comes to us in the winter--is just
as easily identified by his orange-coloured shoulder patch--in place
of white--and white rump, which is most conspicuous during flight. The
greenfinch is marked, when in flight, by the yellow rump and bright
yellow patches at the base of the tail feathers. Who could mistake the
goldfinch for any one else but himself? He looks like a butterfly as
he flutters about on the tops of tall thistles. The crimson and black
bands on his head, the glorious blaze of gold on his black wings,
which are further marked with white spots, as also is his tail, make
him the most gorgeous of our native finches. The bullfinch, again, is
easy to distinguish; though from his habit of haunting thickets and
dense hedgerows, he is seldom seen. In flight you may know him by his
white rump, rosy breast, and black head. But his mate is more soberly
clad: though her black head and white rump, will suffice to make sure
of her when, by good fortune, she is encountered.
One of the commonest of what we may call "road-side" birds, is the
yellow-hammer; which can be recognized at once by the bright yellow
colour of its head. As soon as it takes to flight the white feathers
in the tail, and the chestnut rump will make assurance doubly sure.
But in some parts of England one meets with another, and similar
species--the cirl bunting. In this species, however, the male has a
black throat and ear-coverts, and an olive-grey chest-band; while the
female, lacking these distinctive marks, may be recognized by a brown,
instead of a chestnut rump. When in the neighbourhood of swampy places
and reed-beds, a look-out must be kept for the reed-bunting. A small
bird with a black head and throat, and white collar, this is the male.
The female will display a brown head, buff throat and eye-brow, and
white outer tail feathers. In the winter time, near the sea, one may
frequently come across the snow-bunting, which, on the wing, will at
once attract attention by the large areas of white displayed in the
wing and tail.
[Illustration: _Chaffinch and Young_]
The redstart, one of our summer visitors, is a bird which can never be
mistaken. A sight of the russet-red tail alone suffices. But the cock
has the further glory of a mantle of grey, a black head and russet
under parts. He is fond of country rich in old timber, or hill-sides,
where stone walls attract him. His kinsman, the wheatear, returns to us
in the early spring; to give an added charm to our bare hill-sides, and
warrens, sea-cliffs, sand-dunes, and waste places. If you see a small
bird flying low over the ground, with a white rump, and black wings,
you may know that the wheatear is before you. That delightful, restless
little bird, the stonechat, is a near relation of the wheatear. He
too, is fond of waste places, and heaths; more especially such as will
provide him with plenty of furze bushes, or ling, on the topmost twigs
of which he loves to perch, flitting his tail and uttering his fussy
little notes "hweet-chat, hweet-chat." On the wing you may tell him by
his conspicuous white wing-patch, and the broad blaze of white on his
neck, set off by a jet-black head. The female and young lack the bright
chestnut on the breast. The stone-chat's cousin, the whinchat, may be
found in similar situations, but he is of a more roving disposition,
and may be found also in lowland pasture and water-meadows. More
slender in form, he is further to be distinguished by the dark streaks
down his back, white-eye stripe, and greater amount of white at the
base of the tail. Further, there is no white neck patch.
Most people know the common thrush and the blackbird when they see
them, and many country-folk, indeed, recognize no more. Yet there
are five species in all, which may be called "common." They are to
be distinguished, not so much by their flight, as by their general
coloration. Neither the common thrush, nor the blackbird need be
described here: they cannot easily be confounded with any other bird.
But for the moment it might be possible, it is true, to mistake
the mistle thrush for the more common song-thrush. It is, however,
an unmistakably larger bird, and when on the wing appears greyer,
and if seen at close quarters, shows white tips to the outermost
tail-feathers, and a white underwing. On the ground, of course, there
can be no mistaking it, on account of its much more spotted breast;
the spots, too, being much larger, and fan-shaped. During the autumn
and winter there are two other thrushes which should be looked for.
These are the fieldfare and the red-wing. The first-named, it is to be
noted, will be found in small flocks, and if examined on the ground
through field-glasses will be seen to have a slate-grey neck and rump,
and chestnut-brown wings and tail; while the breast is streaked instead
of spotted. In flight the underwing is white, as in the mistle-thrush,
from which it can easily be distinguished by its smaller size, and
the absence of white on its tail. The red-wing, like the fieldfare,
is gregarious. This is an important point to bear in mind; since it
might otherwise be confused, by the novice, with the song-thrush, the
two being about the same size. But seen at rest, close quarters, there
can be no mistake; the red-wing having a conspicuous cream-coloured
eye-stripe, and chestnut-red flank-feathers. The underwing is similarly
coloured. Finally there is the ring-ousel, which, haunts the moorlands
and rocky ravines. But it may be recognized at once by its conspicuous
white gorget, contrasted with its otherwise black plumage.
Of the forty species of British warblers there is not one which the
most expert of our Ornithologists would venture to identify by the
character of the flight alone. Most of these species, of course, are
rare and accidental visitors; many need an expert to distinguish them,
since they represent but Continental Races of our own summer visitors.
About ten species can be called common, or fairly common, in suitable
localities, and the novice must not expect to recognize even these with
anything like certainty. They have no characteristic flight, and they
rarely do more than "flit" from one place to another. In the pages of
this book, then, they can rightly have no place. But some may, perhaps,
be glad of a few notes concerning one or two of the commoner species.
The black-cap, for example, may be readily distinguished by its grey
plumage contrasting with a black cap--reddish brown--in the female.
It has also a peculiarly delightful song, which some prefer to that of
the nightingale. This, the most celebrated of all our warblers--though
for some inscrutable reason some ornithologists appear to regard it
as a near ally of the redstarts and robin!--frequents woods with
thick undergrowth and tangled hedgerows, and hence, is seldom seen,
but may be recognised by the uniform russet-brown coloration of its
upper parts, shading into pale chestnut on the tail, and the ash-grey
of the under parts, shading into white on the throat and abdomen. The
whitethroat may be recognized by the fine white ring round the eye,
grey head, brown upper parts, and buffish pink breast, set off by the
conspicuous white throat, from which the bird derives its name. It is
perhaps the only British warbler which can really be distinguished
during flight, and this only because the outermost pair of tail
feathers are almost wholly white. It may be looked for in hedges and
thickets, as well as on gorse-covered commons. Its near relation, the
lesser-whitethroat, differs in its smaller size, whiter under parts,
and the absence of the rufous edges to the secondaries, which are
one of the distinguishing features of the common whitethroat. The
garden-warbler is much more frequently heard than seen, its song, a
continuous, sweet, and mellow warble, rivalling that of the black-cap,
though softer and less varied. Haunting shrubberies and gardens, it is
yet the mere ghost of a bird, its uniform brown
[Illustration:
1. Sea Gull.
2. Hooded Crow.
3. Gannet.
4. Golden Eagle.
5. Snipe.
6. Redshank.
7. Nightjar.
8. Barn Owl.
9. Rook.
10. Cuckoo.
]
upper parts, and brownish-buff under-parts, coupled with its shy,
retiring disposition make it exceedingly difficult to see. Three other
tantalizing little members of this numerous tribe are the chiff-chaff,
willow-warbler, and wood-warbler. Tantalizing because so frequently
seen during the summer months, so much alike, and yet, somehow,
different. The novice has no name for them; the expert can only tell
them by a combination of characters, and their contrasts. He is guided
rather by their notes and habits, than by their appearance, so closely
do they resemble one another! The chiff-chaff, as its name suggests,
is to be identified by its song--Chiff-chaff, chiff-chaff, chiff,
chiff-chaff-chiff--uttered from the top of a high tree. The singer is
too small to be seen, so that he who would discover what manner of
bird is the songster, must watch in the direction of the sound, till
the singer elects to descend. The willow-warbler is a rather larger
bird with a tinge of yellow in his plumage. Also it is less restricted
to woods and coppices, and has a sweet, indescribable warble. The
wood-warbler is the largest of this trio--from the tip of his beak to
the tip of his tail he may measure as much as five inches--and is also
the most brightly coloured. Above he is greenish, with an eye-brow
of sulphur-yellow, and a sulphur-yellow breast and throat. Since he
is rarely to be found, save in woods of beech and oak, he will, on
this account, the more easily be distinguished from his cousin, the
chiff-chaff and the willow-warbler. This fact again, can be taken into
account when the identity of one or other of these two is in question.
The warblers are essentially birds of the country-side--they cannot
abide the busy haunts of men, who seem unable to settle anywhere
without setting up hideous tramways and ugly buildings. Kindly Nature
is crowded out. The garden, hedgerow, and shady woods are the chosen
haunts of the warblers, though some prefer the reed-grown stream, or
the thickets round quiet pools. The reed and the sedge-warbler will
be found here, but by no means easily so, for after the manner of
their tribe they love seclusion. To find the reed-warbler you must go
to reed-beds, or to osier-beds, and there watch for a little bird,
chestnut-brown above, and white below. But for his constantly babbling
chatter--"churra, churra, churra"--you would never, probably, find
him. Guided, however, by his song, you may succeed in finding him
nimbly climbing up and down the reed stems. Very like him is the rarer
marsh-warbler: but, for your guidance, note that the marsh warbler
has a really melodious song, and is even more likely to be found in
swampy thickets of meadow-sweet than the reed-beds. The sedge-warbler,
though showing a decided preference for streams fringed by osier-beds
and thickets, is more of a wanderer than the other two, since tangled
hedgerows, and thickets, at a distance from the water will often
suffice him. You may know him by the fact that he is of a dark brown
colour above, streaked with a paler shade of brown, while the under
parts are white, tinged on the breast and flanks with creamy buff.
Ornithologists rarely concern themselves with anything but the
superficial characters of birds. Not even the structure of the feathers
interests them, but only their coloration. Hence it is that they have
come, quite commonly, to regard the gold-crest, or "gold-crested wren,"
as it is sometimes called, as one of the tit-mouse group! There is not
even the remotest justification for this view. It is an indubitable
warbler. A glance at the coloured Plate will render any description of
its appearance unnecessary. From autumn to spring you may find it in
most parts of England and Scotland--save the extreme north--hunting in
hedgerows and woods for food. During the breeding season it favours
coniferous woods. Along the south and east of England, one may also
meet with a closely similar species--the fire-crest. But while in the
gold-crest the crown is of a bright lemon-yellow, in the fire-crest it
is of a bright red-orange hue, while the side of the head is marked by
a white stripe bordered with black.
The gold-crest is our smallest British bird. The ranks of our resident
"gold-crests," in the autumn, are swollen by immigrants from northern
Europe, who seek shelter with us because unable to withstand the
rigours of the more northern winter. In the matter of size the gold,
and fire-crested wrens agree, measuring but a trifle more than three
and a half inches from the tip of the beak to the tip of the tail! By
the way, the shape of the beak should be carefully noted. It is that of
a typical warbler.
It may be urged that this description of the warblers might well have
been omitted from these pages, since, in regard to "Flight," nothing
whatever can be said, save that they "fly." There would indeed, be some
justification for such criticism, but it is to be remembered that this
volume is written, not for the expert, but for the novice, who, because
he needs a few concrete examples of the hopelessness of expecting to
identify every bird he may encounter by its flight, and of the methods
he must occasionally adopt, when seeking to name a bird which will not
come out into the open. His course of training, and discovery, will be
much shortened by the realization that birds by no means always reveal
their presence by taking long flights.
What is true of the warblers, in this regard, is true also of our
numerous species of tit-mice. We do not distinguish between them in the
field by their flight, but by their coloration.
But since these are such confiding little birds, coming to our very
windows during the winter months, for food, a few notes concerning them
may be acceptable. The commonest of all is the little blue-tit, or
"tom-tit," as it is so often called. Its beautiful cobalt-blue crown,
blue back, wings, and tail, white face, and yellow breast, are familiar
to us all. Its larger relative, the great tit-mouse--the largest
British tit-mouse--bears a close general resemblance to the smaller
species, but is readily distinguished, not only by its greater size,
but by the broad band of black running down the abdomen. Its flight,
as of all the tit-mice, is weak, and as it were, uncertain, confined
to short passages from tree to tree. The coal tit-mouse and the marsh
tit-mouse are seldom recognized as distinct species, by the novice.
They are very soberly coloured little birds, the coal-tit being of an
olive-grey, tinged with olive-buff, while the sides of the body are
buff: the head and throat are black, relieved by a broad patch of white
on each side and down the nape of the neck. The marsh-tit is, to all
intents and purposes, of the same coloration, but differs conspicuously
in lacking the white patches. The tiny longtailed-titmouse cannot
possibly be mistaken for any other bird. Its delicate hues of pink and
grey, and extremely long tail, make comparisons with any other species
unnecessary.
Where, during the winter, small birds are tempted to come to a tray of
nuts and seeds, placed outside the window, that charming little bird
the nuthatch--a near relation of the tit-mice--will commonly be among
the guests. It cannot be mistaken for any other British bird, its
form and coloration being, alike, distinctive. Its upper parts are of
a delicate blue-grey, its under parts buff, passing into chestnut on
the flanks. The throat is white, while there is a black line from the
beak to the eye, and beyond, spreading as it goes. A relatively large
beak, and strikingly short tail, are features as conspicuous as is the
coloration. Its flight is slow and undulating.
Another little bird which, during the winter, associates with the
tit-mice, is the tree-creeper. It is never seen on the wing, save
when it is flitting from one tree to another, and then its course is
obliquely downwards--from the upper branches of one tree to the base of
another. This it proceeds to ascend immediately on alighting, by jerky
leaps. Its coloration is soberness itself--mottled brown above and
silvery white below. The tail, it is to be noted, is formed of stiff,
pointed feathers, like those of the woodpecker, and, as in that bird,
is used in climbing.
There is scarcely a garden--save in such as are within the area of a
big town--which, during the summer, is not haunted by a little grey
and white bird, with a most characteristic flight--a sudden sally into
the air to seize some insect, sometimes even white butterflies, and
an instant return to the same perch. This is the spotted flycatcher.
In Wales, Devonshire, Cumberland, and Westmorland, one may be fairly
sure of meeting with the pied-flycatcher. He is, so to speak, a black
and white edition of his relative, the spotted flycatcher--but the
black areas in the female are represented by brown. There are, however,
notable differences in the method of hunting, in the two species; for
the pied-flycatcher rarely returns to the same perch after his upward
flight into the air, and he often feeds on the ground.
[Illustration: _Gold Crested Wrens_]
In the straggling hedgerows of the wooded districts of south and
central England, and in Wales, one may often come across the red-backed
shrike; a very handsome bird, with pointed wings, long tail, and low
swooping flights. His red back will alone distinguish him. No other
British bird wears such a mantle. And this is set off by a grey crown
and nape, and black patches on the sides of the head. The topmost twig
of a bush, or hedge, where he can sight his prey from afar, are his
favourite perches. On the east coast of England, during the autumn,
one may sometimes see the great-grey shrike, distinguished readily
by his large size, fan-shaped tail, and grey coloration, relieved by
black ear-coverts, black wings and tail, "blazed" with white, and white
under-parts. His flight is undulating and irregular, while just before
alighting he gives a peculiar upward sweep.
Strangely enough, not only country boys and girls, but their fathers
and mothers, not only confuse swallows and martins with one another,
but these with the swift! Yet they are readily distinguishable. All,
it is true, have long, pointed wings, and forked tails: but their
coloration is very different. The swallow has the most deeply forked
tail of them all, and his steel-blue back, red throat, and rufous
buff-and-cream under parts are unmistakable identification marks.
The martin may be distinguished at once by the conspicuous white
rump patch, and pure white under-parts. These are the signs by which
they may be recognized when on the wing--and they are more often seen
thus than at rest. The sand-martin is a much smaller bird, has a less
markedly forked tail, and is of a uniform pale brown above, and white
below, but with a brown band across the chest. The swift is not even
related to the swallow-tribe. On the wing--and very few people ever
see him otherwise--he is very different. The wing-beat is extremely
rapid and intermittent. While in its shape the wing differs in its
extreme length and narrowness. The flight is extremely swift--hence the
name of the bird. Not its least impressive feature is its wonderful
flexibility. Who has not watched, with delight, a troop of these birds
sweeping down the village street, now skimming the ground, now sweeping
upward and away, round the church tower, accompanied by wild, exultant
screams, as though they were bubbling over with vitality. When high
up they look like so many animated bows and arrows--the arrows being,
perhaps, somewhat short and thick. The swift, it is worth remembering,
is a near kinsman of the humming-bird, which also has a long narrow
wing. Both alike agree in this peculiarity--an upper arm bone of
excessive shortness, and a hand of excessive length. No other birds
approach them in this. The only other bird which has wings quite so
ribbon-like, when extended, is the albatross--one of our rarest British
birds. But here the proportions of the wing are reversed, for the
upper arm bone is of great length, while the hand is relatively short.
There is something inexpressibly soothing about the twilight of a
summer's evening. Most birds are abed. The swift can be heard high up,
the "woolly bats, with beady eyes" are silently flitting all round one,
turning and twisting as no bird ever turns. But for the chorus of the
swifts, like black furies, and heard only at intervals, and faintly,
all is silence, relieved, perchance, by the drowsy hum of a blundering
dor-beetle. Then, suddenly, if one be near some gorse, or bracken
covered common, the stillness is broken by a strange "churring," like
a bubbling whistle, rising and falling in volume. This may be followed
by a loud "clap". And yet the source of these strange notes cannot
be located, nor can any living thing be seen to which they could be
attributed. But keep careful watch. Presently there may emerge from the
gathering gloom a long-winged, long-tailed bird, travelling at speed,
with a twisting flight, and deliberate wing-beats, alternating with
long glide on motionless pinions. As it passes one may notice white
spots on wings and tail. This is the night-jar: a bird of ill omen
among the aged inhabitants of the country-side, for they will assure
you that it is guilty of sucking the milk of cows and goats. Hence, it
is commonly known as the "goatsucker." Poor bird, it is quite innocent
of such misdeeds, for though it has an enormous mouth, armed on either
side with long bristles, it feeds only on moths and beetles.
If you are fortunate, your vigil in the gloaming may be rewarded
by a sight of yet other night-birds. Out of some hollow tree,
or swooping round the barn, may come a ghostly form, borne on
absolutely silent wings: but with a reeling, bouyant flight, which
is unmistakable--this is the barn owl. If you are very fortunate,
you may hear its blood-curdling screech. Once heard you will never
forget it! His cousin, the tawny owl, it is whose musical, if doleful
"hoo-hoo-hoo-hoo-o" has so commonly been misrepresented by poets--and
others--as "to-whit-tu-woo." Its flight is slower and its wings
rounder than in the barn owl, and furthermore, it lacks the glistening
satin-white under-parts of that bird. But its coloration and general
appearance are well-shown in the coloured illustration.
The other species of owls we may reckon as fairly common residents
with us. They are the long and the short-eared owls. But they are very
rarely to be seen on the wing in daylight. Each has the habit, when
excited, of bringing the wings together smartly over the back, so as to
produce a sound likened by some to the word "bock."
Few birds have figured so largely in our literature, perhaps, as the
cuckoo. Though heard by all, he is seen by few: and this because so
many people fail to recognize the charming wastrel when they see him.
In general appearance he recalls the sparrow-hawk. I have known even
game-keepers confuse the two. But the cuckoo is much paler on the back,
and the bars of the breast are finer. On the wing he is much slower
than the sparrow-hawk; his wings are shorter, and his tail is tipped
with white. Immature birds may be recognized by their clove-brown
coloration, and a large white patch at the nape of the neck.
One of the most brilliantly coloured of all our native birds is the
kingfisher. Small streams and quiet pools are its favourite haunts. A
glance will suffice to identify it at close quarters, but even if one
catches sight of its fleeting form at too great a distance to see its
wonderful coloration, it can be distinguished by its extremely rapid
and direct flight, and curiously shuttle-shaped form: an appearance
due to the shortness of its tail, as may be seen by a reference to the
excellent coloured Plate.
The identification of birds in flight will be rendered easier for the
novice if he makes a practice of "expecting" to find particular birds
in particular places. That is to say, the haunts of birds are governed
by their stomachs--they must not stray far from the source of their
food. In a wood, then, you may "expect" to find woodpeckers--though
you will often be disappointed, for they are by no means always to be
seen. But the task of identification will be easier if one has a mental
picture ready of the birds appropriate to the place.
The green woodpecker, our largest native species, often betrays itself
by its remarkable cry, reminiscent of a laugh--"ha, ha, ha," and "pleu,
pleu, pleu." Keep quite still, and presently, as likely as not, it will
suddenly make its appearance with a rapid, undulating flight. As it
alights on some neighbouring tree-trunk, its identity will be finally
established by its green back and wings, yellow rump, and crimson
crown. It ascends the tree by jerky leaps. Where ant-hills abound
it may often be seen on the ground, moving about with awkward hops,
exploring the hills for ants. The greater and lesser spotted woodpecker
may also sometimes be seen here, especially if there is much old
timber about. In spring its presence is often made known by a peculiar
drumming sound--never forgotten when once heard--made by excessively
rapid blows with its beak on the trunk, or branch of a tree. On the
wing it may be recognized by its "dipping" flight, and strikingly
piebald appearance. At close quarters the strongly contrasted black and
white plumage is relieved by crimson undertail-coverts, and a crimson
crown. The lesser-spotted woodpecker is a much smaller bird--about the
size of a sparrow, or chaffinch--and is barred with black and white;
there is a patch of crimson on the head of the male. It has a habit of
keeping more to the upper branches of the tree than the other species:
but, like its greater cousin, it "drums" on the tree during the spring,
but less loudly. Its spring cry, "pee-pee-pee," is like that of the
wryneck. This is a near relation of the woodpeckers, but very different
in coloration, being beautifully mottled and vermiculated with grey and
brown. But for its spring cry, just alluded to, it would escape notice
altogether, so closely does it match the bough it is perched upon.
Unlike the woodpeckers its tail-feathers are not developed to form
stiff, pointed spines. This is accounted for by the fact that, though
it ascends tree-trunks readily, it does not hammer at the bark with its
beak, and so does not need stiff tail-feathers to afford leverage. Its
flight is slow and hesitating. It is commonest, it may be remarked, on
the south-east of England.
[Illustration: _Great Spotted Woodpeckers_]
[Illustration: Drumming Snipe.]
CHAPTER VII.
How to tell Birds on the Wing
(_continued_).
"The seamew's lonely laughter
Flits down the flowing wave;
The green scarts follow after
The surge where cross-tides rave."--_Fiona Macleod._
Falcons--golden eagle--harriers and sparrow-hawk--The heron--The
cormorant, shag, and gannet--The petrels--Guillemots, razor-bills,
and puffins--The ducks--The great crested grebe and dabchick--The
pigeons--The "plover tribe"--The gulls and terns--The game birds.
Our native birds of prey, the owls and
hawks, have been so harassed by game-keepers that many species are
now exterminated, while others are but rarely seen. Some, however, in
favoured localities still remain to us. At one time the owls and hawks
were believed to be nearly related: they were distinguished as the
"Nocturnal" and "Diurnal" birds of prey. We now know that they are not
in the remotest degree related. The owls, indeed, are closely related
to the nightjars. They have been already discussed here. The hawk tribe
must now have their turn.
The one most commonly seen to-day is the kestrel, which is really
a falcon, not a "hawk." No bird is so easily identified on the
wing. And this because of its habit of hovering in mid-air as though
suspended from the sky by some invisible thread, while it searches
the earth far below for stray mice. The kestrel's lordly relative,
the peregrine-falcon, is now-a-days only to be seen in a few favoured
spots, out in the wilds--on beetling cliffs washed by the restless
sea, or inland precipices. Those who have the good fortune to see it
at rest may know it by its large size, strongly barred under-parts,
dark blue-grey back and wings, and dark moustachial stripe. On the
wing it is a joy to watch, for its flight impresses one as something
irresistible: something from which there can be no escape, so swift is
it, and so terrible in its directness and strength. A few rapid beats
of its long pointed wings, then a long glide on motionless pinions,
and it is swallowed up in the distance. On the moors of Scotland it is
regarded with cordial dislike, because of the terror it spreads among
the grouse. Hence, unhappily, every man's hand is against it.
The little hobby is another of our falcons which is remorselessly shot
down by the game-keepers, who, all too commonly, lack both knowledge
and discretion. In appearance it closely resembles the peregrine, and
its flight is similar. It feeds chiefly on small birds, dragon-flies,
and beetles. You may hope to find it--generally in vain--in well-wooded
districts, from April to September, in the southern counties of
England. In the north of England and Scotland, if Fortune favours,
you may find the merlin; our smallest British falcon; the male
scarcely exceeds a blackbird in size. Moors and the heath-covered
brows of sea-cliffs are perhaps its favourite haunts. Its flight is
swift, buoyant, and low. Unlike the hobby, gliding movements are not
conspicuous. The male is of a slate-blue, and has a broad black band
across the tail. The female is larger than her mate, dark brown on
the back and wings, and white, streaked with brown, below. It feeds
almost entirely on small birds, but varies this diet with beetles and
dragon-flies.
Wherever there are deer-forests in Scotland, even to-day,--but nowhere
else in Great Britain--may you count on seeing the golden-eagle. And
it is a sight to gladden the eyes. Its great size, broad wings, and
wide-spread, upturned, primaries, are unmistakable, when seen on the
wing--and it is rarely that you will see it else.
Those who cannot contrive to visit the haunts of the golden-eagle may
find ample compensation in watching the flight of the common buzzard in
Wales, the Devonian peninsula, and the Lake District. Though time was
when it might be seen all over England, wherever woods abounded. Its
flight, when hunting, strikes one as somewhat slow and heavy. In fine
weather, however, as if for the mere delight of the exercise, it will
mount heaven-wards in great sweeping spirals, holding its broad wings
almost horizontally, and spread so that the primaries stand widely
apart for half their length, and in this joyous movement they will
remain aloft for hours on end.
But for the untiring efforts of the Royal Society for the Protection
of Birds, none of our larger birds of prey--save, perhaps, the golden
eagle, which is carefully cherished in the deer-forests--would now be
left to us. The case of our harriers seemed hopeless. But, thanks to a
zealous protection, a remnant remains.
The harriers are in many ways extremely interesting birds. In
appearance, when closely examined, they present one remarkable feature.
And this is found in the curious arrangement of the feathers of the
face which radiate from the eye as a centre, as in the owls, to form
a "facial disc." They are all large birds, of slender build, and have
a habit of flying close to the ground with their long, slender legs
dangling, crossing and re-crossing the same area till they are sure
they have examined it thoroughly. Frogs, eggs, small birds, and voles
form their principal food. Every now and again they will rise and
circle round at a considerable height, seeking a new feeding ground.
The marsh-harrier is our largest harrier, and has rounded wings, and
slower wing-beats than the others, from which it is further readily
distinguished by its chocolate brown coloration, cream-coloured head,
and grey tail and secondaries, which contrast strongly with the black
primaries. The hen-harrier breeds only in the Orkneys and the Outer
Hebrides. It is distinguished by its grey coloration and pure white
rump-patch. Montagu's harrier is a somewhat smaller bird, and has black
bars on the secondaries. In flight it is more graceful and buoyant than
its relatives, and this is accomplished by three or four wing-beats,
alternating with a long glide on half-raised pinions. It, again, nests
annually in East Anglia, thanks to protection.
There remains but one other bird of prey to mention here, and this is
the sparrow-hawk. It may be easily recognized during flight by its
short, rounded wings and long tail. The female, which is much larger
than her mate, has the under parts distinctly barred. The breast of
the male is similarly marked, but the bars, being of a pale rufous, or
rust-colour, and much narrower, are less conspicuous. It has a very
rapid and gliding flight, just above the ground, or along hedgerows,
which it scours in its search for small birds.
There may be many who will fare forth to find the harrier on the wing.
If they succeed they will indeed be fortunate. But there is one bird
that most certainly will be seen in the "harrier-country," and that is
the heron. There can be no mistaking him. He may be found, a large,
grey bird, standing contemplative, knee-deep by the river's margin,
or in some ditch, awaiting the moment to strike at some unwary fish,
frog, or water-vole. The moment he discovers that he is being watched
he will be on the move. He rises heavily, almost awkwardly, with
flapping wings and outstretched neck: his legs dangling down. But no
sooner is he well on the way than he hauls in his neck till the head is
drawn close to the body, and straightens out his legs till they extend
behind him like a pair of streamers. Henceforth his flight is easy and
graceful enough. This is the bird which was so much prized in the old
days of "hawking." The invention of the gun ended this most fascinating
form of sport.
Let us turn now, for a little while, from moor and wood and fen, to
the sea-shore, and, for choice, to a rock-bound coast with towering
cliffs. Here you will find a number of species which will never be
found inland. They love the sea, whether it be shimmering in the sun of
a blazing June day, smooth as a millpond, or in a fury of thundering
billows, lashed by a roaring gale in bleak December. The bottle-green
shag is one of these. You cannot mistake him. Perched on a rock he
sits upright, and, in the spring, wears a crest upon his head. On
the water he floats with the body well down, and every few moments
disappears with a spring into the depths, for his never-ending meal
of fish and crabs. His flight, just above the water, is strong and
rapid. His cousin, the cormorant, is a conspicuously larger bird, with
a bronze-coloured plumage. In the breeding season his head has a hoary
appearance, due to the presence of numerous filamentous feathers, known
as "filoplumes"; while the throat is white, and there is a large white
patch on the thigh. He has a habit, after a full meal, of sitting on
some convenient perch with wings spread wide open and open-mouthed,
apparently as an aid to digestion. But he is by no means so wedded to
the sea as the shag. Rivers and inland waters will serve him as well as
the sea.
[Illustration:
1. Partridge.
2. Gannet.
3. Whitethroat.
4. Red-backed Shrike.
5. Magpie.
6. Goldfinch.
7. Great Crested Grebe.
8. Buzzard.
9. Puffin.
10. Grey Wagtail.
]
The gannet, though very nearly related to the cormorant, is a bird of
very different habits and appearance. When adult it is snow white in
plumage, with blue beak and feet, and can be mistaken for no other
bird. Its peculiar mode of fishing was described in Chapter II.
Finally, there are two most interesting features of these birds which
are worth remembering. To wit, the toes are all enclosed within one
web, and they have no nostrils, and but the merest apology for a tongue.
And now we come to the petrels. These are for the most part nocturnal
birds, spending the day in burrows. They would, therefore, find no
place in these pages but for the fact that one may occasionally be seen
at sea when one is fishing off the shore in a boat. The commonest is
that known as the Manx shearwater. Rather larger than a pigeon, it may
be distinguished by its flight, which is rapid; the wings presenting
periods of rapid quivering, alternating with long sailing with fixed,
widely spread, narrow pinions. At one moment one sees only the deep
black of the back, the next the pure white of the under parts as the
birds turn now this way, now that, holding the outstretched wings at
right angles to the surface during the turn, so that one wing barely
misses the waves, while the other points skywards.
Sometimes too, one may see the little "Mother Carey's Chicken." A tiny
sprite sooty-black in colour, and with a white rump patch, it often
flies so close to the water that it is able to patter along the surface
with its feet, as it flies.
The fulmar petrel is indeed a child of the sea, for, except in the
breeding season, it never comes to land. But at sea you may have
the good fortune to see it off the east coast of Great Britain, and
the north and west of Ireland--and in winter off the south and west
coasts of England. Though in coloration resembling a common gull, it
may always be distinguished, when on the wing, by its narrow wings,
curved like a bow--not sharply angled as those of a gull, and the
primaries are not black-tipped. Its flight is strong and powerful:
slow wing-beats alternating with long glides. On far St. Kilda, in the
breeding season, you may find them in great hosts. For some unexplained
reason they are increasing in numbers, and may now also be found
breeding in the Shetlands, Hebrides, and Orkneys.
Some who read these pages may, perchance, be stimulated by a desire to
enlarge their acquaintance with our sea-birds by spending a day at sea
in a small row-boat. For choice, one of the larger breeding-stations
should be visited. Horn Head, Donegal; St. Kilda, The Scilly Islands,
the Bempton cliffs, Yorkshire; The Farne Islands, Fowlsheugh,
Stonehaven; the Orkneys, the Shetlands, or the Hebrides, are all
renowned resorts. Here are thrilling sights indeed. Guillemots,
razor-bills, and puffins are congregated in swarms, which must be
seen to be believed. Few birds are more easy to tell at sight as they
scuttle past one on the way down to the water from the cliffs, or
returning laden with food for their young. The puffin is easily the
most conspicuous, since he flies with his little yellow legs stuck out
on each side of his apology for a tail. And for a further token there
is his great red and yellow beak. The guillemot has a sooty brown head
and neck--in his breeding dress--slate-grey back and white under parts,
and a pointed beak; while the razor-bill, similarly coloured, is to
be distinguished by the narrow white lines down his highly compressed
beak. By good fortune, the white-winged black guillemot may be found
among the host. His white wings contrasting with the black plumage of
the rest of the body, and his red legs, suffice to identify him.
On the Farne Islands, as well as on the Orkneys and Shetlands, you
may be sure of finding the Eider-duck, one of the most singular, and
most beautiful members of the duck family. It is singular because of
its coloration; the under parts of the body being of a velvet black,
while the upper parts are white, thus exactly reversing the normal
distribution of these "colours." The rosy hue which suffuses the
fore-part of the breast, and the bright green patch on the cheek,
make up an unforgettable scheme of coloration. The female is very
soberly clad, being of a dark brown, barred with black. A further, and
valuable, identification mark is furnished by her beak, which, like
that of her lord, seems unusually long, owing to the sloping forehead.
The flight is slow and close down to the water.
The sheld-duck is another strikingly coloured species that is commonly
seen on sandy shores and estuaries. There can be no mistaking it. On
the wing it has a conspicuously pied appearance, while the flight
seems slow and rather laboured. Seen at rest, and fairly near, a broad
chestnut band across the breast, and a black band down its middle will
be noticed, while the black head and neck are admirably contrasted
with a coral red beak. The legs are pale pink. In winter, on parts of
the east coast, they sometimes form flocks of several hundreds. The
heavy-bodied, black ducks, one often sees scurrying along, close to the
water, sometimes in immense flocks, are common scoters. The male is
entirely black, with an apricot yellow beak-patch, the female is a dark
brown, with grey cheeks.
[Illustration:
1. Peregrine Falcon.
2. Kestrel.
3. Merlin.
4. Golden Eagle.
5. Montagu's Harrier.
6. Goshawk.
7. Osprey.
8. Sparrow Hawk.
]
Though the duck-tribe is represented by a considerable number of
species, the number likely to be seen by the casual wanderer is very
few; for these birds mostly keep well under cover during the day. In
addition to the three species just described there are at least two
others which are not infrequently seen, out in the open, during the
day. One of these is the goosander, which, on the lochs and rivers of
Scotland, is common; and it is also frequently encountered in similar
situations in the northern counties of England. You may know him by his
bottle-green head, which bears a crest, black back, and white wings.
His breast is suffused with a wonderful pale salmon colour--which fades
away within a few hours of death, leaving the breast white. The beak is
long, pointed, and coral red. Moreover, its edges are armed with horny
teeth. For he is a fish-eater, capturing his prey by diving. On the
wing he is very fast, but he rises from the water but slowly. His mate
has a reddish-brown head and neck, and a grey back. The second species
referred to is the mallard, though it is only very occasionally, and
by accident, met with during the day. Its appearance has been so well
represented in the coloured Plate that there is no need for description.
When on the margins of lakes, large ponds, or slow-moving streams, keep
a look-out for two very remarkable divers--the great-crested grebe and
the dabchick. Both float low in the water, and may be identified at
once from the fact that they have no tail. The great-crested grebe has
a conspicuous dark chestnut-red frill round his neck, which can be set
out like an Elizabethan ruff, at will, though this is rarely done save
in the courting season. The dabchick is a small bird--rather smaller
than a pigeon--and has no erectile ornaments. The "grebe-flight"
is shown in the coloured drawings, and it has further been already
described. They will vanish beneath the water with startling
suddenness, and remain below for a surprising length of time; emerging
at last far from the spot at which the dive was taken.
One of the commonest birds of the country-side is the ring-dove,
or woodpigeon. He is the largest of our pigeons, and may further
be distinguished by the white half-ring round his neck. His flight
scarcely needs to be described, for it differs in no essentials from
the pigeons of our dove-cotes. His courtship flight has already been
described here. The stock-dove is not quite so conspicuous, but may be
readily distinguished from the fact that the neck has no white patch,
while the out-spread wings are marked by an imperfect bar of black. It
is a bird, by the way, which shows a strange diversity of taste in the
selection of the site for its nursery--a rabbit-burrow, a hole in a
tree, an old squirrels drey, or the cross-beams in an old church tower!
The rock-dove haunts deep caverns worn out of the cliffs, both inland
and on the coast. But one can never be certain that one is watching
_really_ wild birds. Certain it is that most of the "rock-doves" one
sees are domesticated birds run wild. This is the ancestor of our
dove-cote birds, from some of which, those with a white rump and two
black wing-bars, they cannot be distinguished. It is on account of this
ancestry that our domesticated pigeons never alight in trees. They are
inherently cliff dwellers. The turtle dove is a summer visitor to
the British Islands. The cinnamon brown of its back, bluish ash-grey
head, wing-coverts and rump, the patch of black on its neck, and the
fan-shaped tail, tipped with white, readily distinguish it from the
other three species just described.
Where the summer holidays are spent by the sea--in places where
there are no bands, piers, "promenades," and other abominations of
"civilization"--one may spend delicious hours watching some of our
"wading-birds." On such parts of the coast as have a rocky shore one
may be sure of finding the handsome oystercatcher, a black-and-white
bird, with a long red beak, and flesh-coloured legs. His loud,
shrill "_wheep-wheep_" seems to harmonize perfectly with his wild
surroundings. His striking coloration, shrill note, and swift powerful
flight, make confusion with any other bird impossible. One is also
sure to find the ringed-plover. A little bird with a pale brown back,
a white forehead with a bar of black above it, black face, and a black
band at the base of the white neck. The beak is short, and the legs
yellow. The wings, in flight, are long and pointed, and marked with
a white bar. The outer tail-feathers, spread during flight, are also
white. It runs rapidly about, swiftly picking up sand-hoppers and
other small creatures, and always travels in small flocks. Commonly
associated with the ringed-plover one finds the dunlin, grey above,
white below, and with a long, black beak. The peculiarities of its
flight, and its strikingly different summer dress have already been
described here. Sometimes you will meet with the common sandpiper; a
small bird, about the size of a thrush, who runs on rather long legs,
and constantly flicks his tail up and down. His coloration is of a
bronzy-brown, above, more or less conspicuously marked with darker
bars, and white below. In flight he shows long, pointed wings, and a
tail broadly tipped with white and barred with black. More often you
will find him on the banks of streams. His cousin, the redshank, a much
larger bird, has already been described here in regard to his spring
love-making. Later in the year he may be distinguished, when on the
wing, by the large white rump-patch, white secondaries, white tail,
barred with black, long pointed wings, and long, red legs.
The wary curlew, already referred to, is really a moorland bird,
but spends the autumn and winter by the shore, or on the mud-flats
of estuaries. His peculiar cry, a shrill "_cour-lie_," readily
distinguishes him. Added to this is his large size, brown coloration,
and long, curved beak. On the wing, the rump and upper tail-coverts are
conspicuously white.
The "waders," sometimes collectively referred to as the "plover-tribe,"
are represented in the British Islands by a very long list of species,
of which only the commonest are mentioned here. Many, however, are
mere casual visitors. Near allies of this "tribe" are the gulls and
terns. The peculiarly graceful, elastic flight of these birds surely
needs no description. Even town-dwellers know them well. For during
the winter months they follow the rivers far inland. Even in grimy
London they may be seen in hundreds during the winter months. The
black-headed gull is by far the commonest of these winter visitors. But
at the same time, to the uninitiated, the name "black-headed" must seem
singularly inappropriate; for its head is emphatically _white_. At no
time, indeed, is it ever _black_. But keep careful watch of the hosts
which throng the river from January, onward, till they depart for their
breeding quarters, and you will see them gradually developing a dark
patch on each side of the head. And this slowly spreads till the whole
head is of a dark sooty brown. Immature birds may be picked out by the
presence of brown feathers in the wings, and a black bar across the tip
of the tail. Here and there among them, one may see much larger birds
of a brownish grey colour, and with black beaks and pale coloured legs,
in place of the cherry-red of the beak and legs of the "black-headed"
species. These are the immature stages of the greater, and lesser
black-backed gulls; or of the herring gull. When fully adult the two
first-named have the back and wings of a dark slate colour, the rest of
the plumage dazzling white. The beak is pale yellow, with a red spot on
the angle of the lower jaw. During flight the wings are also black, but
the primaries have white tips. The herring gull has a pale pearl-grey
back.
With a strange perversity the black-headed gull is commonly called, by
the novice, the "kittiwake." This is a totally different bird, rather
like a herring-gull in miniature, but with a green beak and short,
black legs. Moreover, it is rarely seen inland. It breeds in vast
colonies on the ledges of precipitous cliffs along the Scottish coast
and the west of Ireland. There are colonies, too, on Lundy, the Scilly
Isles, and the Farnes.
One other gull must be mentioned here, though it is not common, save in
the northern parts of Scotland. But it is a regular winter migrant down
the east coast of England during the winter. This is Richardson's skua.
You may tell it at once by its dark brown coloration, and long, pointed
tail. It gets its living mostly by robbing other gulls, chasing them
till they disgorge their latest meal, which is seized in mid-air as it
falls sea-ward!
Finally, a word or two about the "game-birds." These are all birds
easily distinguished by reason of their short, rounded, deeply convex
wings, which, driven with incredible speed, produce a "whirring"
sound--very pleasant to the ears of the sportsman. The flight is never
continued very far. The English partridge may be distinguished by the
horse-shoe mark on the breast: the French partridge by the beautiful
pearl-grey colour of the flanks, relieved by short bars of black, and
chestnut-red, and red legs and beak. It is also known, indeed, as
the "red-legged" partridge. The pheasant is a far larger bird, with a
long, pointed tail. The grouse is confined to moors. His heavy build
and red coloration distinguish him at once. The black-cock is a still
larger bird; the male with a wonderful metallic, steel-blue plumage,
and lyrate tail. His mate--the "grey-hen"--is chestnut brown, barred
with black. The capercailzie is the largest of all, almost rivalling
a turkey. His size alone suffices to distinguish him. Moreover, only
a very few can enjoy the pleasure of gazing at him, for he confines
himself to the coniferous woods of Scotland.
[Illustration: Buzzard Soaring.]
CHAPTER VIII.
The Wings of Nestling Birds.
"The blue eggs in the Robin's nest
Will soon have wings, and beak, and breast,
And flutter and fly away."--_Longfellow._
The wing of the unhatched bird--Of the coots and water-hen--The
Hoatzin's wings--The wing of Archæopteryx--Moulting--The nestling
game-birds and ducks--Teaching the young to fly.
At first sight it may seem a little strange
to introduce nestlings into a book devoted to birds in flight. But
there are aspects of the wing of nestling birds which must, indeed, be
borne in mind when considering the wing of the adult.
It was pointed out, in Chapter I, that the wing of the adult had but
three fingers and two wrist-bones. This condition represents the last
stage in the evolution of the Avian wing. The wing of the nestling
gives a clue to an earlier stage in its history. But we can get even
further back than this. For if we examine the wing of an unhatched
bird, we shall be able to get still nearer to the birth, and growth of
the wing out of a reptilian fore-limb. Here as many as six wrist-bones
may be found. And the "palm-bones," which in the adult are welded
together, are here quite separate. This stage, then, carries us
back towards the ancestral, reptilian, fore-limb used for walking,
or perhaps for climbing. And there is another sign of this earlier,
reptilian, period to be found in such a wing. At the tip of the thumb
and first-finger, in unhatched ducks, game-birds, and water-hens, for
example, you will find a small claw. By hatching-time the claw of the
first finger will have disappeared, but it is still retained in the
case of the duck and the water-hen. In the adults of all three you will
rarely find more than the claw of the thumb: and this now serves no
useful purpose whatever.
Indeed, there seem to be only two tribes which have any use for
wing-claws during nestling life. One of these is represented by the
gallinules, that is to say, the coots, and water-hens, and their kind.
You may test this whenever you have the good fortune to capture a young
water-hen. Place him outside the nest, and especially if it happens to
be a little raised, you will see him make his way back, using feet,
wing-claws, and beak. His wings, it will be noticed, at this stage are
used as fore-legs. The other tribe is represented by that strange bird
the hoatzin of the Amazon. Here the two claws are really large, and
they play a quite important part in his early life.
For the young hoatzin is hatched in a nursery--a crude nest of
sticks--placed on the boughs of a tree overhanging the water. As soon
as hatched he begins to climb about the branches. Should he fall, by
some mischance, into the water, he promptly swims to the bank; and by
the aid of his long first finger, and wing-claws, and his huge feet,
soon climbs back. But the most wonderful part of his story is yet to
come.
[Illustration: _Grouse_]
So long as these youngsters can only scramble about they are in
constant jeopardy. A wing-surface at least big enough to break the
force of a fall is an urgent necessity. And so the growth of the
quill-feathers is, so to speak, pushed forward with all possible speed.
But if all the feathers grew at the same rate, there would speedily
come a time when the outermost feathers would make the claw at the
end of the finger useless, while the wing-surface, as a whole, would
be insufficient. To obviate this difficulty, the development of the
outermost feathers is held in abeyance till the inner feathers of
the hand, and the outermost of the fore-arm, have grown big enough
to suffice to break the force of the fall. As soon as this stage
is arrived at, the outermost quills, whose growth has been held in
abeyance, rapidly develop; the finger decreases in length, and its claw
disappears, while that of the thumb soon follows suit. And thus it
comes about that the hand, in the nestling, is relatively much longer
than in the adult. But in its mid-period it may be taken to represent
the adult stage of the wing of the ancient Archæopteryx. This bird
could have been but a poor flier, and probably during the time it was
moulting its quills it was absolutely flightless, so that it needed a
permanent finger-tip, and claw, beyond the margin of its wing-surface.
This matter of "moulting," by the way, needs, at least, passing
comment. All birds renew their plumage at least once: the body plumage
often twice in the year. The old feathers fall out, and their places
are taken by new ones. But their growth is slow. In geese and ducks,
and some other birds, the wing-quills are moulted all at once, so that
flight, for a week or two, is impossible. But they can escape from
their enemies while thus at a disadvantage, by taking to the water. In
all other birds the quills are moulted, and renewed, in pairs: so that
at no time are they left flightless.
But this by the way. Let us revert, for a moment, to the hoatzin's
wing. The appearance of the outermost quills of the hand, it will be
remembered, is delayed till the inner feathers have grown long enough
to "flutter," at least, for a short distance, then the growth of the
complete series proceeds apace. This has been called an "Adaptation"
to enable these youngsters, active from the moment they leave the egg,
to move about in comparative safety. But it is more than this. It is a
survival of an ancient order of things which takes us back to the first
known birds.
This is certainly a very remarkable feature, but it gains an added
interest from the fact that it has a parallel in the history of the
development of the wing in the game-birds. If you look carefully at
the downy chicks of the pheasant, or even at barn-door fowls, you
will remark that the wing-quills develop with surprising rapidity: so
that they have feathered wings while the rest of the body is still
down-covered. This enables them the more easily to escape prowling
foxes and other enemies. In young ducks exactly the opposite condition
obtains, the body is fully feathered long before the feathers of the
wings appear. And this because they do not need to fly when danger
threatens, but take to the water instead. But to return to the chicks
of the pheasant. The wing of the chick develops at a very rapid rate.
Within a few hours after hatching, the first traces of the coming
flight feathers can be seen, and presently a large wing is covering
each side of the tiny body. At this stage many often die. The wings,
which can then be examined at leisure, reveal an extremely interesting
condition. For they repeat the features which obtain in the wing of the
nestling hoatzin: inasmuch as the outermost quills are also, as yet,
non-existent; and there is a free finger-tip. But it is not nearly so
long as in the hoatzin, and there is no terminal claw. Surely, from
this, we may infer that the delayed development of the outer quills is
a survival of a time when the ancestors of the pheasant were arboreal,
and hatched their young in trees. Otherwise all the wing-quills should
develop at the same time, and at the same rate. Here, then, is another
instance of what can be learned of the past history of a bird by a
careful scrutiny of the nestling. Sometimes we shall find our evidence
in the wing, sometimes in some other organ. The sequence of plumage
affords abundant evidence of this. But that is another story.
So much for the "intensive" study of the wing. A brief reference must
now be made to the constantly repeated statement that nestling birds
are "taught" to fly by their parents. There is no evidence whatever to
support this belief: and much that goes to show its improbability.
Failing more suitable sites, sand-martins will often elect to build
their nests in the crevices of the masonry of bridges.
From the mouth of this substitute for a burrow is often a sheer drop of
many feet to the stream below. When the nestlings, fully fledged, leave
their nursery for the first time they must either "fly" from the moment
they take the first plunge from the masonry, or die. Failing to make
the appropriate movements of the wings nothing can save them from a
watery grave. There can be no "teaching" to fly. Indeed, death no less
certainly awaits every house-martin when it plunges into space from the
edge of the nest. The appropriate wing-movements, necessary to produce
flight, in short, are "instinctive." Those with defective instincts are
forthwith killed by falling to the ground. They leave no offspring to
inherit their defects.
Perhaps the most convincing evidence of all as to the "instinctive"
nature of flight, in nestling birds, is furnished by the mound-birds,
of the Malay Region and Eastern Australia.
These extraordinary birds lay their eggs in heaps of decaying
vegetable-matter, or in the soil near hot springs; and there leave
them to their fate. They lay very large eggs, it is to be noticed, so
large that the growing chick finds nourishment enough within the egg to
enable it to pass the ordinary nestling stage while still within the
shell. By the time it emerges it has both grown and shed its first coat
of nestling-down, and has developed long wing-quills. Having burst its
prison walls it wriggles its way up through the loose earth, to the
light of day, ready to fight its way in the world unaided. Here, then,
there can be no question of "teaching" the young to fly.
But some birds, at least, do, indeed, receive instruction when on
the wing. And in such cases, it will be noticed, their food can only
be captured by dexterous movements in full flight. For a day or two,
for example, young swallows simply practice flight, to exercise and
strengthen their wings. They are fed by their parents when at rest. The
next step comes when they are fed on the wing, taking their food as
they hover on trembling pinions from their parent's beak. In a little
while the food is dropped as the parent passes, and the youngsters are
made to catch it as it falls. From thence, onwards, they have to do
their own hunting. The clumsy ones must die. Eagles and hawks, in like
manner, teach their young to capture swiftly moving prey by dropping
food to them in mid-air. If one fails to catch it the parent swoops
down and seizes the hard-won meal before it reaches the ground; then
mounting aloft with it, drops it once more, till, at last the required
dexterity is gained.
[Illustration: Gulls.]
CHAPTER IX.
Flightless Birds.
"And first, I praise the nobler traits
Of birds preceding Noah,
The giant clan, whose meat was Man,
Dinornis, Apteryx, Moa."--_Courthope._
The steamer duck--The owl parrot--the flightless grebe of
Titicaca--The dodo and solitaire--The ostrich tribe--The penguin's
wings.
The poet who penned the above lines thought
more of rhymes than of reasons--as Poets so often do. What were their
"nobler traits"? He omits to mention them. None of them were ever
carnivorous: and the Apteryx could by no stretch of the imagination be
called a "giant." The one outstanding feature which does distinguish
these birds he fails entirely to appreciate--and this is their
flightless condition.
A flightless bird is an anomaly. Yet there are some who profess to
believe that this state affords us an insight into the early stages
of the Evolution of the wing. As a matter of fact it demonstrates the
exact opposite--its degeneration.
How is it that birds ever came to such a pass? A study of living
flightless birds, and birds that are well on the way to this condition,
will afford us a ready answer.
Whenever we find birds living, so to speak, lives of languorous
ease--where there are no enemies to be evaded, where there is an
abundance of food to be picked up on the ground all the year round,
and the climate is kindly, there flight is no longer practised. Year
by year, generation after generation passes by, and no use whatever
is made of the wings. In all such cases these once most vital organs
dwindle away, and finally vanish. We can trace every step in this
process of decay.
We may begin with the "steamer-duck" of the Falklands. In this species,
after the first moult, the power of flight is lost for ever. Among
living birds only a few species, apart from the ostrich-tribe, are
in this dolorous case. The owl-parrot, or kakapo, of New Zealand, is
one of these. A grebe found only on Lake Titacaca, perched high up a
mountain-side is another. In both these birds the keel of the sternum
is represented by the merest vestige, the breast-bone being reduced to
the condition found in the ostrich-tribe.
The two giant pigeons, the dodo, and its cousin the solitaire, afford
instances where the loss of flight has been followed by extinction;
owing to the invasion of their haunts, through the agency of man, by
pigs and other domesticated animals, which destroyed their eggs and
young.
The ostrich-tribe is peculiarly interesting: owing to the fact that
their wings present a really wonderful series of degenerating stages.
The wings of all differ conspicuously from those of other birds in the
great length and looseness of the texture of the feathers. Those of the
African ostrich are the largest of all; but they are quite useless for
the purpose of flight, though they are used as aids in running. In the
South American ostrich, or rhea, they are also large, but again useless
for flight, for the "quill-feathers" are very weak, and have no "web,"
such as one finds in the quills of flying birds. And besides, the
muscles of the wing have degenerated, the breast-muscles having become
reduced to mere vestiges.
In both the African and South American ostriches, the skeleton of
the wing, compared with, that, say, of a swan, would seem, to the
inexpert, to be quite normal. But with the cassowary, the emu, or the
apteryx matters are very different. Here, at the first glance, it is
apparent that the process of decay is far advanced; for the bones of
the hand have, as it were, shrunk up, so that a mere stump is all that
remains. The wing of the cassowary is further remarkable for the fact
that some of the fore-arm quills, or "secondaries" are represented
by long, stiff quills, resembling spines of a porcupine; the "vane"
of the feather, which normally runs down each side of the shaft, has
vanished altogether. What part they play in the bird's life history it
is impossible to say. They certainly cannot be used as weapons, and
they as certainly are not "ornaments." In the extinct moas the wing had
still further degenerated. In some species no more than a stump of
the upper arm bone was left, and in others not only this, but even the
shoulder-girdle had vanished, so that only one pair of limbs remained.
Another remarkable flightless bird is the penguin. Here the wing has
changed its form to assume that of a paddle; superficially identical
with that of the whale, or the turtle, or that of the extinct
sea-dragon ichthyosaurus. These paddles have been "re-modelled," so
to speak, to enable them to be used for what we may call flight under
water. Most birds which swim under water use the legs for propelling
the body: but the penguin uses his paddles instead. The paddle of the
turtle has similarly evolved out of a fore-leg used for walking on
land. The common tortoise may be taken as the type of this leg. In the
river, and pond-tortoises, the stumpy foot of the land-tortoise gives
place to a broad, webbed foot. In the turtles this webbed foot gives
place to the paddle.
After what has been said about the penguin it is instructive to turn
to the wings of the auk-tribe--the guillemot, razor-bill, and puffin.
These are very efficient for normal flight, but they are equally
efficient for use under water. For these birds swim as penguins do,
when submerged. Why then, did the penguin suffer the loss of the use of
his wings for flight?
[Illustration:
Cassowary. Penguin.
Ostrich. Kiwi.
]
This question leads to another. Why did that giant razor-bill known as
the great auk become flightless? It would seem that its wings somehow
failed to keep pace with the growth of its body, so that while they
remained sufficient for flight under water, they became useless for
flight in the air. Its failure in this led to its extinction, for
it was unable to escape from its arch-enemy man. When the old-time
sailors, somewhere about one hundred years ago, discovered its haunts
in Iceland could be profitably invaded for the purpose of collecting
feathers, and bait, they speedily wiped out the race; for being
flightless they were unable to escape the marauders once they had
effected a landing. Unhappily there was no Bird Protection Society in
those days, to stop this senseless slaughter.
Here our survey of Birds on the Wing ends. It began with flight through
the air, it ends with flight through the water. It is not a little
surprising, surely, to find that the same wing can be efficiently
used for both these extremes of motion. And still more surprising to
find that, this being so, the penguin should have been forced, so to
speak, to adopt the expedient of evolving a paddle; and so forego
the power of aerial locomotion. The skeleton of this wing, it was
pointed out, differed in no essential from that of the typical avian
wing. In some points, however, it has changed conspicuously. For
the bones have become greatly flattened, and the several parts of
the wing--arm, fore-arm, and hand--can no longer be bent upon one
another in the Z-shaped fashion of normal wings, while the "quill" or
"flight-feathers" have been reduced to so small a size that they are
unrecognizable.
[Illustration: Vultures.]
_Cheltenham Press Ltd._
_Cheltenham and London._
* * * * *
Transcriber's Note
All obvious typos were corrected and hyphenization was standardized.
The italic labels on the illustration facing page 102 were standardized
to match the other illustration's text. Illustrations were repositioned
so that paragraphs were not split.
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