The bird; its form and function

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American ature Series
Group II. The Functions of Nature

See SPiN
ITS FORM AND FUNCTION

BY
C. WILLIAM BEEBE

Curator of Ornithology of the New York Zoological Park and Life Member of the
New York Zoological Society ; Member of the American Ornithologists’
Union and Fellow of the New York Academy of Sciences
Author of “ Two Bird- Lovers in Mexico”

WITH OVER THREE HUNDRED AND SEVENTY ILLUSTRATIONS
CHIEFLY PHOTOGRAPHED FROM LIFE
BY THE AUTHOR

"4 ) Qh 3
7 e Ne ast Ie
Ns oaanyyi~*\\,
Gi

\Mientonomee
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= UNG) ego
SS apy <>)

nS ie <HSONGS
HENRY HOLT AND COMPANY 7 6! SY 4S
1906

Copyright, 1906
BY
HENRY HOLT AND COMPANY

Published September, 1906

ROBERT DRUMMOND, PRINTER, NEW YORK

DEDICATED
IN GRATITUDE AND ESTEEM
TO
Professor benry Fairficld Osborn
BY HIS FORMER PUPIL
THE AUTHOR

PREFACE

We find to-day some thirteen or fourteen thousand
different forms, or species, of birds upon the earth. For
many years ornithologists have laboured to name, and to
arrange in some rational order, these multitudinous forms
of bird life. Some such arrangement is, of course, a neces-
sity—without a handle we should indeed be handicapped
in studying a bird; but let us not forget that classification
is but a means to an end.

Far too many students of birds follow some such mode
of procedure as this: When a new bird is found, it is shot,
labelled, preserved in a collection and forgotten; or, if
studying the bird with a glass, all effort is centred in
finding some characteristic by which it can be named,
and, succeeding in this, search is at once made for still
another species, whose name can in turn be added to a list.
Observing the habits, the courtship and nest-building,
and memorizing the song, is a third phase of bird-study—
the best of all three methods; but few indeed have ever
given a moment’s thought to the bird itself.

I have lectured to an audience of teachers, every one
of whom was able to identify fifty birds or more, but not
one among them knew the significance of the scales on

vil

Vill Preface

a bird’s foot. It is to bridge this gap that this book is
intended—an untechnical study of the bird in the abstract.
This, it seems to me, is the logical phase of bird life,
which, with an earnest nature-lover, should follow the
handbook of identification—the study of the physical
life of the bird itself preceding the consequent phase
of the mental life, with its ever-varying outward ex-
pression.

Far from considering this treatment exhaustive, one
must remember that any chapter subject could easily
be elaborated into one or more volumes. I have intended
the book more as an invitation than aught else: for each
to observe for himself the marvellously fascinating drama
of evolution; to pass on from the nature stories of ideal-
ized composite animals and birds to the consideration of
the evolution of all life; to the tales of time and truth
which have been patiently gleaned by the life-long labours
of thousands of students.

Whenever possible I have illustrated a fact with a
photograph from a preparation or from a living bird,
believing that, where verbal exposition fails, pictorial
interest will often fix a fact in the memory. First of all
we must consider a few of the more important and sig-
nificant of the bird-forms of past ages; because no one
who is interested in living birds from any standpoint
should be entirely ignorant of a few facts concerning the
ancestors of these creatures. Otherwise it is as if one,
entirely ignoring the rest of the plant, studied certain
leaves and flowers, knowing not whether they came from

tree or vine.

Preface 1X

In my treatment of the various phases of the bird’s
physical life I have been considerably influenced by the
many questions which I have heard asked by visitors to
the New York Zoological Park. The short list of books
in the Appendix will indicate the sources whence much
more detailed information may be obtained by those who
desire it.

Some two dozen of the illustrations are from outside
sources, and for permission to use these I am indebted
to Dr. Wiliam T. Hornaday, the American Museum
of Natural History, Prof. A. Smith-Woodward, Prof. R.
S. Lull, A. E. Brown, Esq., Mr. R. H. Beebe, Mr. T. H.
Jackson, Mr. Harold Whealton, and Mr. E. H. Baynes;
and for the use of specimens to Dr. F. A. Lucas, Dr.
Robert Ridgway, and Dr. Jonathan Dwight, Jr. Unless
otherwise indicated, the illustrations were taken by the
author.

The work of Mr. Walter King Stone in the paint-
ing for the frontispiece and a number of text cuts is
gratefully acknowledged; and for the skilful printing of
many of the photographs my thanks are due to Mr. E.
R. Sanborn.

To my wife, for constant and valuable help, criticism,
and suggestion in all departments of the book, I render
my sincere appreciation.

To take a few dead facts and clothe them with the
living interest which will make them memorable and full
of meaning to any lover of birds, and at the same time
to keep them acceptable in tenor and truth to the most
critical scientist—this has been my aim.

. Preface

A few chapters of this volume have already appeared
in print in “Outing,” “Bird-Lore,” and the “New York
Evening Post.”

C. Wo B:

New York Zoo.oacicaL Park, May, 1906.

CHAPTER PAGE
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CONTENTS

xi

Sie beyediee B.

CHAPTER I
ANCESTORS

ZITH the exception of Astronomy, the science
which most powerfully dominates our imagina-
tion is Paleontology, or the study of the life of
bygone ages. Of all things in Nature, the stars symbolize
absolute immensity, their distances stretching out beyond
our utmost calculation. So the revelations of Palzeon-
tology take us far beyond the sciences of life on the earth
to-day, and open vistas of time reaching back more than
five-hundred-fold the duration of the sway of mankind.
Fossil bones—philosophically more precious than any
jewels which Mother Earth has yielded—are the only
certain clews to the restoration of the life of past ages,
millions of years before the first being awakened into
human consciousness from the sleep of the animal mind.
Until recently, Paleontology has been popularly con-
sidered one of the dryest and most uninteresting of the
’ologies, but now that the fossil collections in our museums
are being arranged so logically and so interestingly, the
most casual lover of Nature can read as he runs some of

2 The Bird

the ‘‘poems hidden in the bones.” As Professor Huxley
once said, ‘Paleontology is simply the biology of the
past, and a fossil animal differs only in this regard from
a stuffed one, that the one has been dead longer than
the other, for ages instead of for days.”

A great many more fossil mammals and reptiles have
been discovered than birds, and the reason may perhaps
be conjectured. The bones and bodies of birds were in
former times as now very light, and if death occurred on
the water, the body would float and probably be de-
voured by some aquatic reptile. Then, again, when some
cataclysm of nature or change of climate obliterated
whole herds and even races of terrestrial creatures, the
birds would escape by flight, and when death eventually
came, they would be stricken, not in flocks, but singly
and in widely scattered places as to-day.

For perhaps a million years in the past, birds have
changed scarcely at all,—the bones of this period belong-
ing to the species or at least genera of living birds. But
in the period known as the Cretaceous, when the gigantic
Dinosaurs flourished and those flying reptile-dragons—
the Pterodactyls—flapped through the air, a few remains
of birds have been found. Some of these are so com-
plete that almost perfect skeletons have been set up,
enabling us vividly to imagine how the bird looked when
swimming through the waters of our globe, or flying
through the air, perhaps four millions of years ago.

The most remarkable peculiarity of these birds was
the possession of teeth. Two of the most well-known
examples are called IJchthyornis and Hesperornis. The

Ancestors 3

bones of these birds were discovered by Professor Marsh
imbedded in the rocks of western Kansas, and they are
now preserved in the museum of Yale University. Pro-
fessor Marsh tells us that Hesperornis, the Bird of the

Fic. 1.—Restored skeleton of Ichthyornis (after Marsh). 1/2 natural size.

West, “was a typical aquatic bird, and in habit was
doubtless very similar to the loon, although, flight being
impossible, its life was probably passed entirely upon
the water, except when visiting the shore for the purpose
of breeding. The nearest land at that time was the suc-

4 The Bird

cession of low islands which marked the position of the
present Rocky Mountains. In the shallow tropical sea,
extending from this land five hundred miles or more to
the eastward, and to unknown limits north and south,
there was the greatest abundance and variety of fishes,
and these doubtless constituted the main food of the
present species. Hesperornis, as we have seen, was an
admirable diver; while the long neck, with its capabilities
of rapid flexure, and the long slender Jaws armed with
sharp recurved teeth, formed together a perfect instru-
ment for the capture and retention of the most agile fish.
The lower jaws were united in front only by cartilage,
as in serpents, and had on each side a joint which admitted
of some motion, so the power of swallowing was doubt-
less equal to almost any emergency.’’

Hesperornis had numerous teeth set in grooves like
those of serpents and crocodiles, but in [chthyornis (¢ Fish-
bird,’ so called because its vertebrae are biconcave like
those of a fish) the teeth were in separate sockets as in
alligators. The latter bird was not large, being about
the size of a pigeon, and it had well-developed wings.

It is interesting to compare Hesperornis with the
eroup of penguins, both being highly specialized, although
in ways so different, for an almost wholly aquatic life.
Hesperornis swam by strong strokes of its great webbed,
or lobed, toes, its wings dangling uselessly for genera-
tion after generation, until all trace, save a vestigial
humerus, of their bony support disappeared. Penguins,
however, make but little use of their feet in swimming,
only occasionally aiding the tail in steering; but they

Ancestors 5

literally fly through the water by means of their flipper-
like wings.

The large size of the leg and toe bones of Hesperornis
shows that great speed was attainable in the water,

en paeeanenicd Gibieien oT ce eT ct ee eee

qin ————"

TE ores ue VEEL Bs aaa BEE: : z

cu i i —— x 5
ali je

—

Fic. 2.—Lower jaw of Ichthyornis (after Marsh). 4/5 natural size.

Fig. 3.—Lower jaw of Alligator. 1/6 natural size. The teeth are set in distinet
sockets both in the extinct bird and in the living reptile.

while only a single bone remained to show where the

wings of its ancestors were situated. It is doubtful if it

could stand erect upon land, being in this respect more

helpless even than a grebe. Its nest, if it made one,

must have been at the very edge of the shore, from which

6 The Bird

it could wriggle or push itself with its powerful toes into
the water. The thought of the untold generations of
birds which must have preceded this toothed, wingless,
feathered being, makes the mind falter at the vast stretches
of time during which evolution has been unceasingly at
work.

When we examine the skull of Hesperornis we get a
clew to the reason why this great creature, nearly as large
as a man, succumbed when some slight change in its
environment called for new adjustments in its habits of
life. Its brain was comparatively smaller than that of
any existing bird; and this absence of brain power im-
pled a total lack of that ingenuity, so prominent in the
crow, which, when man alters the face of the land, changes
its habits, and with increasing wit holds its own against
guns and traps.

When /Hesperornis passed, it was succeeded by birds
much smaller in size but of greater wit—loons and grebes
—which hold their own even to the present day.

When in the depth of the winter, a full hundred miles
from the nearest land, one sees a loon in the path of the
steamer, listens to its weird, maniacal laughter, and sees it
slowly sink downward through the green waters, it truly
seems a hint of the bird-life of long-past ages.

We must now pass back, as nearly as can be estimated,
over two millions of years, through the ages when the
Iquanodonts and Megalosaurs lived, long before the first
serpents had evolved and about the time when the first
timid forerunners of the mammals made their appear-
ance,—tiny insect-eating creatures which were fated to

Ancestors 7

remain so long subordinate to the masterful giant reptiles.
This was about the middle of the Jurassic period, and in
deposits of this epoch have been found remains of the
very first birds of which we know anything.

Two specimens have been discovered and named Arche-
opteryx (ancient-winged-creature). J'rom these two little
stone slabs, one in the British Museum and the other at
Berlin, we know that these birds were about the size of
a crow. Instead of the broad, fan-shaped tail of modern
birds, the tail of the Archwopteryx was a long, jointed
affair like that of a lizard, and was fringed with large
feathers—a pair growing from each of the twenty joints.
The wings were not large, and instead of the fingers being
concealed by feathers, there were three entirely free
digits, each armed with a claw, in front of each wing. The
skin-covered Jaws were furnished with teeth, but the feet
and legs were much like those of an ordinary crow.

Taken all in all, this was a most wonderful discovery,
linking birds and reptiles together, and proving beyond
all dispute the fact of their common origin. Perhaps the
most surprising fact was the remarkable development. of
the plumage of the wings and tail, showing that perfect
feathers were in existence at least six millions of years
ago.

In the rocks deposited in very ancient epochs are
found many footprints which were supposed to be those
of huge birds, but it is more probable that they were
made by certain three-toed reptiles which, like birds,
walked or hopped on two feet. Indeed Nature seems to
have made several abortive attempts to produce bird-

8 a he “Bird

like creatures before she struck the right adjustments.
Pterodactyls failed to become birds because they depended
on a broad web of skin, like the wing of a bat, thus miss-
ing the all-necessary feather-ideal; Dinosaurs began at
the wrong end, learning to stand on their hind feet and
to hop, but never the delights of flight. These offshoots
sooner or later were forced to the wall, but Archwop-
teryx seems to have been very near the true line of
descent.

But after all, what a meagre record we have of the un-
told myriads of generations of birds which have succeeded
each other through ages past! It is to be hoped that
many more fossils may be discovered, for the hints given
us in the anatomy of birds, and the glimpses of past his-
tory which flash out from the development of the chick
within the egg,—all this evidence is becoming ever more
and more clouded and illegible.

Having learned that birds are descended from a rep-
tile-like ancestor, it is interesting to search among living
reptiles for the one which most resembles birds, and we
have no choice but to select the alligator—cold-blooded,
scaly, bound to the earth though he is. A second near
relation is to be found in the group of long-extinet Dino-
saurs. A complete record of past ages would show the
ancestral stems of alligators, Dinosaurs, and birds grad-
ually approaching each other until somewhere, at some
time, they were united in a common stock. But we
must guard against the notion that birds are descended
from any group of living reptiles; which is as fallacious
an idea as that we Americans trace our direct descent from

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Fie. 4.—Archeopter

10 The Bird

the Chinese, or that mankind is descended from the chim-
panzee or gorilla.

For the purpose of making more clear and interesting
the ways in which birds have become especially adapted
to their surroundings and needs, we may consider Arche-
opteryx as resembling closely the typical original bird-
type from which all others have at least indirectly evolved;
and thus having obtained a definitely fixed starting-point,
we may consider how some of the more representative
birds of the present day came to acquire their widely
differing structure and characteristics.*

The tree of evolution of reptiles may be compared to
a growth where several great trunks spring from the
ground close together, towering up separately but equally
high; the topmost twigs of which are represented by the
living species of serpents, turtles, lizards, and crocodiles
respectively. A very different arboreal structure is pre-
sented in the genealogical tree of the Class of birds. Here,
from a short trunk, we have many radiating branches,
widely .spreading and with thickly massed twigs, confu-
sedly intermingled; so slight are the divergences between
adjoining groups and so equally do almost all share be-
tween them various reptilian characteristics.

It is not necessary to concern ourselves now with the
processes of evolution, especially as scientists are still in
doubt as to the exact methods. Let us read our Darwin,
and hope for another, philosophically as great, to com-

* There are one or two reasons for regarding Archwopteryx as merely
the tip of a parallel branch, but one sprouting close to the base of the avian
tree.

Fic. 5.—Archeopteryx preserved in the Berlin Museum. ‘The skull, vertebra,
forelimbs and flight-feathers are remarkably distinct. 1/3 natural size.
II

12 The Bird

plete the work, meanwhile adding our own mite of truth-
ful observation to swell the whole, and help prepare the
way for this other. For even Darwin’s theory of evolu-
tion was but the consummation of theories of former
years and centuries,—beginning with Thales and Anaxi-
mander, in the days of early Grecian civilization: in-
deed Aristotle, coming but two hundred years later, is
the only name in the history of zoology worthy of a
place with that of Darwin.

From the fragmentary evidence afforded by Archweop-
teryx we may conclude that this Bird of Old had a short,
blunt, skinny bill of moderate size, furnished with teeth
which would enable the owner to feed upon Jurassic
berries and fruit, or more probably a carnivorous diet of
lizards and insects. Its wings were weak, hinting that
it was a flutterer rather than a true flyer, perhaps only
sealing like a flying squirrel from the summit of one
tree to the base of the next. Even this would give it
an immense advantage over its terrestrial and arboreal
non-flying enemies. The three free fingers on each wing
would allow it to climb easily, to pry into crevices for
insects, or to draw a_ berry-laden branch close to its
bill.

Doubtless it frequently walked or ran on all fours, the
more probably from its weak-loined condition,—the bones
of the thigh-girdle not being fused together as in modern
birds. Its tail has already been mentioned—a_ long
double-feathered appendage, composed of a score of
little vertebrae jointed together,—as we will later see
the true forerunner of the modern fan-like tails. Its

Fic. 6.—Restoration of Archewopteryx (adapted from Smit). Notice the teeth,
three fingers, and lizard-like tail.
13

14 The Bird

feet and legs were little different from those of perching
birds of to-day, with strong toes well adapted to cling
to a branch. Finally, from a cast of the brain, which
fortunately was found with one of the fossils, we know
that, although small, it was that of a true quick-witted
bird. As yet science has no more to tell us.

Our fancy may add an archaic attempt at song—a
lizard’s croak touched with the first harmony, which
was to echo through all the ages to follow; we may also
imagine, if we will, leathery eggs deposited in a rotten
knot-hole of a Jurassic conifer.

In both islands of New Zealand well-preserved remains
of giant birds have been discovered, to which has been
given the name of moas. One species must have reached
a height of ten or eleven feet, which would make it
tower above the largest living ostrich. They were, in
fact, not unrelated to these latter birds and, like them,
were flightless (in some cases absolutely wingless), and
they had great massive feet and legs. Native legends
among the Maoris hint that these birds were in existence
during the last few centuries before the coming of the
white men.

In South America also, giant birds lived in ages past.
One, the Phororhacos, stood seven to twelve feet in
height, with a head and beak like that of a gigantic eagle.
Unlike all eagles, however, this bird could not fly and
doubtless ran down its prey, as a chicken runs down a
grasshopper.

It is an interesting fact that in South America there
lives to-day a bird known as the Seriema, which is prob-

Ancestors 15

ably at least an indirect descendant of the Phororhacos.
The Seriema defies exact classification, sharing characters
of cranes, bustards, and eagles. Its beak and inner
claw are like those of a bird of prey, while in form of
body, and in the other claws of the toes, and in the legs
it is crane-like. One of these birds which I have ob-
served for years in captivity is as gentle and as fearless
as a bird can be. It will chase insects and field-mice
outdoors in the Zoological Park, and will occasionally
stalk solemnly into my office and, coming close to my
desk, watch me closely. It has most beautiful eray-
blue eyes, with long eyelashes (Fig. 199), and if the
birds of past ages were as comely and as lovable as this
interesting species, I regret that only their fossil bones
are left to us. As the Seriema runs down and kills a
mouse, so the giant Phororhacos, doubtless, overtook
and slew creatures as large as a deer. Its skull (Fig. 7)
is drawn to the same scale as that of the living Seriema
(Fig. 8).

The evolution which has gone on since these epochs
of old, bringing into being the wonderfully varied forms
of penguin, ostrich, albatross, peacock, and humming-
bird, may be summed up in two words which it is well
to know and remember,—Adaptive Radiation. This is
the spreading out or radiating of bird-forms descended
from the ancient stem, into all parts of the earth, each
coming into contact with a particular environment, to
adjust itself to which, its various organs and parts exer-
cise different functions, until the friction of the “struggle
for existence” has moulded each to its particular niche.

16 The Bird

If its lines lie in happy places, its race is established,
and it pursues and flees, it fights and plays, it sings with
joy or pants with fear, and Evolution marks another
success in its inexorable movement onward and upward,
—a new species is born!

Earth has few secrets from the birds. With wings
and legs there is hardly a spot to which they cannot and
indeed have not penetrated. Some find food and con-
tentment in the desolate wastes of the far North; others
spend almost all of their life on or above the sea far from

Fie. 7.—Skull of Phororhacos, drawn to scale with Fig. 8. 1/6 natural size.

land; thousands revel in the luxuriance of reeking trop-
ical jungles; a lesser number are as perfectly suited to
the blazing dust of the desert; and there are birds which
burrow deep into the very earth itself. Day and night;
heat and cold; water, earth, and air, have all been con-
quered by the thirteen or fourteen thousand species of
birds which share the earth with us at the present day.
These brethren of ours, whose clans have so bravely
conquered the dangers of millions of years, and at last
have gained a foremost rank in the scale of living crea-

Ancestors 17

tures, now find themselves face to face with the culmi-
nating effort of Nature,—Mankind. They cannot escape

Fria. 8.—Seriema, a living descendant of Phororachos, with characters of Cranes
Bustards, and Eagles. 1/6 natural size.

bd

from us, though the least among them laughs to scorn
our efforts at following through the air. Yet all must

18 The Bird

return sooner or later to earth for rest and food, and thus
all are at our mercy.

Let us beware of needlessly destroying even one of
the lives—so sublimely crowning the ages upon ages of
evolving; and let us put forth all our efforts to save a
threatened species from extinction; to give hearty aid
to the last few individuals pitifully struggling to avoid
absolute annihilation.

The beauty and genius of a work of art may be recon-
ceived, though its first material expression be destroyed;
a vanished harmony may yet again inspire the composer;
but when the last individual of a race of living beings
breathes no more, another heaven and another earth
must pass before such a one can be again.

CHAPTER II

FEATHERS

ANY definitions of the Class of birds have been
given, but all fall short in some particular, or

are weak in having exceptions. FEATHERED is
the one word which always holds true. All birds have
feathers, and nowhere else in the world are similar struc-
tures found. A feather, like an egg, is perfect in its
adaptation to the bird’s requirements, and also, like the
egg, its structure is rather complicated.

Structure and Development

First let us look at the skin itself in which the feathers
grow. To skin a bird is an easy matter, for the skin,
or integument as it is called, is very slightly attached
to the muscles underneath. The skin of a dove is almost
like tissue-paper, and tears so easily that it is a marvel
how the hundreds of feathers find a sufficiently strong
attachment. Thin as is this skin, it is made up of three
separate layers, but in order to make our feather-study
enjoyable by not overburdening it with too many details,
we will consider only the two more important layers of
the skin—a deeper one, the dermis, and an outer, more

horny covering, the epidermis.
19

20 The Bird

A list of all the structures of animals which are prod-
ucts of the outer layer alone would be a long and _ sur-
prising one, and we would be very ready to grant the
importance of skin. Such an enumeration would include
all claws and talons, nails and teeth, the rattles of a
snake, spurs, hairs, the scales of fishes and _ reptiles,

Fic. 9.—Tarpon-seale, shark-tooth, and peacock-feather; showing diversity of
structure derived from the skin alone. 1/2 natural size.

spines, whalebone, beaks and feathers. Even the horn
of a rhinocerus is only a solid mass of agglutinated
hairs, while as the antithesis to this may be mentioned
all down and feathers: the tiniest fluff from a humming-
bird to the great pinion of a condor.

If we examine a newly hatched dove or sparrow,
the little, ugly, sprawling creature, at first glance, seems

Feathers 21

to be entirely naked; but a closer inspection shows
scanty tufts of down scattered irregularly over the body.
This, like the set of milk-teeth in mammals, is useful
only for a time, and is later pushed out by the second
or true plumage. Even more numerous than the down-

Fig. 10.—Brown Pelican nestlings, showing feather papillae on body and wings.
About 1/4 natural size.

tufts are little pimples or dots, many hundreds of which
cover certain parts of the skin. Each of these will event-
ually give rise to a perfect feather—quill, vane, barbs,
and all.

The under layer of skin, or dermis, is very thin in
birds, much more so than in reptiles and other animals.

22 The Bird

The first intimation of the appearance of a feather, or
of down, is shown by a thickened group, or pimple, of
cells in this under layer of skin, which grows and presses
upward toward the outer layer—the epidermis. This is
exactly the way in which the scales of fishes and reptiles
begin to form; and if, at this stage, the tiny projection
should flatten out, the shining scale of a carp, the armor

Fig. 11.—Sprouting feathers of a 12-day embryo chick. Magnified 25 diameters.

of an alligator, or the cobble-scale of an iguana lizard
might result. Indeed, in the feathers of a penguin we
find transition stages of flat, almost unsplit feather-
scales; while on the legs and feet of birds are reptile-like
scales.

The evolution of scales, hair, and feathers is a most
interesting problem, most of the details of which are
beyond the scope of this work. Suffice it to say that

Feathers 22

in sharks, which are among the most primitive forms of
fishes, the skin is covered with tiny denticles or spines,
which consist of enamel and dentine, and which rest on
small bony plates. This form of scale is the most ancient
known, and the hint of teeth which the description con-
veys is not misleading; for we find that in some of these
voracious fishes the spines in the skin become enlarged
near the edge of the mouth, merging imperceptibly into
the rows of cruel teeth which, to a certain extent, are
homologous with the teeth of all higher animals. In
other fishes the denticles become flattened scales, and
many of these fish have teeth of corresponding plate-
like form. So it is interesting to know that the scales of
fishes and reptiles, the feathers of birds, and the teeth
of animals have all evolved from skin structures which
at an early stage of growth bear considerable resemblance
to each other.

But, in our young bird, the slender finger of cells
which reaches upward, and whose base at the same time
sinks deeply into the dermis, does not broaden out, but
splits longitudinally into a number of folds, which grad-
ually dry apart and harden into the slender, silky fila-
ments which we know collectively as down.

At the base of, and in fact attached to, the little pro-
jection which gives rise to the nestling down is a small
circular body of cells, which grows but little while the
down plumage is serving its use; but when the bird is
ready for a coat of true feathers this lower cellular mass
begins to grow upward into a second finger, or column,
of cells, pushing the base of the down feather out of its

24 The Bird

socket. This growth continuing, the down is lifted clear
of the skin, being supported on the new structure, and
o#

Fig. 12.—EKarly stages in the development of a down feather, showing close
resemblance to scale of fish or reptile.

Fra. 12a.—Later stages of Fig. 12, showing the first splitting up of the
feather pulp.

soon brushed off and lost. Thus, little by little, in
shreds and tatters, the baby plumage is shed and replaced

Feathers 26

by true feathers, which overlap, protecting the body from
heat and cold, dust and rain.

Fig. 12b.—Last stages in the formation of a down feather, showing the plumes
well above the surface of the skin, as in a newly hatched chick. All greatly
enlarged. :
At the time of the first moult, this succession of

feathers can be observed in almost any young bird, being

more noticeable in large species, which have very thick

26 The Bird

or lengthened down, as gulls and ducks. A Red-winged
Blackbird, or for that matter almost any passerine nest-
ling, looks very odd when it rises up in the nest, gaping for
food; the long gray streamers of down waving like an
aureole around its head. In some water-birds this nest-
ling down retains its usefulness for nearly two months.

Fic. 13.—Feather from the head of a young Bobolink, with down still attached
to its tip. ‘Twice natural size.

The feathers which replace the down are, when they
first appear above the skin, rolled tightly and bound up
in the thin tissue of the horny sheaths, so that they
resemble a bundle of withes wrapped together in a cloth.
In many young birds the feathers remain in this condi-
tion until they are nearly full grown, and a young cuckoo

Feathers 27

or kingfisher is a curious-looking object, most of the
bird’s body seeming to be tiled with small, bluish sticks.

Fig. 14.—Tip of feather from the crown of a young Song Sparrow, showing
connection with down. Magnified 25 diameters.

Fic. 15.—Duck Hawk moulting into juvenal plumage, with the natal down coming
away in shreds and tatters. 1/4 natural size.

When the folds of the developing feathers are sufficiently
dry, they burst their sheaths and rapidly spread out.

28 The Bird

The appearance of a young kingfisher or heron may be
completely changed within a few hours time, so quickly
and simultaneously does the first suit of feathers unroll.

The condition of young birds when hatched varies
greatly in birds of different groups. Nestlings are, in
many ways, like human babies, and there are as many
differences in the one class as there are in the other,

Wig. 16.—Growth of an Ostrich feather from sheath to plume. 1/5 natural size.

between those from different countries, only Nature does
for the little birds what parents do for the babies.

We see American babies wrapped in furs and blankets,
wheeled in carriages, and rocked to sleep; while a tiny
savage is strapped tightly to its mother’s back, and as
soon as possible allowed to run where it pleases, find its
own toys and develop its little muscles, gaining a degree
of health and strength which many a civilized child would
envy. So with birds, the highest—such as crows and

thrushes—are hatched almost naked and must be warmed

Feathers 29

and cuddled and fed for many weeks, before they learn
to take care of themselves; while birds lower in the
scale—as our quail—are born covered thickly with
down and with wings nearly feathered, and in a few days
can fly and find their own food.

So a bird naked at birth is very helpless, one covered
with down is more capable of taking care of itself, while

Fic. 17.—-Nestling Kingfisher with feathers still in their sheaths.
2/3 natural size.

the few which are completely feathered when hatched
may be said to have no chickhood except in the egg.

In the Crested Screamer (Fig. 264) the down-like
character of the body-feathers of the adult birds may be
a hint of the plumage of very ancient types of birds such
as Archeopteryx.

Now we are ready to begin our study of the perfect
feather itself, and we will, for once, have to disregard
our rule of starting with the simpler form—the scale of

30 The Bird

a reptile—and working up to a feather; for, if we except
the down, there seems to be no connecting link left.

Fig. 18.—Young Brown Pelicans; hatched naked and helpless (altricial).
1/4 natural size.

Fic, 19.—Young Red Jungle Fowl one day old; hatched covered with down and
able within a few hours to help itself (precocial). Almost natural size.

Although that old, old fossil bird Archeopteryx
still retained reptile-like teeth, fingers and tail, it had

Feathers 21

feathers which were apparently as perfect as any we may
examine to-day. When some form of scale had once
changed so that it was of use in flight, the hollow elastic
vane took first place at once, and all intermediate stages,
which perhaps had been acquired merely for warmth,
went to the wall. A creature could have flight if pro-
vided with perfect feathers, or it could retain its scales
and find existence possible along the old reptilian planes
of life, but no awkward scale-flutterer could long be
tolerated. All through the evidences of evolution we
find instances like this,—a change for the better beginning
slowly, through many channels, then the one best suited
forging ahead with inconceivable swiftness, and crushing
out all other less adapted structures. Hence the rarity
of “missing links.”’

Feathers are certainly among the most beautiful
objects in Nature; and when we learn a little about their
structure, they will be still more interesting. No matter
how closely we may examine them, with hand-lens or
microscope, their beauty and perfection of structure only
increase. If we study a feather, say from the wing of a
pigeon, we see that its whole structure is subservient to
two characteristics—lightness and strength. What won-
derful elasticity it has! We can bend the tip so that it
touches the base and it will spring back into shape with-
out breaking.

If we look closely, we will see that each feather is
composite—feathers within feathers. The quill gives off
two rows of what are called barbs which together form
the vane of the feather; each of these barbs has two

32 The Bird

rows of barbules, and these give rise to a series of curved
hooks, known as barbicels, which work into opposite
series of grooves, so tightly that air cannot force its way
through the feather. When the wings are pressed down-
ward, the phenomenon flight is made possible by the
accumulated resistance which the flight-feathers offer to
the air. At the lower end of our pigeon’s feather, bar-
bicels are present only near the quill. Therefore the

Fic. 20.—Two interlocked barbs from the vane of a Condor’s wing-feather, show-
ing barbules and barbicels. Magnified 25 diameters.

tips of the barbs are loose and fluffy, unconnected and
useless for flight. This is the condition in all down and
in the feathers of the ostrich and cassowary. We might
naturally think that feathers stiffened by so many close
rows of interlocking barbicels would be useful in many
ways beside flight. But fluffy feathers are evidently just
as efficient in keeping warmth in and rain out as the
other kind; so Nature, economical to the most micro-
scopic degree, has lessened the number of, or has never
provided, barbules and barbicels wherever a feather is
not needed for flight or steering.

Feathers 33

The two lines of barbs which grow out on each side
of the quill are very elastic and so intimately hooked to
each other that they will bend some distance before sepa-
rating. If we ever tried to force our way through a

Fic. 21.—Model showing interlocking barbules and barbicels of feather,
greatly enlarged.

bramble of sweet-brier or blackberry-vines, we can more
readily appreciate how these barbs and the interlocking
barbules clutch each other. The thorns in the bramble
catch our clothes and, when we move, the elasticity of the
long stems tends to make them hold the tighter.

We notice that one line of barbs—that along the
inner curve of the quill—is much longer than that on the
outer curve and we might think the air would force this

34 The Bird

upward and escape beyond the edge. So it would, if it
were not for the arrangement of the feathers on the wing,
which overlap like the tiles on a roof, each vane over-
lying and holding down the long barbs of the feather
in front, while, above and below, other shorter feathers
help to bind the whole tightly, thus enabling the bird at
every stroke to whip a wingful of air downward and
backward.

A feather and its parts, like all the rest of the bird, is
composed of cells—empty and hollow ones in this in-
stance, as we can easily see for ourselves by placing a
barb from a pigeon’s feather in a drop of water and
looking at it under a low-power magnifying-lens. The
network of horny cells is very plain.

It is a simple matter to say that a feather consists of
quill, barb, barbules, etc., but to appreciate the wonder-
ful complexity of this structure let us make a little cal-
culation. Suppose we have a wing-feather from a com-
mon pigeon with a vane about six inches long. If we
have patience enough to count the barbs on one side of
the quill, we will find there are about six hundred of
them. So the vane of the entire feather has twelve
hundred of these little side featherlets. One of these,
from a narrow part of the vane, will show under the micro-
scope about two hundred and seventy-five pairs of bar-
bules, which multiplied by the number of barbs on that
side amounts to three hundred and thirty thousand.
Making a very low estimate of the whole vane, we have
nine hundred and ninety thousand separate barbules on
this one feather, and when we think of the innumerable

Fic. 22.—Feathers illustrating conditions where barbicels are unnecessary and
are hence reduced or entirely lost, causing downiness. 3/5 natural size.

(a) Primary of Pigeon—an important flight-feather; hence possessing a stiff
vane. (b) Under wing-covert of a Great Blue Heron; downy portion was over-
lapped by the adjoining feather. (c) Wing-covert of Owl; the downy edge makes
possible the all-important noiseless flight of this bird. (d) Feather of Ostrich;
the power of flight being lost, the feathers are downy throughout the entire vane.

35

36 The Bird

finer hooklets, and then the number of feathers on the
pigeon’s body, we can echo the exclamation of Solomon:
“The way of an eagle in the air” is “too wonderful for
me!”’

Another beautiful adaptation to flight is seen in our

Fic. 23.—Feathers of Condor and Emeu. ‘The aftershaft in the former is reduced
to a downy filament at the base of the vane; in the latter it equals the feather
itself in size.

feather. The upper part of the wing must of course be

perfectly level, with no projections to catch the air and

retard motion. So, on the upper side of the feather, we
notice that the lines of barbs spring out flush with the
flattened quill-top, while below, the shaft projects promi-
nently from the vane. The obliquely forward direction
in which the barbs grow, the change in shape of the

Feathers a7

quill—round where the body or body-feathers conceal
it, square where it supports the vane,—and many other
niceties which we can each detect for ourselves, show
how exquisitely exact is the adaptation of a feather to

its uses.

Fig. 24.—Powder-down patch on the breast of a live Great White Heron.
2/3 natural size.

Growing from the under side of the quill, at the be-
ginning of the vane, is a tiny feather known as the after-
shaft. In an ordinary down-feather of a young bird this
is of considerable size, but it is either small or entirely
absent in an ordinary feather. It reaches its greatest
development in the emeu and the cassowary, where it is

38 The Bird

as long and as perfect as the main feather. The origin
and use of this feather-double is not known.

Parrots, herons, and some other birds have a most
convenient arrangement—a kind of automatic clothes-
cleaner and valet combined. Concealed by the long body-
plumage are several dense patches of down-feathers which
grow quite rapildy, but instead of constantly increasing
in length, the tips break up into a fine, white, greasy
powder. This works its way through the entire plumage,
and is doubtless of use in keeping the feathers in good
condition and the body dry. Most of the birds possess-
ing this convenience are comparatively free from lice, so
this natural dressing may be as unpleasant to these ver-
min as camphor-balls are to clothes-moths.

The forms and textures of feathers are innumerable,
and the uses to which they are put, more than we would
ever imagine, but these will be spoken of under the chap-
ters treating of the different parts of the body where they
are found.

Arrangement

In examining a nestling we will notice that the feather-
dots are not scattered at random over the surface of the
skin, but grow in lines and tracts, whose limits are very
sharply defined. In an adult bird, say an English Spar-
row, this is even more noticeable. If we part the feathers
on the centre of the breast, a broad, bare area is seen,
with only a thin scattering of soft downy feathers. Under
the wings are other naked spaces, and several more are
on other parts of the body. The most ancient birds were

Feathers 39

probably covered uniformly with scale-feathers, but as
these increased in length there was less need for an un-
broken covering, the feathers of one portion overlapping
and protecting the surrounding parts, and besides, for
ease in active motions, bare patches of skin were required.

It has been found that the arrangement of the feathers
on a bird’s body varies in different groups, and, such
variation being rather characteristic of these larger divi-

Fic. 25.—Nestling Crow, showing feathered and infeathered portions of the body
(pteryle and apteria). 1/2 natural size.

sions, pterylosis—as it is called—is of some importance
in classification. Penguins only, of existing birds, have
feathers growing uniformly on all parts of the body. In
the ostrich, which has given up flight and taken to run-
ning, the body feathers have grown over almost all the
bare spaces which existed in its flying ancestors. There
are two’ marked exceptions due to the present habits of
these birds. Like the camel, when resting, these giant
birds lean upon their breasts. This portion of the body

40 The Bird

is provided with a thick, callous pad, which, by constant
use, is thus kept bare of feathers. In addition, the under
sides of the degenerate wings are also free of plumage,
owing no doubt to the continual close application of
these organs to the sides of the body. The other bare
areas are almost obliterated, but the legs are bare, thus
allowing perfect freedom in action.

Some birds, such as vultures and cassowaries, have lost
all feathers on the head and neck, or other portions of
the body, from various causes, as for cleanliness, or, in
some cases, probably for ornament. This will be spoken
of more in detail in a later chapter.

Moult

The waste of internal tissues and organs in animals
is repaired by means of the blood which brings them
fresh material and carries away worn-out cells, as it
traverses arteries and veins. [Entire parts, as the tails of
tadpoles, may even be absorbed; but, in general, skin
structures when old and worn out are cast off and renewed
from the lower, or derm, layer. This takes place in various
ways. The skin, even to the covering of the eyeballs,
may come off entire, as is the case among snakes, or por-
tions peel off and tear away, as in lizards. Warm-blooded
animals also shed, or cast, their outside covering; mam-
mals shedding their coats of hair, and birds their feathers.
In the latter class this process is called moulting.

The nestling down and the feather which replaces it
can hardly be considered as separate structures, as the

Feathers 41

same channel perforates both and the nutriment pith
which supplies the down traverses the hollow quill of
the succeeding feather. <A bird’s swaddling-clothes and
his first full dress are cut from the same piece. But when
these perfect feathers reach full size, the aperture at the
base closes, all blood-supply is cut off, and the feather at
the commencement of its usefulness becomes a dead
thing. There is no vital connection between the feathers
of all the following moults. Each is separate, the papilla
or feather-cells reawakening to new activity every time
the process occurs. So when a bird’s wing is clipped, no
pain is felt, any more than when a person’s hair is cut.
Such feathers are of course not renewed until the succeed-
ing moult. If a feather in a living bird be pulled out,
it will be replaced immediately by another, and this will
be repeated as often as the feather is removed.

In cassowaries, each moult is advertised by dangling
streamers of the old plumage still attached to the tips
of the incoming feathers, but this connection is not a
living one, the adult feathers being as lifeless as those of
other birds. As powerful savages often exhibit very
childlike traits, so these great birds are absurdly marked
with what, in other species, are sure signs of recent chick-
hood.

The changing of plumage of the Brown Pelican is well
shown by the illustrations. The naked young (Fig. 18)
become covered with papille (Fig. 10) which soon burst
into a coating of the softest white down (Fig. 36); this
in turn gives place to the juvenile plumage of gray, the
features of the wings and shoulders appearing first (Fig.

42 The Bird

37). This is also the winter plumage of the adult birds,
both sexes moulting alike into the rich-hued breeding
plumage (lig. 38) of yellow, chocolate, and silver-gray.
The feathers of the entire bird are moulted or fall out
naturally at least once a year, and in some cases twice
or even three times. If we were asked at what season the

Fic. 26.—Flight-feathers of Chimney Swift clogged with soot, showing necessity
for moulting.

principal annual moult would be most likely to occur,
the fall of the year would suggest itself, and such is the
case, for a number of good reasons.

First, the hardest work which birds have to do, hatch-
ing and caring for their young, has, at this season of the
year, Just been accomplished, and has doubtless told
heavily on their plumage. Breast-feathers are worn thin,
tails are badly frayed, and wing-pinions are broken and
ragged. Two alternatives confront birds at this period.
Those species which are to take their migratory flight

Feathers 43

over hundreds of miles of land and water must have
perfect wings and rudders to carry them safely, against
contrary winds and sudden accidents. Others which are
contented with the food found near their homes, and
elect (by the laws of their kind) to remain, must be pre-
pared to withstand the blasts of winter. Their plumage
must be abundant and thick to keep out the cold and
snow, and to enable them to bury their tender eyes and
feet in its warm mass. Otherwise the tiny round fluffs
huddled close to the trunks in the evergreens would drop
stiffened to the ground during some long winter night.
So a renewal of plumage in the fall is most necessary to
the life of birds.

A baby robin, secure from most enemies in his nest,
with parents to supply his every want, acquires his wing-
quills only when his nestling down is shed. He is care-
fully watched and tended during his first flights, and
takes such good care of these flight-feathers that they
serve to carry him to his winter home far to the south-
ward. But a brood of a dozen or more little Bob-whites
whose wing-feathers sprout with the most marvellous
rapidity, from the moment the birds tumble out of their
white shells, would fare ill indeed if they had to trust to
these nursery quills all the first winter, with hungry
foxes sniffing for their scent, and more-to-be-dreaded owls
shadowing their trembling covey. Nature has come to
their aid, and when they have fairly worn out their wings
in the first awkward attempts at flight, new feathers
come in, and this succession of quills keeps them in fine
flying condition until full grown. Indeed so solicitous is

44 The Bird

Mother Nature about the ground-nesters that she puts
strength and vigor into the coverts, or upper feathers on
the little wings; so that these shoot forth with an energy
far beyond what is usual, for a time lending their aid in
flight, although they are not true primaries. Later they

Fic, 27.—Iridescent feather from the breast of a Rufous Humming-bird, showing
wearing off of the tips of the barbs, caused perhaps by rubbing against the
petals of flowers. Magnified 25 diameters.

are far outgrown by the flight primaries, and then func-
tion only as protectors of these more important feathers.
The extreme in this precocious development of chicks
is found in those strange Australian birds, the mound-
builders, which are left from the first to shift for them-
selves; even the duties of incubation being shirked by
the parents. This necessitates a perfect ability on the

Feathers 45

part of the young birds to take care of themselves as
soon as hatched. They pass the entire first moult within
the egg itself, and are covered with perfect feathers and
fully developed flight-quills when they emerge from the
shell. A wild duckling, although provided with a thick
waterproof coat of down, has, like the robin, to wait a
long time for his flight-feathers; but his aquatic habits
and powers of diving make the dangers to which he is
exposed far less than is the case with the young Bob-
white.

The causes of wear and disablement to feathers would
make a long list if we but knew them all. As one instance
take the wings of a Chimney Swift after she has reared
her brood in the depths of some blackened chimney, or
even a lightning-struck hollow tree. Her primaries are
so matted and clogged with balls of soot that she would
often find the migratory flight difficult indeed, were the
feathers not replaced by new ones.

When birds return from the South, and when a hint
of spring warns winter residents to cease their roving,
they prepare to develop all the advantages which may
in any way aid them in securing a mate. Some indus-
triously practise dance-steps, others flight-evolutions, a
larger number rehearse their songs under their breath,
while still others passively await the development of
plumes, gorgets, spots and splashes of colour which, if
the feathers come out large and brilliant, may stand them
in as good stead in their wooing as any song or antic.
Thus we find a class of birds which have a partial or com-
plete moult in the spring. These feathers may last all

46 The Bird

summer, or may drop out as soon as begins the hard
work of building the nest or feeding the young, with which
labor they might interfere.

To return for a moment to the fall moult. If a spar-
row or lark should shed all of its large wing-feathers
simultaneously, it would have slight hope of ever living
long enough for new ones to grow out again. If such
defenceless birds were compelled to hop helplessly along

Fig. 28.—Wings of English Sparrow, showing two feathers of each wing being
moulted simultaneously.

the ground, weasels and cats would be able to catch
hundreds of them without effort. This is avoided in all
land birds by the moulting of only a pair of primaries,
as the large flight-feathers are called, at a time, one from
each wing. This process usually starts with the pair
farthest from the front of the wing, and the second pair
does not fall out until the first pair of new feathers is
nearly of full size. Thus all danger of a crippled flight
is avoided.

One of the most interesting phases of Nature is the
way she provides for exceptions to what we are pleased
to call her laws. Some birds, unlike those mentioned

Feathers 47

above, shed every primary in their wings at once, so that
their angular stump-feathered wings are perfectly useless
for flight. In this class are many water birds—ducks,
geese, flamingoes, snake-birds and others. Just before this
wholesale moulting occurs, a flock of wild ducks will

Fig. 29.—Wing of adult Mallard Duck, with the new set of flight-feathers
just appearing.

make their way, by an unfailing instinct, to some large
body of water where they can swim and dive in safety
and, if need be, never come within reach of enemies on the
shore until the new feathers are strong enough to bear
them up.

Associated with this temporary disablement is another
provision for the safety of certain birds of this class. Our
common Mallard Duck, for example, is sometimes com-

48 The Bird

pelled to undergo the fall moult in a rather small body
of water, where danger menaces on all sides. Although
when flightless he swims low among the thick water-reeds,
yet his briliant colours—iridescent green and white—
would too frequently mark him out. So the invisible
cloak of his brooding mate is dropped over him for a
while—his colours vanish, and by a partial moult thus
sandwiched in, the hues of his plumage change to an
inconspicuous mottling of brown, hardly distinguishable
from the female. Then when the splitting of his quill-
sheaths hints of coming power to take care of himself
again, the dusky mantle is lifted, and, triumphantly
treading water, he stands upright and shakes his glisten-
ing wings, daring his enemies to catch him if they can.

‘

This has been happily termed the “eclipse” plumage. In
certain portions of the Old World where foxes are scarce
and the ducks have been persistently pursued by men
in boats, the knowing birds have changed their habits
and, when their wing-quills fall, they make their home
in deep woods, finding greater safety there than on ponds
or lakes.

A somewhat similar condition occurs in the Black
Grouse of Europe, which loses the conspicuous black
feathers of the head and neck during the helpless period
caused by the moult of its tail-feathers.

This additional moult brings us to the consideration
of the birds which have no less than three changes of
plumage, and here we find the cause intimately connected
with the colour of the birds’ surroundings. Ptarmigans,
which are species of grouse living in the far North, moult

Feathers 49

Fig. 30.—Eclipse plumage of Mallard Duck. Male in full breeding plumage
(the brilliant green of the head and neck is lost in the photograph).

Fig. 32.—Female Mallard.

50 The Bird

after the breeding season into a special gray or dark
plumage, harmonizing well with the autumnal shades of
the grass and lichened rocks. In the late fall a second
plumage of immaculate white is assumed, affording these
birds great protection on the snowy wastes where they

Fig. 33.—Willow Ptarmigan in early spring, with brown feathers beginning to
replace the white. 1/4 natural size.
live. In spring a third suit is donned—brown and_ parti-
coloured like the environment, which late in the year is
still covered with patches of snow here and there. This
too is the nuptial plumage, and lasts until the gray garb
completes the cycle of the year’s changes. The wing-
feathers are white all the year, but when the wings are

Feathers GH

closed they telescope so neatly beneath the feathers of
the shoulder that they are not noticeable while the bird
is in either the autumnal or vernal plumage.

As the feathers on the flipper-like wings of a penguin:
resemble the scales of reptiles in appearance, so this

Fic. 33a.—Ptarmigan in the fall, showing the gray autumnal plumage (which
has replaced the brown of summer on the upper parts of the body and wings),
gradually giving place to the white of the coming winter feathers. Wild
birds in Alaska. (Harold Whealton, photographer. )

homology is carried out in the method of shedding them.

Unlhke the dropping out of feathers one by one, as in

other birds, these come off in flakes, like the skin of a

lizard. The feathers of the back loosen, shrivel up, and

fade to a brownish hue before they peel away.

G2 The Bird

We have seen how birds, by moulting their feathers,
change the colour of their plumage; in some cases several
times each year. There is, however, still another way in
which the appearance of new colour is brought about.
Not by increase of pigment, for the feather when once
full grown is dead; but by the mere breaking or fraying

Fic. 34.—The three moults of the Ptarmigan, shown in three individuals.
(Courtesy of American Museum. )

of the edges of each feather. It is thus that the Snow-
flake brushes off the rusty trimmings of his winter’s suit
and returns to his home in the far North, dressed in spick-
and-span black and white. A much more familiar exam-
ple is to be seen at our very doorstep. The cock English
Sparrow in midwinter is even more sombrely clad than
usual; but as spring approaches, although he can attain
to no elaborate song or flowing plume, yet even this

Feathers re

commoner feels the call of love for beauty, and day by
day the dusty brown tips of his throat-feathers wear
away one by one, and leave exposed the clear black
centres; and behold, the vulgar frequenter of our streets

Fig. 35.—Two male English Sparrows, showing the difference in colour caused by
wear of the feather-tips between October and April.

and alleys, flaunts a jet cravat before the eyes of his lady-

love!

Colour.

The very interesting uses which the colours of birds
serve, the part they take in courtship, in evading danger,
or in enabling birds to find each other, are many. These
uses have been much written about, but of the nature
and formation of colour less is known. Few of us have

54 The Bird

probably ever given a thought to the colours themselves
Why is that feather blue? Why—because it 7s blue!
There are two principal ways in which colours are
produced in feathers: first, when a real colour-pigment
is present, and again when the structure of the feather is
more or less like miniature prisms in shape, breaking up

Fig. 36.—Young Brown Pelicans in the downy plumage. 1/6 natural size.

the rays—rainbow-like—into the iridescence of the spec-
trum. In the case of almost all the beauties of Nature,
the more closely we examine them, the more beautiful
they become. But this is not true of the iridescent
colours of birds such as hummingbirds, unless we con-
sider the structure. The colour itself disappears under
the microscope, and only gray or black tints are seen.
The black, red, brown, and yellow colours of feathers

Feathers ay

are almost always due to pigment or colouring-matter in
the shaft or vane. If we take a black feather and hold
it to the light, it will still look black; if we pound it with
a hammer, it will not change.

Green is never found as a pigment except in the
feathers of a small family of birds called plantain-eaters
or turacous, which inhabit West Africa. For some time
it was thought that the natives dyed the birds artificially,
as when these birds were kept captive, the magnificent
scarlet patch on the wing would gradually fade and
become a dull gray. It is a fact that this colouring-
matter washes out when the feather is washed in alkaline
water. ven ordinary water will be slightly tinged if the
feather is soaked in it. The pigment contains about ten
per cent of copper, and this can be extracted chemically
in the form of a metallic powder. The plumage of almost
all brightly coloured birds will fade in the course of years,
if the feathers are left exposed to direct sunlight; but, like
photographic plates, the hues of some birds are more sen-
sitive than others to the light. The delicate reds and
yellows on the lower parts of Mexican Trogons are par-
ticularly evanescent, and the rose-pink of the African
Fairy Warbler disappears a short time after death.

We might speak of a third class of colours, which are
due to both pigment and structure. For instance, no
blue pigment is known to exist in the feathers of birds,
but blue feathers contain a brown or yellowish pigment
which is encased in the horny coating of the feather.
Between this outer sheath and the underlying pigment
is a layer of many-sided cones or small projections which

56 The Bird

have numerous little ridges extending down the sides,
and in some way, by reflection, these change the yellow
or black to blue. If we take a parrot’s feather and
pound the blue portion, that colour will disappear and
the vane will become black.

It is surprising to see how the colours of many beau-
tiful feathers will vanish when we hold them between
our eye and the light. When we look at feathers under
the microscope, and see their horny rays, we forget, for
a time, the delicacy and fluffiness which the bird’s plumage
as a whole exhibits, and we are constantly reminded of
the scales of reptiles. And in colour we have another
similarity between the two: lizards have both pigment
and prisms, and the scales of large snakes glow like opals
when the sunlight falls on them.

White never exists as a pigment in the feathers of
birds, but is always due to innumerable air-spaces in the
substance of the feather, by which the rays of light are
reflected and deflected until, as in snow or foam, all
colour is lost and white results.

In any one Order of birds there may often be found
a series of species with colour patterns grading into each
other and connecting two extremes, perhaps very diverse
in appearance. But it is seldom that we can examine
such a series at once, and, except in a large collection of
birds’ skins in a museum, these wonderful life-chains, or
twig-tips of the tree of evolution seldom appeal to us
very forcibly. But in a feather it is different. We may
find on one bird a most delicately graduated series, show-

ing every step in the process by which simple unicoloured

LS

‘azIs [einyeu g/T ‘*siapynoys
pue SSUIM UO MOYS 0} SurmUIFeq I9,UIM 4say ey} jo esvumjd Avis ayy YIM

9 o] . .
aq UMOIG UMOIS-]JReE— Ee “DTT

58 The Bird

or spotted feathers assume most intricate and complex
colour masses and patterns.

Darwin illustrates this very plainly in the case of the
Argus Pheasant, and pays a fitting tribute to the evolu-
tion of the marvellous colour patterns among birds. “The
ocelli on the wing-feathers of the Argus Pheasant are
shaded in so wonderful a manner as to resemble balls
lying loose within sockets. That these ornaments should
have been formed through the selection of many succes-
sive variations, not one of which was originally intended
to produce the ball-and-socket effect, seems as incredible
as that one of Raphael’s Madonnas should have been
formed by the selection of chance daubs of paint made by
a long succession of young artists, not one of whom in-
tended at first to draw the human figure. In order to
discover how the ocelli have been developed we cannot
look to a long line of progenitors, nor to many closely
allied forms, for such do not now exist. But fortunately
the several feathers on the wing suffice to give us a clue
to the problem, and they prove to demonstration that a
graduation is at least possible from a mere spot to a
finished ball-and-socket ocellus.”’

Two feathers from the wing of a Vulturine Guinea-
fowl have been chosen to illustrate a more simple but
no less beautiful colour evolution. On the less exposed
side of one of the feathers are three or four series of irregu-
lar white spots which tend in places to form transverse
bands. On the opposite side of the shaft near the tip
these spots are still distinct, but as our glance passes
gradually toward the base of the feather, the spots con-

wh g

oe

38.—Adult Brown Pelicans in full breeding plumage. 1/8 natural size.

59

60 The Bird

verge more and more, until two distinct longitudinal
lines are formed, with traces of a third near the quill.
A smaller feather from the same wing is marked with
spots which are nearly circular and which show faint
traces of encircling bands of white pointing toward a
still more elaborate system of decoration.

bia. 39.—Evolution of a colour pattern upon two feathers of a ulturine Guirea-
fowl; a stripe breaking up into dots, these forming cross-vars, and on the
second feather a regular series of dots encircled with white.

It is interesting to conjecture in which direction the
decoration of feathers is proceeding. In the case of the
guinea-fowl, are the spots converging into lines or are
the lines the more ancient, and for some reason grad-
ually splitting up into smaller divisions? This is hard to
decipher, and if we look at the rest of the guinea-fowl’s
body, the matter becomes only the more complicated.

Feathers 61

For, higher up on the wings, and on the shoulders, we
find that the fine specks which were barely noticeable on
the tips of some of the wing-feathers, are in the ascend-
ant, and absorb or replace the white spots over the whole
feather. The faint trace of the third line near the shaft
of which I spoke, has suddenly assumed an unexpected
importance and has spread out into a broad central band.
The young or the female might give us a clew; for in
many birds the coloration of these shows a more ancient
arrangement of colour pattern than the feathers of the
male.

The Indian Wood Ibis—what an imbecile it looks to
our eyes when we observe it in a zoological garden; what
a fishy smell it generally diffuses, how unpleasant are its
feeding habits, and what a dull black and white colora-
tion it has! Surely here is a bird with nothing which
could possibly appeal to our exsthetic sense. But we are
mistaken. Some of the innermost feathers of its wings,
seldom visible, except when the bird partly spreads them,
are of the most beautiful rose hue, shading at the tip
into a deeper pink. Seldom, even in Nature, will we
find tints comparable to the delicacy and bloom of these
hidden feathers.

We have gone into these details only to show the
possibilities of a little feather-study. Even our common
Plymouth Rock chickens and hundreds of other birds
will show us unthought-of beauties, and in the fields or
in a zoological park we have only to use our eyes more
carefully to realize how touch we usually pass by un-
noticed.

CHART Bi. VEL
THE FRAMEWORK OF THE BIRD

HEN we look at a living bird, we see only feathers,
horn, and skin, and we sometimes forget that

hidden beneath all these are many bones,—the
framework of the body. If we wish to alter the style of
architecture of a house, we need only to change the ex-
terior, columns, arches and windows, while the stone
foundation and brick walls may remain as they are. So
in fashioning new forms of life, Nature has often altered
the covering, and even the muscles and organs, of ani-
mals to such an extent that we would have little clew
as to the relations of these creatures, were it not for the
underlying bones, which are so deeply seated that they
react less slowly to changes in the outside life. If a fish,
a lizard, a bird, a whale, and a man should be presented
to us for classification, we might well hesitate until we
had seen their bones, when there would flash upon us
the same moulded type running through all.

The study of the skeleton, or Osteology, is like all
other ’ologies; it can be made as dry as the bones them-
selves; or the very opposite, by leaving the minor details
and less important particulars to text-books, choosing

only the most significant facts. One may smile at the
62

\

Fig. 40.—X-ray photograph of the front view of a homing Pigeon, showing the
bones clearly through the surrounding flesh. Observe the light, spongy
character of the skull and the bones of the limbs, the latter appearing almost
hollow. The crop filled with corn is visible spread out at the base of the
neck, and low down in the body, near the right thigh, the grit and pebbles
within the gizzard are very distinct. About the tarsus of the right leg is
seen the metal tag which was used for the identification of the living bird.
(Photographed by Dr. Henry G. Piffard.)

63

64 The Bird

thought of bestowing an encomium on a jaw-bone, and
yet the history of the lower part of a sparrow’s beak
opens a vista so far-reaching that the mind of man falters
at the thought; it shows the last roll of an evolving
which, could we follow it back, would merge the man, the
whale, the bird, the lizard, the fish, into one.

Let us look at some of the bones of a sparrow or
dove or chicken. One way to do this is to place a dead
bird in a box pierced with numerous holes, leave it near
an ant-hill, and wait for the industrious insects to do
their work. Another way is to clean as much flesh as
possible from the skeleton and deposit the bones in a
pail of water. In a few days they can be washed white
and clean. Perhaps the easiest way of all is to save what
bones you can of a boiled chicken. These are of large
size and will show us all we wish to know.

The framework of a bird consists of a long jointed
string of bones called vertebrae, with the brain-box or
skull at one end and a blunt tail at the other. Near
the middle, the outcurving ribs extend around the organs
of the body, and, with the breast-bone, form an encircling
protective sheath. Two short series of bones project in
front of the ribs—the bones of the wings,—and two more
behind the ribs—those of the legs and feet; while at the
point of attachment of each of these four limbs there
radiates a trio of bones.

The back-bone is the fundamental and oldest part of
the skeleton, and though we cannot follow its evolution
directly backward through the long ages, yet there is
sufficient gradation among living creatures to give us

Fic. 41—Common Fowl, showing relation of the bony framework or skeleton
to the contour of the body. Notice large eye, long and mobile neck, the
knee wholly within the body plumage, and the well-developed keel hinting
of ancestors with strong powers of flight. 1/4 natural size.

65

66 The Bird

hints of the way it originated. In the lowest of fish-like
creatures—the Amphioxus, a tiny animal, an inch or two
in length, living in the sand along our shores—there is
a thread-like cord of a gelatinous substance (not carti-
lage, however) extending down the back, known as the
notochord. He looks like some kind of worm, but this
little gristle is his badge of nobility and lifts him clear

Fig, 42.—Amphioxus, one of the lowest vertebrates, with a mere thread of
gristle foreshadowing the back-bone of higher animals. This creature bur-
rows in the sand along the Atlantic coast.

of corals, snails, insects, and worms, into the realm of
back-boned animals. This notochord les underneath a
thin white line which is all the spinal chord he has, and,
at the front end of this, a tiny dot of pigment stands
for brain, eye, and ear. Indeed Amphioxus has neither
skull, brain, nor limbs.

The history of the back-bone, like human history, is
not altogether a majestic upward evolution; it has its
tragedies and set-backs, its hopes and failures. In the
waters along our Northern seashores are creatures, some
sponge- or lichen-like, others with strange bulb-like bodies

The Framework of the Bird 67

growing on the end of long stalks. We call them almost
plants. But they hold a secret from the crabs and snails
which crawl about, and when the fishes brush against

Fig. 43.-—A colony of living Boltenia, photographed by the author in the Bay
of Fundy. The Boltenia is one of Nature’s failures to make a vertebrate.
The larva is active and has a notochord; the adult is degenerate and fixed
on astem. Found in five fathoms and deeper off rocky coasts north of Cape
Cod.

them—if their poor dull senses only knew it—they
might claim a blood-brotherhood. When they were
young, for a little while, a gelatinous notochord was
theirs also, but this, with all the hopes that such a be-

68 The Bird

ginning brings, of fish, of bird, of man even, soon melted
away and there they nod and sway in the watery cur-
rents, never to know of the opportunity Nature has
snatched from them—why, who can tell?

In adult sharks, the back-bone has become jointed
and flexible, and a crude kind of skull is present, but
still more important is the presence of four fins which
correspond to the four legs of lizards and to the wings
and legs of birds. A curious basket-like skeleton pro-
tects the delicate gills, and it is probable that this existed

Fic. 44.—Back-bone of Dogfish, with simple cartilaginous vertebre.

long before the limbs appeared. All of this is composed
of gristly cartilage. In the higher fishes, bone replaces
the cartilage, and when the lowly tadpole—fish-like at
first, swimming about by means of the fin around his
tail—pushes forth his legs and climbs upon the land, our
skeleton is well on its way birdwards.* Reptiles of old
took to trees; their back-bones grew less flexible, so that
they might safely sail through the air; feathers replaced

* The actual evolution of birds was of course not through fish, tadpoles,
and reptiles as we know them, but by some line of creatures unknown to us

forever, and resembling some of these other living Classes at least in the pos-

session of gills, scales, ete.

The Framework of the Bird 69

scales, two fingers of each hand were lost, and one from
each foot; teeth disappeared; a beak of horn proved
best; intelligence increased and the forehead rose high,
and behold,—a bird! Can we then despise even an Eng-
lish Sparrow?

All these things we have learned from a comparison
with creatures other than birds, and we may, without
trouble, take one more glimpse into the dim past. Let
us go to the hencoop, where for three days the patient
biddy has been sitting on her precious eggs. We will

Fie. 45.—Neck vertebre of an Ostrich, highly complex and bony in structure.

rob her of one—she will not miss it—while from it we
may learn many wonderful things. Rest the warm egg
in a dish of sand, carefully picking away the shell from
the upper part. A glance at the tiny embryo lying on
the yolk within will show a double series of tiny squares
extending down the long diameter of the body. These
are the first hints of the spinal column, and if we could
follow its further development we would see something
of great’ interest. The squares are now divided up like
beads, just as are the bones of our bird’s vertebrae; but
in reality this first segmentation is a false one. It is sim-

70 The Bird

ply a copy of the primitive flakes or Joints of the tiny
muscle-beginnings, and is comparable to the Joints or
rings in the body of a beetle, butterfly, or earthworm.
In a short time all the squares will fuse together, and not
until later will they separate again into divisions which
will ultimately form the real bones of the spinal column.
Every little chick, before it hatches, goes through the
same strange changes,—living reminders of the evolution
which has gone on in past ages of the earth. It is inter-

Fic. 46.—Muscle-plates, or false vertebree, of third-day embryo chick.
Magnified 25 diameters.

esting to note that the vertebrae of the embryo chick
pass through a stage when they are biconcave,—a condi-
tion found both in Amphioxus and Archeopteryx.

This digression upon the back-bone history may seem
out of place, but in reality such a bird’s-eye survey of
the past, imperfect as it is, will add a new interest to
our handful of chicken-bones.

The Framework of the Bird 71

Let us suppose that we have strung a wire through
the hollow centre of the back-bone of our chicken, to
which the ribs are still attached, and that we have be-
sides the skull and the bones of one wing and one leg.
Compare them with those in the illustrations and we will
see if they can tell us aught of interest.

The bones of the neck are all separate, and slide back
and forth on the wire, like beads on a string. How unlike

Fig. 47.—Front and rear views of seventeenth and eighteenth cervical vertebre
of Ostrich, showing complicated saddles and sliding surfaces, giving great
freedom of motion.

the long smooth ribs are these vertebrae, bristling with

spines and projections! How is it that a bird can be

comfortable with a string of such irregular-looking ob-
jects run through its body? But fit two of these bones
together and see how beautifully they saddle end to end,
every convexity or projecting knob exactly adjusted to

a corresponding concave portion of the neighbouring bone.

These saddles are characteristic of birds alone. Every

one of the sixteen bones of the neck is different from its

72 The Bird

fellows and exactly suited to the requirements of its
position, but the first two following Just behind the skull
are so radically unlike the others that we know at once
that they must serve some particular purpose. The first
is littlke more than a simple ring * of bone, and 1s called
the atlas, after the mythological giant who held up the
heavens upon his shoulders; named very aptly too, for

Fra. 48.—Atlas and axis of Jabiru, separated. Fic. 49.—Atlas and axis of
Jabiru, joined.

this tiny collar of bone supports the skull itself. The
next vertebra is ring-like too, but has a curious knob in
front, which projects forward through the atlas and forms
the

a pivot on which the head turns, hence its name,
axis.
Let us compare the neck-bones with those of a reptile
and a man. Although, as a whole, the bones of the
* This-bone is formed chiefly of two intercentra, which are small bones,
very characteristic of reptiles (chevron-bones of the tail) and are not uncom-

mon among the lower Orders of birds.
+ In Hornbills the atlas and axis are fused together.

The Framework of the Bird 7

skeleton of a bird are more or less soldered together,
yet the neck is far more flexible than in either of the
other examples. Indeed the neck of a bird has greater
freedom of motion than that of a snake. <A lizard can
turn his head only a little way around, and we ourselves

can look only across our shoulder, but with a bird it is

Fie. 50.—American Egret, showing curves into which the neck naturally falls
when the bird is at rest. When striking at a fish the vertebrae straighten
out.

very different. Watch a heron or, better still, a fla-
mingo and see its neck describe figures of eight as he
arranges the feathers on its back. Few people would
ever imagine that there are exactly twice as many neck-
bones in a sparrow as in a giraffe, but such is the case,
there being fourteen in the former and seven in the latter.
In the neck of a swan there are twenty-three of these
bones.

74 The Bird

The remaining vertebre, those of the upper and lower
back, are very different from those of the neck. The
flexible neck enables the bird to reach all parts of its
plumage with its beak, and to pick up food from the
ground or from twigs overhead, but the all-important
function of flight must be provided for by means of a

Fic. 51.—White-throated Sparrow, three inches tall, with fourteen neck vertebre.
(Compare with Fig. 52.)

rigid body-frame. In reptiles and in the embryos of
birds only two pelvic vertebre are fused together, but
in adult birds many dorsal and caudal vertebrae (as many
as 23 in some cases) are fused into a single bone. Thus
the rib-bearing upper back vertebrae are partially fused
together, and below them those of the lower back have
merged until it is difficult to realize that this portion of

The Framework of the Bird mG

the skeleton was not originally one bone. Passing on for
a moment to the bones of the tail, we find a number of
separate pieces, ending in a curious-shaped bone, called
the ploughshare. This is at the tip of the tail, or “‘pope’s

Fie. 52.—Giraffe, reaching with tongue for leaves perhaps eighteen feet above the
ground, with but 7 neck bones.

nose,”’ of the chicken and really consists of many verte-
bre fused together. It is necessary for this to be large
and strong: for it supports all the feathers of the tall.
But to be of efficient aid in steering, the tail, like the
rudder of a ship, must have freedom of motion, and

Fig. 53.—Pelvic vertebre of young Alligator.

Fic. 55.—Pelvic vertebre of Bald Eagle. In the reptile, where there is no need
for rigidity, only two typical pelvic vertebrx are joined together; in the birds
many dorsal and caudal vertebre are joined with these to make a rigid frame
for flight and for bipedal locomotion. 76

The Framework of the Bird 16

hence the separate bones which unite it to the vertebrze
of the lower back. The evolution of the tail will be
treated of in another chapter.

Ribs

The ribs are the long, narrow, double-headed bones
which curve out from the vertebre of the upper back
and, uniting with the breast-bone, form a barred pro-
tection for the heart, lungs,
liver, and other organs. These
are the ribs proper, but there
are Other smaller ones, called
false or floating ribs, which
reach only part of the way
around the body. Look at
the largest ribs of the chicken
and an added provision for
making this box of bone more

solid willbe seen. Fromnear _ F'6. 56.—Ribs of Hatteria Lizard,
with uncinate processes.

the centre of the upper part

of each rib a small bony projection laps across the rib
next behind and thus forms a kind of lattice-work,
movable but of great strength. A further interest
attaches to these cross-rib pieces when we learn that every
bird except the Screamer possesses them, while else-
where they are found only in crocodile-like reptiles
and in the Hatteria Lizard of New Zealand.

The similarity of the ribs—slanting one after another

78 The Bird

around toward the breast-bone—hints of something
which perhaps has never occurred to us. We spoke of
the worm-like appearance of the lowly Amphioxus—
the sand-fish with the shadow of a back-bone. When we
think of a worm we think of a creature very much alike
from head to tail, one in which a section across the neck
is not very unlike one across the centre of the body or
near the tail; indeed that is exactly what the word Am-
phioxus means,—like head, like tail. This repetition of
segments or similar parts Is a sign of low degree in the
scale of life, as it harks back to the time when the very
highest form of life was worm-like.

The flesh of a salmon or of a trout shows such a con-
dition very well, the body consisting of flake after flake
of flesh. Now in birds and the higher animals this divi-
sion into successive segments is hardly noticeable, and
almost every inch of a man or bird, from head to toe,
seems very distinct and individual. But ribs bring back
the old ancestral condition very vividly, and when a
peacock, strutting proudly before us, resplendent from
beak to tail, picks up and swallows an unfortunate angle-
worm, we may remember that, no matter what geological
eras or inexplicable physical gulfs separate the two, the
bird carries within his body indelible imprints which
insolubly link his past with that of the lowly creature
of the dust.

As in various other cases throughout nature, when the
many ribs of the bird’s ancestors began to be reduced in
number, some attained to other uses beside that of arch-
ing around the whole body and protecting the heart, the

The Framework of the Bird 79

lungs, and other organs. Look at the two neck-bones of
the ostrich in Fig. 47, where in addition to the central
aperture, through which the spinal nerve-cord passes, two
other openings will be seen, one on each side. Through
these the vertebral arteries carry their burden of pure
blood. The outer wall of this bony canal, extending up
the whole length of the neck, is formed principally by
what is left of the ribs which were once long and free,
like their fellows farther down the back. Though re-
duced to a tiny fragmentary arc of bone, yet they still
perform a protecting function.

In Archeopteryx (Fig. 5) there existed well-developed
abdominal ribs, exactly like those found in crocodiles
and other reptiles. In no living bird, however, are these
found.

Breast-bone

The lower portions of the true ribs of our chicken
are separate pieces of bone, slanting in a forward direc-
tion and attached by a movable joint to the upper parts.
These end close together along the sides of the large
breast-bone, or sternum as it is called. In fact the origin
of the sternum can be traced to the fused ends of these
ribs, and in the sternum of an immature ostrich (Fig.
58) the line of juncture between the two lateral halves is
still distinct or even open. To the edge of this bone,
nearest the head, two column-like shoulder-bones are
attached, and in some birds the wish-bone is also joined
to it (Fig. 103).

The sternum is one of the largest single bones in

80 The Bird

the body of the chicken, and is very different from our
own breast-bone, which is long and narrow. The pos-
terior edge of the sternum is of many shapes, varying in
birds of different species. Deep channels may extend
into each side, leaving long slender splinters or spines

Fic. 57.—Ribs and sternum of Flamingo; notice what a complex box of bone
is formed by the vertebr, scapula, ribs with their uncinate processes, and
the sternum; notice large keel for the attachment of flight-muscles,

of projecting bone, or this channel may be partly closed,
forming a round hole quite through the bone. The
sternum and its various processes are of considerable
value in classification, the same configuration being found
throughout allied groups, in consequence, doubtless, of
the slight chance of modification resulting directly from
any specialized habits in the life of the bird. The portion

The Framework of the Bird 81

of this bone which is most characteristic of birds is the
central ridge or keel which projects straight out from
the surface of the sternum. This is of the utmost im-
portance in giving firm anchorage for the great flight-
muscles of the breast.

Fie. 58.—Ribs and sternum of Ostrich; notice absence of keel correlated with
loss of power of flight. The suture through the centre of the sternum reveals
its paired origin.

The keel is of many shapes, but when well developed
is generally very high at the upper end of the breast-
bone and becomes lower as it slopes gradually backward.
In birds which have lost the use of their wings the keel
has disappeared completely, the sternum being flat, as
in ourselves. This is its condition in the ostrich and

cassowary, and it is the character which has given a

82 The Bird

name to two great divisions of birds: Rati’te@ (those with
flat breast-bones, raft-like), including the ostrich, rhea,
emeu, cassowary, and apteryx; and Carina’te (birds
with keeled breast-bones, boat-like), including all other
living birds, whether flyers, as the thrushes, storks, and
gulls, or swimmers like the penguins. But this differ-
ence in breast-bones is far from being as profound as
other differences existing between certain birds which
are alike in having keels to their sternums. The pres-
ence or absence of a keel is not of great taxonomic im-
portance.

The size of the keel is a pretty sure criterion of the
flying powers of a bird, that is, Judging not the actual
duration of flight, but the actual muscular power and
amount of energy used in flying (Fig. 59). The alba-
tross, and other birds which, trusting to the air-currents
to bear them upward, flap seldom and soar much, have
comparatively smaller keels than do those birds which
flap their wings more frequently. Thus the pigeon has
a very good-sized keel; while in the humming-bird this
bone is enormous, compared to its spread of wings. Dr.
Frederick A. Lucas has expressed this very graphically
in a diagram, where it is supposed that the albatross,
pigeon, and humming-bird have an equal spread of wings.
On comparison, the keel of the first is seen to occupy but
a small fraction of the surface of the same bone in a
humming-bird. To account for this we must realize
that the wings of the humming-bird execute from six
hundred to a thousand strokes a minute; while the alba-
tross may soar for miles with wings held outstretched

The Framework of the Bird 8 3

and all but motionless. It is said that, comparatively,
the muscular energy is greater and the wing-bones more
powerful in a hummingbird than in any other animal.
Nature has a puzzling way of achieving similar results
in a very similar manner in creatures wholly unrelated.
We have a good example of this in bats and birds, both

Fig. 59.—Comparison of the size of the keel of the Albatross, Pigeon, and Humming-
bird, supposing all to have an equal spread of wing. (Courtesy of Dr. F. A.
Lucas. )

of which have independently learned to propel them-
selves through the air by means of their front limbs.
If we take the breast-bone of a common bat and that
of a small bird and place them together, few persons
unacquainted with the bones of the two types could tell
which was that of the bat,—different as that little crea-

84 The Bird

ture is in external appearance from a bird. Their keels
and sternums are very much alike. This is called par-
allelism, and sometimes it gives a great deal of trouble
to naturalists when they are trying to find the right
relationships between living animals.

Shoulder-girdle

It will be remembered that mention was made of the
trios of bones which radiate near the Juncture with the
body, of each wing and each leg,—girdles or arches they
are called. The pectoral, or shoulder, girdle meets the
upper arm-bone of each wing at the shoulder-joint. If
we run our hand along the back of our shoulders, we
will feel a prominent bone, called the shoulder-blade, and
in almost the same place in our chicken we notice a very
long and thin bone. This is the scapula, and is one of
the pectoral-girdle trio, the other two being known as
coracoid and clavicle.

The coracoid is a short, but stout, column of bone
joined to the shoulder-blade and extending down and
backward to the breast-bone. This coracoid bone is
especially developed in birds as compared with other
creatures. When their forefathers began to scale through
the air, thus putting a great strain on the muscles of
the breast, Nature seized on these coracoid bones, giving
them such strength and thickness that they have become
the pivots upon which, at each swift vibration through
the air, turn the marvellous wings of a modern bird. In
reptiles, this bone is divided into two weak, thin plates

The Framework of the Bird 85

which would hardly afford strength for a single wing-
flutter. Since mammals in their high evolution have
found no use for this bone, it has become reduced to a
small projection on the shoulder-blade.

The clavicle we will recognize instantly, when we
give it another name—the wish-bone or merry-thought.

Fic. 60.—Pectoral girdle of bird (seapulas, coracoids, and clavicles); compared
with the scapula and coracoid of a young Leopard, the latter bone in the
Leopard being reduced to a tiny process.

In birds the wish-bone is generally V-shaped, the two

clavicles usually meeting and fusing at their tips. Through

this V-shaped opening in the neck, the cesophagus and
the windpipe pass from the throat into the body cavity.

We too have wish-bones, although they are not placed
exactly as are those of a chicken. We call them collar-
bones, but by whatever name we know them they are
of importance, both in ourselves and in birds, in serving
to brace out the shoulders. In creatures which, unlike

86 The Bird

mankind and most birds, have less varied movements of
the fore limbs, the clavicles have fallen into disuse, as
in the lion and the horse. But in climbing, burrowing,
and flying animals, such as the squirrel, mole, and bat,
these bones have been of active use and are well devel-
oped. But to keep its wish-bone a bird must continue
to fly: for Nature is opposed to useless parts. So, in
the flightless cassowary and ostrich, the wish-bone is
very small or altogether absent. Parrots are almost
alone in appearing to suffer no inconvenience in flight
by the lack of clavicles,—these being greatly reduced in
some species.

In that anomalous bird the Hoatzin, the clavicles
are fused not only at their base, but the tips are ossified
firmly to a projecting spine of bone from the upper part
of the breast-bone.

In glancing back over the lower back-boned animals
we realize that a shoulder-girdle of bones is of no use
without a limb. Therefore we find the first hint of the
shoulder-girdle in sharks, in which we also find the first
limbs, or fins. In these fishes it 1s nothing but a single
bar of soft cartilage. In the girdle supporting the pec-
toral fin of such a fish as the trout or other bony fish,
we find the adumbration of some of our bird’s bones.
When we remember how very wing-like is the movement
of a fin in the water, we will not be surprised to learn
that the girdle is almost all epiclavicle; these bones
being the forerunners of clavicles, and giving place, in
the higher forms, to the real wish-bones which steadily
increase in size and importance. We would hardly

The Framework of the Bird 87

recognize in these primitive types the wish-bone of our
Christmas turkey.

In terrestrial quadrupeds and birds we usually find
the front limbs near the front part of the body and the
hind limbs much farther back, but it is interesting to

Fic. 61.—Girdle of a bony fish.

notice that in the fish, Fig. 61, all four limbs or fins are
very far forward, almost or quite in the head region
itself. This is a result of the function of balance which
these structures almost wholly perform, the fin of the
tail furnishing the locomotive power.

It is very interesting to notice how many bones have

kept to their respective places in the evolution of animals,

88 The Bird

no matter how much change has occurred in their
shape and size. ‘Take, for instance, the shoulder-blades.
When a tiger crouches they are very conspicuous, and
whether we take a frog, a turtle, a lizard, an armadillo,
a mouse, or a horse, we may always be sure of finding a
scapula in the region where we have observed it in the
bird. This is an important fact, and one which makes
the identification of many bones an easy matter.

Thigh-girdle

The shoulder-girdle which we have just examined
was not joined to the back-bone, but only saddled on
the ribs, the scapula extending backward, Just clearing
them. What kept it in place in the chicken’s skeleton
was the fact that it was strongly attached to the sternum,
and this in turn joined to the back-bone by means of
the ribs. But the pelvic arch or thigh-girdle is very
different. If the entire framework of the bird is to be
supported on two legs, the point of attachment of these
limbs must be solidly fixed to the back-bone of the body.

Although there are as many bones supporting the leg
or thigh as there are bracing the shoulder, we would
never know this from examining our chicken. As in
other places in a bird’s skeleton, the bones—six In this
case—have fused together in one solid piece, and only
in very young birds are they separate.*

The names of the bones composing the pelvic girdle,
or arch, are the ilium, ischium, and pubis. The easiest

* They were separate also in Archwopterye.

The Framework of the Bird 8g

way to locate these is first to find the socket in which
fits the head of the thigh-bone. This is the deep cup-
shaped depression on each side, and all three bones join
in making the socket. The ilium lies along the back
and forms a sort of roof over the portion of the back-
bone in this region. If we look at the under side of this
bone, we may see the fused vertebre more distinctly—
fourteen or fifteen of them. The two deep depressions
in Which the kidneys of the bird were located are also

Fia. 62.—Pelvie girdle of a bird.

now visible. As the coracoid is the great pivot of the
wing, so the ilium helps most to bear the strain of hop-
ping and running. In the frog, which progresses by
hops or great leaps, the ilium is also largely developed;
indeed we can see it through the skin, thus giving the
broken-back appearance to that creature.

‘ach side of the thigh-bone box is formed by the ischium,
Which is closely fused with the ilium except in most of
the ostrich-like birds, the tinamous, and in reptiles,
where these bones are free throughout their entire length.
We can readily make out the pubis as a slender bar of

go The Bird

bone extending backward from the thigh-socket, sepa-

Fic. 64.—Pelvie arch of an embryo bird,
to show similarity of the two as
contrasted with Fig. €5

Fig. 65.—Pelvie arch of an adult bird.
(The three figures by courtesy of
Prof. H. F. Osborn.)

rated from the ischium
(except at the extreme
end) by a long open slit.
In other animals these
bones are as different in
shape as can be imagined,
but, almost without excep-
tion, the position of each
is relatively the same. The
extreme extension, forward
and back, of the ilium
above the back-bone, thus
joining with more vertebre,
is directly connected with
two-legged erect locomo-
tion. <A parallel condition
is found in some Dinosaurs
—those extinct giant rep-
certain of which

tiles
walked more or less on
their hind legs.

Another fundamental
resemblance is found be-
tween the thigh-girdles of
Dinosaurs and other rep-
tiles and that of a bird in
the egg. As is shown in
Figs. 63-65, the pubis slants

slightly forward in both reptile and-embryo bird; but in

The Framework of the Bird gI

the adult bird the shifting backward of this bone until it
is parallel with the ischium is wholly an avian feature.

Fig. 66.—Bullfrog. The bend in the back shows the great development of the
ilium for bipedal locomotion in the sense of leaping ability.

Wings

We will now consider the framework of the fore limb,
or wing, of a bird, and a glance at the illustration show-
ing the arm of a man and the wing of a bird will at once
make plain the relation between the two. Here we again
find a great help in the fact that many of the bones keep
to their respective places in frogs, lizards, birds, and man.

We know but little of the direct change from a fin to
a hand or foot, although there are some fishes living at
the present day with large finger-like bones in their pec-

92 The Bird

toral fins. Even among fossil forms there have as yet

ee

been found no ‘‘missing links” in this respect. But how-
ever it came about, it is certain that when the fish-
amphibians of olden time, venturing into shallow water,
felt more or less solid mud under them, and tried to
move about upon it, their fins must have become pressed
downward, and before they could safely push themselves
about on dry land or lift their bodies clear of the ground,
the stiff fin-rays must have become split up into a few,
thick, bony rays or toes. We know that these were
originally five in number on all four limbs, and when-
ever, among living creatures, we find a lesser number, the
reduction has been brought about by some subsequent
change in the life of the animal. As yet, however, we
know of no direct transitions from fins to feet.

The requirements of flight demanded a fin-like stiff-
ness in the wings of birds, and therefore many of the
smaller bones of lizards, counterparts of which we find
in our own wrists and hands, are in the bird fused together.

The upper arm-bone, or humerus, corresponds exactly
to our bone of that name, and when we feel the two long
bones of our. forearm and look for them in the bird, we
find both very plainly represented, the large one with
notches, where the great wing-feathers are fastened, being
called the ulna, and the smaller, straighter bone the
radius. In our wrist there are eight little bones which
are joined to each other so delicately that we can move
and turn our hand in every direction. But when a bird’s
wing is extended, if the wrist was at all flexible, the pres-
sure of air on the great wing-feathers would turn the

The Framework of the Bird 93

Fig. 67.—Wing of Pigeon, feathered.

Fig. 69.—Arm and three fingers of a man.

94 The Bird

wing-tip around and make flight impossible. So but
two of these small bones are free in our chicken’s wrist,
although in the small chick several more (six in all) are
separate.

If we double back our fourth and fifth fingers and
imagine that they have disappeared, extend our other
three fingers and then suppose that all our wrist-bones,
save two, have fused with the three long bones leading
to the base of our thumb, index and middle fingers,* we
will have an idea of the condition of our chicken’s wing,
and indeed there is very little difference between this and
the wings of all other birds.| We have two separate
bones in our thumb, and three in each of the next two
fingers, and the bird has the same number, except in
its third finger, in which there is but one. The principal
value of this comparison is to show us that the bird,
even in its most characteristic and specialized organ,—
the wing, is not physically so unlike ourselves as we
might at first glance suppose. When a bird folds its
wing against its body, the joints are bent sharply, and
the Z, formed by the elbow and the wrist, almost closes
up. We can place our arm and hand in much the same
position.

If we move our arms slowly up and down, little by
little greatly increasing the speed, we will realize how
much greater strength and rigidity the whirring wings

. . waerlitce 11 77
* Some morphologists homologize the fingers of a bird’s wing with the
second, third, and fourth digits of a pentadactyl hand. The question 1s still

a mooted one.
+ In the embryos of some birds, traces of a fourth finger have been found.

70.—Skeleton of wing of Condor, compared with Fig. 71.

Fig. 71.—Skeleton of a man’s arm; notice close correspondence of bones in the
two. (The extended thumb of the human hand is not silhouetted against
the background, and hence not very distinct.)

g6 The Bird

of a hummingbird or a grouse require than do the slowly
flapping pinions of a gull or an albatross. When we
compare the relative shortness of the upper arm-bone,
or humerus, in the former groups with the long wing-
bones of the sea-birds, we again realize what exquisite
adaptations exist everywhere in Nature.

The proportionate length of the various parts of the
fore limb of a bird forms an interesting corollary to its
habits of life. For example, the hand in penguins and
in hummingbirds is very long indeed; while in the os-
trich the humerus is considerably longer than the fore-
arm and hand combined. (Compare Figs. 269 and 272.)

Before we leave the wing-bones, it will be well worth
our time to consider for a moment how limbs first origi-

2.—Diagram showing the origin a paired fins (limbs) from a continuous
fin-fold. (After Wiederscheim. )

nated. In the lowest of fishes, such as our friend the

Amphioxus and in lampreys, limbs are altogether absent,

but in embryos of sharks we get a hint of what the first

zreat fish-like forms were like. Along the lower part of

each side of the body there runs a continuous fin, so that

The Framework of the Bird 97

the front view of a section would be something like this,
the dorsal fin being above and the lateral

fins on each side. Now owing to certain laws

of mechanics, whenever such a creature as this

moved about in the water, the stress of bal-

ancing would be thrown most heavily on two points in
these side fins, and gradually at these two nodes the fin
became more strongly developed; while between these
points it degenerated and finally disappeared. So in
modern fishes we find the quartet of limbs alone left of
this continuous fin or fold of skin.

Look at a little embryo in the egg, taking one which
has been incubated for six or seven days, and see the
curious paddle or fin-like wings and feet—simply four
rounded flaps projecting from the body

as unlike the
limbs of the chick when it emerges from the egg as can
be imagined (see Fig. 367). The ridge or fin of skin in
the early, soft-backboned creatures could have been of
no use whatever, except in balancing. In fact if we
watch a trout carefully, we will see that it is the tail-fin
which does almost all the propelling, the front- and hind-
limb fins simply acting as guides and balances.

So in this instance (as indeed in almost every organ
in ourselves as well as in birds) we learn that the original
function was entirely unlike that which the part now
serves. The idea of miraculous change, which is sup-
posed to be an exclusive prerogative of fairy-tales, is a
common phenomenon of evolution, and the shadows of
these miracles of the past are forever coming and going,
over the growth of the tiny bird hidden in the egg.

98 The Bird

Legs

The leg of our chicken, as we have seen, is attached
to the great bone of the thigh-girdle. Being used for
locomotion on land, the foot is not very different from
that of a lizard, but there seems something very strange
about the leg. Can it be possible that a chicken’s knees
bend backward? If so, it must be different from all
other two-legged or four-legged creatures. Much of a
bird’s leg is concealed beneath its feathers, and when we
see the bones as far up as the thigh-joint, we understand
our mistake at once, and see that a bird has knees which
bend in the same way as our own, that is, forward in an
opposite direction from the elbow. The knees of a bird
are usually concealed within the skin of the body, as in
the short-legged ducks, and are never visible outside
the plumage. Hence the wide-spread mistake concern-
ing them. For this reason the femur, or thigh-bone, is,
in birds, relatively very short, even in the long-shanked
herons and flamingos, the extra length of limb resulting
from the elongation of the next two lower joints.

The thigh-bone, or femur, alone forms the upper leg,
or “second joint,’ and two bones, as in the forearm,
the next portion below. One of these, the tibia, 1s much
the larger and is the ‘“‘drumstick” of the chicken.* When
we cut the dark meat from this portion, our knife some-
times slits off a splinter, which is the second bone of this
joint, the fibula.

* To the lower end of this are fused, in the bird, the bones which corre-
spond to our heel-bone and the small astragalus.

The Framework of the Bird 99

In the chicken, we next come to a single long bone
called the tarsus, which is, in life, covered with scales.

Fic. 73.—Skeleton of an Ostrich Fic. 74.—Human leg and foot.
leg and foot.

In the embryo it is composed of several separate bones.*
The simplest interpretation we can give to the foot of

* These correspond in ourselves to the bones of the upper foot and the
second row of carpals, this joint of the leg coming, therefore, really between

the bones of the ankle, instead of, as in ourselves, between the ankle and the
lower part of the leg.

100 The Bird

the chicken, in comparing it with our own, is to imagine
that our small toe has completely disappeared; the great
toe (corresponding to the thumb of the forelimb) is
turned backward, and the heel is lifted high from the

Fic. 75.—Living Ostrich, showing entire leg; notice the knee almost
within the body.

ground, the several bones of the upper foot being greatly
lengthened and fused into one. So we, like bears and
raccoons, walk with our whole foot, from toe to heel, flat
upon the ground, while a bird, like a cat or a horse, walks
on its toes alone.

Fig. 77.—Jaguar, showing progression upon toes alone (digitigrade).
(Sanborn, photo. Courtesy of N. Y. Zoological Society.)

101

Fia. 78.—Wood Ibis, resting temporarily upon its whole foot.
(Sanborn, photo. Courtesy of N. Y. Zoological Society.)

Se iret

ARAN fo9Pesati

———— if

Fic. 79.—Bear, walking upon the whole foot (plantigrade). Compare with

Wood Ibis.
102

CHAPTER IV
THE SKULL

BIRD’S skull has been called a “poem in bone—
its architecture is the frozen music of Sao

ne rhy inane rhymes of a oe pneaniniine an
which constructed the noble edifice when they sang
together.”’ We should all ‘‘be able to whistle some bars
of the cranial song—the pterygo-palatine bar at least.”’

We perhaps know that there are twenty-eight bones
in our own head, and if we attempt to dissect the skull of
a fish we will find many more, but at first glance the
skull of our chicken seems to be composed of but one
solid bone. Indeed, if we except the lower jaw and
few others, such as the two little bones which unite it
to the skull, the entire cranium is soldered together, and
the lines of Junction obliterated. In young birds these
seams are more or less visible, although the soldering
process begins very early.

The origin of the skull is wrapped in obscurity, and
neither the student of fossil bones, nor of those beneath
the skin of living creatures, nor yet the diligent watcher
of the mysterious panorama of life in the egg, can tell

us very much, although many theories have been sug-
103

104 The Bird

gested. The poet Goethe thought the skull was merely
a continuation of the neck-bones, very much expanded
and changed, and although the division of the skull into
three roughly outlined rings is possible, yet we have no
direct proof of the truth of this theory.

Fortunately, in the skulls of most animals, the bones
are separate, and by keeping in mind the constancy of
their position, the puzzle of the skull of a chicken begins
to clear up.

Just as the first back-bone was a gelatinous or gristly

Fic. 80.—Cranium of Dogfish, cartilaginous, generalized in structure.

one, so the old type of skull was entirely gristly or car-
tilaginous. Sometimes on the seashore near the huts of
the fishermen, we may pick up a strange-looking object—
translucent and looking as if it were made of hard white
rubber. Clinging to it is perhaps a long string of delicate
beads of the same substance. This is the skull and back-
bone of a dogfish or shark, and although the skull is
very unlike the chicken’s cranium, vet many of the parts
in the latter are faintly foreshadowed in the cartilage
skull washed up by the waves.

Through all the long ages of geological epochs, myri-

The Skull 105

ads of creatures were changing in form and structure,
some growing too bulky and helpless and vanishing,
others developing powers of running, burrowing, flying
and leaping. But it is a very remarkable and wonder-
ful thing and very fortunate for us poor mortals, striving
after knowledge of the past, that in each general class
of creatures, certain ones should have found a niche
where they were removed from the fierce struggle for

Fic. 81.—Skull of young Alligator. Bones massive and solid, adapting their
owner to an active aquatic life but to sluggish terrestrial movements; eye-
cavities and brain-case very small, the jaws (organs of prehension) composing
by far the major part of the head.

existence, and where for year after year, century upon
century, they and their descendants changed but little.
We might mention Amphioxus and sharks among fishes,
Necturus among amphibians, Sphenodon among reptiles,
and the duck-billed mammal and others among. hair-
covered creatures. These may be meaningless names, but
if one will read about them and then examine their skins
and skeletons in our museums, many a glance will be

given into the ages of the past, compared to which the

106 The Bird

few thousand years during which man has reigned seems
but a day,

When we study the early structure of some creature,
say a bird, we find that before it emerges from the egg
the skull is soft and cartilaginous, open and quite differ-
ent in shape from what it will be eventually, and it is
most startling to find a living creature—a shark—with

Fra. 82.—Skull of Bald Eagle. Bones light and spongy, fitting for a very active
aerial life; orbit very large and brain-case capacious, showing great advance
beyond reptilian condition.

a skull which never gets beyond this condition. It is
as if the curtain of eternity had been, for a moment, drawn
aside for us, and a glimpse given into the past—a past
so remote and clouded that our keenest searches seem
to reveal but dim, skeletal forms of weird shapes, which
yet we know must have blended and imperceptibly
merged, through millions of years, into the present life
of the earth.

Looking at the chicken’s skull as a whole, we notice

a number of uses which the various parts serve. The

The Skull 107

large rounded portion taking up most of the skull proper
is, of course, the box of bone which protects the brain.
On each side, a large cavity shows where the eyes are
placed, and if we compare this skull with that of a cat
or dog or with that of a human being, we will see what
great importance eyes must be to a bird; the cavities
for them are so much larger than in other animals. Back

BreainCase

2 Lower Jaw

Fie. 83.—Skull of Fowl, showing orbit, brain-case, ear, lower jaw, premaxillary
(Pmx.), maxillary (Mz.), vomer (Vo.), lacrymal (Ze.), jugal (Jw.), palatine
(Pal.), pterygoid (.Ptg), quadrate (Qd.), and supra (Sup. occ.), ex (Ex.
occ.), and basioecipital bones. (After Parker.)

of each eye-case we see an irregular opening, the portal

of the ear; and in front of the brain two apertures in the

beak open toward the organ of the nose. The prominent
beak and wide-spreading lower jaw are chiefly concerned
in the procuring of food. We need not bother with the
names of all the bones, but there are some too interest-
ing and with too strange a history to be passed by.

Let us glance at the back of the skull for a moment.

Here we find a large round opening through which the

108 The Bird

spinal chord passes into the brain, and below it is a
small knob, which in the living bird fitted into the first
vertebra of the neck. It is a very tiny projection of
bone, but fraught with significance: for if we look at
the skulls of a frog, a mouse, a cat, a horse or aman, we
will see that the head hinges upon two bony projections,

but in all birds and reptiles there is but one,—a very

Fig. 84.—Rear views of bird (Hornbill) and mammal (Yaguarondi) skulls. Notice
single facet (occipital condyle) in the bird and two in the mammal, connecting
skull with the neck-bones.

plain hint of the relationship of these two Classes, so dif-
ferent in external appearance. The head thus pivoting
upon a single point, the bird can turn its head much
farther around than if there were two points of attach-
ment. Before we leave this great opening, as the scien-
tists call it when they speak of it as the foramen magnum,
it may be worth while to mention the remarkably con-
stant position of the bones around it. Whether these
are all separate, or solidly fused into one, we may always

The Skull 109g

know them by their position relative to the brain open-
ing; the upper edge of the hole is always formed by the
supraoccipital, the lower by the basioccipital, the two
sides by the exoccipitals.

Although many bones of the skull, such as the supra-
occipital, keep their names, whether found in salmon,
frog, lizard, bird, or man, others identical in position
have had new names given them. For instance, a small
bone directly in front of the eye is known as the lacrymal,
from its close relation to the tear-duct, but in fishes the
bone is called the preorbital, as a suggestion of fish-tears
would be rather absurd.

We may find the dried ear-drum, or tympanum,
stretched tight across the entrance of the ear-cavities,
and if we break this, or even look carefully through the
transparent membrane, a long thin bone may be seen
beneath, extending backwards from the under surface of
the drum. This is the columella, or little column of
bone, and will have an interest for us later on.

If we examine the way in which the upper and lower
mandibles or jaws are joined to the skull, we will find a
very ingenious arrangement; one very different from
that in ourselves. If the beak of a bird is to serve as
hand, lips, and mouth, it must be as free and movable as
possible, and instead of the upper jaw being fixed im-
movably to the skull, and the lower jaw swinging up
and down from it, we find that the upper jaw is attached
very loosely, while each side of the lower mandible hinges
upon a loose irregular-shaped bone, known as the quad-
rate. A long slender bone connects the quadrate with

[KO The Bird

the upper mandible, which bone we may call the jugal.
Indeed when we come to look closely at the quadrates
we find that they are very important, and in addition to
supporting the bar of bone from the upper jaw, and
pivoting the lower Jaw, they bear another pair of bones

Fig. 85.—Columella in ear of Snowy Owl (magnified 2 diameters).

extending inward from them, beneath the skull, to the
broad thin palate or roof of the mouth.

In a chicken the individual movement of the upper
jaw is not very great, but in some birds, such as parrots,
it is much more noticeable. With a sharp knife we can
entirely detach the upper and lower jaws of most birds,
without cutting through a bone, the connection consist-
ing only of exceedingly tough tendons. When we found
our shark’s skull we perhaps wondered what had become

The Skull VU

of the jaws with the many rows of teeth, and we may
now guess that they were attached so loosely to the skull
that the action of the water washed them away with
the flesh. This was the case, and in all fishes we find
both jaws as separate bones. Among reptiles we find
the quadrate bone free only in snakes, an admirable
adaptation which enables them to swallow their prey
entire.

The bones forming the palate, or roof of the mouth,
are of the greatest value in classification. No matter
how specialized the habits or the food of a bird may be,
the palate appears to be the last portion of its structure
to respond to any recent outside influences. Thus while
the absence or presence of a keel to the sternum is a
character of little value in separating the ostriches and
their allies from all other birds, yet the radical differ-
ence shown by the palate bones in the two groups is
reliable evidence of their early divergence from each
other. These taxonomic characters may be found in
any good book on systematic ornithology and need
not detain us here.

Although we have the skull and both jaws of our
chicken, yet some very important and interesting bones
are lacking, and to find them we must find the tongue
of the bird. For a bird’s tongue, as well as that of other
creatures, 1s not all flesh or horn, but underneath there
is a jointed framework of bone, which is called the hyoid.
We may compare its shape to that of an arrow, with a
central head and four barbs, two very short and blunt
and two long jointed ones.

112 The Bird

It may seem to us that the mandibles, the jugal, the
palate, the quadrates, the ear-bones, and the hyoid are
an unmeaning jumble of irregular bones, apparently
bearing no relation to one another,
and with absolutely no interest
outside the fact that each is very
well suited to its particular use.
If scientists had studied only the
bones of adult animals, we might
have groped in vain for any an-
swer to the question of how these
bones came to be what they are.
But the science of embryology, or
egg-life, has unfolded wonderful
things, and, as we shall soon see,
nothing more marvellous than the
strange story of these bones.

The eel-like lampreys which
crowd up our shallow brooks in
April to spawn are curious crea-
tures, and not the least remark-
able thing about them is the fact
that they have no jaws, although
they have an elaborate cartilagi-
Hia786-—Gil-basketof Uamnprey- oust iet work pravecuinc= sant

supporting the gills. We perhaps thought that every

vertebrate animal in the world had jaws of some kind, and
perhaps even lampreys had them long ago, before their
habit of sucking did away with any need for chewing.
But the reason I have spoken of the lamprey is because

The Skull 112

3)

it brings vividly to mind the image of an animal which
must have once existed—a fish-like creature with no
jaws, but with a gristly mass which held up and pro-
tected the delicate blood-fringes, or gills, by means of
which all true fishes breathe.

Our shark is a very convenient starting-point, and
before going further we should mention the technical name

Fic. 87.—Gill-bars of Shark.

of this group — Elasmobranchs, or strap-gilled fishes.
There are usually five of these gills, and within each
strap or fold of skin is a jointed arch of gristle.

All this may be very true, say you, but what bearing
has it on the skull of the chicken?

We have seen that in sharks the number of gills has
been greatly reduced, and a pair of very loosely attached
jaws has been acquired,—and the truth gradually dawns

114 The Bird

upon us: the jaw of a shark is nothing but a greatly
changed gill-arch, which has doubled up, bent forward
and hinged to the skull. The skin has grown over the
edge, and the> bony scales in the skin, standing up on
end, have become teeth.

And now to our bird. In the embryo chick four
eill-arches are at first distinguishable, but these soon
begin to alter their position, to fade away, or to change
in some way, and in our bony skull we may trace them
as follows (see Fig. 89). The upper half of the first gill-

Fic. 88.—Lower mandible, tongue, and hyoid bones of Bald Eagle.

arch forms the bones of the upper jaw, palate, Jugal, and
quadrate, and the lower jaw completes the entire arch.
The central part of the second gill fades into nothing,
but the top is present as the columella-bone of the ear,
while the base is transformed into the head and two
blunt barbs of the arrow-like bone of the tongue. The
two long barbs of this bone correspond to the third gill

The Skull TLS

and, from their rod-like jointed character, they look
very much like the real gill-arches of a fish. The fourth
arch vanishes.

Such is the almost incredible alchemy which Nature
has wrought from a plastic rod of gristle,—transforming
it into beak, tongue, and ears. Few of us, when watch-

Parx.

Fre. 89.—Ultimate distribution of the four embryonic gill-arches in the skull
of the adult bird. The dotted portions are not developed. (Adapted from
Newton.) Compare with Figs. 83 and 88.

ing the gently waving gills of a fish, have realized how
much we indirectly owe to them. A noted German
anatomist—I<arl Gegenbaur—believes that we owe even
our hands and arms (by way of the pectoral fins of fishes)
to portions of the gill framework, but this theory is not
generally accepted.

CHAPTER V

ORGANS OF NUTRITION

<1\N other pages we shallconsider some of the things

4 I &

4 ‘ :

i(eal’| upon which birds feed, and shall see how surely

ACD } :
the methods used in the search and capture of

this food mould the bird’s structure, modifying its form

from beak to toe; and now is it not possible to find some-
thing of interest in the food after the bird swallows it?
Indeed even before the swallowing takes place, if we
watch carefully we may notice something which we did
not before know.

In the first place the bill of a bird is, of course, a
primary factor, not only in procuring food, but often in
killing and preparing and also holding it while it is being
made ready to swallow. Less confusion will result, how-
ever, if we leave the consideration of the beaks and bills
to a later chapter.

After the bill (which corresponds to our mouth and
lips) come the glands of the mouth and here we again
enter the portals of physiology,—for some unknown
reason dreaded by many of us, and systematically shunned,
as dry and ultra-scientific. On the contrary there are
interesting facts awaiting us in all its branches. After

a brief consideration of the more important, we shall
116

Organs of Nutrition “V7

surely return to outdoor study of the daily life of these
creatures, with more balanced interest, and a “little
knowledge” which, instead of being a ‘dangerous thing, ”
will, in this instance, add many fold to our appreciation
of the external results of these functions, whose work-
ings are ever concealed from the light of day.

The digestive apparatus of a bird, or indeed of any
creature with a back-bone, is in reality a tube or canal,
which begins at the mouth and extends through the
body. Certain portions are contracted or expanded, and
specialized to store up, moisten, grind, dissolve, digest, or
absorb the food substances which pass through.

The Salivary Glands

The mucous membrane, or lining, of the entire diges-
tive canal is very delicate and requires to be kept con-
stantly moist. The lining of the mouth and throat, being
so exposed to contact with the outer air, requires some
special provision to lubricate it. This is accomplished
by certain glands, some beneath the tongue, others situ-
ated in the upper portion of the mouth. These are not
found in fishes, nor in other creatures which live alto-
gether in the water; but in reptiles several groups are
distinguishable. In birds they vary greatly, some having
scarcely a trace, while others have large well-developed
glands. Salivary is the common name given to certain
of these; and we will let that name represent all.

In ourselves, saliva is an important aid in digestion.
Besides moistening the food and softening all hard por-
tions, it exerts active chemical effects, as, for example,

118 The Bird

changing starch to sugar and in many other ways making
ready the food, that the important changes which take
place in the stomach may begin at once. In birds, how-
ever, the saliva has but little chemical effect on the food,
its principal use being to moisten the substances before
they are swallowed.

It is not often that Nature, when she has produced

Fic. 90 —Nest of Chimney Swift; twigs glued together with saliva.

an organ or special tissue by the elaborate synthesis of
evolution, confines its use to any one function. If birds
were provided with salivary glands intended only for the
purpose mentioned above, they soon found other uses for
them. In a woodpecker we will find very large salivary
glands on each side of the mouth. These secrete a sticky
liquid which covers the long, many-barbed tongue and 1s
an efficient aid in picking out insects from their holes in
the bark and wood of trees.

Organs of Nutrition 119

Many birds carry in their beaks the grasses and
twigs with which they construct their nests, and if a sticky
fluid helped them to get their food, why would it not
also soften the twigs and make them easy to bend? Not
only this, but certain birds, such as our Chimney Swifts,
are provided with saliva in such quantities, and of such

tenacious consistency, that the entire nest—a mosaic of

Fig. 91.—Nest of Esculent Swiftlet (edible bird’s nest) composed entirely of saliva.

small twigs, each about an inch in length—is set in saliva
cement, and fastened to the vertical side of a chimney
or charred tree-trunk by the same means. Even this is
only a step, or link, in the direction of the extreme use-
fulness of saliva, for the little East Indian birds known
as Swiftlets (one of which ornithologists call Collocalia
juctphaga) make their nests entirely of saliva or mucus.
The second part of the scientific name, which means an
eater of seaweed, refers to the idea formerly held, that

120 The Bird

the nests consisted entirely of half-digested seaweed, but
it has been proved that this is not the case. The homes
of these birds are the “edible birds’-nests” held in such
esteem by Chinese gourmands.

The Tongue

If we had a long series of birds’ tongues before us,
we would be surprised at the great variety of shapes and
sizes. Observing the good-sized tongues of sparrows and
other small birds, we would turn to a pelican expecting
to see an enormous affair to correspond with the huge bill
of that bird. On the contrary we will find a tiny incon-
spicuous flap not larger round than a toothpick. This
reminds us of the condition of the tongue in some fishes,
where it is a very simple structure indeed. The king-
fisher also has a small tongue, and the same is true of
many other fish-eating birds, such as pelicans and most
of those which feed on large insects. The reason is ob-
vious. The food, which is swallowed whole, is of such
large size that a tongue of even moderate proportions
would be only in the way.

The tongues of many birds are provided with oblique
series of teeth, either soft and fleshy or horny in struc-
ture, which point backward toward the gullet and must
be of great help to the bird in guiding and swallowing its
food. These teeth are especially abundant around the
glottis, or opening to the windpipe, guarding it from
chafing or from the chance of food choking it up.

In ducks and geese we find tongues large and of com-
plicated appearance. The edges are often toothed or

Organs of Nutrition 121

fringed to correspond with the serrated or otherwise
indented edges of the mandibles. One which is before me
as I write is very elaborate. It is that of a wild Mallard
Duck. At the tip is a thin, distinct flap or lamella, horny
and with smooth edges. Behind it the tongue enlarges
abruptly into a thick oblong mass, deeply grooved down

Fic. 92.—Bill of Brown Pelican, showing extreme reduction of tongue in a bird
which swallows whole fish.

the center. The edges of the anterior half are fringed
with a double line of horny hairs, while in the posterior
portion the upper line is replaced with tooth-like struc-
tures. The upper surface is smooth in front, but farther
back two central folds arise and curve over laterally,
forming tube-like grooves. Still more posteriorly, fleshy
recurved teeth are visible, singly, in groups, or in regular
lines. The tongue of our common barnyard duck is

122 The Bird

similar to this and is well worth examining. The use of
such a complicated organ in a bird of so simple feeding
habits as the duck is hard to explain.

We will hardly find two tongues that are alike, and
even the tips differ, and show as wide a range of varia-

Fras. 93 and 94.—Top and side views of the tongue of a Mallard Duck, showing
complicated structure in the tongue of a bird which sifts its food from the mud.
tion as the remaining portions. In many birds, such as
owls, larks, and swifts, the tip is bifid, or double-pointed,
bringing to mind the forked tongues of snakes and cer-
tain lizards. In woodpeckers the tongue is round and
exceedingly long, and can usually be thrown out some

distance beyond the tip of the bill.
Our common Flicker, or Golden-winged Woodpecker,

Organs of Nutrition 123

possesses a tongue of remarkable length, even for a wood-
pecker, and while feeding, the bird will often shoot it

Fig. 95.—Head of Flicker, showing tongue slightly protruding

out two or three inches beyond the tip of the beak.

Easily and without a hitch it disappears again, appa-

Fig. 96.—Skull of Flicker, showing rear branches of the hyoid bone, curving up
over the skull and down into the right nostril. The front of the tongue is
visible beyond the tip of the beak.

rently down the very throat of the bird. If we carefully
remove the skin from the skull of a dead Flicker, the
magic will become plain. When we spoke of the skull

124 The Bird

of a bird, mention was made of the two long bones which
branched out from the rear of the tongue and which are
all that remain of the third ancestral gill-arch. In the
Flicker, the slender, white tongue divides into these two
branches just in front of the glottis and from here they
extend backward, passing one on each side of the wind-
pipe, and on upward, following the curve of the skull,
then forward, lying together upon the forehead. Not
even here do they end, however, but actually reach some
distance into one nostril! So when this bird stretches
out its tongue, the tips of the rear branches leave the
opening of the nose and shoot around over the surface
of the skull until they have gone as far as possible. No
wonder the poor ants have but little chance when a
Flicker visits their hill and sets the marvellous mechanism
of his tongue rapidly to work. And no wonder the
enthusiasm of an ornithologist never fails, when he thinks
of the scores of similarly interesting structures still await-
ing investigation.

The tip of the tongue in the sap-sucking woodpeckers
is beset with numerous hairs forming a brush-like instru-
ment, but spines take the place of hairs in the species
which feed exclusively on insects. It is known that the
exact proportion of insects in the diet of any particular
kind of woodpecker is reflected in the more or less per-
fect adaptation of the minute structure of its tongue to
that end.

In the sapsuckers, too, the tongue is comparatively
short, doubtless because the sap flows readily from the
holes which these birds bore. Hence they require no

Organs of Nutrition h25

such extension of tongue as the deep burrows of the
ants necessitate in the case of the Flicker.

Thus the tongue of a bird seems a very unstable
character, acted upon quickly and radically by any
change in the diet of the species. The entire tip of the
tongue is frequently frayed out into a kind of brush,
remarkably developed in
the parrot-like lories. Yet
this curious. structure is
probably only an elonga-
tion of the papille, hom-
ologous with those which
make the tongue of a cat
or lion so rough. Cocka-
toos, although first cousins
to the lories, have very
different tongues, thick and
fleshy with club-shaped
tips.

In our common gold-
finch, the sides of the
tongue curl inward, form-

Fie. 97.—Thick fleshy tongue of Cockatoo. ing an admirable seed-
scoop, while the same or-
gan in the chickadee, being distinctly cleft into sev-
eral prongs at the tip, has been likened to a ‘four-
tined pitchfork” on which its little owner impales the
myriad .grubs and insects for which it so industriously
searches twigs and leaves. The great particoloured bill

of a toucan conceals a very curious tongue—a_ long

126 The Bird

thin affair, narrow throughout its whole length and so
thickly bordered with a deep, delicate fringe that it
bears a decided resemblance to a feather.

Fic. 98.—Feather-like tongue of Toco Toucan.

The tongue of a flamingo is thick and fleshy, filling
the entire cavity of the lower mandible and in shape
I

.

reflecting its crookedness. The upper edges of the man-

viaaibeicail ues
a es
Zi) DD aT”

spacer

tee, — ri

Fra. 99.—Tongue of Flamingo within lower mandible (natural position).

dible approach each other so closely that they perma-
nently inclose the tongue, motion being only possible in

Organs of Nutrition 127

a forward or backward direction. Along the sides of the
tongue are two series of fleshy teeth, in shape exactly
like the poison-fangs of a rattlesnake.

Mention must be made of the unique and greatly
specialized tongues of Hummingbirds and Honey Creepers.
The outer edges of this organ are curled into two tubes,

Fig. 100.—Side view of Flamingo’s tongue, forcibly lifted above mandible, show-
ing fleshy recurved teeth.

which are more or less split and frayed near the tip,

forming delicate brushes—efficient instruments either to

suck up nectar or to flick out insects from the heart of

corollas.

The Crop

From the back of the throat to the stomach extends
a tube, the gullet or cesophagus, through which the food

in feeding.

f the bill

sition o

16)

ing p

, show

amingoes

Fig. 101.—Young FI]

128

Organs of Nutrition 129

descends after it leaves the mouth. In some birds this
is a simple tube of the same diameter throughout, always
moist from the secretion of (mucous) glands which are
found abundant in its walls, but serving merely as a
passage for the food on its way to the stomach.

In another class of birds an enlarged chamber is
present, called the crop. This serves a somewhat simi-
lar purpose as the external pouch of the pelican; that
is, it acts as a receptacle for food. No especial digestive
glands are found here, and the only agents acting on

Fic. 102.—Brush, or tube-like tongue of Honey Creeper. Twice natural size.

the food are water, the secretions of the salivary glands,
and the heat of the bird’s body. The crop exists only
superficially in some birds, the dilation being hardly
noticeable.

From these we find a succession of more distinctly
marked permanent crops, until in grain-eating birds this
organ is very prominent. If we examine an English
Sparrow after it has made a hearty meal in the chicken-
yard, we will find the crop filled with grains of wheat,
some cracked in pieces by the bill, others entire.

130 The Bird

When we sought the extreme in the provision of saliva
in birds, we had to refer to a swift, living in caves in
islands of the Malay Archipelago, but to find the highest
degree of development of crops is a much easier matter.
In the ordinary pigeon the crop is of very great size
and divided into two lobes. The capacity of the crop
in some birds of this class is astonishing. As many as
sixty-three acorns have been found in the crop of the
English Wood-pigeon. If we look at the crop of a pigeon
before its young leave the nest, we will discover a func-
tion of this organ which would otherwise never be sus-
pected. We know that herons and some other birds
feed their young on fish half-digested by themselves.
This process is known as regurgitation. If we have ever
seen a pigeon with the beak of its young half down its
throat, pumping something into the offspring’s mouth,
we have probably thought that a similar habit was being
shown, —half-digested grain taking the place of the
heron’s fish. But such is not the case. At the time
of the breeding season, the folds of membrane in the
crops of both parent pigeons thicken and secrete or
peel off in curdy cheesy masses—“pigeon’s milk’ some
call it—and this forms the food of the young birds So
in pigeons the crop not only receives food, but at times
provides it.

Now for a glance at some of the oddities in the struc-
ture of crops. The Hoatzin—a strange bird of Brazilian
swamps—which harks back to its reptilian ancestors in
many ways, has a very curious crop. There are strong
muscles in its walls, the use of which, it is said, is to

Organs of Nutrition at

squeeze out the juice of the thick leaves of the Arum
arborescens which forms its food. Thus it has a gizzard-
like function, and has become so important in the life-
economy of the bird that it has developed out of all
proportion, and occupies so much space that the keel
on the breast-bone has had to give way in part to make
room for it, and even the arms of the “wish-bone” have
been bent outward. In this remarkable bird the pro-
ventriculus and gizzard are reduced, their functions being
usurped by the crop.

The facility with which most birds are able to eject
the contents of their crops serves several useful pur-
poses, besides the feeding of the young of herons, cor-
morants, and others. When vultures have gorged them-
selves to repletion on the flesh of any animal, they usually
retire to some near-by retreat and sleep until digestion
has taken place. But if they are suddenly approached
or alarmed, they will instantly eject all they have swal-
lowed and, thus lightened, take safety in flight. Pelicans
and Wood Ibises also have the habit of ‘unswallowing’
their fishy meals when frightened. Petrels and many
fish-eating sea-birds appear to have a supply of oil always
in readiness, which they shoot from the mouth to a con-
siderable distance, surving as an efficient means of self-
defence when taken in the hand after being wounded.

In birds of prey generally, but especially in owls,
another use for this habit is found. Owls always swallow
their smaller prey entire, sometimes crushing the skulls
of mice and plucking out the longer wing and tail-feathers
of birds. Although their crops are not nearly so mus-

22 The Bird

Ll
>

cular as that of the Hoatzin, yet there must be powerful
movements of the walls, for the mice and birds are de-
nuded of hair and feathers and even the bones are in
some way removed from the body, and all are ejected
in a neat oval ball.

If we find some hollow tree where an owl has _ its

Fic. 103.— Keel of Hoatzin, repressed by crop.

regular sleeping-place, many of these pellets may be
found on the ground below, showing the results of each
night’s hunting. The skulls in them are often in such
perfect condition that the species of rodents may be
identified. Besides allowing the bird conveniently to get
rid of the indigestible portions of its food, this habit
seems to be necessary to the health of the bird. In

Organs of Nutrition ian

captivity, owls and hawks are never so healthy and active
when fed on fleshy meat alone, as when a dead mouse or
sparrow, rat or pigeon is given occasionally. In dissecting
specimens which have had nothing but a flesh diet for a
year or more, I have found the throat and gullet in a very
bad condition, as if the lack of some scouring process,

Fic. 104.—Food-pellets ejected by Great Horned Owl, containing
remains of rodents.

such as is afforded by the pasage up and down of the
indigestible hair and feathers, had actually resulted in
the death of the bird. I have seen owls try to eat the
straw on the fioors of the cages, when not provided with
food in the condition in which they find it when at lib-
erty.

In cormorants and birds of similar voracious fish-eating
habits, the entire gullet serves as a receptacle for food,
while the fish first swallowed are undergoing the process

134 The Bird

J

of digestion lower down. Here, as in many other in-
stances, we have a condition very similar to that in some
crocodiles in particular. These ravenous scaly

reptiles
creatures have such powerful organs of digestion that even
bones are dissolved, but the stomach is comparatively
small, and when a crocodile makes a large meal, it is at
first stored away in the wide gullet.

The Stomach and Gizzard

In the present chapter we might easily be led into
details which would strand
us in the midst of “dry,
technicalities, but we will
try to avoid all this and
choose only the interesting
facts.

The chief organ of di-
gestion, in birds as in other
animals, is of course the
stomach. In many fish-
eating birds this organ is
merely a simple, more or
less enlarged chamber, rather
crop-like except that it con-
tains numerous digestive

glands.
Fig. 105.—Caracara, showing crop dis- dee Sass feo
Ponded ant toca The typical bird-stom-

ach, however, is compound,

or formed of two more or less distinct parts. The first

Organs of Nutrition 1°25

portion—known as the proventriculus—is the smaller, and
contains very active digestive glands, sometimes ar-
ranged in patches, but more usually forming a band. If
the lower part of the cesophagus of an English Sparrow
is removed, slit open and washed, these glands can be
easily seen, being more of a rose tint than the paler tissue
of the portion nearer the mouth. The walls are thicker
in this glandular area. This can be seen to better ad-
vantage in a young chicken,
where the glands take the
form of conical protuber-
ances which dot the entire
surface. Nature has _pro-
duced curious modifications
of this typical fore-stomach,
as in snake-birds, which have
the glands of this portion en-
closed in a sac, in shape not
unlike a small crop. Here
the food is softened and acted

Fig. 106.—Glands of the stomach of a UpOn chemically by the secre-
ger fee care tions from the walls.

The second division of the stomach is the gizzard,
an organ made to perform most powerful compressing
motions, thus crushing and macerating the food, so that
when passed on into the intestine, every particle of nour-
ishment may be extracted from it. When we think of
beauty of colouring in birds, it is their plumage which
at once presents itself to the mind, and yet a gizzard
has a real beauty both of shape and hue. ‘This organ,

136 The Bird

in a chicken, is in shape like a double convex lens. The
cavity in the centre is lined with a tough yellow membrane,
sometimes almost as hard as bone. ‘Two great tendons
spread over the outer surface on each side, and although
in life forever buried in the absolute darkness of the
bird’s body, yet when brought into sunlight they shine
with an iridescence like the beam from a spectrum.

It is hardly possible for the gizzard to grind up food
in the sense of having much lateral motion, like the move-
ment of the jaws In chewing, but it shuts together again
and again with great force. Gravel and sharp stones are
swallowed by many birds, and are of great importance
in helping to grind the food. The number and size of
these stones are sometimes almost beyond belief. I
have known a cassowary to swallow over a quart of rubble
in one day, and have given a quartz pebble twice as large
as a hen’s egg to one of these birds and watched it slip
down the bird’s throat as easily as a cube of carrot. This
particular bird preferred smooth white quartz pebbles,
and would search through a whole heap, picking out stones
of this character. The same preference was exhibited
by the gigantic extinct birds of New Zealand called moas.

Mr. Frederick Chapman, writing of a portion of New
Zealand where the skeletons of moas were found in great
abundance, says: “When we came upon the ground
disturbed by the wind (the soil being shifting sand)
we soon found a number of distinct groups of gigantic
gizzard-stones. It was impossible to mistake them. In
several cases they lay with a few fragments of the heavier
bones. In all cases they were in distinct groups; even

Organs of Nutrition KQ7,

where they had become scattered, each group covered
only a few square yards of ground, and in that space
lay thickly strewn. . . . The peculiar feature of the
stones was that they were almost all opaque, white quartz
pebbles. In one place I found a small group of small
pebbles of different colour, more like the few brown water-
worn pebbles which may be picked up hereabouts. These
lay with a set of bones much smaller than the very large
bones I found with most of the clusters of pebbles.

“T did not gather these brown pebbles, as I thought
it uncertain whether they were gizzard-stones or not,
though it is possible that the species to which the smaller
stones belonged was not so careful in selecting white
stones.

“A glance at the pebbles lying around in the sur-
rounding country showed that the quartz-pebbles were
not collected here. ... Mr. Murdock and I collected
three sets of pebbles, and these I can pronounce com-
plete, or nearly so. It is beyond question, too, that each
set belongs to a distinct bird. No. 1 weighs 3 Ib. 9 oz.;
No. 2 weighs 4 lb.; while No. 3 weighs no less than 5 lb.
7 0z.! This giant set contains individual stones weighing
over 2 oz.; indeed, I have picked out eight stones weigh-
ing almost exactly 1 pound.”

The gizzard of a bird is reflective of its diet, and is
very quickly affected by any change in the food. For
example, a captive gull when fed exclusively on fish
has but little muscular power in the gizzard, but a diet
of grain will produce a change in that organ, giving it
grinding power sufficient to crush the kernels of corn.

138 The Bird

a

That this is something more than an abnormal con-
dition brought about by artificial means is proved by
the fact that in the Orkney Islands the wild gulls feed
in winter, spring, and summer on fish, and at this time
are gizzardless; but in the fall they change to a diet of
corn and develop a very respectable gizzard. So we
see that this organ, apparently so independent in func-
tion and individual in appearance in many birds, is in
reality only a physiological change from the stomach
proper.

The history of the development of this organ may
be traced in various living species, from the soft mem-
branous sac of a fish-eating bird to the knot of tendons
which forms the gizzard of certain Fruit-pigeons. These
birds feed on nutmegs and other very hard, almost stony
nuts, and to enable the bird to crush these, the lining of
the gizzard is covered with several score of conical pro-
jections, horny in consistence. These are probably the
nearest approach to “hen’s teeth” we are likely to find.

What a boon to a business man who indulges in a
daily ‘‘fireman’s lunch,” if his masticatory function
could be an internal and unconscious one, as in a bird!

A crocodile, which has so much in common with a
bird, is provided with a gizzard, which, like that of a
chicken, is round, muscular, and has two great side ten-
dons, and no less than five pounds of grinding-stones
have been found in one of these reptiles.

Many interesting adaptations are found in the stom-
achs of birds, made necessary by special requirements
in the diet. As an instance of this, the snake-bird has

Organs of Nutrition 139

a dense mat of hair at one end of the stomach, the free
ends of which point outward, brush-like, and prevent
the accidental entrance of any small fish-bones which
otherwise might get into the small intestine. The giz-
zard of a cuckoo, when opened, often gives the impression
of a similar coating of hair lining the entire organ, but
these are in reality only the hairs of caterpillars upon

Fic. 107.—Cluster of matted hairs in the stomach of a Snake-bird.

which these birds feed, which have become detached
and have lodged in the folds of the gizzard lining.

When considering the crops of birds we noticed the
curious way in which a pigeon feeds its young, by re-
gurgitating a cheesy substance which forms in its crop,
and we will now speak of something still more remark-
able. The strange nesting habits of the hornbills are
foreign to this volume, but we cannot leave the subject
of gizzards without touching on the manner in which
the male birds of this group probably feed their impris-

¥40 The Bird

oned mate and young. I say probably, because no one
has seen them do this, but as in captivity the operation
occurs repeatedly during the breeding season, there can
be but little doubt concerning its evident significance.
After walling up his mate and her egg in some hollow
tree, the male hornbill takes upon himself the labour of
supplying her with food throughout the period of incu-
bation and the subsequent rearing of the young bird.
Instead of bringing food piecemeal,—nut by nut, grape
by grape,—the lining of the entire gizzard peels off at
certain frequent intervals, appearing, when ejected at
the mouth, like a small bag or purse, the puckered open-
ing (heightening the simile) serving to retain securely
the contents of the gizzard,—a dozen or score of grapes
or other fruit. This, the male bird, in his native land,
doubtless takes in his beak to the tiny opening of the
walled-up nest and delivers into the bill of his mate.
How admirable a spouse this, who not only seeks and
provides sufficient food for his temporarily helpless
family, but bears it to them wrapped in a packet torn

from his very body—if not a “pound of flesh,” at least

enough to make a lunch-basket!

The Intestines

Beyond the gizzard is the intestinal canal, which
varies greatly in length in different birds. The ostrich
has forty-six feet of this digestive tube, while the nectar
and tiny insects snatched by a hummingbird in its flight
are digested in a delicate hair-like duct but two inches in
length. Although comparatively of such great length, the

Organs of Nutrition 141

way in which this part of the digestive tract is coiled and
twisted in the body cavity of the bird allows it to take
up the least possible amount of room.

The function of this long tube is to absorb the nutri-
ment from the food after this has been moistened by
the salivary glands, crushed by the gizzard, and acted
on by the stomach acids, and secretions from the liver
and pancreas. The digestible parts are then taken up
by the blood through the walls of the intestine. In
many of the lower types of birds, such as the cassowary,
ostrich, and screamer, the arrangement of this long
digestive tract 1s very simple, much like the condition
to be found in alligators.

CHAPTER VI

THE FOOD OF BIRDS

HE organs and physiological functions of a bird,
as of animals generally, are so interrelated and

intimately dependent on each other that it is a
rather difficult matter to consider any single one by
itself without being led into another’s province. For
example: we have for the subject of this chapter the
food of birds, and unless we are very careful, we shall
overstep the bounds of our theme. To limit our subject
clearly we will consider only adult birds.

We have all seen the pestiferous sparrows picking
up grain in the chicken-yard; we have admired the skill
which the red-breasted robin exhibits in spying and
extracting earthworms on our lawns; our memory re-
calls the osprey dropping upon his fish, and the wood-
pecker chiselling to the wood-borer; but did we ever stop
a while and attempt a “bird’s-eye view” of all the classes
of substances which birds find good as food?

The ways in which this food is sought and caught,
killed and prepared are wonderfully varied, and some
idea of the remarkable variety of substances laid under
contribution as food by birds of different orders may

be had from a brief review of the principal divisions
142

The Food of Birds 143

into which these substances are classified, and the part
they take in supplying birds with food.

As with all animals, certain mineral salts are very
necessary to a bird’s existence, such as the substances
from which the calcium phosphate for the bones, and
the calcium carbonate for the shells of the eggs, are de-

Fic. 108.—Finch, a bird with heavy, thick bill adapted for crushing seed.

rived. The gravel and pebbles swallowed by birds in
the course of their daily feeding should hardly be men-
tioned in this connection, as this is only done for the
mechanical assistance, derived from the hard surfaces,
in triturating the food.

Vegetable-feeders form a large group among birds, and
they alone would offer an interesting field for study, as

144 The Bird

there is such specialization for feeding on particular
varieties or portions of plants. We find fruit- and grain-
eaters, besides those which feed almost entirely on buds,
leaves, berries and nuts, nectar, sap, and even pollen.
Lichens form a considerable item in the bill of fare of
ptarmigans, the Arctic grouse. We have even dedicated
certain plants to birds which show a decided partiality
for them,—duckweed and partridge-berry.

Fic. 109.—Vireo, ‘an insect-hunter. with a delicate, hooked bill.

There is no doubt that a great many plants benefit
from the cross-fertilization of their flowers by humming-
birds carrying the pollen from blossom to blossom. Of
one of the sugar-birds of South Africa it is said: ‘‘When
sucking up the nectar of one of the larger protea-blossoms,
the bird perches on the edge of the flower, plunges its
long bill and the greater part of its head downwards
among the petals, and retains it in this position until

The Food of Birds 145

satisfied. As a result the narrow, shaft-like feathers of
the forehead frequently become saturated and _ stained
with juice and dusted over with pollen, and it is probable
that this bird plays an important part in the cross-fer-
tilization of several species of protea.”’

Desmids and diatoms, those one-celled microscopic
organisms which are almost on the border-line between

FOOD OF VARIOUS BIRDS.

Fig. 110.—Sea-urchin.

plants and animals, I have found in large numbers in
the digestive tracts of ducks and other birds which are
accustomed to find their food by sifting the mud at the
edges of ponds and lakes.

Sponges, at least in a decayng state, are devoured by
crows, as I can testify from observation after dredging
expeditions in the Bay of Fundy.

146 The Bird

We should scarcely think that those watery creatures
sea-anemones, hydroids, and jelly-fish (some of the latter

Fic. 111.—Caterpillar.

consisting of over 95 per cent water) could afford much
nourishment to any animal, and when crows and gulls
are seen tearing large stranded jellies into pieces, it is

Fic. 112.—Cocoon.

probably only for the sake of the semi-parasitic shrimps
which make their home in the interior canals of the

The Food of Birds 147

masses of animate gelatine. But the fresh-water hydra,
belonging to the same division as the hydroids, is eaten
in myriads by ducks and geese. These and many other
birds are remarkably fond of duckweed, which they
devour with such evident pleasure that they must enjoy
it as much as cats do catnip, or canaries hempseed. As
the under surface of these small water plants is the fa-

Fic. 113.— Butterfly with wing torn by bird.

vourite home of the hydra, they necessarily form a por-
tion of the food of these water birds.

Roundworms, flatworms, and leeches are devoured
by many aquatic birds, while earthworms form a staple
article of diet with such different species as thrushes,
woodcocks, and cranes. A favourite morsel of the curi-
ous apteryx of New Zealand is a gigantic species of worm,
twelve to twenty inches in length, which is highly phospho-
rescent. The apteryx seeks its food by night, and when

148 The Bird

devouring one of these worms, the whole bird is lighted
up, and after its meal the bird’s bill is illumined by the
mucus which adheres to it.

Starfish and sea-urchins are sought out by crows,
ravens and gulls, and perhaps other birds. They break
into them by main force, or
else carry them to a height
and drop them on the rocks.
I have even seen a Bald
Eagle, when fish and Fish-
hawks were scarce, deliber-
ately break into and devour
a green-spined urchin.

If, as is said, immense bow-

head whales subsist entirely

Fie. 114.—Snail.

on minute larval shrimps,
then it is not surprising that many thousands of shore-
birds are well nourished by the myriads of shrimps and
prawns, large and small, which every tide leaves exposed.

It is a mere truism to say that insects form the sole
food of scores of species of birds, and enter into the diet
of many hundreds. It has been said that without birds,
within a space of ten years, the earth would not be habit-
able for man, owing to the unrestricted increase of nox-
ious insects. There is doubtless not a single group of in-
sects which does not suffer from the appetite of one or
more species of bird. The eggs and larve are dug and
pried out of their burrows in the wood by woodpeckers
and creepers; those underground are scratched and
clawed up to view by quail, partridges, and many spar-

The Food of Birds 149

rows; warblers and vireos scan every twig and leaf;
flycatchers, like the cat family, lie in watch and spring
after their prey, only in the air instead of on the ground,
feeding more particularly on low-flying insects; while
swifts, swallows, and martins glean their harvest from the
diurnal hosts of high-flying winged creatures. Many

Fic. 115.—Crab.

times when we think hummingbirds are taking dainty
sips of nectar from the flowers, they are in reality pick-
ing minute spiders and flies from the deep cups of the co-
rollas. When night falls, the insects which have chosen
that time as the safer to carry on their business of life
are pounced upon by nocturnal feathered beings—the
cavernous mouths of the whippoorwills engulf them as
they rise from their hiding-places, and the bristles of

150 The Bird

night-hawks brush them into rapacious maws, if per
chance they have succeeded in reaching the upper air.
In tropical forests, where insects are everywhere
abundant, the birds seemed to have realized the fact that
to each is apportioned certain phases of insect life, and
that by hunting in large flocks, instead of competition
resulting between birds of different species, they play
into each other’s hands (or rather beaks). It is of such
a flock that Hudson writes: “The larger creepers ex-

Fie. 116.—Squid.

plore the trunks of big trees, others run over the branches
and cling to the lesser twigs, so that every tree in their
route, from its roots to the topmost foliage, is thoroughly
examined, and every spider and caterpillar taken, while
the winged insects, driven from their lurking-places, are
seized where they settle, or caught flying by the tyrant-
birds.”

The Wattled Starlings or Locust-birds of South Africa
live in flocks of thousands, and so dependent are they
on locusts as food, that their habitat and place of nest-

The Food of Birds Bit

ing is influenced by the presence or absence of these in-
sects. “When pursuing a flight of mature locusts these
starlings perform various extraordinary and_ beautiful
aerial evolutions with the object of intercepting and sur-
rounding a portion of the swarm, and in doing this their
movements closely resemble those of another locust-
destroying starling, the beautiful rose-coloured Pastor
of eastern Europe and Asia. Individually the two species
are very different; collectively and under similar condi-
tions their actions are quite
similar. Starting in a dense
‘ball-like’ mass, they suddenly
open out into a fan-shaped
formation, then assume a
semicircular arrangement, and
finally end by forming a
hollow cylinder in which a
portion of the locusts are
enclosed; as the imprisoned
insects are destroyed, the rae = Rateleanabee:
starlings gradually fill up the
hollow of the cylinder until they again assume their ‘ball’
formation and proceed to follow the remaining locusts.
The ground below the flock is covered with the droppings
of the birds and the snipped-off legs and wings of locusts.
At other times the starlings station themselves on the
tops of bushes and trees, from which they dart on the
flying insects like flycatchers.

“In Cape Colony the Locust-birds usually breed in
very large colonies, in localities in which the locusts have

T52 The Bird

deposited their eggs. For hundreds of yards every thorny
bush is packed full of cup-shaped nests, even the spaces
between the nests being often filled up with sticks or
rubbish, through which narrow passages are left for the
ingress and egress of the birds. Many starlings that can
find no room in the bushes build on the ground, or under

Fic. 118.—Brown Pelicans diving for fish. (Sanborn, photographer. Courtesy
N. Y. Zoological Society.)

stones, or in holes, and these unfortunates, together with
their eggs or young, ultimately become the victims of
the smaller carnivorous mammals or of snakes. It fre-
quently happens also that either the young locusts are
hatched in insufficient numbers or that they migrate before
the young starlings are fledged. In either case large
numbers of birds perish of hunger, the majority of the

The Food of Birds G3

old birds and the more advanced young following the
locusts.”’

Slugs and snails are eaten by thrushes and many other
small birds with avidity, and the name “Snail-hawk”
has been given on account of one bird’s fondness for these
mollusks. The Oyster-catcher feeds on clams and oysters
and derives its name from the facility with which it in-
serts its bill and pries open the shells. The Courlan,
a near relative of the rails, feeds on clams and mussels
and has a most ingenious method of obtaining its food.
In shallow water it feels about with its feet for these
mollusks, and when they are found the bird inserts its
bill between the valves with a sudden quick stroke, and,
thus suspended, the heavy shell and its occupant are
carried to the shore, where the shell is forced open and
the animal eaten. Crows treat shell-fish in the same
way that they do sea-urchins and crabs, carrying them
aloft and, after dropping them, descending to feed
on the nutritious flesh exposed by the shattered
shells.

Squids, the “head-footed” leaders of the division of
mollusks, are eaten by penguins at least, and so numerous
and at times so conspicuous a feature of marine life are
they that probably many other birds also feed upon
them. Even deep-water snails and crabs are not safe,
as the sturdy sea-ducks will sometimes dive to a depth
of one hundred and fifty feet to feed upon them.

Fish count many enemies among birds, which have
numerous ways of obtaining their victims from ocean or
lake. Some of these are so ingenious that they well

it yt The Bird

deserve notice. In their variety they rival the methods
of man himself, and we find many analogies between the
two. Penguins earn their food with perhaps the hardest
work, as they follow the fast-swimming fish of the open
ocean in their own icy element and capture them not-
withstanding their speed and quick turns.

We must not forget the slim, evil-looking snake-
birds of the tropical swamps, which also dart through
the water, but impale their victims on their needle-pointed
beaks, suggesting the fish-spears of mankind. Cormo-
rants and sheldrakes also dive after the fish on which
they feed.

Next in the list of strenuous seekers after fish we
must mention the osprey, which hovers on slowly vibrat-
ing wings, treading the air, as it were, over some favourite
spot, until a finny back shows itself near the surface,
when, giving itself to gravitation, the bird drops like a
plummet. It seizes its prey in its talons, while our com-
mon kingfisher, after watching patiently from some
branch overhanging the water, uses its bill to capture
the fish. Terns dive for their fish, gulls usually snatch
them from the surface, and skuas and jaegers get theirs
at second hand, stealing fish from the more skilful fishers
of the sea. When schools of mullet leap in frantic fear
from the water to escape the attacks of porpoises, or
when the dolphins force the flying-fish above the surface,
the merciless Frigate-bird has but to pick and choose.
Certain cormorants are the analogues of man’s gill-nets,
a flock of these birds surrounding a school of fish in a
half-cirele and driving them ashore or into shallow water.

oor

Casydvisojoyd ‘soudeg "pT ‘o7) “SMBID S4t Ul Ysy YIM AoiIdsO—6IT “DIT

156 The Bird

Herons are the ‘still-fishers’ of the bird world, and stand
in the shallows, silent and motionless as the reeds around
them, with their lance-like beaks in rest and their necks

Fic. 120.—Great Blue Heron, a still hunter. (Sanborn, photographer. Courtesy
j N. Y. Zoological Society. )

at a hair-trigger poise. So we see that few kinds of fish,
from the lowly lamprey to the jewelled brook trout,
escape the sharp eyes of birds, and even when decayed

The Food of Birds 157

masses of fish are thrown ashore, feathered scavengers
are always alert.

Frogs always suggest storks to our minds, the rela-
tion being of course solely a gastronomic one, and indeed
most of the near relatives of the frog pay their tithe to
birds in a similar way.

Fie. 121.—Wild Mouse, the most frequent victim of birds.

Turtles, lizards, and snakes enter largely into the food
of certain birds, some of which, such as the Secretary-
bird and our native Road-runner, are adepts in the cap-
ture and killing of members of the latter division of
reptiles. Certain sea-eagles subsist chiefly upon sea-
snakes.

158 The Bird

The most unpleasant items in the bill of fare of the
bird kingdom are birds themselves, although few, if any,
hawks or owls feed exclusively on members of their
own Class. The most systematic cannibal among birds
is the Peregrine Falcon or Duck Hawk, and, where birds
are abundant, this fastidious gourmand merely eats the
flesh of the head and neck and the eyes of each victim,
leaving the remainder of the body untouched. Occa-
sionally, as among other animals, a bird of strictly vege-
tarian habits will attack another bird, even one of its
own kind, and kill and eat it in the most matter-of-fact
way.

Owls are the terror of many birds, from the tiny Elf-
Owl which sometimes finds a sparrow too great a match
for him, to the great Strenuous Owl of Australia, which
snatches full-grown Lyre-birds from their perches. But
these birds of the night are ever ready to vary their
diet; as we read of certain owls in India feeding chiefly
on fish and crabs which they snatch from the water. In
that same country, too, bats form a large part of the
Barn Owl’s diet.

The eggs of birds are delicacies which many feathered
robbers, such as Jays and crows, can never resist. There
are two birds, however, one a raven and one a hawk,
which well deserve the eggs which they steal,—so inge-
nious is their method of obtaining them. In South Africa,
on an ostrich-farm, when a female bird has left her nest
for a few minutes, a black form will often appear and
hasten toward the great white eggs. Hovering over
them the raven will let fall a stone into their midst,

The Food of Birds 159

instantly swooping down and regaling himself on the
yolk pouring out through the crack in the shell. His
beak being too weak to break the shell, he has learned
to adopt this effective method. A similar remarkable
habit is related of the Black-breasted Buzzard of Aus-
tralia, but in this case it is an emeu which is the victim.
After breaking a hole in the thick shell, this bird inserts
its foot and carries the egg to its nest.

Perhaps every Order of the higher warm-blooded
animals may be included in our list, from the sloth which
mutely resigns itself to the terrible grip of a Harpy
Eagle to the human child which is powerless before the
attack of some bird of prey frenzied with hunger. In
certain districtS eagles and hawks have been shot
smelling strongly. of skunk, but whether that fearless
animal really figured in their diet remains to be proved!
If any entire group of mammals is to be excepted from
the birds’ bill of fare, it is only that of the whales, although
indeed, when one of these leviathans dies from any cause,
his blubber and oil furnish food for sea-birds of many
kinds.

The small gnawers of wood, the rodents, suffer most
heavily, and untold thousands are devoured by hawks
and owls, while cranes, shrikes, and ducks make away
with their share.

This brief and very imperfect review of the vast
variety of substances eaten by birds is at least instruc-
tive in revealing vividly the complex interrelations of
all organic life on the earth. <A counter-list of animate
creatures which cause the death of birds would be as

160 The Bird

surprising in its numbers and

extent. Every class of living
beings appears, at certain phases
of its existence, to check or come
into intimate contact with other
unrelated groups, radically affect-
ing the most isolated, in ways
too subtle for our observation.
A little green flycatcher snatch-
ing a tiny gnat from its hiding-
place beneath a leaf seems
a trivial incident, and yet Petes eee nee

(the watcher) an active
hunter.

events no more important than this are felt around the

the effects of accumulated

world, so delicate is the balance of Nature.

Oddities of Birds’ Diet

To give any adequate idea of the vagaries of the diet
of birds would require a volume by itself, but certain changes
in feeding habits, due to
some increased pressure in
the struggle for existence,
are too interesting to be
passed by unnoticed. They
show us how plastic and
adaptive birds as a whole
are,—how, often, instead

Fic. 123.—Red Squirrel (the watched), Of giving up and becoming
food of hawks and owls. 5 : 5
(R. H. Beebe, photographer.) extinct, a certain race will

The Food of Birds 161

instantly accept changed conditions and flourish under
the new régime.

As the range of diet of the whole Class of birds is so
vast, doubtless the food of the individual species varies
more than we should ever suppose, but many instances
are recorded of birds regularly feeding on food for whose
capture they seem very ill adapt-
ed. Insects form the staple food
of all flycatchers and_ tyrant-
birds, but the Sulphur Tyrant and
several others readily devour
snakes. They dash down at one
of these reptiles, catch it up in
their beak, and, flying back to
a branch or stone, hammer the
snake flail-like, until its life is

Fic. 124.—Texas Kingfisher battered out. Certain small king-
athe fishers living in New Zealand
have deserted the habits of their group, and subsist on the
remarkable diet of “flies, young birds, and cherries”!
The change in habits of the Kea Parrot is only too
well known, especially to the sheep-raisers in New Zea-
land, the home of these birds. Originally exclusive
fruit-eaters, they have lately become so fond of the fat
from the backs of living sheep that they have developed
into ravenous birds of prey, vivisecting their victims and
rejecting all but the choicest morsels. Gulls have long
been known to enjoy an insect diet, and on the pampas
in the vicinity of Buenos Ayres the people look and pray
for flocks of gulls as the only relief from the hordes of

162 The Bird

grasshoppers which occasionally devastate that region.
In the antipodes we find a gull with crepuscular habits,
whose entire food consists of night-flying moths.

Birds in captivity may sometimes be induced to eat
food which they would never touch when in a state of
freedom, but there are three species of birds the variety
of whose natural diet will challenge that of any living
creature. The first is a Burrowing Owl. This bird will
not disdain vegetable food, and in its underground dining-
chambers have been found remains of ducklings, spar-
rows, mice, and many other small birds and_ rodents;
snakes and frogs, besides spiders, beetles, and apparently
all small forms of life which these little birds are able to
catch and kill. But leaving even the Burrowing Owl
far behind in this respect is the Chimango Carrion-hawk
of southern South America. Hudson tells us that noth-
ing comes amiss to these birds. The vulture habit is per-
haps strongest, and all offal and decaying meat is pounced
upon with eagerness. All wounded and sickly creatures
are closely watched until they die, or, if the opportunity
offers, are despatched at once. When a large extent of
grass is burned, bountiful repasts are ready for these
birds in the shape of roasted snakes and small mammals.
Eggs and young birds are especial dainties for the Chi-
mango, and young sheep are often attacked, bringing to
mind the Kea Parrot. The bird is, at times, a vegetable-
feeder, and in fact it would be hard to find any organic
object near its home, the edibility of which it has not
tested.

The Red-winged Starlings of South Africa during

The Food of Birds 163

the greater part of the year feed upon larve and insects,
but grapes, figs, and other soft fruits are eagerly devoured.
They catch locusts and flying ants and occasionally devour
the young of small birds. When their travels take them
near the seashore they search the seaweed for snails
and shrimps, and one of the greatest delicacies is the

Fic. 125.—Moth and Hummingbird. Both half natural size.

fruit of the syringa-tree, “on which they sometimes gorge
themselves until they are no longer capable of flight, . . .
affected by some narcotic property of the berry itself.’

This state of semi-intoxication is by no means rare
among fruit-eating birds, when over-ripe or fermented
fruit is abundant.

164 The Bird

The great extent to which all the external organs
and parts of birds are adapted to facilitate the obtain-
ing of food is evident in every species; but in humming-
birds this adaptation is especially apparent, because we
can compare these feathered mites with other creatures
far beneath them structurally, but with feeding habits
and general environment so similar that such a com-
parison is fraught with interest. These other creatures
to which I refer are hummingbird moths. Again and
again collectors have shot the moths, mistaking them
for hummingbirds, as the manner of flight is the same
in both, and the way in which each species poises before
a flower, probing it with proboscis or bill, is identical.
Of the way this wonderful resemblance is carried out
even in details of the body Bates writes: “It is certainly
very curious, and strikes me even when both are in the
hand. Holding them sideways, the shape of the head
and position of the eyes in the moth are seen to be nearly
the same as in the bird, the extended proboscis represent-
ing the long beak. At the tip of the moth’s body there
is a brush of long hair-scales resembling feathers, which
being expanded look very much like a bird’s tail.”

It seems very improbable that this resemblance can
be attributed to mimicry, as neither has many danger-
ous enemies, their marvellous powers of flight being an
all-sufficient protection. So we are left to conclude that
it is solely to similarity in method of seeking their food
that the likeness is due.

CHAPTER VII

THE BREATH OF A BIRD

HINK of a mite of a hummingbird shooting
southward mile after mile; his singing wings

, beginning their throbbing in the cool damp air
of an Alaskan fall, whirring through the dry heat of des-
erts and around the wind-eddied spurs of mountain-ranges,
until they hum in the warm atmosphere of Mexico or
Brazil, where tiny insects are never lacking throughout
the winter! How exquisite an adjustment must exist
in his organs; how mankind’s engines of locomotion are
put to shame! The only comparison of which we can
think is with an insect, —a sphinx-moth ora beetle, whose
wings of gauze lift and carry their owners so easily, so
steadily. It will be interesting to keep this similarity
in mind, superficial though it is.

Birds require, comparatively, a vastly greater strength
and “wind” in traversing such a thin, unsupporting
medium as air than animals need for terrestrial locomo-
tion. Even more wonderful than mere flight is the per-
formance of a bird when it springs from the ground, and
goes circling upward higher and higher on rapidly beating
wings, all the while pouring forth a continuous series of

musical notes, the strength of the utterance of which
165

166 The Bird

is attested by their distinctness in our ears after the bird
has passed beyond the range of vision. A human singer
is compelled to put forth all his energy in his vocal ef-
forts, and if, while singing, he should start on a run even
on level ground, he would become exhausted at once.
The apparatus which gives to a duck the “wind” to out-
strip an express train, and to a Mockingbird notes which
hold us spellbound as by a motif of grand opera, is most
interesting, and as easy to understand in its general scheme
as it is effective in operation.

The Trachea, or Windpipe

Look into the beak of a sparrow or pigeon and directly
back of the tongue, on the floor of
the mouth, a narrow slit is visible
—the glottis, or opening of the
windpipe. In the gaping yellow
mouth of a nestling robin this
may be seen to excellent advan-
tage, and watched as it widens and
narrows with each breath. But
give the young bird a mouthful
of food, and this air-passage closes
instantly and remains so until all
danger of an intruding substance
is past. No matter how suddenly

you may eject a stream of water

‘om a medicine-dro ea a
f1 e-dropper imate the Gaia a.

bird’s mouth, reflex action will a Pelican.

anticipate the danger of choking and close the aperture.

The Breath of a Bird 167

The swollen rim of this opening suffices to close it, and
there is no elaborate trap-door arrangement as in mam-
mals, only a few backwardly directed fleshy points.
Birds have no trace of an “‘Adam’s apple.” The vocal
chords and other adjuncts to the voice of mammals
are entirely absent in birds, not a single note or song
being produced in the upper
throat.

Passing down the neck
from this orifice is the wind-
pipe, which follows the
course of the cesophagus, or
food canal, passes to one
side of the crop and _ be-
tween the two branches of
the wish-bone, and_ finally
divides into two equal parts
called bronchi, which carry
the air directly to the lungs.

Fic. 127.—Windpipe and cesophagus of

mparison bird compared; the former always dis-
Co SENG of the two tended; the latter soft and collapsed.

tubes which traverse the

throat and neck of birds shows them to be very different
in appearance and structure, and consideration of their
respective functions gives us the key to this dissimilarity.
The only occasion for the cesophagus to open is to permit
the passage of food, and thus a limp, fleshy canal answers
all requirements. The windpipe, on the contrary, must
always be wide open, and not only this, but it must be kept
open no matter what the pressure upon it. In addition,
it must be flexible, yielding to every motion of the neck,

168 The Bird

and elastic, in order to stretch and contract as the bird
reaches out or draws back its head.

We find a most ingenious arrangement fulfilling all
these requirements. A series of bony rings is imbedded
in the wall of the trachea, beginning with that portion

Fic. 128. Fie. 129.
Fic. 128.—Windpipe of Flamingo, extended and contracted, showing delicate
mechanism of supporting rings.
Fic. 129.—Syrinx-drum of Mallard Drake; the windpipe above; the bronchi
below leading to the lungs.

immediately back of the glottis, and extending through-
out its entire length. The membrane which connects these
rings is so elastic that a section of trachea can be drawn
out until it is twice as long as when contracted. When
in the latter condition (I have in my hand an inch of
the windpipe of a flamingo, but the general structure

dhe Breath of a Bird 169

is common to all birds) the trachea appears to be com-
posed of alternating half-rings, but when elongated
these are seen to be complete, the illusion being pro-
duced by the overlapping of half of each ring by an equal
part of the rings on each side. When the trachea is ex-
tended, the only hint of this clever device is a small notch
on the sides of every ring. The illustration demonstrates
the working better than any description.

Nature is ingenious but not perfect, as is seen even
in the inch of Flamingo’s trachea which I have utilized
for illustration and description. Two of the rings do not
“jibe” on one of their sides, and overlap the wrong way,
but the loss in motion is infinitesimal, the defect being
hardly noticeable even when the rings are bent into a
semicircle.

In a very young English Sparrow there are about
fifty rings around the trachea, appearing to be of a more
cartilaginous nature than those of the flamingo. This
latter long-necked bird has no less than four hundred and
fifty rings.

In some members of the Class of amphibians (frogs,
toads, and newts) the trachea is supported by small ir-
regular pieces of cartilage, tending in the higher forms
toward ringed areas. Among reptiles an intermediate
condition exists, complete rings being present, but of
cartilage instead of bone.

The wonderful music of birds is produced in a rela-
tively small area, known as the syrinx. This organ is
situated at the point where the trachea divides into the
two bronchi. The latter arise as if by a splitting of the

170 The Bird

windpipe, and the effect is heightened by the rings which
extend as far as the lungs, which are half-rings or semi-
circles, the inner halves being replaced by membrane.
This organ is peculiarly characteristic of birds, there
being not a trace of it in any reptile.

But though the syrinx alone is concerned in the pro-
duction of sound, this may be modified, made resonant,
or given a reverberating quality by a special structure
or by windings of the trachea before it reaches the syrinx,
and which are perfect analogies of human musical instru-
ments. Many species of ducks have an enlarged box of
bone, a kind of drum, on the lower portion of the trachea,
sometimes of one shape, sometimes of another, serving,
doubtless, to give power to the bird’s voice. Cranes and
swans have veritable French horns in their breast-bones.
The windpipe enters between the arms of the clavicles
or wish-bone, and describes an S or even a more intricate
figure before passing out and dividing into the two bronchial
tubes. When a Trumpeter Swan stretches out its neck
and utters a musical clang, most maligned by comparing
it to a whoop, we should remember the cause of its mellow-
ness. In the majestic Whooping Crane of our Western
States, which in a few years will have vanished from the
earth, the windings of the trachea reach their maximum.
The entire windpipe of this bird is four feet in length, and
of this, one-half is coiled within the sternum, or breast-
bone, giving remarkable volume and resonancy to the
voice.

The Breath of a Bird 171

Fig. 130.—Breast-bone of Sandhill Crane.

Fic. 131.—Breast-bone of Whooping Crane, showing convolutions of trachea
within the keel.

Tie. The Bird

The Syrinx

This organ is peculiar to birds and, as stated before,
is alone concerned in the production of the voice, although
the tongue in parrots may be of some aid in distinctness
of articulation. But this is not true of any other Order
of birds, and the operation of splitting the tongue of a
magpie or crow to “make it talk” is as unnecessary as
it is inhumanly cruel.

The syrinx is singularly uniform among birds, and
this seems the more remarkable when we consider the
ereat variety of vocal sounds which are produced. The
position and the structure of this organ vary within nar-
row limits, but in general it is composed of several modi-
fied rings of the lower trachea or upper bronchial tubes.
The membranes which cover the inner half of each bron-
chial tube unite at their juncture with the windpipe
and extend some little way into it as a thin median fold
of tissue, supported by a bony framework. The tense-
ness or looseness of this membrane is governed by special
muscles, of which there are from one to seven pairs. It
is by the action of these muscles that the varying tones
of croak, scream, warble, or trill are produced, the air
from the lungs rushing out through the bronchial tubes
and past the varying aperture controlled by the syringeal
membrane.

We may dissect out every muscle and study trachea,
syrinx, and bronchi with all the apparatus and instru-
ments afforded by modern science, and yet the mystery

The Breath of a Bird ie

of song is not solved. The marvel of the Canyon Wren’s
melody becomes but the more wonderful; the voice of
the Seriema, carrying over a mile, and the never-to-be-
forgotten evening song of the Solitaire only impress us
with the failure of the scalpel and microscope to explain
more than superficially the varied expressions of life.

Lungs and Air-sacs

At the beginning of this chapter a bird was compared
to an insect, and the reason will now be apparent. The
body of an insect is aerated by means of an intricate sys-
tem of tubes ramifying throughout the body, which in
many instances are connected with air-sacs. The com-
parison with a bird is not to its lungs, which are small
and compact, but to a series of nine air-sacs, distributed
through much of the body,—four pairs, and two which
have coalesced into one.

When a bird is dissected, the thin membranous walls
of these air-cavities are collapsed and rather difficult
to make out, being very similar in appearance to other
connective tissues of the body. But if we insert a small
blowpipe into the trachea of a dead bird, tie it tightly
about with a piece of string and blow into it, all the air-
sacs will become distended and_ bladder-like and can
easily be made out. It is remarkable how closely these
sacs fit around the viscera and muscles, occupying every
crevice and filling the whole body of the bird with air,
thus reducing its specific gravity, and making it a crea-
ture literally “of the air.’ There is sometimes a layer of

174 The-bird

air between the muscles and the skin, and when we
handle a bird thus aerated the skin crackles under our
touch.

The lungs and air-sacs send off tiny membranous
tubes which enter the bones of the limbs and skull and
sometimes even the small bones of the wings and _ toes,
which are hollow and thus filled with air. It seems in-
credible, but nevertheless it is true that the connection
between the lungs and the upper arm-bone of a bird is
so substantial that a bird which has had its wing broken
with shot is able to breathe through the splintered end
of this hollow bone when its windpipe is completely
choked with blood.

We may compare the body of a bird to a submarine
boat with many water-tight compartments, and as such
a vessel is made buoyant by admitting air to these bulk-
heads, so a swimming bird may float high out of water
by inflating its sacs and filling its bone-cavities with air.
Conversely, when we see a grebe slowly and mysteriously
submerge its body, we conclude that it has but emptied
its lung auxiliaries.

We now come to the most important part of the re-
spiratory system, where the blood and the air come into
closest contact and exchange gases, the oxygen of the
air vitalizing the entire body. IH we follow the two
bronchial tubes after they leave the syrinx, we shall find
that each enters a lung, and passes through it, giving
off a number of side branches which open into the vari-
ous air-sacs. The lungs are not elastic and, instead of
lying freely in the body, are flattened against the back-

The Breath of a Bird P75

bone and ribs, and when carefully removed show fur-
rows made by these latter bones. There is still much
to be learned of the manner of a bird’s breathing, but
it is probable that there is a sidewise or dorsal expan-
sion of the ribs, rather than of that portion corresponding
to our chest. In a bird the latter region is chiefly an im-
mense flight-muscle, which could hardly yield to the
action of breathing while carrying on the tremendous
work of keeping the wings in motion, and when a

Fic. 132.—Cross-section of wing-bone of Ostrich and Black Swan. In life the
bone of the Ostrich is filled with marrow; that of the Swan with air.
bird squats on a branch with its breast pressed close
to the perch, “chest expansion” must be all but

impossible.

We cannot help being surprised at first when we see
how small are the lungs of a bird in comparison with
the size of its body.

The first thought that occurs to us is that the air-
sacs in birds, and the hollow cavities of the bones, must
function chiefly as aids to flight, and we should expect
to find as best flyers those birds in which the air-cavities

176 The Bird

are most numerous, but there are many exceptions. The
bones of storks and vultures (birds of great powers of
flight) are extremely pneumatic, while the bones of the
flightless ostriches are filled with marrow, and in the
aquatic penguins even this is reduced to a thread, the
bones being almost wholly osseous tissue. A swan,
although a heavy bird, flies remarkably well when once on
the wing, and is highly aerated, but, on the other hand,
terns and swifts—past-masters both in aerial evolutions
—have solid bones!

Now an athlete who is trained in running has always
a very large lung capacity. Two persons of equal health
and strength, one of whom has run many races or who
has the power of keeping up a dog-trot for hour after hour,
while the other has led a more sedentary life, may show
a remarkable difference in the amount of air which they
can draw into their lungs—perhaps one hundred or one
hundred and fifty cubic inches more in the case of the
runner. The average person uses only about one sey-
enth of his lung capacity in ordinary breathing, the rest
of the air remaining at the bottom of the lung, being
termed ‘‘residual.’”’ As this is vitiated by its stay in the
lung, it does harm rather than good by its presence. When
great exertion is required, as in running, the person who
can admit the largest amount of fresh air to his lungs in
each breath has command of an equally great power
of action.

As we have seen, the lungs of a bird are small and
non-elastic, but this is more than compensated by the
continuous passage of fresh air, passing not only into

The Breath of a Bird 7.

but entirely through the lungs into the air-sacs, giving,
therefore, the very best chance for oxygenation to take
place in every portion of the lungs. When we compare
the estimated number of breaths which birds and men
take in a minute—thirteen to sixteen in the latter, twenty
to sixty in birds—we realize better how birds can per-
form such wonderful feats of song and flight.

Birds, having no sweat-glands in the skin, and the
action of the capillaries being impeded by the feathers,
would have no way of regulating the temperature of the
body, much as this is necessary in flight, if it were not
that the great quantity of air exhaled with each breath
relieves the body of any excess of heat.

However directly or indirectly the air-sacs are con-
cerned with flight, a bird which sings uninterruptedly
as it flies upward must be immeasurably aided by the
great quantity of air at its command. And again, when
a Prairie Hen inflates the orange-hued air-sacs on both
sides of its neck, there is only one explanation as to
their use, at least at the time of courtship, namely, an
added decoration, and as an aid in the ‘booming”—
factors both of which, for aught we know, may help to
soften the hearts of the coquettish females.

Looking down the scale of life we find an animal among
the reptiles with a lung which at once suggests that of
a bird. The lungs of a chameleon are spongy and com-
pact in front, but farther back they are hollow, and

give off a dozen or more finger-like tubes or lobes, thus
foreshadowing, at least in appearance, the air-sacs
of birds.

178 The Bird

We have learned that the chick in the egg passes
through a stage when it possesses several well-de-
veloped gills. This proves that in the dim, distant past
the ancestors of birds were once
aquatic and fish-like. But how about
lungs? Fishes have none, and indeed
in their aquatic life such organs would
be useless. Nevertheless, as we shall
see, the lungs of reptiles, birds, and
mammals are legacies from the crea-
tures of the sea.

Many fishes have within their
bodies a thin-walled sac, known as
the swim-bladder. This is filled with
gas, and as the fish ascends to the
surface, or dives to where the pres-
sure of the water is very great, the
amount of gas varies; so that the

specific gravity of the fish changes
with that of the water. This swim-
°; bladder is generally connected with
pa eee ea ne in these two structures we have the

dition in bird.

the throat by a delicate tube; and

homologues of the birds’ lungs and
trachea. Proof of this is to be found in the growth of the
lungs in all young chicks. A tiny bud appears upon the
primitive cesophagus, just behind the little gill-clefts, and
increases in size until it is larger than the food-canal itself.
It then in turn divides into two equal parts which become
diminutive flaps, or canals—the beginnings of the lungs.

The Breath of a Bird 179

A simple experiment will show what fishes have a
eanal, or duct, leading from the throat to the swim-blad-
der and what have not. If a goldfish and a perch or
sunfish be placed in a bowl of water and the air exhausted,
the two latter will be forced to the surface, while the gold-
fish will soon eject a few bubbles of air, or gas, from its
mouth and stay at the bottom. Thus we can see the ad-

OW
()

Fie. 134.—Diagram of growth of lungs. X, the lower part of the primitive diges-
tive tract, divides into two. parts, XX, the lungs.

vantage of such a canal in enabling the fish to regulate
the amount of gas in the bladder.

When the fish-like creatures of old took to living on
land, the change from swim-bladder and gas to lung
and air was a remarkable example of change of function
of an organ, and the more we learn of the lungs of living
creatures the more marvellous does this transformation

180 The Bird

seem to us. In changing, Nature seems to have tried
numberless experiments, only a few of which have sur-
vived. For example, we know that fish breathe by a
sort of swallowing, the water being taken in at the mouth
and poured out through the gill-clefts. So in frogs and
salamanders we find that, although they possess lungs,
yet they still employ a swallowing process to get the air
down their throats. This is the reason why a frog will
suffocate if its mouth is held open. There are certain
salamanders which are wholly without lungs, their moist
skin being so vascular that the blood is purified through
it. But strange to say, these amphibians still swallow and
swallow, as did their ancestors, although no air passes
down their throats, and indeed there is no place to which
it could go! As we have seen elsewhere, birds exhale
air largely by the action of certain abdominal muscles.
Watch a goldfish rise to the top of the water and eject or
gulp down a bubble of air, and observe the rapid breath-
ing of a bird, and you have the two extremes before you
—the swim-bladder of ages ago and the wonderful lungs
of a bird of to-day.

The Heart and the Life-blood

Perhaps the most wonderful organ in a bird’s body
is its heart. In the very lowest of back-boned animals
the heart is merely a long tube, in fact a simple artery
or vein, which contracts at certain intervals and so pro-
pels in a forward direction the fluid which it contains.
A fish may almost be said to have its heart in its head,
so far forward in its body is it placed; nevertheless, as

The Breath of a Bird 181

is the case in all the warm-blooded creatures above it,
the heart is nearer the under side of the body—the breast
—than near the back. And herein hes an important
difference between the two great divisions of the Ani-
mal Kingdom, vertebrates and invertebrates,—the former
always having the heart near the breast, while in the back-
boneless organisms it is near the back.

The heart of a fish is fairly concentrated and muscu-
lar, but the blood which passes through it is but an im-
pure and sluggish stream. In reptiles both pure and
impure blood is found in the heart, but they mingle, and
thus half destroy the purifying action of the lungs. This
explains why these animals are cold-blooded, and also
accounts for their usual lethargic disposition and low
mental plane of life.

In crocodiles we find a significant condition. There
are four chambers in the heart, as in mammals and in
birds, but this avails nothing; for, leading from the heart
are two arteries instead of one, and where these cross

each other there is a tiny aperture—a small opening in
the partition which allows the impure blood to leak into
the stream of pure, red blood, and so a crocodile is only
a crocodile, although evolution has lifted his heart al-
most to a level with birds and the warm-blooded ani-
mals. If this tiny hole could become closed, and the
two streams of blood be kept separate, the eyes of the
crocodile would brighten, his activity increase many fold,
and in fact his entire plane of life would be changed.

I have thus briefly reviewed the heart in the lower
vertebrates in order to give a more vivid idea of this organ

182 The Bird

in birds. Here we find an organ remarkably large in
a conical knot

proportion to the size of the bird’s body
of muscle, the power of which is almost beyond belief.
The heart of a bird is said to beat a “hundred and twenty
times a minute when the bird is at rest. The first flap
of the wings doubles the pulsations, and when the bird
is frightened or exhausted the number of beats are too
many to be counted.”

There are four separate chambers, known as right and
left ventricles and auricles, and the partition which di-
vides the heart in the middle is blood-tight so that not a
particle of “bad” blood can get through and vitiate the
life-giving stream which has Just come from the lungs.

A Bluebird is perched on a twig near its nest mur-
muring its sweet warble; a Wood Pewee, half hidden
in the shadows of some dense, moist forest, speaks to
us in its sad dreamy phrase; how calmly, how quietly
they sit! It seems impossible to believe that every drop
of blood in their bodies is rushing back and forth with
inconceivable rapidity—from heart to head, from body
to wings and legs, and back again!

Let us take the blood as it is Just leaving the heart
in the breast in one of these little feathered beings, and
trace its course through the body and back again to
the starting-point. The left ventricle opens into the
aorta, the greatest artery, or blood-tube leading from
the heart, in the body. The clean oxygen-food-bearing
stream rushes through this channel, which we may com-
pare to the trunk of a tree, and is carried into branch
arteries, dividing finer and finer, just as the trunk of

Fig. 135.—Circulatory system of Pigeon (injected), showing blood-vessels rami-
fying from the heart to every part of the body.
183

184 The Bird

the tree merges into limbs, and these into branches, twigs,
stems, and at last into the delicate foliage. This last
we may liken to the, capillaries or hair-tubes in which
the blood does its real work of supplying nourishment
directly to the tissues, and where it receives the waste
matters, carrying them away in its current.

When we have followed the divisions of a tree out
to the foliage, we may find that they touch and interlace
with the foliage of another tree, and this is very much
like what occurs in the course of the blood. The capuil-
laries run together and form larger vessels, these in turn
coalesce, and soon the blood—dark now and filled with
the waste matters of the body-cells—is flowing through
only two large veins (veins always lead toward the heart).
These enter the right auricle, which opens into the right
ventricle. rom here the blood rushes to the lungs to be
purified and back again to the left auricle and ventricle,
and its cycle is complete.

If we look at a drop of bird’s blood (or that of any kind
of warm-blooded creature) under the microscope, we shall
see thousands upon thousands of oval dises, or corpuscles,
like tiny platters floating in a fluid. These flow about
under the cover-glass through little channels, mechanic-
ally and very slowly of course, and giving but a faint
idea of the way they must tumble and rush after each
other through the veins and arteries of the bird. Seat-
tered among these oval bodies will occasionally be seen
others of indefinite shape and white in colour. As we
watch one of these tiny cells, the thought suddenly comes
over us,—what are birds indeed but collections of untold

The Breath of a Bird 185

millions of one-celled animals! For here before us we
have what is almost exactly like the little flowing drops
of jelly called Amcebee which we may find in quiet ponds
and watch as they move about in search of food; flowing
around a bit of nutriment, digesting it and flowing away
from the waste matter which is left. This is Just what the

Fic. 136.—Blood-corpuscles of bird.

white corpuscles do; they flow around the food which is
absorbed by the walls of the digestive canal, and in fact
‘act like tiny independent animals, parts though they are
of the great whole. The oval corpuscles carry and dis-
tribute the oxygen, and here we have in a sentence the
inner ‘living’ of a bird: the food-canal bringing in food
and preparing it; the windpipe and lungs admitting

186 The Bird

oxygen; and the blood taking up and transporting both
to every part of the body.

The normal temperature of our body is about 984°;
if it rose to 106°, we should soon succumb to the burning
fever, while the little bird before us is healthy and com-
fortable with a temperature of 110° to 112°!

a

Fia 137.—Ameeba, greatly magnified. (Courtesy of Dr. G. L. Calkins.)

The next time you see a wee chickadee, calling con-
tentedly and happily while the air makes you shiver
from head to foot, think of the hard-shelled frozen in-
sects passing down his throat, the icy air entering lungs
and air-sacs, and ponder a moment on the wondrous little
laboratory concealed in his mite of a body; which his
wings bear up with so little effort, which his tiny legs sup-

ithe Breath of a Bird 187

port, now hopping along a branch, now suspended from
some wormy twig.

Can we do aught but silently marvel at this alchemy?
A little bundle of muscle and blood, which in this freez-
ing weather can transmute frozen beetles and zero air
into a happy, cheery little Black-capped Chickadee, as he
names himself, whose bravery shames us, whose trust-
fulness warms our hearts!

And the next time you raise your gun to needlessly
take a feathered life, think of the marvellous little en-
gine which your lead will stifle forever; lower your weap-
on and look into the clear bright eyes of the bird whose
body equals yours in physical perfection, and whose tiny
brain can generate a sympathy, a love for its mate, which
in sincerity and unselfishness suffers little when compared
with human affection.

waren, vee

‘ eee

3 Re be

Fig. 138.—Chickadee in the snow.

CHAPTER VIII
MUSCLES AND NERVES

Muscles

=IRDS exhibit probably a greater degree of activity
than any other class of animals. Some seem

never to be still, and, whether soaring, fluttering,
running, hopping, climbing, dancing, or swimming, every
motion is the result of the action of one or more muscles.

The entire flesh of a bird is divided up into layers
or bundles of distinct muscles, each having its function,—
raising, lowering, or in some way moving feathers, eye-
lids, legs, wings, tail, and other portions of the body. The
number and intricacy of these muscles can be imagined
when it is stated that in a goose there are more than twelve
thousand muscles or parts of muscles immediately be-
neath the skin, which serve to raise or otherwise move
the feathers.

In a penguin the muscles immediately beneath the
skin are unusually well developed, and for an excellent

(as

reason. By means of them the water “may be readily
expelled from the interstices of the plumage so soon as
the bird quits the water. Were it otherwise, in the low
temperature of the Antarctic region, which the majority

of these birds inhabit, their plumage would soon be frozen
188

Muscles and Nerves 189

into an icy mass, the high temperature of the bird being
of itself insufficient to obviate this, although assisted
by the great development of the subcutaneous fatty
layer, which far exceeds in thickness that of the corre-
sponding structure in the member of any other group
of birds, and recalls to mind the fatty deposit of ‘blub-
ber’ of the seals and cetaceans.”’

When we looked at the blood of a bird, we saw the
tiny white corpuscles, which in life flow and move in
every direction, constantly changing their outline; and
now if we take a piece of a bird’s muscle or flesh and
examine it carefully, after “teasing” it out into shreds
with a needle, we shall see another kind of cell-animal.
These are long and generally pointed, each a single cell
with a tiny spot or nucleus in it, differing from the white-
blood animals in being able to stretch out and contract
in only one direction. When we will our arm to close
together, bringing our hand close to our shoulder, a thick
colony or bunch of these muscle-animals shortens, be-
comes stouter, and bulges up under the skin on our upper
arm.

In our own body the bones of the spinal column are
movable, and we can bend in almost every direction,
and so we are provided with many important back-muscles.
But if we have ever carved a chicken, we shall remem-
ber that the ribs and shoulder-bones are close to the sur-
face, and but poor pickings are to be had from them.
The breast and chest, on the contrary, are hidden in a
thick mass of muscles, most of which are concerned with
moving the wings in flight. The immense pectoral or

190 ‘ithe Bird

breast muscle, which makes possible the all-important
downward sweep of the wings, weighs one-fifth as much
as the entire bird, bones and all. This arrangement of
a great weight of muscle hung below the point of attach-

Fic. 139.—Wing and breast of Pigeon, showing immense pectoral muscles, and
tendons of wing used in flight.

ment of the wings is, for mechanical reasons, the only

one possible in a bird of flight; since any excess of weight

above the wings would instantly overbalance the bird.
If we remove the skin from the upper arm of a bird,

Muscles and Nerves Igl

we shall see a tangle of bundles of red flesh—the muscles
which unite to make the arm of a bird such an exquisite
flying-machine. Where a muscle narrows and is fastened
to a bone, its fibres merge into a thin, tough white cord—

Fig. 140.—Model of bird’s foot, showing perching tendons; toes extended.

a tendon. This is not elastic like the main portion of
the muscle, but is much more tough.

In the slender legs and feet of birds there is little more
than bone, tendon, and skin. The tendons which clasp

and unclasp the toes are very interesting, and if we will

192 The Bird

bend the tarsus back and forth in the leg of a dead chicken,
the workings of these strands of tissue may be traced
beneath the scales. Reference to the photograph, where
catgut replaces these tendons, will make their workings

still more plain.

Fic. 141.—Same as Fig. 140; toes contracted.

Many birds cannot flex the leg without drawing the
toes up, and we may be sure that these birds are safe
when they perch; the closer they sit to the branch the
tighter becomes their grip. But this safety mechanism
is not found in all perching birds by any means (Fig.
143).

A strange thing about muscles is that there are fine

Muscles and Nerves 193

wavy cross-lines, or striations, on those which are moved
voluntarily, such as the muscles of the neck or wing;
but those which are moved involuntarily, as the gizzard,
are smooth and without the cross-lines.

Fig. 142,—Amazon Parrot in sleeping position, hanging by its toes; illustrating
the wonderful strength of the tendons.

Among birds new muscles have appeared, or old ones
have split up or so changed in position that it is all but
impossible to compare them, muscle for muscle, with other

194 The Bird

animals. There are so many resemblances between birds
and reptiles that we naturally turn to the latter for com-
parison, but even here we find a great unlikeness. We
learned, when we reflected on the number of ribs of a
bird, that the repetition of so many similar structures
was merely the last remaining vestige of ancestral body
segments, which reach their extreme development (in
number and similarity) among the worms; but in regard
to muscles birds show little or nothing of this. In liz-
ards we may count dozens upon dozens of bands of muscles
succeeding one another, all more or less alike, from head
to tail, but it is only in the neck of a bird that we shall
find anything like this.

In order to give to muscles a firm anchorage, they
must of course be attached to the bones. At these
points of attachment deep furrows or cavities are often
found in the surface of the bones, and in still other ways
we are reminded, even in fossil bones, of the flesh and
muscle which once moved them. ‘These muscle impres-
sions are often a valuable source of identification in
naming the bones of creatures which, many thousands
of years ago, disappeared from the earth. And indeed
so great variety exists in the muscles of living birds that
many of them, those of the upper arm for example, are
of considerable value in classification.

Nerves

The last great system of internal organs which we
shall consider, and perhaps the most mysterious of all,
is that of the nerves. We have learned that the back-

C61

“yosod S41 07 aSoO Burysood ‘1opqaw A, Weds po}eompy-yoetg SunoX—Epy “O17

196 The Bird

bone supports the entire body and gives a point of at-
tachment for the limbs, but long before limbs were found
among animals on the earth, in fact long before bone
existed, a sheath of cartilage surrounded and supported
the primitive spinal cord of creatures which lived long
ago in earlier epochs of the earth’s history. So we may
say this protection to the nerve-trunk is the most im-
portant, as 1t was the original, function of our vertebre.
When “brainy” creatures appeared, that is, when the
front end of the nerve-cord became enlarged, it needed
some special protection, so a box—the skull,—first of
cartilage, then of bone, was evolved.

One more fact which may hark back to old, old times,
and then we shall leave the past as perhaps trespassing
too much on the province of the chick while he is yet
within the egg. Birds (and all the higher classes of ani-
mals) have what we may call two separate systems of
nerves, although in some ways they are insolubly con-
nected with each other. The brain and spinal cord send
numerous branches which subdivide into countless nerve-
lets, permeating every portion of the body, as we can
easily prove by the feeling, on pricking our skin anywhere
with a needle. This is the principal nervous system of
back-boned animals, and it is by this that birds, and all
creatures with well-developed nerves, see, hear, taste,
smell, and by which they send messages to the muscles
when they desire to move them. Below the vertebral
column is another lesser system which sends nerves to
the digestive tract and other organs, the movements and
functions of which are not under control of the will, and

Fig. 144.—Nervous system of Pigeon, showing large eyes and brain, and nerves
iy 18 ] 5 8 A
leading to wings and legs.

198 The Bird

this is the sympathetic or reflex system. It is a very
wonderful thing, this not having to think about the heart
beating or the lungs expanding.

We can understand how a muscle (such as the heart)
can pump the blood through the body, but we know little
or nothing of the action of nerves. An eagle soars high
above the clouds; a rabbit is discovered crouching in
a field far below; the eye of the eagle telegraphs this
discovery to the brain; a message is sent along the spinal
cord, switches off to the wings, repeats to the muscles,
which half close and set the great pinions firmly; the
eye is the pilot, never leaving the mark; a triple message
now goes out, to the wings to hold back, to the legs to
reach forward, to the talons to open and clutch! All
is done without a break or hesitation, so quickly that
one’s eye can hardly register the act, and all by means
of impulses sent through the finest of white, hair chan-
nels, consisting of a substance so unstable that it tears
and falls apart, like wet tissue-paper, when we examine
it. And if the sending and receiving of impulses seems
wonderful to us, what can we say of the brain, the master
of all, where instinct, mind, soul,—no matter what we
call it, directs the whole life? It is here that fact upon
fact, experience upon experience, is stored from the mo-
ment the bird breaks its shell throughout its whole life-
time, and it is from the brain that the benefit derived
from this perception of experience, failures and successes,
causes and effects, is intelligently brought into play and
made to redound to the bettering of the subsequent
life.

Muscles and Nerves 199

When we carefully remove the upper part of a bird’s
skull, we find that the brain occupies the whole interior,

Fic. 145.—Comparison of skulls of Heron and Hawk, showing unlikeness caused
by difference in manner of procuring food.

the shell or box of bone which protects it being very thin,
although strong. It would be very interesting if we could
compare the short and thick bullet-shaped skull and brain

200 The Bird

of a rapacious hawk with the thin-templed head of a
in the first we
have the bump of combativeness well developed, analo-

)

timid heron and say, ‘“phrenologically,’

gous to a prize-fighter; in the second case, timidity is
prominent! But unfortunately, characteristics such as
these are compound, and made up of many simple fac-
tors, the synthesis of which is not confined to any par-
ticular “bump.”

At the first sight of the bird’s brain we are struck
with the very great size of the two larger masses of brain-

matter—cerebral hemispheres these are called. It is in
these that the higher faculties reside, and when these are
destroyed, all knowledge, all power of voluntary move-
ment passes from the bird. These great brain-halves
are much larger than in the brain of a reptile, in fact the
cerebral hemispheres, set deep in the great buttressed
skull of a full-grown crocodile, are no larger than those
of the duck which he snaps up. Not only this, but in
the days of the Archwopteryx (which had a typical bird-
brain), the monster Dinosaur, T’riceratops, 25 feet long,
had, in its 6 feet of skull, a brain proportionately only
one tenth as large as that of a modern crocodile! When
compared with a mammal there is seen to be a conspicu-
ous difference, since the outer surface is perfectly smooth
in birds, but is wound about in convolutions in the higher
four-footed animals. This latter condition is said to indi-
cate a greater degree of intelligence, but when we look
at the brain of a young musk-ox or walrus and find convo-
lutions as deep as those of a five-year-old child, and when
we compare the wonderfully varied life of birds, and

Muscles and Nerves 201

realize what resource and intelligence they frequently
display in adapting themselves to new untried con-
ditions, a smooth brain does not seem such an inferior
organ as is often inferred by writers on the subject. I
would willingly match a crow against a walrus any day,
in a test of intelligent behaviour!

Between the hemispheres is a small projection which

Fic. 146.—Vertical section through skull of bird, showing great size of brain.

is called the pineal body. It is very tiny, and we know
little of its function at present, but its history is one of
the most interesting chapters in the evolution of the
bird, which we shall leave to the chapter on the senses.

The other most conspicuous part of the brain is the
cerebellum, or “little brain,’ a section of which shows
a most remarkable tree-like appearance. This has been
called the arbor vite—the tree of life.

It is in this portion of the brain that a few tiny drops

202 The Bird

of blood are found when a bird dies of fright, which oc-
curs more often than in any other class of animals. Sports-
men have fired at a bird, missed it completely, and yet
have seen it drop dead as suddenly as if it had received
the full charge. In captivity, herons succumb more
frequently to fright apoplexy than other birds. When
we assume the care of any creature, bird or beast, we
should treat it as a timid child, and the person who moves
quietly but unhesitatingly will win the confidence of
wild creatures much sooner than when he alarms them
by sudden motions, or arouses their suspicions by jerky
half-hearted approaches.

There are twenty-four nerves given off in pairs from
the brain, which pass out through minute holes in the
skull, and energize eye, ear, tongue, and other organs.
Kach of these has an individual name, and as they are
homologous with similar nerves in ourselves, the same
name is retained, such as the olfactory, or that leading
to the nostril; and the pathetic, the function of which
is to control the obliquely raising eye-muscle, producing
a pathetic expression, although 1t must be confessed that
the effect of this in the immobile face of a bird is not
especially affecting.

Back of the cerebellum is a thickening of the spinal
cord, and after again narrowing it enters the bones of the
neck and back, as the true spinal cord. At the base of
the neck and near the thigh-joints this cord increases
in size, large nerves being given off at these places to the
wings and legs. It terminates in a fine white thread.

CHAPTER IX

THE SENSES

IK have seen that the brain is the storehouse of
facts and experiences, but whence come these

and how do they gain admittance to that soft
gray matter which is one of the wonders of the world?
There are five channels (and sometimes there seems the
shadow of a metaphysical sixth) which are cognizant of
and receptive to environmental influences. These are
the nostrils, eyes, ears and tongue, and the tactile nerves
of the surface of the body; or in other words the bird is
in direct connection with his surroundings on land or
water or in the air, by means of the senses of smelling,
seeing, hearing, tasting, and feeling.

The Sense of Smell

The sense of smell is dependent upon the diffusion in
the air of minute particles of objects, and naturally is
effective at very short distances compared to the senses
of sight and hearing, which require only vibrations in the
atmosphere. When we remember that the nostrils of
birds are usually encased in horn and that there is no
exposed moist surface, as in the nose of a dog, we shall
see how it is that this sense is but little developed among
feathered creatures.

203

204 The Bird

Fig. 147.—Nostrils of bird encased in horn.

Fig. 148.—Nostrils of deer encased in moist flesh.

The Senses 20%

In all animals the mucous membrane which lines the
nasal cavity is very delicate and filled with nervelets.
These nervelets unite and form a single nerve on each
side which passes to the brain and transmits the impres-
sions derived from the odours in the air. The thin bones
within the nostril, which, in dogs and deer, curl and re-
curl in delicate lines and
scrolls and thus expose
such a large surface to
the odour-bearing air, are
but poorly represented in
birds. The simple curve
of the bone in the nos-
trils of birds is very simi-
lar in structure to that
found in reptiles.

The question whether
wuliuness perceive: their — te. joe qurbinal ecmulla odor: In a
preva byaciehtronemellynag... PU Were Boxes are Far mnore simple.
been decided in favour of the former sense. Lacking the
ability readily to distinguish delicate odours, we find
among birds none of the glands which are so common
among hairy-coated creatures: the oil-gland is the only
one on the body, and this is practically odourless. But
sight as is the scent which diffuses from birds, it is
sufficient to enable a dog, with his wonderful keenness
of smell, to detect a crouching bird some distance
away.

The woodcock of our inland swamps and marshes,
and the apteryx of New Zealand, probably have the

206 The Bird

sense of smell most acutely developed, although in both
cases it is the delicate nerves of touch in the bill which
are most helpful in detecting the presence of the earth-
worms which constitute the food of these birds.

To whatever degree the nostrils of land birds aid
their owners in procuring food, it is certain that those

Fic. 150.—Head of Apteryx, showing tactile hair-like feathers, nostrils at tip
of beak, and small eyes.

species which feed entirely on fish, which they swallow
whole, have little use for nostrils, except for breathing.
Thus Nature, ever on the watch to economize, has re-
duced these organs, in such birds as pelicans and cor-
morants, and, at least in the adults, the nostrils are com-
pletely filled up with bone and horn.

The Senses 207

The Sense of Sight

Birds, so wonderful and interesting in all their structure
and life, have that most treasured of all the senses—
sight—so highly developed that there is nothing with
which we can compare it among living creatures. With
our great telescopes we can see to a greater distance than
any bird; with the high-power lenses of our microscopes
we can distinguish infinitely smaller objects than any
feathered creature is capable of perceiving, but where
else on the earth is there an organ of vision which in a
fraction of time can change itself from telescope to micro-
scope; where is the eye that, seeing with wonderful clear-
ness in the atmosphere, suddenly adapts itself to the re-
fraction of water, or (less slowly, although no less surely)
to the darkness of night?

Next to our powers of reasoning, we value sight above
all things, and fortunate indeed should we be could we
but exchange our imperfect vision for sight like that of
an eagle! Little need of spectacles or binoculars has he,
for the perfection of his eye enables him to become near-
sighted or far-sighted at will.

“The eye,” says Professor Coues, “is an exquisitely
perfect optical instrument, like an automatic camera
which adjusts its own focus, photographs a picture upon
its sensitized retinal plate, and telegraphs the molecu-
lar movements of the nervous sheet to the optic ‘twins’
of the brain, where the result is translated from the phys-
ical terms of motion in matter to the mental terms of
consciousness. But no part of the nervous tract, from

208 The Bird

the surface of the retina to the optic centre, sees or knows
anything about it, being simply the apparatus through
which the bird looks, sees, and knows. In this Class of
vertebrates the optic organs, both cerebral and ocular,
are of great size, power, and effect; their vision far tran-
scends that of man, unaided by artificial instruments, in
scope and delicacy. The faculty of accommodation, that
is of adjusting the focus of vision, is developed to a marvel-
lous degree; rapid, almost instantaneous changes of the
visual angle being required for distinct perception of
objects that must rush into the focal field with the
velocity at least of the bird’s flight. Observe an eagle
soaring aloft until he seems to us but a speck in the blue
sky expanse. He is far-sighted, and, scouring the earth
below, descries an object much smaller than himself,
which would be invisible to us at that distance. He
prepares to pounce upon his quarry; in the moment re-
quired for the deadly plunge he becomes at once near-
sighted, seizes his victim with unerring aim, and sees well
how to complete the bloody work begun. A humming-
bird darts so quickly that our eyes cannot follow him,
yet he instantaneously settles as lightly as a feather upon
a tiny twig. How far off it was when first perceived
we do not know; but in the intervening fraction of a
second the twig has rushed into the focus of distinct
vision, from many yards away. A woodcock tears
through the thickest cover as if it were clear space, avoid-
ing every obstacle. The only things to the accurate per-
ception of which birds’ eyes appear not to have accom-
modated themselves are telegraph-wires and light-houses;

The Senses 209

thousands of birds are annually hurled against these
objects to their destruction.”

A bird’s eye is very large in proportion to the size of
its head, and is correspondingly perfect and delicate in its
workings. It rests in a deep cavity hollowed out of the
skull, and is protected. by soft cushions of fat and controlled
by bands and pulleys of muscle which control its motions.

Looking closely at the eye of a live bird, we at once
remark its brightness—that alertness of expression which
so truly reflects the virile life of these creatures. The
eye, more than any other part of a living organism, is
an index to the relative power of its intelligence—more
surely than all the other facial features taken together.
The eyes of a sloth are expressionless black spots, and
even those of an orang-utan are bleary and watery.
But a crow or magpie, or any other bird you may choose,
though with horny, shapeless lips, nose, and mouth, looks
at us through eyes so expressive, so human, that no won-
der man’s love has gone out to feathered creatures through-
out all his life on the earth. A dog is a four-legged, hairy
animal with the eyes of a bird.

The eye of a bird appears perfectly round, and is
composed of a central area of black, encircled by a ring,
sometimes hardly distinguishable from the inner divi-
sion, or again it may be highly coloured. The circular
centre or pupil is always of a uniform black, and no won-
der, for ‘it is not a thing—it is the hole in a thing.” As
when we look through the lens of a camera, only the
blackened inside of the bellows is reflected to us, so in
the eye of a bird, the delicate living lens, itself invisible,

210 The Bird

reflects the black pigmented tissue at the back of the eye-
ball. The image passes through this lens and is thrown
upon the curtain of jet, and here the brain nerves find it
and know it—how, we cannot even guess.

If the eye-camera of the bird has no long bellows to
focus out and back, it has something infinitely better—
the coloured ring or iris which surrounds the pupil. We

Fra. 151.—Head of living Sloth.

are all familiar with the way the oval iris of a cat nar-
rows to a slit in bright sunlight and broadens at night
to let in all the light possible. Look closely at the eye
of an owl or parrot, even in broad daylight, and the
circle of the iris will be seen to contract and enlarge at the
will of the bird. We have always been inclined to pity
the poor “blind”? owl during the daytime, but the truth
is that, because of this power of adjustment, almost

The Senses 211

all owls can see very well, even in sunshine, although of
course their eyes are especially adapted for use in the dim
light of the evening and of thestars. In Nova Scotia I have
noticed Barred Owls flying about and feeding at noonday.

Fic. 152.—Duck Hawk. (Courtesy of N. Y. Zoological Society.)
Compare the alert expression with the sloth in Fig. 151.

Birds have well-developed lachrymal glands, although
it is seldom that they actually shed tears. Still I have
seen a flamingo in a flying-cage weeping copiously from
terror, anticipating all sorts of torture from a harmless

212 The Bird

condor which was playfully galloping around the fright-
ened bird.

Millions of years ago, in the geological period of time
known as the Jurassic, there existed gigantic sea-lizards,
which we call Jchthyosauri. All we know of them we
have learned by study of their fossil bones which, through
the ages, have been preserved in rocks. One notable

Fig. 153.—Brown Thrasher with eyes wide open.

thing about them was the great size of their eyes—meas-
uring as much as twelve and fourteen inches across.
These orbits were surrounded by a series of bony plates,
and in certain birds of to-day we find a similar circle of
small overlapping bones.

To make the simile between a camera and an eye hold
good, we must show that the latter is provided with a

The Senses 21

LoS)

Fig. 154.—Brown Thrasher with nictitating membrane drawn.

Fig. 155.—Same with eyelids closed.

214 The Bird

shutter, and in fact our bird has not one, but three—
eyelids we call them. So “between winks” all day our
bird is taking snapshots, inconceivably more perfect and
continuous than any cinematograph ever produced. We
have but two eyelids, and every time we wink these
shoot toward each other, moisten the surface of the eye-
ball, clear it of dust, and are back in their places so quickly
that we are not aware of any interruption of our vision.
The upper lid has most to do with covering the eye. In
almost all birds this condition is unusual and the lower
lid comes far upward over the eyeball. Perhaps the most
notable exception to this is among the Great Horned Owls,
where the action of the two lids is like that of our own.
When birds are sleepy these lids close, but usually
in winking, the third eyelid, or nictitating membrane, alone
is drawn across the eye. This lid is a delicate, semi-
transparent sheet of tissue, which, when not in use, les
snugly packed away in folds at the inner corner of the
eye, held back out of sight by its own elasticity. It is
drawn across the front of the eye by a slender thread of
tendon which is suspended, pulley-like, from a muscle
which keeps it from pushing against the optic nerve.
When you see an owl in the daytime with eyes dull
and glazed, this third eyelid is drawn partly across them,
diluting the strong glare of light and yet enabling the
bird to distinguish much that is going on. When an eagle
turns his head upward and looks full at the sun, it is not
“unwinkingly,” but with the help of this eyelid shield.
It is interesting to know that this membranous lid
is found in many other creatures, from sharks to monkeys,

The Senses 2G

although usually much less perfectly developed than it
is in birds. Alligators, however, have it fully functional.
In the inner corner of our own eyes we may detect a trace
of it, useless to us, but showing that far back in dimly
imaginable geological epochs our forebears had need of a
third eyelid.

Fig. 156.—Vestige of nictitating membrane in a human eye.

The Sense of Hearing

“The Gauls,” says Livy, “having discovered that the
rock Carmentalis was accessible, one night when it was
pretty clear, sent a man to examine the way, without
his arms which were afterward handed to him. Others
followed, lifting and assisting each other, according to
the difficulties which they encountered in the ascent, till
they reached the summit. They proceeded with so much
silence that neither the sentinels nor even the dogs, ani-
mals usually so vigilant as to be aroused by the slightest
noise, took any alarm. They did not, however, escape
the notice of the geese, which, being sacred to Juno,
had been fed by the Romans notwithstanding the famine
caused by the siege. This saved the capitol; for, by

216 The Bird

their cackling and beating their wings, they roused Mar-
cus Manlius, a brave soldier and formerly consul, who,
snatching up his arms and giving the alarm, flew to the
ramparts, set upon the Gauls, and by precipitating one
of them over the rocks terrified the rest so much that
they threw down their arms.” So also Pliny, Atlan, and
Columella vaunt the hearing of Geese. But leaving leg-
endary lore, it is certain that birds would not have the
power of producing the most varied as well as the sweet-
est sounds in all Nature, had they not been provided
with powers of hearing, correspondingly acute and dis-
eriminating.

The organ of hearing is complicated and there are
many points about it which are still mysteries to scientists.
The flap of skin to which we give the name of ear is
entirely absent in birds, and indeed in ourselves is a very
unimportant part of the auditory apparatus, serving
only as a collector of sound-waves. The opening of the
inner ear on each side ot the head, in birds, is usually
protected by a cover of feathers which are bristle-like,
partly denuded of barbicels, doubtless to avoid any muf-
fling of sound-waves. In owls this opening is of very
large size and protected by a movable flap of skin which
may serve to aid in focussing the sounds from below—
a very useful function to an owl at night, silently wing-
ing its way over field and meadow in search of mice and
other terrestrial prey. A rather singular fact is that in
many owls the two ear-openings are unlike, one being
larger and of a different shape from the other, and this
asymmetry extends even to the form of the skull itself.

The Senses 217

Two membranes are stretched across the ear-tube,
and between these a tiny bone, the columella, is sus-
pended, taking the place of the chain of three bones in
the ear of a mammal. When sound-waves strike against
the outermost membrane, or drum of the ear, vibrations
are transmitted by the little bony suspension bridge to
the inner membrane, and this in turn troubles the fluid

Fie. 157.—External ear of Barred Owl.

which fills the inner ear. The hair-like endings of the
nerve of hearing are affected by the vibrations of the
fluid and thus is hearing accomplished. Rather say,
thus the disposition of the physical components of the
ear may be explained; but how anything more than the
monotone of a sea-shell’s cavity is translated to the brain,
no one can say.

The fluid contained in three semicircular canals, situ-

218 The Bird

ated in the inner ear—which occupy the three planes of
space,—exercises a most important function, that of equi-
libration. They have been compared to the glass tube
filled with water and a shifting bubble of air, by centring
which a surveyor knows his instrument is perfectly level.

If these canals be injured or cut, the bird loses all
control of his actions; if a certain one of the three canals
suffers, the bird moves its head rapidly sideways and
spins around in a circle; if another of the trio is by an
accident severed, the motion of the head is back and
forth, and the bird is compelled to execute forward som-
ersaults; when the third of these canals is cut the bird
continually falls backward. In reptiles and mammals
the same thing occurs, so the wisdom of Nature in pro-
tecting these delicate organs by a sheath of hard bone
is very apparent.

The Sense of Taste and Touch

“The hands of birds being hidden in the feathers
which envelop the whole body,—their feet and their lips
and usually much, if not all, of their tongue, being
sheathed in horn,—these two faculties would appear to
be enjoyed in but small degree.”’

The sense of taste is probably the least developed
of all. The nerves which find their way through the
pores of the bill and tongue are more properly those of
touch than of taste, and this seems the more credible
when we consider the food of many birds, which is swal-
lowed entire, besides being so hard that nerves of taste
would be useless. Parrots and ducks, with their fleshy

The Senses 219

tongues and ample membranes of the mouth, doubtless
possess this sense to a considerable degree, while in birds
which are exclusively fish-eaters we may expect to find
taste least developed, the character of their food pre-
cluding all need for this faculty.

But from no bird is taste entirely absent, as we may
easily see by presenting some nauseous insect, which
will be instantly rejected with very evident signs of dis-
gust, the bird wiping its bill on a branch and shaking
its head violently.

The sense of feeling, although much deadened by the
feathery and horny character of a bird’s integument, is
most active at the tip of the tongue and the beak. At
the base of the feathers, especially those of the wings and
tail, tactile nerves are found, so that even a touch on the
tips of the feathers awakens a response in the nervous
system.

The delicacy of the tactile touch is remarkable in those
long-billed birds which seek their food in the muddy
bottom of shallow water, detecting by means of their
sensitive bills the presence of worms and snails,—aided
little or not at all by eyesight. In the woodcock and
apteryx this dependence on the senses of touch and smell
has even wrought a change in the position and character
of the eyes. The upper mandible of the woodcock is
probably unique in being so sensitive and mobile that the
distal third can be curved some distance upward, the base
of the two mandibles remaining close together. This is
an admirable provision by which, when the bird has driven
its beak deep down into the moist soil, it may feel about

OtS

‘TIIq ey) JO pus ay} Ye SoATOU 9[IOe} JOF ssurusdo Surmoys ‘[[Iquoodyg jo ][NYS—'SeT “Oy

The Senses 221

and seize the earthworm for which it is seeking. The
eyes have become unusually large in consequence of its
nocturnal habits and in addition are placed far back
upon its head, permitting a clear lookout for danger,
above and even behind, while probing with its head held
close to the ground.

Fig. 159. Fic. 160.

Fic. 159.—Photograph of living Woodcock with bill closed.
Fig. 160 —Same with bill open, showing mobility of upper mandible. The bird
is thus enabled to feel about and seize the earthworms deep down in the mud.

Thus ends our brief survey of the five senses; that of
smell taking note of minute particles of matter diffused
in the air; sight and hearing depending on vibrations of
the atmosphere ; the sense of taste detecting matter which
is dissolved in water, and that of feeling making the bird
cognizant of the qualities of bodies by actual contact.

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CHAPTER X

BEAKS AND BILLS

PIE a man’s hands and arms tightly behind his
NW} back, stand him on his feet, and tell him that
he must hereafter find and prepare his food,

build his house, defend himself from his enemies and
perform all the business of life in such a position, and
what a pitiable object he would present! Yet this is not
unlike what birds have to do. As we have seen, almost
every form of vegetable and animal life is used as food
by one or another of the species. Birds have most. in-
tricately built homes, and their methods of defence are
to be numbered by the score; the care of their delicate
plumage alone would seem to necessitate many and varied
instruments: yet all this is made possible, and chiefly
executed, by one small portion of the bird—its bill or
beak.

If one will spend an afternoon at a zoological park,
or with any good collection of live birds, watching the
ways in which the bills of the various species are used,
one will not boast of his own accomplishments, when
it is realized how much more, comparatively, the bird is
able to achieve with the aid of two projecting pieces of

horn.
223

224 The Bird

More than a single volume could be filled with in-
teresting facts about the bills of birds and the uses to
which they are put,—hardly any two species using their
beaks in a similar manner. The general way in which
the vast subject of the adaptation of the bird to its needs
and to its surroundings is treated in this volume will,
it is hoped, be a stimulus to the reader to observe for
himself,—to discover the thousand and one facts to

Fic. 162.—Beak of Snapping-turtle. (Courtesy of N. Y. Zoological Society.)

which Nature has not yet given us the key. Our lan-
guage is too often lacking in phrases expressing delicate
shades of meaning, and thus we are compelled to identify
structures among the creatures which rank below us
with portions of our own anatomy corresponding only in
relative position or a general vague likeness of function.
We are accustomed to speak of the mouth of a starfish,
the arms of a sea-anemone, the foot of a snail: in these
respective cases, structures specialized for receiving food,

Beaks and Bills 2D

reaching about, or for progression being understood. But
no one would think of alluding to a bird’s lips or nose; both
are included in the terms beak, or bill, and nostrils.

The finding and securing of food being the most im-
portant problem which birds have to solve for themselves,
it is for these purposes, and especially the last mentioned,
that we find bills most adapted. This is so universally

Fig. 163.—Bill of American Raven.

the case that we may often judge accurately of the kind
of food of a certain bird from a glance at its beak.

As is the case with so many other avian structures,
the horny, toothless beak or bill is duplicated elsewhere
in Nature only in a group of reptiles, the turtles and tor-
toises, whose mandibles furnish a splendid example of
parallel evolution.

In certain of those long-extinet Dinosaurs, such as

220 he Bird

Triceratops, an interesting transitional condition is found.
The front of the mouth was beak-like and horny, while
farther back were the masticatory teeth.

Starting with the generalized beak of the Arche-
opteryx, which, we remember, was furnished with teeth,
we are almost at a loss in which direction to turn,
so many and so varied are the beaks of modern birds.
No trace of teeth, however, is to be found in the adults
of any of them. The bill of a crow or raven and, to a
lesser extent, that of his near relatives, the Jay and the
blackbird, is perhaps in shape most like that of the ‘bird
of old,’ and is suited to the many purposes which the
varied life of these intelligent birds requires.

The crow or the raven is an excellent example of a
modern bird with a remarkably generalized diet, in striking
contrast to those birds whose bills show them to be fitted
for feeding only on some strictly defined food. With
his strong, ample beak the crow can dig up recently
planted corn, or crack the hard shells of acorns; he en-
joys stealing the eggs and the young birds of thrushes,
orioles, sparrows, warblers, and quail, and I have seen
a crow chase, capture, and carry off a half-dozen wild Mal-
lard ducklings in one morning! These birds are, in ad-
dition, able to capture insects of all kinds, besides pick-
ing berries, and ducking their heads under water in quest
of the shrimps which live in tide-pools. In short, their
bill serves them well in procuring many kinds of food,
from earth, water, or tree; as well as in carrying great
quantities of sticks, which they use in the construction
of their nests. These birds are so skilful with their

Beaks and Bills 227

Fic. 164.—Beak of Gannet.

Fic. 165.—Beak of Cormorant.

Birds closely related, but procuring food in different ways.

228 The Bird

beaks that a new trick is learned in a very short time.
In captivity a crow, when it thinks no one is watching,
will often take a morsel of food, thrust it beneath a piece
of sod, and cover it up with grass, almost with one
motion of the beak.

Functional or adaptive radiation is beautifully il-
lustrated by the beak of a gannet, cormorant, snake-
bird, and pelican—birds which are closely related to
one another structurally, also having in common a fish
diet, swallowing their prey whole. The gannet’s beak
is thick and very strong, and along the inner edge is a
series of fine serrations pointing backward. The bird
dives, from a great height, into the water and seizes the
fish in a grip of steel. The upper mandible of the cor-
morant is furnished with a large, sharp hook, with which
the bird gaffs its prey, pursuing it under water. The
snake-bird, or darter, has a bill like a needle, with which
it spears the fish, impaling it through and through; while
the pelican, because of its great pouch least vicious of
all in its methods, simply engulfs the fish, the water in
which it is swimming and all, then straining out the liquid,
tosses the unfortunate into the air and swallows it
head first. The under mandibles of this bird are long
and pliable and so arranged that they can bend far apart,
thus making of the great bag of skin beneath the bill
and throat an admirable fish-trap.

This is one of the many instances where several closely
related species, with needs so similar that there is danger
of fatal competition, are able to exist in great numbers
and to avoid all undue struggle for existence by having

Beaks and Bills 229

Fic. 166.—Beak of Snake-bird.

Fia. 167.—Beak of Pelican.

Birds related to each other and to Figs. 164 and 165, but with different feeding habits.

230 The Bird

each an individual method—a niche into which it fits
perfectly in the great scheme of Earth’s hungry creat-
ures. The snake-bird’s prey is in the water of dense

Fic. 168.—Brown Pelican catching fish, showing bag-like distension of lower
mandible. (Sanborn, photographer. Courtesy of N. Y. Zoological Society.)

swamps and bayous; cormorants and pelicans amicably
share inland lakes and tidal waters; while the haunt of
the gannet is the high seas.

Even more closely related to each other are terns

Beaks and Bills 2201

and Black Skimmers. Except in their bills these birds
are almost identical in structure, but the bill makes a

Fic. 169.—Bill of Tern.

Fic 170.—RBill of Skimmer

Closely related birds which differ in their feeding habits.

vast difference in the appearance of a bird, as is very
apparent when these two species are seen flying about

222 The Bird

J

together on their breeding-grounds,—low, sandy islands
along our coast. The small, delicately pointed beak of
the tern finishes off its neat appearance, and the entire
bird is the personification of grace, as it dashes through
the air, or plunges headlong into the sea,—to rise almost

immediately with a

small fish in its beak.
The beak of the
skimmer lends a heavy

aspect to the whole

| bird. Itis long
and high, and
the lower man-

|

| Fra. 172.—Two-year-old Skim-
mer, reared in_ captivity,
showing abnormal growth
of mandible, due to lack
of friction against water.

Fig. 171.—Bill of young Skimmer, showing under
mandible already slightly the longer.

dible extends a full inch beyond the upper. Both are
as thin and as pliable as paper-knives. A unique method
of obtaining food is the secret of this apparent deformity:
the strong wings of the bird enable it to fly very close to

Beaks and Bills. a

the surface of the water, so close in fact that the lower
mandible dips below the surface, thus ploughing a zig-

zag furrow and catching up any organisms, shrimps or
fish, which chance to be floating on the water.

Fia. 173.—Bill of Merganser, a fish-eating duck.

Fig. 174.—Bill of Shoveller Duck, a bird which strains its food from the mud.

Among ducks, we find those which feed on fish, and
those which sift their food from the mud at the bottom
of ponds, and these differ radically in respect to their
beaks. The fish-eating merganser has perhaps, of all
living birds, the nearest resemblance to a toothed beak.

234 ihe Bird

The deep serrations, however, are but indentations in
the substance of the strong, narrow bill of the bird.
When once in this saw-like grasp, the most slippery fish
is helpless. The beak of the Shoveller Duck shows how
well Nature has provided for its wants. The beak is
arched and spatulate, while the sensitive epidermis is pro-
longed at the edges into a series of comb-like teeth,—
analogous to the whalebone in the mouth of a whale.
Through this sieve the water is drained out, leaving
entangled the edible worms and insects.

If we should elevate our Shoveller Duck, placing him
on long, slender legs and providing him with a corre-
spondingly long neck, he would indeed be in a_predica-
ment, since only the tip of his beak could be brought
to bear in feeding. Now a flamingo is really a long-
legged duck, which feeds in much the same way as the
Shoveller, and the difficulty mentioned is overcome in
& most ingenious way. The mandibles are bent down-
ward, almost at right angles, so that, when the head
reaches the ground, not the tip but the whole inverted
bill is in a position to sift out food. To meet the reversed
condition, the lower mandible is deeply arched, instead
of the upper as in the Shoveller Duck.

We are able to follow the probable evolution of such
remarkable beaks as those of the flamingo and skimmer
by observing the growth of this organ in any individual
from the time when the bird hatches from the egg until
it is full-grown. In the very young flamingo chick there
is no sign of the subsequent deflection, the mandible
being short, perfectly straight, and rather slender. As the

FOUR STAGES IN THE DEVELOPMENT OF THE BILL OF THE
FLAMINGO.

Fie. 175.— Young bird in down.

Fria. 177.—Young in gray plumage, later stage.

Fic. 178.—Adult living bird.

236 The Bird

bird at first feeds upon regurgitated food, taking it drop
by drop from the bill of the old bird, it of course has
no need of the curved beak of its parents. Later, when
its bill has increased in length and has begun to be marked
by the ultimately sharp angle, the birds begin to sift
from the coral mud the small mollusks of which their
food consists.

Until its wings are full-feathered the young skimmer
is compelled to limit its wanderings to the sand-dunes
along the shore near its nest. Thus, although at birth
the lower mandible is a trifle longer than the upper, yet
even when the birds are half-grown the disparity in length
between the two mandibles is but slight. Later, when
the young bird is able to join its parents in their skimming
of the seas, the lower mandible quickly attains its full
development. The friction of the water upon the bill
must be considerable, as in a skimmer which I have had
for years in captivity, the lower mandible grew remark-
ably fast, measuring 6% inches from base to tip when
the bird was eighteen months old.

Herons and ibises, through all the years, sought their
food in much the same places as have ducks; the straight-
billed herons seizing their living prey with a single light-
ning dart, as it swims past them; the spoonbills spatter-
ing in the shallows; and the curved-beaked ibises prob-
ing every crevice along shore. The spoonbills swing
their necks and heads from side to side, as they walk
slowly through the water, gleaning their food with the
motion of a mower wielding his scythe. Two of the
herons are interesting enough to hold our attention for

Beaks and Bills 2077,

a moment. The common Black-crowned Night Heron
is abundant throughout most of North America, and he
fishes in legitimate heron fashion; but his near relative,
the Boat-billed Heron, is a more tropical species. In
voice, appearance, and structure there is little to choose
between the two birds,—except that the latter has a broad,
scoop-like beak,—a pelican’s fish-trap in miniature, which
seems to answer every requirement of this strange-look-
ing bird. From the
muddiness of the water
in the tropical swamps
from which I _ have
flushed these birds, it
seems probable that much
of their food may be
lesser fry than fish.
Pebbles and _ shells,
which shelter so many
toothsome morsels along

the shallows of our sea-

Fic. 179.— Bill of Great Blue Heron.

shore, offer sumptuous
feasts to birds furnished with beaks adapted to prying
and probing, and we find all sorts of sizes and shapes.
A collection of bills of various wading-birds would look
like a complete set of surgical tools! There is the stilt,
whose bill is almost straight; the ibis, with mandibles
curved downward to probe the crevices between the
pebbles on which he stands; the avocet has a pair of
recurved pliers, which search out the worm or snail in
the deepest fissures ahead of him. At the slightest touch

238 The Bird

of such a beak, the oysters and other large bivalves
close with a snap, defying these birds to penetrate their
living armour. Indeed, more than once a gull or wader
has rashly pecked at the sweet flesh, when the two tight-
fitting doors have suddenly closed, pinning the bird help-

Fic. 180.—Boat-billed Heron.
Figs. 179 and 180 represent birds with slightly different feeding habits.

less and holding it captive despite its struggles, until
the rising tide has ended its life.

But along comes a bird, well named Oyster-catcher,
and woe to the mollusks now. It allows them to close
tightly upon its bill, the mandibles of which are thin
like blades, many years antedating man’s oyster-knives.
The mollusk is wrenched free by the sturdy bird, car-
ried from the water still gripping the bird’s bill, and is

Beaks and Bills 239

Fic. 181.—Spoonbill, with spatulate Fig. 182.— White Ibis, showing
mandibles curved bill.

Fig. 183.—Bill of Avocet, recurved for probing.

240 ahesind

then pried open and eaten. The bill of this bird shows
the wear and tear of forcing apart the shells, and it is
sometimes slightly bent to one side. The short-billed
gulls are denied the power of opening these oysters and
mussels, but they sometimes get an unlawful feast by fol-
lowing up and robbing the Oyster-catchers of the shells
which the latter have opened.

The bill of the Shell Ibis of India may be likened to
an ordinary lemon-squeezer, having a cavity in which

Fic. 184.—Bill of Oyster-catcher; used for prying open the shells of mollusks.

the half-lemon rests before it is compressed. When
the mandibles of this bird are closely opposed the central
portion of the beak gapes slightly. In this cavity the
bird firmly holds the shells of the land-snails upon which
it feeds, until it can bring the pressure of both mandibles
to bear and so crush the shell of the mollusk.

The asymmetry of the bill—as seen in the Oyster-
catcher—is not accidental, but constant, in the Crook-
billed Plover of New Zealand. In this bird the bill is

Beaks and Bills 241

permanently bent to the right, a beautiful adaptation
to help the bird in its search for insects, which, in the
dry country that it inhabits, are found almost entirely
under stones.

As a rule, beaks are rather immovable throughout
their length, but in the woodcock, and to a less extent

Fic, 185.—Bill of Crook-billed Plover, for probing under stones.

in the Dowitcher Snipe, the extremity of the upper man-
dible can be raised some distance (Figs. 159, 160). This
extreme sensitiveness is especially necessary, as the eyes
of the woodcock are placed very far back on the top
of its head, and are of little or no use in seeking food.
What an interesting study the various beaks of land
birds would offer, were we able to devote to them the

242 The Bird

space which they deserve! They defy classification and
refuse to be arranged in any linear sequence. The ma-
jority of those birds which have their beaks armed with
a strong hook feed upon living prey,—from the great
mandible of the Golden Eagle to the tiny vireo, which
snaps up the dancing gnats.

The owls and the parrots, which, by the way, are
much more closely related than most of our classifications
would indicate, have bills very much alike, and afford

Fig. 186.—Bill of Golden Eagle, hooked for tearing prey.

a striking example of two large related groups of birds
whose diet has become radically unlike, although even
in this case “blood will tell” and the Kea Parrot slips
back into carnivorous habits with ease.

Owls tear their prey apart with their beaks, or swallow
it entire, but parrots gnaw and gnaw upon their nuts
and seeds, reducing their food to powder. This grind-
ing and rasping is aided by several file-like ridges which
many parrots have within their beaks. The hinging
of the upper mandible with the skull is more evident in a

Beaks and Bills 2.4.3

parrot than in any other bird. This arrangement allows
much freedom of motion.

It is not clearly known what use the immense beaks
of toucans may serve, although there seems little excuse
for this ignorance in those who know the birds in their
native haunts. The delicate, spongy texture renders the

Fic. 187.—Toucan, showing enormous bill used perhaps for reaching fruit on
the tips of branches.
clumsy-looking appendages exceedingly light, and they
are usually banded or marked with brilliant hues,—blue,
yellow, red, brown, green, or black. But light as the
beaks are in these birds, in the unrelated but similarly
monstrous-beaked hornbills the weight must be con-
siderable, for the first two vertebre of the neck in these

244 The Bird

latter birds are fused together, to yield a firmer support
for the muscles of the neck.

Chimney Swifts and hummingbirds both feed upon
insects and are rather closely related to each other, but
here again the most decided difference is to be found in
their bills. The broad, flattened mandibles of the swifts

Fie. 188.—Bill of Toucan; cut open to show its light, spongy structure.

open wide, as the birds dash through the air, engulfing
gnats and flies with wonderful skill; while the humming-
birds, as we all know, probe the deepest calyxes. Could
two bills more unlike be imagined? In very young hum-
mingbirds the bill is short and broad, very like the swift
type, and later its long and slender shape is acquired

Beaks and Bills 245

very rapidly, as we can see in Figs. 190 and 191. There
are many resemblances between hummingbirds and _in-
sects, due entirely to the similarity in their feeding habits.
Certain flowers are especially adapted in structure to
attract certain bees or moths, which in return unconsciously
cross-fertilize the blossoms; and certain of the various
bills of hummingbirds reflect the exact contour of the
corollas in which the birds seek their food. Among
hummingbirds the various shapes of bills of other groups
are reproduced again. Humming through the air about
us in the tropics speed miniature avocets, ibises, stilts,
mergansers, and we realize, as never before, the never-
ending devices of Nature, providing for the needs of all,
from the greatest to the least; endless patterns paral-
leling each other, but never identical. Indeed, in the
great family of South American birds known as Wood-
hewers the diversity in shape, size, and direction of bills
is so great that it seems as if not a niche, or crack, or hollow
in the bark of any tree in the forest where these birds
abound would afford a safe retreat to an insect!

It remains to mention the woodpecker’s bill, which
is used chisel-like, for excavating his home as well as
in boring for grubs. With his beak the nuthatch ham-
mers his acorns, and the tailor-bird sews his nest. The
thick conical beaks of all sparrows and finches are for
cracking seeds; while the weaker, more slender beaks
of warblers, thrushes, and wrens reflect a diet of insects.

Among the finches is a group of several species which,
by a thrust of the bill, have at their command a new
source of food, one which there are none to dispute with

246 he Bird

Fic, 189.—Bills of adult Hummingbird and Chimney Swift, showing great dis-
similarity in form, due to different methods of procuring food.

Fic. 160.—Bills of young Rufous Hummingbirds, showing swift-like character.
(Photograph by Finley & Bohlman.)

Fic. 191.—Slightly older Hummingbirds, with bills half as long as the adults,
(Photograph by Finley & Bohlman.)

247

248 The Bird

them. Both mandibles of the crossbill are curved into
sharp hooks which cross one another, either to the right
or left, thus forming a unique pair of pliers, with which
the bird pries out the seeds shut tight behind the over-
lapping scales of pine-cones.

Fic. 192.—Two extreme types of Hummingbirds’ bills, adapted for insertion
in flowers with shallow and with deep calyxes.

The beak of a bird is always growing, and in captivity,
from lack of proper use, the mandibles sometimes grow
to a great length, and, if not trimmed, will often inter-
fere with the bird’s feeding.

Perhaps the most remarkably adapted beaks in the
world are those of the male and female Huia birds—

Beaks and Bills 249

natives of New Zealand —in which not only is the bill
of the species designed for a special method of procuring
food, but the bills of the two sexes are very different in
form and use, and complement each other’s methods.
Concerning the peculiar use of the bill in the Huia birds,

Fie. 193.—Bill of Purple Finch and Crossbill compared; the latter specialized
for extracting seeds from pine-cones.

Professor Newton writes: “Its favourite food is the grub
of a timber-boring beetle, and the male bird with his short
stout bill attacks the more decayed portions of the wood,
and chisels out his prey, while the female with her long
slender bill probes the holes in the sounder part, the hard-
ness of which resists his weapon; or when he, having
removed the decayed portion, is unable to reach the grub,

250 The: Bird

the female comes to his aid and accomplishes what he
has failed to do.”

The bill of a bird, besides serving in so many other
ways, is invaluable in preening the plumage, arranging
disordered feathers, drying them, and, most important
of all, in pressing out the oil from the gland on the lower
back, and with it carefully dressing all the feathers, giv-

Fic. 194.—Bill of male and female Huia Birds, showing difference of the bill
in the two sexes.

ing to them that brightness and gloss and also the water-
proof quality—so surely a sign of perfect health in a
bird. When, after the bath of a caged bird, you see the
drops roll from its feathers, literally like “water off a
duck’s back,” then the good health of the bird is certain.

The all-important use of the bill as a needle, shuttle,
pick and shovel, auger, or trowel in nest-building does not
concern us here, nor does its function in expressing emo-
tion, or in taking the place of the voice or of the foot.

Beaks and Bills 25.1

All this is expressive rather of the mental than the phys-
ical life of the bird.

Within a period of five minutes I have observed the
following uses of the beak of a parrot perching in my
study. With its mandibles it picked up a sunflower
seed and comminuted it; it then hooked the upper man-
dible into a wire and swung itself along; gnawed at a nest-
ing-hole it had begun to excavate; nibbled gently at
my finger, showing affection; bit fiercely in anger and
fear at a dead snake which I presented; preened several
feathers of one wing, smoothing out all the dislodged
barbs; rattled its beak along the wires to make a sound
to attract my attention; and finally seized its water-pan
and turned it over in pure playfulness!

CHAPTER XI
HEADS AND NECKS

HE head of a bird is indeed a wonderful object,
when we consider its comparatively small size

and yet realize that it contains the brain, as
well as being the seat of the five senses. It also sup-
ports that most important organ the beak, which, as we
have seen, takes the place of hands and tools in the life
of its owner.

Of expression, with the exception of that caused by
raising its feathers, the bird has but little; although
fear, that emotion which must needs be expressed all too
often in the life of these timid and comparatively de-
fenceless creatures, 1s made apparent by the dilating
eyes and the open, panting beak. The only exception
which comes to mind is the Crowned Crane, Fig. 206,
the suffusing of whose bare, white cheeks indicates the
changing emotions. Perhaps the best index is to be
found in the crest, which we will find to be developed to
a very remarkable degree.

The eyes of most birds are placed at the sides of the
head, in such a position that the bird cannot bring both
to bear simultaneously upon the same object, but is com-

pelled to turn its head and look sideways. As _ birds
252

Heads and Necks 253

spend so much of their time in the air, or in trees, where
danger may threaten from all sides, above or below, this
arrangement is most useful to them, giving them com-
mand of almost their whole surroundings, whereas, with-
out turning the head, we can see only ahead of us. In
much the same relative position, the two ears are placed,

Fie. 195. Fic. 196

Fic. 195.—Head of Dove, with eyes at side
Fic. 196.—Head ot Owl, with eyes in front Showing difference in position of
eyes In a pursued and a pursuer in Life’s race
and the absence of a directive outer ear renders the bird
susceptible to sounds coming from every direction.
Owls, for very obvious reasons, are interesting excep-
tions to the above statements. Living most of their
active life at night, playing always the role of pursuers,
these raptorial birds have few enemies to fear; and their
subsistence depends upon the keenness of their senses
when focussed in one direction—downward. When its
strong, soft-feathered pinions carry a mousing owl over

Zi The Bird

field and stubble, the head, like the nose of a hound, is
held low, and, that not a rustle nor a motion of the little
field-mice may be lost, the ear-openings are turned down-
ward and the eyes look full upon the ground. Look a
Barn Owl in the face and you will see the entire cir-
cumference of both eyes, but a dove—one of the pursued
in life’s race—shows in the front view only the profile
of the eyeballs. The same story is told in the eyes of
the fox and the rabbit—examples of Nature’s parallels,
which are never repetitions.

It is interesting to compare the eyes of owls with those
of mammals in general. With the exception of man,
and of some of the monkeys, we find that when the eyes
show but slight divergence the animal is invariably a
lover of the dusk, or is wholly nocturnal. We know that
when we are asleep, or are under the effects of ether, our
eyes tend to roll upward and outward, and now we realize
that the cause of this is the old ancestral pulling outward,
toward monocular vision, as in the fish or rabbit or dove.
Our distant ancestors, far from having books or work
which focussed their attention directly in front, had
most vital need of looking out for dangers in all direc-
tions.

Another adaption found in the eves of almost all noc-
turnal birds is the great size of the orbit, fully one half
of the skull being hollowed out to receive the eyeballs.
No degeneration of the eyes, as a result of nocturnal habits,
is recorded among birds, such as exists in moles and bats,
except in the case of the apteryx, the diminutive New
Zealand representative of the ostrich-like birds. The

Heads and Necks 255

Fig. 197.—Skull of Owl.

Fia. 198.—Skull of Apteryx.

Showing opposite effects of nocturnal habits on the size of the eyes.

256 The Bird

small eyes of this bird become dazzled by strong light,
its food being detected by the senses of touch and smell.

The eyes of the woodcock show an interesting adapta-
tion to its habits. The bird feeds at night in marshes,
probing the mud for worms and, being in frequent danger
of attack from owls or other foes, it has need of constant
vigilance. So we find that its eyes, which are large and
lustrous, are placed far back on its head and also up near
the top of the skull. Useless in guiding the bird in its
search for food, they have become altered in size and posi-
tion and so best fulfil their function of aiding their owner
to all but look through the back of its head.

Even the iris of a bird’s eye may share in the won-
derful colour scheme of its feathers, although the most
common hue is a hazel-brown. And in birds of two
related species or races, there is sometimes a marked dif-
ference in the colour of the iris; such, for example, as be-
tween the Red-eyed and White-eyed Vireos, or the simi-
larly named Towhees. Puffins have blue irides, pigeons
pink ones, while young Bald Eagles have brown eyes
which, in the adult, turn yellow. The eyes of Barred
Owls seem to be a deep, lustrous black, but they are really
dark brown; while the great yellow eyes of Snowy and
Horned Owls are the most brilliant bits of colour about
these birds. In cormorants the irides are a glittering
emerald-green.

It might be thought that “making eyes” was con-
fined to the more frivolous of our own race, but certain
it is that, whether or not it plays a part in charming the
females, the irides of the males of a number of species

Heads and Necks 257,

of birds change, at the season of courtship, from a dull
hue to some bright tint, either red, green, or yellow.
Although eyelashes, as we understand them, are
merely stiffened hairs which have been inherited from
hairy-coated ancestors, yet among birds we sometimes
find lashes similar in appearance and function, but struc-
turally derived from feathers. The ostrich has well-

Fic. 199.—Head of Seriema, showing eyelashes.

developed eyelashes, which must be of value in helping
to exclude the dust of the desert; but why such birds
as hornbills and the Seriema should possess them we
cannot say.

A savage thrusts feathers into his hair, warriors of
old bedecked their helmets with flowing plumes, the
opera hat of milady is by way of wonderful and strange
creations; but withal feathers are really beautiful only

8 The Bird

fo)
~

(ny

where they by rights belong—upon a bird. Among
birds we find a more remarkable development of crests
than in any other class of animals. Indeed nearly all
birds have the power of slightly raising the feathers on

the head.

Fic. 200.—Crest of Java Peacock.

Most, if not all, plumes and crests are probably orna-
mental, and, since many are more highly developed in
the male sex and at breeding-time, we must conclude
that they are of value in attracting and holding the at-
tention of the females during the period of courtship.

What a list of these crests we may compile in a walk
through a zoological park! The photographs show the
grace and delicacy of these feathers, to which words can

Heads and Necks 259

add nothing. Note the slender shafts which rise from
the head of the Indian Peacock, each one tipped with a
dainty feather tuft; and the variation in the crest of its
splendid cousin from Java. In one of the Birds of Para-
dise, six long, fan-tipped shafts extend backward from
the head, much longer than, but similar to, the crest of
the Indian Peacock. The California Partridge bas a tiny,

Fie. 201.—California Partridges, showing difference in crest of male and
female birds.

club-shaped crest which points in a forward direction,
and, when the bird is excited, the feathers which com-
pose it spread out, breaking into a fan. The ornament
of the Plumed Partridge is a long, sweeping plume. The
crest of the curassow is most peculiar, being composed
of curly, recurved feathers, resembling in texture and
appearance jet-black or parti-coloured shavings.

The nuptial plumes of the Night Heron hang far down
upon its shoulders, and the soft barbs are curved inward,

260 The Bird

forming a slender tube. The glory of the Great Crowned
Pigeon is a maze of lavender lacework,—one of the most
beautiful of all crests; while the most graceful, perhaps,
is the mist of filmy whiteness which, at the slightest breath
of air, floats about the neck of the Snowy Egret, like
the mantilla of a senorita. Cockatoos are decorated
with a profusion of beautiful crests, each characteristic.
These are under the complete control of the birds, and
take an important part in expressing changing moods
and emotions. The crests may lie so flat as to be ordi-
narily invisible, when, in a flash, the whole head is sur-
mounted by an auriole of colour or whiteness. An ex-
cited Leadbeater Cockatoo is a wonderful sight. Before
the crest is raised, all that is visible is a single, rather
elongated white feather, but a wealth of colour is hid-
den, which flares out, showing a band of scarlet close to
the head, next a streak of bright yellow, then a second
band of red, and finally the white tips of the crest feathers.
The nod or jerk of the head in spreading wide the crest
reminds one of the sudden flick with which a fan is thrown
open.

Concealed crests bring to mind the Kingbird and the
Ruby-crowned Kinglet, both of which derive their names
from their crowns of ruby. It is said that the former
bird is aided in its search for food by the bright spot
of colour which, flower-like when exposed, attracts in-
sects. This, however, should be confirmed before being
accepted as a fact; although in a tropical flycatcher,
which has a beautiful red and purple transverse crest, the
evidence of this novel use seems fairly well corroborated.

Fic. 202.—-Crest of Banded Curassow (female).

Fic. 203.—Crest of Victoria Crowned Pigeon.

261

*

Fig. 204.—Harpy Eagle. (Courtesy of Dr. Frank Baker.)

262

Heads and Necks 263

The Laughing Thrush of the Himalaya Mountains
has every feather upon its head lengthened and perma-
nently erect, forming a soft, spreading halo.

Fig. 205.—Hooded Merganser. (From a photograph provided by the American
Museum of Natural History. )

In almost every Family of birds we find certain spe-
cies with long, well-developed crests. Among the ducks,
the Hooded Merganser has a compressed, semicircular
halo of delicate feathers, while the Mandarin Duck has
a broad, many-coloured, erectile crown, which is con-

264 The Bird

spicuous even in contrast with the gorgeous ornamenta-
tion of the body of this feathered harlequin. Of birds
of prey, the Harpy Eagle has perhaps the most imposing
crown of feathers.

Sometimes the crest is sharply set off from the rest
of the bird’s plumage, as in the scarlet-plumed wood-
peckers, whose crests give them the appearance of having
long hair, which is gracefully brushed straight backward
and upward.

We must not discuss the subject of crests without men-
tion of two birds of extraordinary appearance, the Crowned
Crane and the Umbrella-bird. The former illustrates
admirably what strange and unfeather-like forms, feathers
may assume in the course of evolution. The illustration
shows better than words can describe the dense, velvety
cap of plush-like feathers, and the glorious crown of a
myriad radiating points—a decoration unrivalled, even
among birds, in exquisite colour and delicacy. In addi-
tion to this, the cheeks are entirely bare of feathers, and
the lower half suffused with blood, which shows through
the skin,—an ever-changing blush of deep pink.

The decorations of the Umbrella-bird are as beautiful
as they are bizarre; while if shorn of its crest and streamers,
this bird would resemble a small crow in appearance.
The crest really bears a resemblance to the article which
has given the bird its name—a high, arching mass of
feathers, overshadowing the entire head and beak, con-
tinually spreading and partly closing again, as the bird’s
emotions change. Irom the neck of the bird dangles a
streamer of black feathers, as long as the bird’s entire

Heads and Necks 265

Fig. 206.—Crowned Crane.

Fia 207.— Demoiselle Crane.

266 The Bird

body and which, when it flies, blows back between its
feet. The filament of feathers looks for all the world
as if a strip of the bird’s plumage had caught on a thorn
and torn loose. The core of the streamer is a very slender

Fic. 208.—Umbrella-bird.

ribbon of skin which hangs from the neck. Would that
we could state the causes and the manner of the devel-
opment of these curious structures which our fancy likens
to an umbrella and a feathery handle!

One or two small tufts of feathers may spring from

Heads and Necks 267

some part of the head of a bird, such as the feather “horns”’
of owls, motmots, and larks. In Screech Owls these

)

prominent “ears” certainly play a useful part in breaking
up the outline of the bird, rendering it very difficult of
detection when it 1s perched upon some jagged limb or
stub. Or again, tufts or pencils of feathers may arise
from near the ear, or over the eye; as shown by the Dem-
oiselle Crane (Fig. 207), some of the Puffins, and the Man-
churian Pheasants (lig. 209). The Great Bustard has long
tufts of chin-feathers which, like wide-spreading whiskers,
spread to each side, and the Bearded Vulture has a simi-
lar goatee of stiff, black bristles.

Of the wonderful crests, frills, ruffs, breastplates, and
cloaks of hummingbirds there is no room to speak, and
indeed no words or pictures can aught but parody them.
The eye alone can record their marvels, in the collection
of a museum, or, better still, in the living birds, as the
little creatures hover over their favourite flowers, or
vibrate before us, fanning the air in our very faces with
their invisible wings.

Brief mention should be made of two Birds of Para-
dise, those beautiful creatures inhabiting a region where
the eye of man seldom sees them.

The Six-shafted Bird of Paradise is found only in
New Guinea. ‘The plumage appears at first sight black,
but it glows in certain lights with bronze and deep pur-
ple. The throat and breast are scaled with broad, flat
feathers of an intense golden hue, changing to green and
blue tints and certain lights. On the back of the head
is a broad recurved band of feathers, whose brilliancy

Fig. 209.—Head of Eared Pheasant.

Fic. 210.—Head of Great Horned Owl.

_

Heads and Necks 269

is indescribable, resembling the sheen of emeralds and to-
paz, rather than any organic substance. Over the fore.
head is a patch of pure white feathers, which shine like
satin; and from the sides of the head spring the six won-
derful feathers.”

Fig. 211.—Six-shafted Bird of Paradise (a mounted bird). (From a_photo-
graph provided by the American Museum of Natural History.)

Head decorations reach the acme of strangeness in
the King of Saxony’s Bird of Paradise. The bird itself
is sombre-hued and small, about the size of our robin,
with nothing unusual about its appearance, except for
the two streamers springing from opposite sides of the

270 The Bird

head. They are twice (or more) the length of the body,
and, far from being feather-like, they are best described
as a series of thirty or forty tiny flags of blue enamel,
each separate, each hanging pendent from the main
shaft (Fig. 212). It would seem as if Nature herself
could go no farther in unusual decoration than this.

Fic. 212.—King of Saxony Bird of Paradise. (From a photograph provided
by the American Museum of Natural History.)

In the Double-crested Pigeon of Australia the core
or fleshy covering of the beak is completely feathered;
while some of the birds known as plantain-eaters are
feathered to the very tip of the short beak with plumes
of delicate green, tipped with white. The extreme of
feathering is shown by the Cock-of-the-Rock, in which

Heads and Necks 27K

the whole beak, in fact every part of the head except the
eyes, is buried in a maze of soft, orange plumes.

As the antithesis to this condition, we find many
birds which have the head partly or entirely bare of
feathers, such as the vultures and some of the waders.

In the former group this lack of feathers is doubtless

Fic. 213.—Head of male Condor

of value in enabling the birds to avoid soiling their plu-
mage, when engaged in their scavenger work. The great
Condor of South America has, just below this naked area,
a necklace of the whitest of fluffy down, and in addition
the male has a large wattle of skin upon the front of the
head. The Caracara of Mexico is partly vulturine in its
habits, and the feathers have disappeared from part of
its face. Wherever the skin of the head and neck is even

27.2 The Bird

Fic. 214.—Caracara, partly vulturine in habits.

Fie. 215.—Young King Vulture.

Heads and Necks 273

partly bare, ornamentation often takes the form of many-
shaped and often highly coloured wattles, such as we see
highly developed in a King Vulture.

The most common example of this is seen in a domestic
rooster or a turkey, but in many other birds these wat-
tles of skin are very brilliant in hue. Indeed the casso-
warles are resplendent in their gorgeous hues of blue, yel-
low, red, and many other intermediate shades. Turkeys
too, at the breeding season, develop bright colours.
The Yucatan Wild Turkey, which has thus far resisted
all attempts at domestication, has the bright blue naked
skin of the head, dotted with tubercles of the most. bril-
liant orange, while a long tube-like wattle, also tipped
with orange, dangles down over the beak. The wattles,
or caruncles, of the Bell Bird are interesting as being con-
nected with the windpipe in such a way that they become
inflated with air when the bird utters its wonderful note.

In the White Ibis the face only is bare, in the spoon-
bill the head and face, and the whole head and neck in
the Marabou Stork; the effect of this condition in the
latter bird being heightened by the enormous pouch
which hangs suspended from the neck. The same is true
of the Adjutant.

A close inspection of the neck of one of these storks
will show that, while ordinary feathers are absent, there
is a scanty covering, here and there, of what looks like soft,
curling ringlets of chestnut hair. The resemblance is
absolutely perfect, and no naturalist in the world, if shown
one of these locks, would say that it came from a bird
and not from one of the hair-covered mammals!

Fic. 216.—Head of domestic cock. Extreme development of comb.

Fic. 217.—Head of domestic cock. Extreme development of crest.
274

Heads and Necks 27s

We must pass by all the strange ornaments of horn
upon the heads of birds, such as the scarlet plate of the
gallinules, the immense recurved casques of the hornbills,
the use of which is as yet unknown, unless it be purely
ornamental. But the impressive helmets of the cassowaries,

|

|
|

Fig. 218.—Head of Wild Turkey.

Fig. 228, demand especial notice in this volume, as being very
useful adaptations to life in a dense forest. These great
running birds are the only members of their Sub-class
which inhabit thickly forested regions, and in speeding
with great leaps and bounds through the undergrowth, the
tall, smooth helmet of horn protects the head of the bird

The Bird

Fic. 219.—Head of Adjutant.

Fic. 220.—Ringlet of hair from the

neck of an

Adjutant.

Heads and Necks 277,

and shunts off the hanging lianas and vines which would
otherwise impede its progress.

In our hasty paragraphs we have seen to what a re-
markable extent the ornamentation of the heads of birds
is carried, and as many extraordinary examples could
be given of decoration of the neck. The Loon has a
speckled black and white throat with a long colour band-
age of black feathers wound about its neck; the cervical
ruffs of our Ruffed Grouse are like wings in miniature;
in the Golden and Amherst Pheasants this form of orna-
ment is extended into a circular ruff of black and gold
and black and white respectively; while in the Superb
Bird of Paradise a shoulder-cape flares back, large enough
to cover almost the entire body of the bird, giving it the
appearance of being clothed in two distinct sets of plu-
mage! The nuptial attire of the Ruff, a species of sand-
piper, is as greatly developed, except that it forms a
double cloak over the breast.

This cloak or shield of feathers in the Ruff plays a
vital part in the life of the bird. We must first notice
the remarkable variation in the pattern of this cloak of
battle,—for such it really is. If we could see fifty Ruffs
standing side by side, some would be seen to have ruffs
of pure white, others of gray, black, orange, buff, or chest-
nut, while the waving ear-plumes are also independent
in colour, varying from white to purple, green, or blue.
Then there is a type of Ruff with barred cloaks, another
with spotted patterns, and so on in almost endless
variation. This condition of affairs is wholly unlike
the uniform pattern of colouring of other wild birds.

278 The Bird

Fig 221.—Lady Amherst Pheasant.

Fig. 222.—Casque of Hornbill.

Heads and Necks 279

We can only compare these little Joseph-coated birds
with the unnatural sports among domestic poultry and
pigeons.

But whatever their colour, these Fighting Snipe find
their ruffs of service in their encounters at the breeding
season. Four male birds which I observed in captivity

Fig. 223.—Ruff with battle-cloak partly moulted.

were adorned respectively,—plain gray, dotted gray,
chestnut barred with black, and a rich golden rufous.
Though no females were present, yet their fighting instinct
often cropped out and a pair of them would dart and side-
step about each other, bills held low and far advanced,
ruff spread out from the breast and trailing low, hiding
almost the whole body. Now and then one of the fencers
would make a vicious dash, sending his bill through the

280 The Bird

feather shield of his opponent. But the force of the
blow would spend itself on the inch of space between the
shield and the feathers of the bird’s breast. When, in
his native haunts, the Ruff has conquered his rival, his
triumphant dances before the female are most elaborate.
While these facts are not exactly pertinent to the physical

Fic. 224.—Breast ornament of a Wild Turkeycock.

life of the bird, yet I mention them to show to what prac-
tical, as well as wsthetic, uses the development of some
portion of the bird’s plumage may be devoted.

What a contrast to the cloak of the Ruff is the pectoral
decoration of the Wild Turkeycock: a great tuft of
coarse, black hair-like feathers, like the tail of a horse

Heads and Necks 281

in miniature, growing almost a foot in length from the
centre of the breast!

The length of the neck of birds is often correlated
with that of the legs,—a long-legged bird of necessity re-
quiring a long neck to permit its bill to reach the ground.
Geese and swans are an exception, and iu their case we

Fic. 225.—Flamingoes Correlation of long neck with long legs

find that the long, mobile neck is of great use in making
up for the awkwardness of their waddle when on land,
and in allowing them to reach beneath them while floating
in shallow water, thus feeding along the bottom.

Herons are uniformly so light of body that they would
have difficulty in steadying themselves in the air, were
it not that, when in flight, their necks become compressed
to an incredible thinness, thus acting as does the cut-

282 The Bird

water of a ship’s prow. The perpetual crook in the necks
of these birds is significant of their method of fishing—a
patient watch until the prey comes within striking distance.
In the snake-bird this crook, or Z-shape, has, by the

Correlation of long neck and short legs due to feeding habits.

Fig. 226.—Swan.
(Sanborn, photographer.)

adaptation of three of the neck-bones, become a veritable
trigger, by the springing of which the bird literally spears
the fish.

If the mention in this chapter of a few examples of
crests and other decorations has seemed in the least to

Heads and Necks 283

verge upon the monotony of a mere catalogue, my plea
is that they have been cited with the intention of empha-
sizing the fact of the remarkable degree which decoration,
pure and simple, plays in courtship. Viewed from such
a standpoint, these facts and comparisons become im-
portant data in the observation of the courtship of birds,

Fic. 227.—Snake-bird, showing crook in neck.

which in its turn is one of the most important and interest-
ing corollaries of the psychology of these beings. Whether
female birds have highly developed zsthetic feelings, or
whether the songs and dances and colour masses act more
along the line of the passes of a hypnotist, is yet to be
ascertained.

It is also hoped that a realization of the more immedi-

284 The Bird

ately practical uses of such structures as the cassowary’s
horny helmet, the feather shield of the Ruff, perhaps the
crest of the kingbird, and many others as yet unknown,
will impel amateur observers to further efforts in the
investigation of the life-habits of birds.

CHAPTER XII

THE BODY OF A BIRD

N experimenting with balloons and_ flying-ma-
chines, weight is a question of prime import-

ance, and among birds there seem to be certain
limits to the bulk of the body, beyond which flight is
impossible. The tiny hummingbirds, with bodies weigh-
ing less than some insects, have remarkable powers of
flight, and throughout all the groups of larger birds we
find certain species with exceptional flight ability, until
in the birds of widest extent of wing, such as the condor
and the albatross, flight seems to reach the acme of perfec-
tion. But the flying birds of actual heaviest bulk are
perhaps the Wild Turkey, the Great Bustard, and the
Trumpeter Swan, the two latter reaching weights of thirty-
two and twenty-five pounds respectively. Even the
gigantic Pterodactyls, those flying reptiles of olden time,
some of which had heads a yard long, and an expanse of
eighteen feet or more of bat-like wings, are estimated
to have weighed but twenty pounds or thereabouts.

But when the necessity for flight ceases, a bird may
begin to assume larger proportions and greater weight
without detriment; just as a mammal which adopts a life

in the dense medium of water may attain a much more
285

286 The Bird

gigantic size than one which has to support its body in
the thinner atmosphere: a whale is to a horse as an
ostrich is to a dove.

The ostrich is the largest of all living birds, a full-
grown male being able to reach to a height of nine feet
and weighing as much as three hundred pounds; but
even these figures were exceeded by its extinct relative
of Madagascar, the moa, whose height is variously esti-
mated at from ten to eleven feet, and whose massive leg-
bones show that its weight must have been much greater
than that of the ostrich.

There is a great difference in the relative condition
of the body in various birds. Herons, even when fish
are abundant, with opportunities of feeding from morn-
ing to night, are thin to emaciation. Truly they belong
to the “lean kine.’”” A fat heron would be an anomaly.
On the other hand, the flesh of many sea-birds seems as
constantly encased in thick, oily layers of fat. Petrels
are used by the inhabitants of some islands as candles,
simply by threading the body of the dead bird with a
wick, the excess of fat burning steadily until the whole is
consumed. Penguins are well protected against the icy
waters of their Antarctic home by a layer of fat under
the skin, so thick in proportion to their size as to remind
one of the blubber of whales.

If we were writing of the bodies of the fur-bearers
instead of birds, we would have much to say concerning
the various kinds of scent-glands and secreted odours;
but in birds the only gland is that above the tail, which
furnishes the oil with which the bird preens its plumage,

The Body of a Bird 287

thus both cleansing it and rendering it water-proof. That
birds, and especially those which, like quail, are found
in flocks, possess odours is borne witness to by the ability
of dogs to point successfully the hidden game; but that
this is of much use in enabling the birds to find one another
is doubtful, both from the fact of the slight development
of the sense of smell, and because of the loud eall-notes
which are so characteristic of these birds. One exception,
however, may be noted, that of the apteryx, which is
said to have a strong and persistent odour, with corre-
spondingly well-developed nostrils.

Again, among fur-covered animals we find usually
a poor development of the sense of sight and but few
of them exhibit bright colours, while, as we have seen,
birds excel in the power of seeing, and, correlated with
this, possess an unparalleled array of colours upon the
body.

There are many ways in which the body or its feathers
are adapted to aid the bird in some special way. For
example, the Puff-back Shrike of Africa has a habit of
suddenly puffing out and erecting a patch of long, loose,
white feathers on its back, giving the appearance of a
large powder-puff, an act so startling and unexpected
being well calculated to make any attacking hawk or
other bird hesitate.

The general texture of the body feathers is usually
an accurate index to the bird’s power of flight. Although
the feathers of the breast and back are never as compact
or as stiff as those of the wings and tail, yet in birds of
good flight their barbs are quite firmly connected. In a

288 The Bird

small African bird, called from its habits the Rock-jumper,
the wings are so small that the power of flight is almost
nil, and we find an interesting corollary in the plumage,

Fig. 228.—Cassowary, showing the loose plumage of a flightless bird. (Sanborn,
photographer. Courtesy of N. Y. Zoological Society.)

which is so loose and fluffy that it blows about in the

least wind. In the ostrich and rhea this down-like char-

acter is still more noticeable and extends even to the

feathers of the wings and tail. The extreme is to be found

The Body of a Bird 289

in the apteryx and emeu (Fig. 23). Compare a feather
of the latter with one of a condor and the difference is
remarkable. So unfeatherlike is the emeu’s plume and
so loose are its barbs that it brings to mind the much-
divided leaflets of an Acacia.

The plumage of the snake-bird is inexplicable. This
bird is so emphatically aquatic that we would expect
a dense, compact covering of the body; but in reality
it more nearly resembles hair or fur, soaking through so
quickly and thoroughly that, after immersion for some
time, the bird becomes waterlogged and has to hang
itself out to dry by seeking some sunlit perch, opening
wide its wings and waving them to and fro.

The feathers of the penguin are small, flat, and rigid,
approaching in these respects the scales of fishes—an
interesting reacquiring of characters consequent upon
an all but wholly aquatic life. It is interesting to com-
pare the colouring of such a bird as the Scaled Partridge
with a fish like the Carp, the dark margins of the feathers
and scales bringing about a remarkable resemblance.

Taking up the subject of colour in general, we realize,
after even a superficial glance at a collection of birds,
that in gorgeousness of hue and diversity of shade and pat-
tern, they are to be compared only with insects. In a
former chapter we have briefly considered the chemical
and optical causes of colour in feathers; but the causes
due to environment (using that word in its widest sense)
cover a vastly greater field and one as yet comparatively
unexplored.

Advancement of actual knowledge of any subject in

290 The Bird

science depends upon two things: first, the accumula-
tion of facts; and secondly, a philosophical spirit capable
of generalizing and bringing order out of the chaos of

Fic. 230.—Carp, a fish with distinctly marked scales. (Keller, photographer.)

these myriad observations. A knowledge of museum
facts is of but slight use in such a subject as the one under
consideration, which requires more adequate knowledge

The Body of a Bird 2g1

than we now possess of the life-habits and the psychology
of birds. This is especially true of the great number of
cases which we can explain only by calling them orna-
mental and decorative. Hence we find one ornithologist

Fic. 231.—White-throated Sparrows. The light-coloured bird is in normal plu-
mage; the dark bird was subjected to moisture-laden air through two moults.

explaining a certain colour as due to one cause, while
another scientist gives an entirely different interpretation
of the same fact.

From personal observation among the birds of the

292 The Bird

New York Zoological Park, I have had opportunity to
record many cases of the effect of food upon colour. An
experiment very commonly known is that of feeding
canaries on red pepper, thus causing their plumage, after

Fig. 232.—Variation due to climate, ete., in races of North American Song Sparrows
(From a photograph provided by the American Museum of Natural History.)
successive moults, to become of an intense orange colour.
This is the more remarkable since the actual red pigment,
or capsicin, of red pepper is not the direct cause of the
canaries’ changed hue, but a fatty substance known as

triolein, which is a constituent of the pepper.

The Body of a Bird 293

It is generally thought that the fact that, in captivity,
Purple Finches and orioles frequently moult into yellow-
ish hues, instead of their rightful tints, is due to some
change in food. Indeed in many species the bright colours
are wholly lacking after a year or two in captivity. But
I have transferred a male Purple Finch, which had for
several years moulted yellow, from a dark cage to one
which was exposed to
bright sunlight, and in
one moult the bird as-
sumed his original and
normal colour.

A more probable ex-
ample of the effect of
food upon colour is seen
in our American Flamin-
goes. In captivity these
birds fade out moult by
moult, until they become
almost white, like the

European species. By
oe é ‘ Fic. 233.—Effect of environment on Bob-
mixing with their food white, shown by specimens from Min-
nesota, Florida, and Cuba. (From a
a quantity of some photograph provided by the American
Museum of Natural History.)
strong but harmless dye,
I have had them either retain their original colour for
years, or at least the fading process has been appreciably
lessened.
The effect of climate upon colour is even more readily
proved, and may be noticed in wild birds as well as in

those in captivity. In regions which have a very dry

294 The Bird

climate, the birds, and in fact all of the animals, are of
a much lighter hue than those living in an atmosphere
of great humidity, where moisture does not readily evapo-

Fic. 234.—Male Scarlet Tanagers, showing moult from the scarlet summer dress,
(a), through the parti—coloured garb (6), into the green winter plumage (c).

rate. Insuch a place birds tend to be very dark-coloured.
In the case of captive birds, I have seen White-throated
Sparrows and Wood Thrushes become almost like black-

The Body of a Bird 295

birds in colour when confined in a bird-house where the air
was constantly moist. Correlated with the effect upon
colour is often a difference in size, and in many instances
among birds the more northerly individuals are larger,
those inhabiting warmer regions being less in stature.
Among wild birds, the Quail, or Bob-white, shows an
almost unbroken series from the northern, light-coloured
variety, ten inches in length, to the Cuban bird, very

Fig. 235.—Siberian Black Lark, male bird in the spring.

much darker in shade and measuring only eight inches
from beak to tip of tail. The race of Bob-whites seems
very susceptible to climatic influence; as in Mexico there
are nearly a dozen different geographical races, each in-
habiting a distinct portion of the country. Many other
wide-spread groups of birds, such as the Song Sparrows,
vary in a similar manner. It is strange what a marked
effect this greater or less amount of moisture has upon
birds, even in very limited districts. A South Ameri-
can pipit, the individuals of which spend their lives on
very circumscribed plots of earth, exhibits two colour

296 The Bird

forms entirely different, and thought to be due solely
to the amount of moisture in the ground on which it lives.
Very dark-coloured and very pale individuals live within
a few hundred yards of each other, in dry and swampy
situations respectively, each, it is said, keeping entirely
to its own little beat.

We are all familiar with the changes of colour due to

Fic. 236.—Nighthawk perching lengthwise on a fallen branch.

age, as, for instance, in the young Rose-breasted Gros-
beaks, which are very different from the male parent, and
the young Bald Eagles, which lack the white colour of the
feathers of head and tail. Certain wild pigeons show
marked differences in colour patterns between the young
birds and the adults, and very good evidence of the gradual
evolution which must have preceded these changes 1s

The Body of a Bird 297

to be found by plucking out a few of the feathers of the
young bird. Those which replace the ones pulled out
will show intermediate stages, which have long since been
dropped from the sequence of patterns, as observed in
the regular moults of the birds.

Another important phenomenon is the seasonal moult,
which was spoken of in the chapter treating of feathers.
In the fall of the year the brilliant Scarlet Tanager assumes
the olive-green dress of the female, and the Indigo Bunt-
ing and the Bobolink likewise don the dull garb of their
mates.

There is another very interesting cause of change in
colour, namely, the wearing off of the brittle tips of the
feather-vane. An excellent example of this is seen in the
Snowflakes, which come south in the depth of severe
winters, flying in small flocks about our fields, like an
animated flurry of the actual crystals. When we see
the birds at this time they are brownish and brownish
white. In the spring, in their northern home, they change
to a clear-cut black and white, not by shedding the entire
plumage, but merely by the breaking off of the brown
feather-tips. By a similar process the Bobolink changes
from the buffy female dress to his rich black-and-white
spring suit, and, as we saw in Chapter II, Fig. 35, the
English Sparrow gains his cravat of Jet.

Another excellent example is found in the Black Larks
of Siberia, the males of which, in winter, are of an almost
uniform sandy colour, like a Skylark, but by the wearing
off of the buff tips of the feathers, the birds become jet-black
in the summer—a most remarkable and radical change.

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The Body of a Bird 299

The relation of a bird’s colours to its haunts and its
habits of life is a subject of intense interest. This is,
of course, not in the same category as the subjects of the
foregoing paragraphs, but indeed includes them all. The
most common class of colours is known as protective.
These are such that the bird resembles its environment
or surroundings and is thus given a better chance of escap-
ing the observation of its enemies. It is evident that,
in a study of this nature, observation of the bird in its
natural haunts is of far greater value than any other
method.

We find that the majority of sparrows, sandpipers,
and quail are gray or brown, like the grasses, sedges, and
leaves among which they live; while the birds which
spend their lives higher up among the branches of trees
are greenish, or at least more brightly coloured.

Many birds which are protectively coloured are dark
above and white or whitish beneath. The significance
of this pattern of coloration has been beautifully demon-
strated by an American artist, Mr. Abbott Thayer. His
experiment, which is as follows, may be repeated by any
one: Take two wooden decoy ducks, and place them
against a sand-bank. Colour one the exact tint of the
sand, or even coat it with that substance. Repeat. this
with the upper parts of the second decoy, making its
back darker than the surrounding sand, but grade the
under ‘part of this one to pure white below. At a little
distance away, decoy number one will still be distinctly
seen; while number two will absolutely disappear, merg-
ing perfectly into its background. The reason for this is

300 The Bird

that the conspicuous white of the under surface of the
second bird is, when normally lighted up by the sun,
neutralized by the shadow of the bird, and the darker
upper parts are softened and toned down by the strong
direct hight; while if the entire bird be unshaded, although

coloured like the environment, the dark shadow beneath
will reveal it clearly.

Whether or not birds really appreciate the value of
the protective colour of their plumage, it is certain that
a quail or ptarmigan will remain crouching on a brown
bit of turf, until all hope of evading danger is gone; while
birds which are very evidently not protectively coloured
are invariably more wary and difficult of approach. When

ebe, photographer. )

R. H. Be

(

tree.

a

Seven young Flickers clinging to

239.

Fia.

301

302 The Bird

a ptarmigan, while yet in the brown garb of summer,
is exposed against a hillside of snow, it becomes very
wary.

It is interesting, in this connection, to observe how a
Nighthawk carries out its colour resemblance to a knot
or a rough piece of bark, by perchiyg, not crosswise, but
lengthwise, along a branch or fallen tree-trunk.

A volume might easily be written of the various ways
in which protective coloration works out among birds,
but there is so great a difference of opinion, and indeed
so many exceptions to every theory which may be ad-
ranced, that it is better, for the most part, to go to Nature
without @ priori theories, and putting ourselves as nearly
as possible in the position of the creatures themselves,
to hope for better ability to see with their eyes. And
it is right along this line that we most need fresh data
and experiments, namely, the actual ability of birds
and insects to distinguish shades, colours, forms, and
motion,—whether efficient in certain ways or not. We
know that many men cannot distinguish a scarlet ball
lying upon green grass; that is, they are partly colour-
blind. If this were the case with certain hawks, a male
Scarlet Tanager would be forever safe from them among
the green foliage.

An important fact, which for years had been appar-
ent to me, but unexpressed until Mr. Abbott Thayer put it
into words, is that colours which we would ordinarily term
conspicuous are often exactly the opposite when found in the
plumage of a bird. Writing of the Motmot in my volume
‘‘Two Bird-lovers in Mexico,” I say: “I have often

The Body of a Bird 208

wondered, when I saw mounted specimens in museums,
with what special immunity from danger these birds
were blessed, their beautiful colouring would seem to be
such a startling advertisement of the bird’s whereabouts.
But in reality the very diversity in hue is their protec-
tion, and they merge per-
fectly into their environ-
ment of green foliage and
bright sunlight.”

Indeed absolute uniform-
ity of coloration instantly
reveals the outline of the
bird entire, and renders it
very conspicuous. Birds
which have but few ene-
mies are often thus mono-
crome in hue. But look

at the photographs and
see how a broken colora- 5. 049. Brown Creeper circling up the
tion baffles the eye. If esc a
the Sooty Tern, Fig. 238, were totally black, it would
be conspicucus even against a patch of dark-coloured
mottled shingle. But the transverse lines of white across
the back totally destroy the symmetry of form, while
the white wing-edges fairly force the eye to call them,
not part of a bird sheltering her eggs, but only two among
a myriad irregular edges of coral rock!

Observe closely the seven young Flickers clinging to
their natal stump. As the warriors of Jason sprang forth
from the ground fully armed, so the very bark, mottled

304 The Bird

with spots of lichen and sunlight, seems to have gendered
these baby birds. Yet they were hatched in a dark hole
from the whitest of white eggs. Is this and a thousand
of other resemblances to be termed accidental? Then
is all Nature one great accident! When the Flicker flies
with swift wing-beat from tree to tree, then the white

Fira. 241.—Laughing Gull on nest.

rump blazes forth. At such moment no protection is
needed; but in these young [lickers upon the tree-trunk,
how exquisitely do their spots deceive the eye! They
are, we say, perhaps sunlight splashes,—nothing more.
Yet others which, like the Brown Creeper, haunt the
tree-trunks of the forest, seem veritably to be but stray
bits of roughened bark creeping here and there.

Ii. Brown.)

A.

(Courtesy of

—Black-necked Swans.

242 —

Kia.

35

306 The Bird

Let us glance at one more bird upon her nest,—a Laugh-
ing Gull. At a distance we see a shapeless blotch of white
sand among the reeds, that is all. We walk over a hundred
other similar patches; but when near enough, we at
last are able to distinguish the dark head and wing-tips,
all but invisible among the shadows, and even through
the centre of the head we can see two spots of light be-
yond,—or no, it is the little subtle ring of white about
the eye!

Two majestic Black-necked Swans may swim closely
along in full view near the opposite bank of a pond, and
yet be totally unrecognizable; showing to the eye as
bodiless necks or neckless bodies, according to the chang-
ing conditions of light and shade around them.

We see a troop of ostriches rushing past. Surely
nothing could hide birds such as these! Again we see
one of these birds prone upon the ground, and a mighty
creature towering eight feet or more above the earth,
becomes naught but a dark ant-hill, which the photo-
eraph picks out clearly, but which in the desert, dotted
with ant-hills, would seldom be noticed even by the hungri-
est of lions.

Of course, like most other theories, this of protective
coloration can easily be carried too far, but there are
hundreds of instances where it seems to answer every
requirement of the case. ew fields offer such opportuni-
ties for original work of the most delightful character.
As one example out of untold numbers, what explanation
ean we give of the Blood-breasted Pigeon or Bleeding-
heart Pigeon, which, as its name denotes, has a splash

The Body of a Bird 307

Fic. 243.—Group of Ostriches on the run. (Cawston, photographer.)

Fic. 244.—Ostrich as it hides from an enemy.

308 The Bird

of blood-like scarlet in the centre of its breast? The re-
markable and inexplicable resemblance is heightened
by the stiffened vanes of the centre feathers, causing them
to appear bedraggled and clotted, as if by an actual wound!
The photograph does but little justice to the bird’s real
appearance.

Another class of colours, while still protective, is so
for a purpose very different from those cases which we

Fic. 245.—Bleeding-heart Pigeon.

have been considering. The colours which we are now
to mention have been aptly called aggressive colours, as,
by their means, a bird of prey is enabled to approach
its victim more easily. So, throughout the entire animal
world we find two phases of phenomena constantly pres-
ent: on the one hand the pursued ones, striving to escape
by all means in their power; and on the other hand the
pursuers, ever trying to outwit those upon which they
prey. If a duck acquires great speed of flight, the Duck

The Body of a Bird 309

Hawk must learn to fly still faster. If the duck learns
to crouch close to the reeds when his flight-feathers are
moulted and he is helpless, the hawk must develop
ever sharper eyesight. We may puzzle and puzzle over
a characteristic habit or a colour of some bird, finding
no solution, until we discover some special enemy or
other factor in its life which makes all clear.

So, among aggressive colours we may mention the
garb of the penguin, which is steel-gray on the back and
silvery white below; not to protect it from danger, but
to enable it the better to approach fish without alarming
them. It is curious how fish-like the coloration of these
birds really is, and they are said frequently to lay feet
and tail together and, drawing their flipper-like wings
to their sides, spring clear of the water again and again,
by a single motion of the back muscles, exactly as the
mammalian dolphins leap ahead of a vessel’s bow.

Again, while we find the ptarmigan mimicking the
snow in colour, we find the Arctic Fox, the Snowy Owl,
and the Gyrfalcon, all of which are enemies of this bird,
also garbed in white. The ptarmigan may crouch upon
a drift, but 1t must ever be on the alert, lest from amid
the snowflakes a white death come suddenly upon it.
Nature is terribly just in her plan of life’s battles.

In the same region with these lives the Ivory Gull,
immaculate as the ice-floe over which it flies, and in its
whiteness we can perhaps read two purposes: a_ better
chance to elude the fierce Gyrfaleon, and a better chance
to float cloud-like unperceived over the unsuspecting fish
which it seeks for food.

Fic. 247.—Pickerel. (Keller, photographer. From life, swimming.)

PREDACIOUS, AQUATIC ANIMALS, SHOWING AGGRESSIVE
COLORATION.

310

The Body of a Bird 2a

An instance of what has been called unconscious
mimicry seems to exist in the cuckoo of the Old World,
which, like our cowbird, is parasitical in habits, making
no nest of its own, but depositing its eggs in the nests of
other species of birds. The cuckoo bears a_ striking

Fig. 248.—Ivory Gull. Aggressive and protective coloration in an Arctic Gull.

resemblance to a small hawk, both in general pattern and
in its darting flight. The name Hawk-cuckoo has been
applied to a genus of these birds in India; the name being
given because of the resemblance to a hawk. This simi-
larity may be of great use in temporarily frightening
away the owners of the nest in which the bird wishes

212 The Bird

to deposit an egg. A few other instances are known, as
where a fierce, bird-killing hawk resembles a harmless,
insectivorous — species,
perhaps by this decep-
tion deluding small
birds.

Many of the plovers
have one, or even two,
bands of black encir-
cling the neck or
breast, and in_ the
Crook-billed Plover of
New Zealand there is
a most interesting mod-
ification of this ap-
parent ornament. This
bird feeds by running
rapidly around boulders
and inserting its crook-
ed bill beneath them

to obtain the insects
Fic. 249.—Gyrfalecon. Aggressive coloration Which compose its diet.
in an Aretie Hawk. :

The pectoral ring of
black, instead of being complete, is said to be often less
developed on the left-hand side. Buller accounts for this
fact by arguing that that side of the bird is much more
exposed to danger, as it continually scurries about the boul-
ders, keeping always to the right, and thus the side next
to the stone needs no protective colouring; and so we
find this one-sided development of the band. How much,

The Body of a Bird

ee:

ws)

in this and in many other so-called protectively coloured
birds, other factors, such as the direct effect. of hight on

Fig. 250.—Snowy Owl.

Aggressive coloration in an Arctic Owl.

the plumage, enter into the causation, can only be solved
by future thorough investigation.

Albinos are occasionally found among widely different

214 ashe bind

9)

Families of birds; but white blackbirds and such freaks
of Nature have but shght chance for life when keen-eyed
hawks are ever on the lookout, and owls are alert for
every tell-tale plume. Again and again hawks have been
known to single out white or whitish birds from a number,
making them the object of attack. When any species
of bird, through change of habit, absence of enemies, or
any other cause, is able to increase greatly in numbers,
albinism is likely to occur more frequently. A good ex-
ample of this is to be found in the naturalized English
Sparrows of our cities and towns, among which a remark-
able number with white feathers, or even with the entire
wings and tail white, are to be seen. This is one of
Nature’s remedies to reduce the excess number, all need
for protective colours having disappeared in the new
environment of these birds. We may be certain that if,
by any fortunate means, hawks or shrikes can be in-
duced to live within the limits of the cities, the albinistic
individuals will be the first to fall victims.

Black phases of plumage occur among some birds,
and a double colour-scheme is found in the common
Sereech Owl,—red and gray individuals being often found
in the same brood, the two phases existing independently
of age, sex, or season.

A vast field for future study and investigation lies in
the meanings of the differences in colour between the
sexes, and in the young birds from both. A hint of the
value of ultimate results in this field (which is without
the scope of this book) is to be found in our young Ameri-
‘an Robin, whose lower parts, from throat to flanks, are

‘oseunyd Surpoorq [NJ UL sjotso] AMOUG—'"[Gz “SIy

Fig. 253.—Fallow Deer fawn one day old.

BOTH SHOWING SPOTS WHICH ARE ABSENT IN THE ADULTS.
316

The Body of a Bird 27

thickly spotted. This gives a clue to the coloration of its
ancestors,—birds probably resembling our Wood Thrush,
and lacking the rufous, immaculate breast of the parents.
We find a similar condition existing among many deer,
whose young are spotted, entirely unlike the brown coats
of their parents.

Fig. 254.—Nestling Turkey Vulture. (T. H. Jackson, photographer.)

In many cases the colouring of the downy young is
the opposite of the adult, as in the Turkey Vulture, the
nestling being clad in down of purest white, and ultimately
moulting into the blackish plumage of the parent birds.

It would be out of place in this volume to speak further
of the wonderful colours which the Class of birds, as a

318 The Bird

whole, exhibits, or of the beautiful plumes which, as
in the case of the Snowy Egret, are assumed only during
the season of courtship. The great majority are now
explained either as decorations to charm the female, or
as mere by-products of the vitality of the bird, according
as to whether one believes in a greater or less degree of
esthetic appreciation among birds. When we consider
the nervous, high-strung natures of birds and realize with
what ease they are thrown into what seems a kind of
trance, it seems unnecessary to credit them with too great
an appreciation of pure beauty. The repetition of many
similar bright spots, as, for example, the eyes of a pea-
cock’s train, may well serve to attract and hold the atten-
tion of the female; while the antics and sounds which
many birds bring into play in courtship may appeal in
some more directly psychic way than we know. That
birds do have a certain appreciation of beauty and _ har-
mony there can be little doubt. When we remember the
jarring discords and clashing tints in which a human
savage takes delight under the name of music and beauty,
we should be very willing to admit some degree of
appreciation to the demure Impeyan Pheasant hen which
chooses among her suitors, clad each in hues such as
artist could never imitate; or the fair Hermit Thrush,
which selects a singer from the incomparable choir of her
serenaders. I believe that future field study and experi-
ments with caged birds will reveal much that we do not
suspect in regard to the causes of coloration.

CHAPTER XIII

WINGS

ae
Py YA,

ie EFORE the front limbs of any creature had be-

Rj come adapted to fight through the air, they

| served to assist the hind legs in locomotion on
the ground, and, ages before this, a many-rayed mem-
brane stretched across the primitive fin, aided its owner
in cleaving a way through the water. So, like a palimp-
sest, if we look beneath the outer covering of feathers,
we see, in the wing of the modern bird, the three fingers
hinting of widely different ancestral habits.

The general structure and appearance of the bills, the
feet, and wings of various birds is the result of a function
characteristic of each. The bills are used to procure
food, the feet to walk or perch, and the wings to propel
the bird through the air. But, as we have seen in the
case of the bill, these organs are put to many other uses
besides the one for which they were primarily adapted.
This is only what we should expect when we consider the
relative high position which avian intelligence holds, and
the remarkable extremes of environment with which
these structures—bill, feet, and wings—are brought into
close touch.

The photograph of the young heron’s wing shows
319

320 The Bird

the two principal divisions into which the flight-feathers
are divided: the primary feathers, or those growing on
the fingers and wrist-bones, and the secondaries which
sprout from the bone of the forearm. The several feathers

Fig, 255.—Young Green Heron, showing various divisions of wing-feathers,

supported by the thumb are also very distinctly shown.
When a wing is greatly elongated it is the secondary
feathers which are increased in number, the two extremes
being represented by the hummingbird and the albatross,

Win

gs 321

each of which has ten primaries, but the one has six and
the other forty secondaries (Figs. 259, 260).*

Let us observe the wings of living birds in the woods
and fields or in a zoological park and see what of interest
we can discover. We have all noticed how well adapted

iti,

as als

Fig. 256.—Great White Heron stretching its wing. (E. R. Sanborn,
photographer. )
to its owner’s many uses is the foot of a parrot—how
hand-like it is;—and now if we again watch one of these
birds we will see that, as we should expect from its being
* Extremes in regard to the number of primaries are the three flightless

groups, penguins with approximately 36, ostriches with 16, and cassowaries
with perhaps but 2 feathers which can be called primaries.

222 The Bird

so much like a human hand, it is not a good walking foot.
When a parrot is in great haste to reach some object
on the ground without flying, it waddles awkwardly, ‘“ toe-
ing in” and frequently tripping up. When this happens,
out fly the wings, and, as if reverting to some clouded
memory of the habits of its pre-Jurassic forefathers, it
walks on all jours. A young Canada Goose, when climb-
ing about its nest, or a Fish Hawk in the downy nestling

Fic. 257.—Nestling Catbird, supporting itself, lizard-like, on all four limbs.

plumage, does the same thing, and young birds of many
species, when too young to stand, push themselves along
the ground with feet and wings; a young grebe doubtless
being the most accomplished in this motion. In certain
adult birds, such as the swan, Osprey, Turkey Vulture,
and the various ostrich-like birds, there are perfect claws
at the tips of one or more of the skin-bound wing-fingers.
These are true relics of a lizard-handed ancestry.
Before going on to find the more curious uses to which

Wings 323

wings are put, we will look at certain birds whose flight
can teach us something interesting. If a pheasant in
captivity becomes suddenly alarmed, or its spacious aviary
tempts it to rise from the ground, we hear a great whirr,—
broad, round-curved wings buzz in a half-circle of haze
around the bird and it is off like a shot to the farther

Fig. 258.—Young Green Heron, reaching out with its wing toward a branch which
it hooked with the sprouting feathers, and steadied itself for a new foothold.

end of the runway. It may go right through the sash
and pane of glass—such is the impetus gained in this mad
rush. ' Fortunate it is for these birds, and for their cousins,
the grouse and quail, that they can thus spring up and
escape from foxes and other enemies to whom their scent
so often betrays them. If the pheasant were at liberty,

324 ihe Bisd

we should see that this burst of speed would end in
a long, slowly descending sail, and with wings held mo-
tionless the bird would sink into the nearest cover. It is
most interesting and exciting to walk through a field
of tall grass where many pheasants are feeding, and see
them shoot up to the right and to the left; a hen with
her brood waiting until one’s foot is almost upon her
before booming away.

In a zoological park we may observe another extreme
of bird flight by watching a condor take wing. He waits
until a breeze is blowing and then, facing the direction
from which it comes, he runs with all his might, flapping
awkwardly until sufficient headway 1s gained, when strong
downward strokes carry him to the perch he has selected.
We may, at first thought, pity him, but if we could see
him soaring for hours high among the cloud-peaks of his
native Andes, we should instead pity the low-flying pheas-
ant.

These two examples—the pheasant and the condor—
show what differences may be found in flying birds, and
as we examine the wings of other species, we find that
each is perfectly adapted to the wants of its owner. A
wing is a most delicately adjusted organ; its feathers
being just strong enough to lift the body of its owner
into the air, and, like evenly balanced scales, the least
excess or lack of use is quickly met by a reaction. Com-
pare the Black Skimmer of the seas, which is only eighteen
inches in length, but whose long wings expand four feet,
with a stubby-winged quail or grouse.

There are some species of flycatchers with wonderful

Wings 2255

Fic. 259.—Wing of Hummingbird with 16 flight-feathers. 1/2 natural size.

Fig. 260.—Wing of Albatross with 50 flight-feathers. 1/28 natural size.

326 The Bird

powers of flight. When perched on a branch, they can
evade the shot from a shot-gun. It is said that one will
sometimes ‘chase another for three or four minutes,
doubling, turning, twisting, and shooting, now brushing
the grass, now rising to a height of at least two or three

Fig. 261.—Condor about to take flight.

hundred feet, and all the movements so rapid that the
eye can scarcely follow them; and at the end of it would
go back to his own chosen weed-stalk, apparently without
a feather ruffled.”

Any attempt to explain the mechanics of the way of a
bird in the air would at most be imperfect in the present

Wings 327

state of our knowledge. Suffice it to say that if we will
think of a bird flying through the air when we ourselves
are swimming in the water, we can realize the achievement
more vividly than from any amount of descriptions and
diagrams.

The under surface of a bird’s wing is concave; and

Fic. 262.—Wing of living Golden Pheasant; rounded and curved for short,
sudden flight.

while the front edge is rather straight and firm, the hinder
rim of the feathers is soft and yielding; thus a downward
stroke both raises the bird or holds it sustained at the
height already reached and urges it in a forward direction.
Similarly we push our hollowed palms backward and pro-
pel ourselves through the denser medium of water.
The manner of flight varies greatly in different birds

328 The Bird

and is often so characteristic that when too far off to dis-
tinguish the colour of its plumage, or for its notes to
reach our ears, the bird may be recognized by the undu-
lations or the directness of its flight. No one who has

ever visited the tropics can have failed to admire the

Fig. 263.—Wing of living Herring-gull; long and narrow for slow,
continuous flight.

soaring vultures,—spots of black swinging across the
heavens or swooping low in grand arcs over the palms.
Gulls and their kindred fly steadily with continuous wing-
beats, which, however, are much less rapid than in the
flight of a duck or a parrot. Many sparrows have an
abrupt jerking motion, hitching themselves over trees

Wings 229

and bushes; while goldfinches and woodpeckers swing
past in long undulations, a loop and a catch, a loop and
a catch,—with wings wide extended, then quickly closed.
Hummingbirds have a remarkably insect-like flight; the
rapid reflex whirr of the wings holding them perfectly
still, poised in mid-air.

When ornithologists think that they have formed a
correct theory of flight and that, given such and such
conditions, certain results must follow, such a bird as the
Crested Screamer soars into their mental atmosphere and
upsets every calculation. Such a bulky and short-winged
bird, by all good “rules” of flight, should confine itself
to short laboured efforts, barely skimming the low bushes
of its South American haunts! But it refuses to be thus
limited. Of this species it is said: ‘The Screamer is a very
heavy bird, and rises from the ground laboriously, the
wings, as in the case of the swan, making a loud noise.
Nevertheless it loves soaring, and will rise in an immense
spiral until it wholly disappears from sight in the zenith,
even in the brightest weather; and considering its great
bulk and dark colour, the height it ultimately attains
must be very great. On sunny windless days, especially
in winter and spring, they often spend hours at a time
in these sublime aerial exercises, slowly floating round
and round in vast circles, and singing at intervals. How
so heavy and comparatively short-winged a bird can sus-
tain itself for such long periods in the thin upper air to
which it rises has not yet been explained.”

I find in my journal the following account of a flight
of vultures which we saw in a desolate alkali desert in

220 The Bird

western Mexico: ‘One of the most wonderful exhibitions
of bird-flight came to us to-day as we left the alkali plain
and rode among the mesquite scrub. A confused mass
of black appeared in the air which, as we advanced, re-
solved itself into hundreds of individual black specks.

Fic. 264.—Crested Screamers.

The atmosphere was so deceptive that what at first seemed
to be a vast cloud of gnats close at hand, was soon seen
to be a multitude of birds, and when a quarter of a mile
away we knew them to be vultures. Three burros lay
dead upon the plain. This we knew yesterday, and here
were the scavengers. Never had we seen Vultures more

Wings 331

numerous or in more orderly array. A careful scrutiny
through our glasses showed many scores of Black and
Turkey Vultures walking about and feeding upon the
carcasses of the animals, and from this point there ex-
tended upward into the air a vast inverted cone of birds,
all circling in the same direction. From where we sat
upon our horses there see ed not one out of place, the

Fic. 265.—Turkey Vulture soaring.

outline of the cone was as smooth and distinct as though
the birds were limited in their flight to that particular
area. It was a rare sight, the sun lighting up every bird
on the farther side and shadowing black as night those
nearest us. Through one’s partly closed eyes the whole
mass appeared composed of a myriad slowly revolving
wheels, intersecting, crossing each others’ orbits, but never
breaking their circular outline. The thousands of soaring

222 The Bird

forms held us spellbound for minutes before we rode
closer. Now a change took place, as gradual but as sure
as the shifting clouds of a sunset. Until this moment
there was a tendency to concentrate at the base of the
cone, that portion becoming more and more black until it
seemed a solid mass of rapidly revolving forms. But,
at our nearer approach, this concentration ceased, and
there was perfect equilibrium for a time; then, as we
rode up a gentle slope into clearer view, a wonderful
ascent began. Slowly the cblique spirals swing upward;
the gigantic cone, still perfect in shape, lifts clear of
the ground and drifts away, the summit rises in a
curve which, little by little, frays out into ragged lines,
all drifting in the same direction, and before our very eyes
the thousands of birds merge into a shapeless undulating
cloud which rises and rises, spreading out more and more
until the eye can no longer distinguish the birds which
from vultures dwindle to motes, floating and lost among
the clouds.”

Concerning the greatest extent of wing which any
bird possesses, there are records of a Wandering Albatross
which measured fourteen feet from tip to tip, but the
condor of South America exceeds this, certain individuals
having an expanse of fifteen feet.

Having considered the finest flyers among the birds,
we may now begin to go down the scale and see what
has happened when certain species have deliberately dis-
carded the wonderful power of flight with which Nature
has provided them and for which human inventors are
so earnestly striving. But always we must remember

Wings 322

that this restriction and disuse have been to subserve some
good and useful purpose,—food perhaps being more easily
obtained, or enemies avoided by terrestrial or aquatic
locomotion. Functional radiation, working always for
the good of the race, once gave to all birds the power of
traversing the globe, passing high over sea and land; but
later this was withdrawn, until in some cases their wings
have become a mockery. The wings of the Owl Parrot
of New Zealand are of full size, but the muscles are so en-
eased in fat that they are useless for flight. These par-
rots feed on ground-mosses, and being nocturnal and
tnerefore having few enemies, their only use for wings
is occasionally to sail gently to earth, like a Flying Squir-
rel, from the trees in the hollows of which they some-
times roost. For this purpose their flabby muscles are
perfectly suited.

The Spotted Tinamou of South America is one of a
number of birds which have not quite lost the power of
flight, but in which, as in the first attempts of a young
bird, almost no control is possessed over the direction
or height of their flight. In fact, the condition is much
the same as that of a man in an ordinary balloon, who
is at the mercy of the wind and the sustaining power of
the gas. Hudson gives the following interesting account
of this bird: “It is an exceedingly rare thing to see this
bird rise except when compelled. I believe the power
of flight is used chiefly, if not exclusively, as a means of
escape from danger. The bird rises up when almost trod-
den upon, rushing into the air with a noise and violence
that fill one with astonishment. It continues to rise

334 The Bird

at a decreasing angle for fifty or sixty yards, then gradu-
ally nears the earth, till, when it has got to a distance of
two or three hundred yards, the violent action of the wing
ceases, and the bird glides along close to the earth for
some distance, and either drops down or renews its flight.
I suppose many birds fly in much the same way; only

Fic. 266.—South American Tinamou.

this tinamou starts forward with such amazing energy
that, until this is expended and the moment of gliding
comes, the flight is Just as ungovernable to the bird as
the motion of a brakeless engine, rushing along at full
speed, would be to the driver. The bird knows the danger
to which this peculiar character of its flight exposes it

Wings BiG

so well that it is careful to fly only to that side where
it sees a clear course. It is sometimes, however, compelled
to take wing suddenly, without considering the obstacles
in its path; it also often miscalculates the height of an
obstacle, so that for tinamous to meet with accidents
when flying is very common. In the course of a short
ride of two miles, during which several birds sprang up
before me, I have seen three of these tinamous dash
themselves to death against a fence close to the path,
the height of which they had evidently misjudged. I
have also seen a bird fly blindly against the wall of a
house, killing itself instantly. A brother of mine told
me of a very curious thing he once witnessed. He was
galloping over the pampas, with a very violent wind blow-
ing in his face, when a tinamou started up before his
horse. The bird flew up in the air vertically, and, beat-
ing its wings violently, and with a swiftness far exceeding
that of its ordinary flight, continued to ascend until it
reached a vast height, then came down again, whirling
round and round, striking the earth a very few yards
from the spot where it rose, and crushing itself to a pulp
with the tremendous force of the fall. It is very easy to
guess the cause of such an accident: while the tinamou
struggled blindly to go forward, the violent wind, catch-
ing the under surface of the wings, forced it upward, until
the bird, becoming hopelessly confused, fell back to earth.
I have often seen a swallow, gull, or hawk, soaring about
in a high wind, suddenly turn the under surface of its
wings to the wind and instantly shoot straight up, appar-
ently without an effort, to a vast height, then recover

The Bird

336

itself and start off in a fresh direction.
when launched on the atmosphere, is at the mercy of

The tinamou,

Fig. 267.—Feathers of Ostrich and Condor.

chance; nevertheless, had this incident been related to

me by a stranger, I should not have recorded it.”
So in this bird we have a most rare and suggestive

instance of a condition where an important organ is actu-
ally in process of losing its primary function, and in so
doing becomes a source of danger to the bird.

In the waters of the sea near the Falkland Islands is
a duck known as the Steamer or Side-wheel Duck. The
young birds of this species are good flyers and whistle
through the air on strong pinions. But maturity, instead
of bringing, as in most birds, a fully perfected power of
flight, takes from them what they have, and after the first
moult they are helpless to rise above the great waves
of their haunts. However, this duck finds another use
for its wings, and the stiffness which forbids their being
used in the air makes of them bladed paddles which are
all the better for their lack of flying power, and with wings
and feet these birds make remarkable speed through the
water—‘‘twelve or fifteen miles an hour”—and they are
thus able to live out their lives in safety. Thus the study
of the flight of these birds carries us a step farther than
the tinamou, with the all-important difference that, in this
case, loss of the primary function is compensated by a
direct adaptation of the wing to the new conditions of life.

In the ostriches and their near allies the extreme reduc-
tion of wings is to be found, and yet in the true ostriches
and rheas the great expanse of soft feathers is a consid-
erable help to the birds when running at full speed, acting
as a sail or aeroplane to assist in the onward motion.
But the contrast between a loose, open-work feather from
the wing of one of these birds and a compact, firmly vaned
plume from a condor’s wing is very striking. The casso-
wary has from four to six flight-feathers, but, far from

338 The Bird

being of any use in supporting his great frame, they are
so vestigial that they look exactly like black slate-pencils
projecting in a row from the little fleshy flap which con-
tains the evidence of his full-winged ancestors

A full-grown ostrich was once imported to this country
from Abyssinia. When the native keepers learned that the
bird was to be sent away, they surreptitiously plucked the

Fig. 268.—Wing of Cassowary, showing degenerate flight-feathers.

poor creature, until but few feathers were left on its body.
The bird was tame, and, by keeping its attention busy
with a basket of carrots, I inserted a piece of white card-
board beneath one of its skinny, denuded wings and se-
cured an excellent photograph (Fig. 269). This clearly
shows the black, curved claws on the first two fingers.
In this same bird I noticed that occasionally the crooked
forearm would be raised, the claw at the end of the wing

Wings 339
drawn up, and the ostrich would scratch its body or head

with this interesting finger relic! When the plume feathers
of the wing are full grown, the foot or leg is thus used,

Fig. 269.—Wing of Ostrich, showing reptile-like claws.

the head or neck being rubbed against its roughened
scales.

The Great Auk—a sea-bird which has become extinct
within the last sixty years—was without the power of
flight, and its living allies, the Razor-billed Auks and
Murrelets, have very small wings and are rather weak

340 ihe e bird

flyers. The latter, in fact, use their wings, the feathers
of which have very stiff and long quills, as much in diving
under water as in flying in the air, and, strangely enough,
they are said to swim breast upward, propelling themselves
by means of both wings and feet. Grebes, too, are very
weak of wing, and these birds cannot rise from level ground,
no matter how much of a fluttering run is taken, and even
in the water much splashing and headway are needed.
Perhaps the most wonderful birds in the world are
penguins, and the strangest part of these strange birds
is the wing. There is no doubt that they are descended
from birds which possessed the power of flight; but the
penguins have discarded this gift and have returned to
a life in the sea, whence in long ages past their forebears
had crawled out upon land. As in the ostriches, the
relics of flight-feathers have increased greatly in number,
but have become small and scaly, and the wings have
virtually become flippers or fins. Instead of a given num-
ber of feathers, divided into well-marked series, the pad-
dles of a penguin are covered thickly with small feather-
seales, and the rigidity of the wings, together with the
rotary movement at the shoulder-joint, make the propeller
of a ship an apt simile. The colour of the feather-scales
on the upper side of the wing is dark, like the back of
the bird, but those on the under side have run rampant,
the white and black being mixed irregularly, not corre-
sponding even in the two wings of an individual bird.
The outline of the wing is exactly like that of a shark’s
fin, the flatness and breadth including even the bones,
while (also like a fin) all of the bending quality of a wing

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342 The Bird

is lost,—all the flexibility of wrist and elbow. With
these propellers the penguins fly through the water, with
almost the identical motion of a bird in the air. Though
it is usually asserted that the wings move alternately,
this was never the case with a pair of Black-footed Pen-
guins which I carefully observed. As regards the speed
of swimming, I found that one of these birds, though in
bad health at the time and so weak that it could take
but a few steps on land, was able to progress under water

Fic. 271.—Penguin swimming with its wings.

considerably faster than a man could walk an equal dis-
tance on land. The greatest speed was about seven miles
an hour; but I have no doubt that when in full health
this rate can be far surpassed.

Surely no fairy-tale can match the marvellous evo-
lution of a penguin’s wing: fin becoming hand, hand
evolving into wing, and wing reacting to the environ-
ment of long ago and again taking on all the outward
characteristics of a fin!

ie =f
Wings 343

Fic. 273.—Wing of Black-footed Penguin, side view.

lic. 274.—Wing of Black-footed Penguin, under surface of wing.

ALL FROM THE LIVING BIRD.

344 The Bird

We have seen how wings guard their owners from the
risk of sudden surprises from enemies, and now let us
observe how, in a sleeping bird, the tender nostrils and
eyes are protected against cold and other dangers. Birds
do not put their heads under their wings, but behind them,
often using the shoulder-feathers as cover. It is inter-

Fig. 275.—Green Heron with head behind wing.

esting to see how many birds, from all quarters of the
earth, have this same habit. The pelican, however, de-
parts from this custom and snuggles his tremendous bill
between the feathers in the centre of his back, and flops
both wings up so as completely to cover it. Even the
cassowary vainly tries to tuck his bill behind his absurd
wing. His smaller wing-coverts are mere soft, loose hair-

Wings 345

like shafts, while the larger quills, as mentioned before,
are reduced to four or six horny sticks.

If we watch an owl flying about its cage at night, or
if, in the woods, an owl passes near, his shadow in the
moonlight is all that warns us of his presence. The feathers
of an owl’s wing are soft and downy, and the bird moves
as lightly as a falling leaf. Little warning, except by

Fic. 276.—Trumpeter Swan asleep.

sight, the mice and birds have of its deadly presence.
Few birds have a flight as noiseless as that of owls, and
in some species the motion of the wings makes, as we
noticed in the pheasant, a very audible sound. When a
widgeon rises from the water, the whistling of its quills,
so dear to the ears of the sportsman, is quite shrill. A
dove claps its wings together above its back while gain-
ing impetus for flight. The characteristic sound from
which a hummingbird takes its name is well known.

346 The Bird

When wild geese and swans nest in captivity, their
wings are put to most excellent use as weapons of de-
fence, and of course this use must come into play fre-
quently when nesting in their native haunts. I have
seen a man knocked breathless by a Canada gander who
thought his nest in danger. When preparing for attack,
the bird approaches hissing, with head stretched low along
the ground, and suddenly, without warning, launches

Fic 277.—Trumpeter Swan preparing to attack an intruder with its wings.

itself straight at one’s breast and, clinging with bill and
claws, beats a tattoo with the hard bend of its wings.
One is not likely to forget such a drubbing for a long
time. The wings of certain birds are armed with weapons
of offence, such as the Spur-winged Goose, Jacana, Plover,
and Screamer. The Spur-winged Goose is a really danger-
ous antagonist and can strike incredibly strong blows,
bringing the sharp spur to bear with telling effect. These

Wings RAT,

spurs are not claws, but correspond in structure to the
ordinary spurs on the legs of a rooster.

The great heavy-headed and heavy-bodied hornbills
fly with great effort, and it is said upon good authority
that when passing low overhead they make a noise like
a steam-engine. Although not strictly within the prov-

Fic. 278.—Spur-winged Goose.

ince of this volume, mention should be made of the inten-
tional use of the wings as instruments of sound,—to at-
tract the females, as in our Ruffed Grouse and other birds.
A little Bush Warbler of Africa has indeed never been heard
to utter a note, seeming to depend upon an occasional
whirr of wings, in lieu even of the usual call-note or chirp.

348 The Bird

In the woodcock we find the vane of the three outer
primaries of the wing remarkably narrowed and stiffened;
probably a direct adaptation for the production of the
high, whistling sound which plays so important a part
in its aerial courtship performance.

Fig. 279.—Wing ornaments of Twelve-wired Bird of Paradise.

As upon all other parts of the bird’s body, we find
beautiful decorations upon the wings—inexplicable unless
we are willing to credit the females with appreciation of,
or at least a reaction to, these beauties. Otherwise we
know not the uses of the brilliant wing-mirrors of ducks,
or the scarlet wax-like tips of the Cedar-bird’s feathers,

Wings 349

or the bizarre decoration of the Twelve-wired Bird of
Paradise.

A strange appendage is found in the wing of the West
African Goatsucker. Conspicuous enough when the bird
is flying, it is wonderfully protected when the bird rests,

Fic. 280.—Wing of Woodcock.

as is its wont, upon the ground among tall, feathery-
topped grasses. From each wing a single long feather
extends in an upward direction, almost bare of barbs
for most of its length, but tipped with a mottled, loose-
vaned tuft which corresponds very perfectly with the
flower-heads of the grasses among which it lives. As

350 The Bird

this decoration, so protective and yet so beautiful, is
assumed only during the breeding season, its use is doubt-
less to aid in attracting the attention of the females.

Herons and other birds make still another use of their
wings and the long, tough flight-feathers: as shields for
parrying the blows of a rival, or to catch the poison of
a snake when it strikes and thus give an opportunity
to seize and despatch the reptile. Two Snowy Egrets
will sometimes fence with each other in play, and use
beak and wing as a soldier would use sword and shield.

I once saw the wing of a bird used in an entirely original
manner—a use peculiar, doubtless, to this individual.
Several spoonbills suffered severely from the frozen
ground upon which they were forced to stand, and no
method of relief was found, except by one of their num-
ber, who every night stretched one wing beneath him,
drew up one foot deep into his plumage, and with the
other stood upon the tips of the primaries.

Much might be written concerning the swiftness of
birds’ flight, but so much of exaggeration has entered
into estimates of this kind that it would be difficult to
select facts and figures of indisputable verity. However,
it may be asserted as at least within the actual facts that
ducks can attain a speed of ninety miles an hour. An
apparently well-authenticated record of a swallow’s flight
at Antwerp is as follows: A gentleman arranged a flight
of homing pigeons from Compiégne to Antwerp,—a dis-
tance of one hundred and forty-eight miles,—and with the
pigeons he liberated a swallow captured on her nest under
the eaves of his house in Antwerp. The swallow, which

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ipher. )

c

, photogr

bird of prey. (Baynes

a

ot

wing

showing typi

Osprey

281.

Fig.

252 the Bird

was marked for identification, covered the distance in
one hour and eight minutes, or at the extraordinary speed
of about two miles and three hundred yards per minute.
The first pigeon to arrive took four hours and a quarter
to make the journey.

Fig. 282.—Terns in flight. (Photograph provided by the American Museum
of Natural History.)

CHAPTER XIV

FEET AND LEGS

e|ARRIED far and wide by the power of flight,

33] no two species of birds have exactly similar
environments. When the wings cease their la-
bour and are folded close to the sides, the bird must depend
upon its feet to carry it to its food and to keep it out of
danger, whether its footing be in a tree-top or on a cliff;

in shallow water or on the deep; in mud, sand, or snow.
Thus we realize the need for many varied adaptations
in the way of feet and legs.

Although birds are descended from five-toed ancestors,
yet no living wild bird, and none of those which we know
only as fossils, has more than four toes on each foot. The
disposition of these toes—four, three, or two, as the
case may be—is always in accordance with the habits of
the bird.

The most common type of avian foot is that in which
the arrangement is of three toes in front, with the fourth,
corresponding to our great toe, pointing backward. This
was the arrangement in our first bird, the Archwopteryz,
and for perching birds, as well as for many others with
very different habits, it has stood the test of six millions

353

354 The Bird

of years, or thereabouts, since the days of its venerable
prototype.

This is the kind of generalized organ which, we should
think, would be able to cope with changes in the bird’s
surroundings more successfully than any other; but that
this theory fails when put to the test is proved by the
variety of specialized toes and legs which we may observe

Fig. 283.—Foot of Alligator.

among the birds on the earth to-day. Indeed, in the
variety of uses which they subserve, the feet and legs
of birds are second only to the bills.

A classification of birds, generally accepted for many
years, was based on the uses of the feet, or mode of loco-
motion. In this scheme birds were divided into runners,
scratchers, climbers, swimmers, perchers, etc. Although

Feet and Legs 2155

these, as exact divisions, have long since been abandoned,
yet it is worthy of note that even in the most modern
classifications many of these groups hold good in the
main, although based on other and more fundamental

Fra. 284.—Foot of Brown Pelican.

characters. Examples of these are the ostrich-like birds,
or runners; the fowl-like birds, or scratchers; and the
Passeres, or perching birds. But there is no doubt that
several unrelated groups have independently acquired the

356 The Bird

specialized type of foot which is adapted to climbing or
to swimming, so that any classification based on such
similarity of locomotion is obviously false.

From the tiny limbs of a hummingbird to the gigantic
shanks of an ostrich, the legs of birds, with a very few
exceptions, are covered with scales, most emphatic re-
minders of the reptilian ancestry of both these extreme
forms of feathered life. The real foot of a bird, as the
term is used in speaking of other animals, extends to the
backward-bending joint, or heel. Part of the lower leg

Fig. 285.—Foot of Raven.

is thus concealed by the feathers and skin, while the upper
leg, or thigh, is generally wholly within the body, as we
saw in the chapter treating of the framework.

As before, we must call on the crow, in many respects
standing very near the top of the scale of bird life, yet
which has found it good to hold to the typical bird’s foot.
And indeed it serves him well, for with it he can walk on
snow or ice; wade in shallow water; perch in trees; scratch
or claw the ground and hold down a crab’s carapace,
while he extracts the edible portion. Not only this, but
he can hop like a sparrow or walk like a lark at will.

Feet and Legs 267

We have hardly to leave the group of birds to which
the crow belongs to find dozens of interesting and unex-
pected adaptations of the feet to unusual habits. For
example, the Rhinoceros-birds of Africa attach them-
selves to some of the larger mammals, such as buffalos,
rhinoceri, or antelopes, and spend much of their time
in freeing these animals from troublesome ticks and other
parasites. The power which these birds possess in their
feet and legs is remarkable. Millais says of them: “The
prehensile power of the claws is, as I found by experience,
so great that when a dead bird which had grown stiff
was thrown on to the back or sides of an ox, so that the
feet touched the animal’s hide, the claws held fast at
once and could not be withdrawn. It is most interesting
to note the way in which a party of these birds will move
about on the body of a horse or ox, searching every part of
him as they run or hop over it in the most lively fashion.
At the risk of being accused of telling a traveller’s yarn,
I must state the fact that they can hop backward quite
as well as forward, and they often make long drops down-
ward from the shoulders to the foreleg, or down the side
of the animal whose coat they are engaged upon. It
is quite immaterial to them how or in what direction
they move.”

No hard and fast laws can be laid down, but it is gener-
ally the rule that birds which are especially at home in
the trees usually hop with both feet simultaneously
when on the ground. Ground nesters and feeders, such
as the Meadow Lark, Bob-white, and Vesper Sparrow,
usually walk or run.

358 The Bird

The great Order of perching birds (Passeres) shows to
what varied uses the typical foot can be put. All birds
of this Order have three toes in front and one behind,
and there is scarcely a place on the globe to which these
birds have not adapted themselves; and recently too,
as would seem probable from the similarity of the foot-
type running through all.

This very foot holds much of interest too, if we con-
sider it from another point of view. Many apes and
monkeys, and we ourselves, still have the five fingers and
toes which we suppose was the number originally devel-
oped upon the limbs of the vertebrate prototype; while
horses and deer—animals much lower in the scale of
life—have had the five original digits reduced to one
or two. So among birds the ostriches and some other
low forms have become extremely specialized in the same ~
respect, possessing but two or three toes, while those
birds which in mental and physical attributes excel all
others of their Class are still more reptilian, and thus
more primitive—more Archzeopteryx-like—in possessing a
larger number of digits—four. Thus when we _ speak
of an animal as high or low in the scale of life, we must
carefully distinguish between mere specialization and
actual upward progress, mentally or physically, toward
some ideal goal. The branch of a tree, which stretches
horizontally farthest from the parent trunk, is not likely
to be the one which reaches upward high enough to catch
the first rays of the morning sun.

The majority of the Passeres are arboreal and the
strength of the tiny tendons which run down the leg and

Feet and Legs 359

through each toe is sufficient to clasp and unclasp a thou-
sand times a day, and to hold and balance the bird on
whatever bending twigs or wind-blown foliage it chances
to alight. In this matter of perching the hind toe plays
an important part, so much so that when the necessity
for grasping ceases, this digit begins to wax flabby and
weak and often becomes reduced in size.

Fig. 286.—Nuthatch on tree, Fie. 287.—Nuthatch clinging to a gloved
clinging upside down. hand. (Bowdish, photographer. )

The creepers, [Iig. 240, are passerine woodpeckers
in habit and forever wind their spiral paths about the
tree-trunks. But the nuthatch is the marvel of the
whole Class of birds in this climbing ability. With no
support whatever from the tail, and without special
adaptation of toes, it defies all laws of gravitation and
creeps up and down or around the vertical trunks, as if
on a level surface. Never a misstep, never a slip, but

360 The Bird

each foothold as secure as if its feet were vacuum-
cupped.

In the swallows the feet are very small, having fallen
into disuse with the great increase of the power of flight.
Orioles and weaver-birds make occasional use of their
feet to hold a strand of grass or string which they are
weaving with their beaks into their elaborate nests, and
certain flycatchers pounce upon and hold their insect

Fic. 288.—Swallow, showing small size of feet.

prey as an owl grips a bird, or a jay clings to a nut; but
with the exception of a few such cases, the feet of perching
birds serve principally the function of locomotion.

As variation in habitat or haunt depends so much upon
the power of locomotion, it will not be out of place to
mention here, in rather more detail than usual, a splendid
example of adaptive radiation which we can all verify for
ourselves.

There is no more wonderful fact in Nature than the way

Feet and Legs 361

in which birds have inherited the earth. When we realize
the immense advantage which the power of flight gives
to them, we do not marvel at this remarkable distribu-
tion, but the more we think about it the more wonders
appear. The utmost efforts which man has made to
reach the North Pole have shown flocks of birds winging
their way still farther to the North, heedless of the ter-
rible cold. In the heat of deserts and the sweltering
jungles of the tropics, birds find congenial haunts and
abundant food. Thousands of miles out at sea, on the
highest mountains, and even in dark underground tun-
nels; the whole day—twilight, midnight, and dawn,—
all have been conquered by these tireless, energetic feath-
ered ones.

When we see a large collection of birds, we can appre-
ciate how they are adapted to such varying conditions
of temperature, of moisture, of light, and of altitude.
Their bodies, wings, legs, feet, and tails—in fact every
organ and member is of all sizes and shapes, and shows to
what condition of life the individual is suited. But when
we come to know birds better, and we realize that there
are wheels within wheels, that behind these very evident
divisions into I’amilies and Orders there are lesser groups,
among the members of which the competition is no less
keen, we look for and find gentler gradations and adapta-
tions which, in their way, are more to be wondered at
than the larger, more radical differences; for these birds
have changed their habits and haunts without waiting
for Nature to adjust their wings or their feet. They have
taken the initiative as it were, and, like a man of letters

362 The Bird

who is suddenly forced to work at some arduous manual
labour, they have entered on new ways of life—ways to
which their structure seems but ill adapted, and yet,
by the very daring of their efforts, they have won success.

The great-grandfathers, many times removed, of the
modern Families of birds lived lives which were much
broader and more generalized than those of their descend-
ants of to-day, and it is this variety, this seeking of new
opportunities and overcoming of new difficulties by the
feathered sons, which makes the study of birds so fascinat-
ing a pursuit.

Let us follow the diverging paths of the later gen-
erations of some of our own birds. Take the wood-
warblers of our own country. The only way we can
imagine what the earlier ancestors of the warblers were
like is to make a composite of the whole Family. All
its members are tiny, delicate birds which feed on the
smallest insects, their bills are slender and pointed, and
their feet and toes like the finest wire. Yet, far from
waiting for Nature to alter these delicate organs, they
have struck out boldly for themselves and, to avoid a
fatal competition with one another, have varied their
methods of hunting and the limits of their preserves so
successfully that a dozen may live in close proximity
and yet never poach on each other’s domains.

Our well-known little Maryland or Northern Yellow-
throat has chosen the low bushes of a marsh as his sphere
in life, and, although he has hidden his face behind a black
mask, vet he is a true warbler, and the blood of his fathers
forces him up now and then into some exposed position,

Feet and Legs 363

where he bursts into a joyous bubbling and warbling,
calling to his brethren of the tree-tops that, though his
haunts are changed, his heart is true to the clan. His
cousin, the Worm-eating Warbler, is tending in his direc-
tion, living in low bushes and in his habits drifting ever
marshward, where there may not be sufficient competition
to prevent his eventually sharing it with his more original
kinsman. The Yellow Palm Warblers, although more
conventional in their ordinary tree-top haunts, have de-
parted from ancient customs in their feeding habits.
They dine on the ground, then fly back to the trees; ob-
serving, like some humans, the traditions of their family
in the spirit, if not in the letter.

The brilliant Redstart clings even more closely to the
ancestral ideas of high trees, and cares little what kinds
he may find himself in; but he has a failing for water,
and if he may not descend, as have his two cousins men-
tioned above, yet he overlooks them and often swings
low through the air toward them. For in his feeding
habits he is one of the most radical of warblers. Has
he not seen the little green flycatchers in the woods, sit-
ting so lazily upon some favourite perch, and with an occa-
sional swoop snapping up an unfortunate insect? Why,
indeed, search all day for the tiny mouthfuls? Why not
wait for them to appear? So Redstart attempts fly-
eatching and with perfect success.

But the active blood which surges through his veins
will not allow him to assume the patient waiting tactics
of the genuine flyeatchers. He may imitate their meth-
ods of actual capture, bagging his game on the wing, but

364 DhesBire

he is still ever on the move, from twig to twig, from tree
to tree. Nevertheless, he has gained an advantage which
ensures to his race a long life; for in a tree whose foliage
and twiglets are being scanned with the microscopic glances
of his relatives, he gets more than the others by watch-
ing for the many insects which are alarmed at the dis-
turbance of the tiny hunters, and which flutter out in
the bright sunshine only to flutter straight down his
throat. Mother Nature has seen his efforts in the new
field with satisfaction, and has given to him a little re-
ward; for from either side of his mouth several stiff bristles
project, and many times, when he has misjudged the dis-
tance or the dodging powers of his prey, these little hairs
shunt the gnat or fly into his mouth.

The Myrtle Warbler is an expert catcher of flies, and
has in addition another string to his bow, which bids fair
to place him at the head of the list of new departures
in warblers. He has learned that bayberries are not only
an occasional welcome variety to the everlasting diet of
insects, but that a warbler can comfortably live upon
them when the cold has benumbed the little winged and
crawling creatures. So, instead of migrating south at
the first hint of winter, these hardy little Myrtle Warblers
sometimes remain with us throughout the whole season of
cold and snow.

A most daring departure from old-established prin-
ciples of the warbler clans is that of the Water Thrushes.
Ages ago, perhaps, we may imagine that some member
of this group, while drinking at a stream or pond, watched
the little bobbing sandpipers as they scurried past along

Feet and Legs 205

the brim, now wading in a short distance, then leaping
to a soft rim of clay, everywhere finding the most delicious
morsels abundant. A strange fascination took hold of the
tree-haunting warbler, and although perhaps you and
I would have said he was a very silly bird and that such
a thing as a warbler turning into a sandpiper was utterly
absurd, yet the little fellow and his descendants persisted.
Sandpipers and sandpipers only they wished to be, and
Nature has given them their wish.

Study the Water Thrushes of to-day. Their whole
life is spent along some stream or pond, searching for
worms and snails in true sandpiper fashion. Not only
this, but even the dipping gait of the pipers has been
copied, and though we cannot give a reason for this char-
acteristic, yet the warblers have learned it by heart,
and many an amateur bird-lover do they confuse! But
the heart of the old clan instinct can never be entirely
eliminated, and even if a warbler should attempt to hum
away his life on the wing like a hummingbird, or to run
with the speed of the wind through dry deserts like an
ostrich, yet, like the Water Thrushes, he would occasion-
ally drift back to the old tree-tops and there sing of the
happiness which is within his heart.

A strange whim of evolution in one member of the
warbler tribe results in his mimicking the sandpiper as far as
terrestrial locomotion, a walking gait, and the peculiar tilt-
ing habit go, but the fondness for water did not accompany
these changes, and so we find the Oven-bird content with
the deep woods where he builds his home upon the ground.
He often returns for a time to the trees, but, like a college

366 The Bird

boy whose whole ideas of life have been changed by ab-
sence from his rural home, the Oven-bird carries aloft
with him the mincing gait of the littoral sandpipers, walk-
ing sedately along the limbs among his agile, hopping,
creeping cousins.

Of the conventional aristocracy of the warblers there
would be much to say had we the space. The Black-
and-white Creeping Warbler has been transformed into a
woodpecker, as far as mode of progression goes; and
lucky for him too, for he never fails to find cocoons
and small edible things among the cracks and crevices
of the bark, no matter how vainly the others may be
searching the overworked twigs and leaves. And Nature
has helped him, too. She has dipped him in a bath of
the essence of these very same crevices and cracks, and
out he has come, covered with the semblance of the rough
surface and the long, dark shadows which may shield
and hide him from many enemies.

Of the typical tree-loving species, the Pine Warbler
haunts the growths which have given him his name; the
Black-throated Green also loves the evergreens, and the
beautiful Magnolia delights in thick forests of spruces.

Thus we have taken a brief survey of the recent branch-
ing of the warbler’s genealogical tree. Each has found
a niche in which to live, and the food and safety which
permit him to rear a nestful of young each year. So far
so good, but we must not forget to give a thought to the
untold thousands and tens of thousands of generations
which have failed in their attempts. Nature has removed
all traces from view and in the general advancement of

Feet and Legs 367

the race as a whole they are forgotten, but it is well for
us to think of them occasionally: their birth, the chance
which came, which seemed so full of promise, which they
so eagerly accepted and which betrayed them; the myriad
little dead forms which gave up their lives in ages past,
and upon whose bodies and whose efforts the birds of
to-day have risen to their present high place in the scale
of the creatures of the world.

We might have used this same illustration, or many
others like it, in connection with almost any other portion
of the bird’s body. Although, indeed, it pertains more
strictly to the mental characters, and so is in a way out-
side the province of this volume, yet its application to
physical adaptations is so evident that its omission would
leave incomplete a most interesting phase of the possi-
bilities of the adaptation of bird structure.

Although among perching birds the bill is the important
organ for procuring food, yet such birds as the Chewink,
the White-throated Sparrow, and the jays, in search of
small insects use their feet to scratch away dead leaves
and rubbish, kicking backward with both feet at once.

There are many curious things about toes to which
we have not yet found the key. Who can tell why the
Horned Lark, Pipit, and some other birds have such
elongated claws on their rear toes? Perhaps the fact
that these birds live almost entirely on the ground may
have something to do with this peculiarity. Any one who
has kept a cage full of small birds will soon have learned
the fact that the claws of birds are continually growing.
In a remarkably short time their claws become long and

368 The Bird

curved, and in a neglected aviary I have seen birds which
were prisoners on their perch, unable to untwist their
claws from it. When wild, birds wear down these struc-
tures by constant rubbing, and if given plenty of rough
bark and wood in their cages, their claws will remain of
usual length.

Although the tarsus, or that portion of the foot which
we usually call the leg, is, in almost all birds, covered with
horny scales, yet these vary con-
siderably in different groups. In
many the scales are small, six-
sided or oblong, as in_plovers.
In some of the higher song-birds
these scales have become joined
together until, as in our robin,
the front of the leg is covered
with a long “boot” of “hor:
The cause of this coalescence yet

Ties Dane ineot Ge es) Denials stove scliscovercd
Eipit. A considerable degeneration of
the legs and feet is found among goatsuckers, humming-
birds, and chimney swifts; but, small as are the feet of
the latter birds, they make frequent use of them to break
off the short twigs which are used in the construction
of their nests. One may take a young swift and place it
against the vertical surface of an ordinary brick (Fig. 326),
and the bird will hold fast without slipping a fraction
of an inch. The slender nails fasten in the slightest
irregularity of the surface and hold the bird safely.
Some species of swifts have all four toes pointing

Feet and Legs 369

forward, forming a four-tined grapple by which they
hang themselves up in their hollow nesting-trees. Whip-
poorwills and some other birds have a curious comb,
or pecten, along the edge of the middle claw, which is
perhaps of use in cleaning the long bristles about their
mouths, or in arranging their very delicate, soft plumage.
Kingfishers and several related groups of birds make so
little use of their feet, except in motionless perching, that

Fia. 290.—Comb on toe of Chuck-will’s-widow.

not only are the toes small and weak, but two of the
front ones have grown together for over half their length.

Perhaps the most interesting condition of toe struc-
ture is found among the woodpeckers, parrots, cuckoos,
and owls. In these groups we find a similar plan of gen-
eral arrangement: two toes in front and two behind.
With few exceptions it is the great, or first, toe and the
fourth, or outer, toe which are reversed. This arrange-
ment of toes is known as yoke-toed, or zygodactyl.

370 The Bird

We have seen that in perching birds the arrangement
is three toes in front and one behind; and now turning
to the woodpeckers we are struck with the excellent
toe arrangement of these climbing birds,—their claws
spreading so that they point almost to the four points
of the compass, thus forming an admirable grapple or
vise, which makes a vertical position as safe for a wood-
pecker as a horizontal one for a percher.

Woodpeckers, the world over, have feet and toes
which are remarkably alike; but in Canada and the most
northern parts of our own country, and in certain por-
tions of the Old World, there are several woodpeckers
which are unique among the birds of this Order in pos-
sessing but three toes. For some unknown reason their
first, or great, toe, which in all other woodpeckers points
backward, has disappeared, leaving but a vestigial trace
beneath the skin, while the outer toe is reversed to take
its place. We may see one of these hardy three-toed fel-
lows sliding and hitching up a pine-tree, pounding and
hammering vigorously, the loss of an entire toe evidently not
handicapping him in the least. In such fashion does Nature
occasionally upset our hard-worked-out theories, leaving
us confused and baffled before her inexplicable surprises.

Is it not rather disconcerting to find that this same
arrangement of two toes in front and two behind also
holds good for the other Orders of birds mentioned above,
the parrots, cuckoos, and owls,—their toes all arranged
in pairs, fore-and-aft? This is an excellent example of
what is called parallelism, or the independent develop-
ment of similar structures.

Feet and Legs 271

Parrots use their feet for more different purposes than
do any other birds: they are the monkeys of the feathered

Fria. 291.—Cockatoo perching with one foot and holding food with the other.

world. They climb wires or branches one step after the
other, their beaks taking the place of a third foot in this

style of locomotion. They pick up food, such as a banana

B72 The Bird

or a nut, and, holding it in the foot while eating, turn
it from side to side as we revolve an apple in our hand.
With their claws they preen their plumage, and push each
other aside when too closely crowded. In fact the functions
of the feet and toes of parrots approach nearer to those
of a human hand than the limb of any other Order of birds.

Fic. 292.—Foot of Cuckoo, perching, and with toes outstretched.

Cuckoos are perching birds, and when we see the skil-
ful way in which they creep through a dense thicket, never
missing their hold, we wonder why all perching birds do
not have this arrangement of two toes in front and two
behind. So completely are our theories set at naught
that we should hardly be surprised to see a bird with
one toe in front and three behind cheerfully hopping
from branch to branch! In the deserts of the south-

Feet and Legs 308

western part of the United States much of the vegetation
consists of prickly cacti and thorny mesquite, most un-
pleasant to perch upon, and here we find the Road-runner,
a kind of ground cuckoo, who has the fore-and-aft toe
arrangement of his arboreal relations, but whose terres-
trial life has developed remarkable powers of running
and leaping. One of these birds can outstrip a horse
for a hundred yards or more and, almost without effort,
can leap upward ten or twelve feet, to all appearances
unaided by its wings.

The owls can move their outer toes backward or for-
ward at will, thus being able to assume the arrangement
of toes both of a crow and of a parrot. However the
yoke, or two-and-two, plan is the one most commonly seen
among these birds. With such an automatic vise-trap
ready to descend silently and with deadly swiftness upon
him, the little mouse in the grass has indeed need to be
ever on the alert. The talons of owls are curved and
under the control of tendons of great strength. Their
chief use is to capture living prey and then to hold it firmly
while it is torn to pieces by the beak.

The deserts and plains where the Road-runner dwells
are also the home of the Burrowing Owl, Fig. 351, which
finds in its sharp little talons admirable picks and shovels,
certainly a novel use for yoked toes. The feet and toes
of birds are, in zero weather, their most vulnerable points
(except their eyes), and they are most liable to be frozen.
In the black wastes of the frozen boreal regions, the Arctic
Owl is able to defy the intense cold, by means of a furry
covering of hair-like feathers, which extends to the very

yes The Bird

claws, and even the soles of the feet are thickly covered,
so that the skin of the bird is never in contact with the
snow and ice on which it roosts.

The osprey, or fish-hawk, can, like the owls, reverse
its outer toe, but all typical hawks and eagles have the

Fra. 293.—Owl gripping a piece of meat.

perching-bird arrangement. The talons of the osprey
are immensely strong, and the scales on the soles of its
feet and toes are hardened and roughened to such a degree
that they are almost spike-like. A more efficient fish-
trap cannot be imagined. The Golden Eagle has a splendid
foot, with great curved talons, which, when they have

Feet and Legs B75

once clasped an object, never let go. It required two
men and two pairs of the thickest buckskin gloves to
obtain Fig. 295, and even then the foot could be held
still for only a moment. As the photograph shows, the

Fig. 294.—Foot of Snowy Owl.

leg is feathered all the way down to the toes in this eagle,
for some unexplained reason, while in almost all its rela-
tives, as in the Bald Eagle, the legs are covered with
scales. The feet and toes of the Harpy Eagle, Fig. 204,
are probably the most terrible of their kind in the world:

376 The bird

certainly they are the strongest. When once they have
closed on an object, and remain clutched, nothing short
of severing the bird’s leg will avail to loosen the fearful

Fig. 295.—Foot of Golden Eagle.

grip. Besides capturing their food, birds of prey carry
the sticks for their nests in their talons.

When, instead of killing its prey, a species of bird
feeds upon carrion, the change in its habits is reflected

Feet and Legs 207:

clearly in the appearance of its feet. Compare the feet
of a vulture (Fig. 296) with those of one of the true birds
of prey (Fig. 295). The muscles are weaker and the claws
are shorter, more blunt, and, as a result, the toes have lost
their clasping power, while the hind toe is higher and so

Fic. 296.—Feet of Vulture. (E. R. Sanborn, photographer. )

small that it is of no use even in perching. Such is the
condition in the condor of South America.

When in captivity an eagle is given a piece of meat, it
seizes the food in its talons and flies to some favourite
spot to devour it, but a condor transports its meal in

378 The Bird

its beak, then holding it down firmly with one of its feet,
it pulls upward and so tears the meat.

So exactly correlated are these changes of habit and
of feet that in the Caracara, a Mexican bird of mixed
habits, partly rapacious and partly vulturine, the toes and
claws are correspondingly midway between the two groups
of birds. This bird lacks sufficient grasping power to
enable it to lift its prey from the ground after the manner
of a true Hawk; but it will overcome this difficulty by
carrying up the object in its beak, and then reaching for-

rard with its feet, while in full flight, and taking a careful
grip with its talons.

In South Africa is a bird known as the Secretary,
which is really a terrestrial hawk, rarely flying, but spend-
ing most of its time stalking about in search of food. Any
one who has seen an eagle progressing upon the ground
by means of its awkward gallop, can realize the impos-
sibility of such a short-legged bird preferring terrestrial
life, but the legs of the Secretary are as long as those of
a crane, although in other respects the bird would pass
for a very long-tailed species of hawk; it is really a hawk
on stilts. However, there are reasons for supposing that
the Secretary Bird may be, not a more or less recent. off-
shoot from the hawks, but a surviving type of old, old
days when there were no hawks and cranes and herons,
but instead, a few strange birds which combined the
characteristics of all these groups.

The skilful way in which the Secretary Bird brings its
feet into play in the capture of serpents, of which it is
very fond, has been described as follows:

Feet and Legs 379

“When the snake strikes, the bird either evades the
blow, by skipping to one side or the other, jumping back-
ward, or springing into the air, or else, as frequently hap-
pens, he simply receives the venomous thrusts of his
antagonist on the broad stiff feathers of the outer half

Fig. 297.—Secretary Bird.

of the long wing, with which he knocks the reptile down,
following up the fall with a vigorous kick. His extreme
agility enables him in a very short time to baffle and
overcome a snake of four or five feet in length, whereupon
he finally seizes it near the head with his bill, and hold-

380 The Bird

ing the body down with one foot, proceeds to swallow it.
In case a snake proves unusually hard to manage on
the ground the dauntless bird watches his opportunity,
seizes his adversary close to the head, and, flying aloft
to a considerable height, lets it drop on the hard ground,
which is usually sufficient to prepare it for the final

ceremony of swallowing.”

Fig. 298.—Feet of Ruffed Grouse, showing snowshoes of horn.

Quail, grouse, pheasants, turkeys, and all the fowl-
like birds are scratchers, according to the old classification,
and they well deserve the name; for scratching first with
one foot and then the other among the leaves and soft
dirt for insects is a very pronounced habit of them all.
The arrangement of toes is the same as in the perching
birds, but the claws are very different. These birds are

Feet and Legs 381

true horny-handed sons of the soil: their claws are stubby,
short, and blunt. Sharp edges would soon be dulled by
scratching, and elongated ones would sliver and break.
So, with his blunt claws, our chicken and his kind are
well provided for.

The most interesting feet among these birds are those
of the grouse. The ruffed drummer of our woods walks
about, in summer, on slender toes over moss and logs, but,
when soft deep snows come, his weight would make it
difficult to keep from being buried at each step. So
Nature provides him with snowshoes. From each side of
each toe a broad, horny comb-like fringe grows out; not
a web of skin which might soon freeze, but rows of horny
projections, as of a myriad extra claws. This distributes
his weight so that he trots merrily over snow through which
a fox sinks deep and flounders awkwardly at every step.

But what of the ptarmigan, that snow-white grouse
of the far North, whose home is amid those frigid barren
regions? This bird is much more of a walker than the
Snowy Owl, and its feet would surely freeze during
the long winters if they were bare of feathers. So we
find indeed that scarcely a claw is visible beyond the
thick feathers which cover legs, toes, and soles. Such
a provision against cold is evident and reasonable enough,
but how are we to account for the feet and toes of the
House Martin of Europe, which are densely feathered to
the very claws? It breeds in Iceland and Lapland, but
only in summer, when it would need no such protection
against cold, and it is also true that it breeds upon the
eliffs of Persia and southern India.

382 The Bird

If we watch a duck as it settles itself for the night
upon the snow, we will see it squat down, snuggle its
beak deep among the feathers of the back, and finally
draw up each foot from the frozen surface and tuck them
up out of sight. Thus they are protected from freezing
during the long, cold night.

The pugnacity of the males of the Order of game-
birds has become proverbial; almost all are “fighting
cocks” and yet their beaks are not fitted for defence or

Fig. 299.—Mallard asleep on the snow, with its feet drawn up to avoid freezing.

offence, nor can they clutch and tear with their claws.
But we find spurs developed on the tarsus, or upper
foot, in fowls, turkeys, pheasants, and peacocks, which
are used with remarkable skill in their battles. In
structure these outgrowths are identical with the horns
of antelopes and cows, consisting of a bony projection
over which grows a sheath of horn. The spurs of the
peacock are long and sharp and are occasionally used
with such effect that the results are fatal to each of the
contestants. A diminutive relative of Pavo, the Pea-

Feet and Legs 383

cock Pheasant of the East Indies, has two, three, or even
four spurs of full size on the legs. The bird photographed
on page 419 had two on the right leg and three on the
left. Yet these birds are not as correspondingly pug-
nacious as we should imagine from their increased arma-
ture.

There is a small group of peculiar birds, known as
Sand-grouse, which in many respects stand midway

Fig. 300.—Spur of Java Peacock.

between the true grouse and the pigeons. In certain of
these the toes, to their very tips, are encased in the skin
of the foot, the effect bemg of a mitten with only the
claws free. The reason for this is yet to be found.

We now come to the water-loving birds, and we find
that .their varying associations with this element have
wrought many interesting changes in their feet and legs.
Those birds which are content to wade along the shallow
margins of ponds and streams require long legs and long

384 ies Bind

toes, the latter to distribute their weight as they walk
over the soft muddy bottom, the former to lift their bodies
above the surface of the water. Such, broadly speaking,
are the plovers and sandpipers and herons. Let us see
how the feet of these birds reflect their habits. With
the exception of the tribe of plovers, almost all have four
toes. The plovers have but three, and these are slender
and not webbed, for although they usually feed on aquatic
forms of life, yet their food is gleaned from the upper
part of beaches, or from the sand-flats when the tide is
out, and they therefore seldom have occasion to swim.
The sandpipers venture into the shallows and are some-
times lifted from their feet by a small inrushing wave.
But the majority even of these go through life unwebbed.
One, the Semipalmated Sandpiper, shows a beginning of
this in the half-webbed condition of the toes, but the
group of phalaropes are actually sandpipers of the sea.
I have seen them in flocks of thousands, resting upon
the surface of the ocean, scores of miles from land. Yet
when ashore they have need to be as active as other mem-
bers of their Order in order to find sufficient food; so, in-
stead of being hampered with a confining web, each toe
has a series of broad scalloped lobes, serving admirably
as water propellers, yet allowing the toes freedom of motion
when the owner is scurrying over the sand.

I have observed Great Blue Herons almost hip-deep
in the breakers along the Florida beaches, yet this is not
a usual haunt for members of this group of birds. They
usually prefer quiet inland waters, where they wade and
watch—ever striving to satisfy their insatiable hunger.

Feet and Legs 385

So, in the case of herons, webs would be superfluous,
length of limb being their only requirement.

The Wood Ibises (or more properly Storks), which
are more active searchers after food than the herons,
make use of their toes to stir up the bottom mud of shal-

f

oh ae
|
|
i
it
¢
|
q

Fig. 301.—Toes of Gallinule outstretched.

low water, keeping the bill ready to snap up any small
creatures thus disturbed. When one sees a flock of gal-
linules or jacanas feeding quietly in their haunts they
appear to be walking on the water, and we find an in-
teresting connection between the structure of their feet
and toes and certain tropical plants. Such are the

386 The Bird

great pads of water-lilies, which in places cover miles of
water, over whose trembling surfaces the birds are able
to run or walk. To enable them to do this without sink-
ing, both the toes and claws are remarkably long and
slender, so that in a bird which stands but ten or eleven
inches in height the weight is distributed over an area
of some fifty square inches. This makes it possible for
them to feed in places too deep for wading birds and too

Fig. 302.- Gaflinule holding food in its foot.

tangled with aquatic vegetation for swimmers readily to
make their way. This is but another forceful example of
the successful adaptive radiation of birds.

Gallinules have found that their long toes can be made
useful in other ways besides locomotion, and we find that
they are well-nigh as skilful as a parrot in grasping and
holding. One of these birds perhaps spies a tuft of
water-soaked reeds. He clasps it firmly, draws it up,
and, holding it in the air near his bill, picks the small
worms and snails from among the stems, finally discarding

Feet and Legs 387

it for another footful. We cannot imagine a heron per-
forming such an action. Although the toes of gallinules
are so long and slender, yet, when the necessity arises,
they can swim quite rapidly for a short distance, working
their feet with such effort that the whole body bobs in
concert. Their cousins,
the coots, resemble the
phalaropes in having
broad lobes of skin
along each toe, so that,
although they and the
gallinules are often
seen feeding in the same
locality, yet the nata-
tory ability of the coot
allows it to venture
beyond the reserves of
the other species. The
toe-lobes also serve an-
other important func-
tion in permitting the
coots to feed upon soft
mud, thus keeping them
from sinking below the

Fic. 303.—Foot of Coot.

surface, just as the horny ‘‘snowshoe” of the grouse sup-
ports it on the snow.

Herons are furnished with a comb-like edge to one of
the claws, similar to that on the claw of the whippoor-
will, but as yet we have no clue to its use. Although
differing so greatly from hawks in their method of feeding,

388 The Bird

yet, when put upon the defensive, herons resort to much
the same tactics as do the birds of prey. When cornered
or wounded, so that escape by flight is impossible, the
bird throws itself upon its back and, with uplifted claws
and levelled beak, awaits the attack of its assailant. The
talons and mandibles of a hawk offer ten sharp points
which can all do severe damage; but the heron depends
only on the grasping power of its toes to hold fast, while
it strikes savage, spear-like blows with its beak.

On the borderland of the fully webbed aquatic birds

Fic. 304.—Comb on the toe of Heron.

we find the flamingo, combining characters of the herons
and ducks. Its haunts are the exposed coral-flats of
tropical keys, where at any time a high tide or a
severe storm may sweep all, old and young, from their
feet. Then it is lucky indeed that the youngsters have
webs between their toes in addition to their long legs.
It is a case of swim or be drowned.

In the great Orders of sea-birds, and in the ducks and
their allies, the three front toes are joined together by

Feet and Legs 389

a web of skin which, when swimming, offers a large area
of resistance to the water when the foot is pushed back-
ward. The chick in the egg has a shadow-membrane
of his fish-like ancestors between his toes, and in these
water-birds the web of skin continues throughout life. In
the terns or sea-swallows, which swim much less than
they fly, the web is excised, or scalloped out deeply, a
return to an almost semipalmated condition.

Fig. 305.—Rough-legged Hawk in position of defence.

A duck or swan out of sheer laziness will often hold
one foot up out of the water and propel itself with the
other, slightly altering the angle at which the web meets
the water, so as to maintain a perfectly direct course.
There is a little-known habit which I have frequently
observed in captive ducks and several times in wild ones,
of swimming thus with one foot when both eyes are shut
and the bird is apparently fast asleep. But, in such a

390 Dhe Bid

case, no attempt is made to proceed in a straight line.
In a pool only thirty feet square I have seen a duck
revolving thus for an hour or more at a time, impelled
with slow, rhythmical (and apparently reflex) strokes. We

Fic. 306.—Foot of Black-necked Swan.

canimagine that such a habit would sometimes be of much
advantage to a wild bird, enabling it to keep away from
enemies on the shore and yet at the same time secure rest.

The name Steganopodes is applied to the gannets,
pelicans, snake-birds, tropic-birds, and cormorants, be-

Feet and Legs 391

cause the toes of these birds are all bound together with
a single web. The hind toe points almost in a forward
direction when the foot is in action, and, to complete
the adaptation for a perfect swimming foot, the outer
toe is the longest, a rare condition among birds. If one
will watch the snake-birds in a zoological park, as they
swim about their glass tank, the extreme delicacy of the
foot mechanism becomes apparent at once.

Not only is the flat side of the leg used as a cutwater,
but the toes curl and uncurl with a slight oblique revolving
motion like the blades of a propeller. When drawn for-
ward through the water they are rolled up into a very
small compass and then instantly spread out as widely
as possible on the return stroke. To the eye it seems
as if the bird was constantly grasping something tangible
in the water and thrusting it behind.

This propeller motion may be observed even better
in a Captive grebe. If the bird’s head is placed in a glass
of water, its feet will move back and forth in the air with
all the motion of swimming. The adaptation for swimming
in these birds is so fundamental and thorough that even
the claws are broadened and flattened until they resemble
finger-nails. On land, grebes are absurdly awkward,
although they can walk upright even up a slight incline.
But they are powerless to rise from the ground, even
with the aid of the wind,—needing the greater speed which
a swimming take-off from the water will give them.

The most aquatic of all birds, the penguins, make
much more use of their wings than of their feet in swim-
ming and diving. The toes are webbed, however, and

392 The Bird

are doubtless of considerable use when the bird is emerg-
ing from the water, which it generally does with a sudden
spurt of speed and a strong leap which lands it on its feet.

In landbirds which have either lost or are losing the
power of flight there is often an interesting correlation
to be observed between the lapsing of this mode of loco-

Fia. 307.—Feet of Penguin.

motion and an increased use and consequent greater de-
velopment of the legs and feet. Of a South African bird,
about the size of our American Robin, known as the Rock-
jumper, it is said: “These curious birds are only to be
found on the rock-strewn slopes and summits of mountain-
ranges where they are able to hop from rock to rock for a

Feet and Legs 393

distance without having to cross level or open ground;

. at the slightest alarm they either drop into a crevice
or bound from rock to rock with extraordinary speed, look-
ing more like india-rubber balls than birds, for there is no
perceptible interval between the end of one leap and the
beginning of the next, and the distance they can clear at a
single hop must be seen to be believed. Should they have
to cross a piece of level ground between two rocks which
they cannot clear with asingle bound, they run across it with
great speed and usually with outspread wings. So feeble
are their powers of flight that they seldom attempt to
fly, and never when in a hurry or alarmed; at the most
they flutter feebly for a few hundred yards down hill.
I have occasionally amused myself by trying to drive
these birds across a piece of open ground, but I have never
succeeded in getting them to quit the shelter of the rocks,
where they easily avoid one by leaping over the stones
or hiding in the crevices. In spite of his loose, fluffy
plumage, which blows about in the slightest breeze and
gives him a rather untidy appearance, the cock is an ex-
ceedingly handsome bird.” So we have here an isolated
case of direct relation between two organs, the balance
of power changing from wing to feet and affecting much
of the bird’s structure, even the plumage losing its cohe-
siveness. The weak-flying Tinamou have unusually sturdy
legs, and many other instances might be mentioned.

For many reasons the most interesting of all birds’
feet are those of the ostriches and their allies, and among
them the most extreme examples of this same cause and
effect are to be found.

394 The Bird

When one trains in college for a long-distance race,
one rule to observe is, never touch your heels to the ground;
run wholly on the ball of the foot. Untold centuries
ago, wise old Nature whispered the very same direction
to those of her children who had most need to run for
their lives in life’s great race, and down through the
ages some of them have never broken training. When
an animal acquires
great speed in running
or leaping, there is a
tendency for one toe
to become greatly en-
larged at the expense
of the others, as is
seen in the case of the
horse, the kangaroo,
and the ostrich.

In the horse only
the middle toe is
functional, the second
and fourth having de-

generated into the

Fig. 308.—Feet and legs of Cassowary.

small splint-bones at
the side of the leg. The kangaroo progresses upon
the fourth and fifth toes, the second and third being
small and skin-bound. The ostrich has but two toes,
one of which, the third, as in the case of the horse, is
very large and armed with a thick claw, which, hoof-
like, grows close to the toe. This toe supports most of
the bird’s weight, while the fourth or outer toe is only

Feet and Legs 395

a

Fig. 310.—Feet of Donkey. Fic. 311.—Feet of young Kangaroo.

396 The Bird

one quarter as large; and indeed it bids fair to disappear
altogether in the course of time, and even now the dimin-
utive nail which is often present is only as large as the
claw of a chicken.

The power of the ostrich to defend itself by kicking
is proverbial, but the claw on the
large toe is blunt and the ability to
inflict injury les in the terrible force
of the blow. Its ally, the cassowary,
has three good-sized toes, and on
the innermost one a specially adapt-
ed weapon in the shape of a strong,
pointed, talon-like claw, four inches
in length.

The two photographs (Figs. 312
and 313) show how similar the
tracks which the modern cassowary
makes in walking over moist clay,
are to those made by the _ bipedal
reptilian Dinosaurs millions of years
ago, which have been found in the
Connecticut valley.
Fig. 312.—Tracks of Casso- Thus in our brief review we have

eee rea seen how the feet and legs of birds
serve them well in walking, hopping, running, perch-
ing, scratching, climbing, burrowing, swimming, diving,
in addition to the finding of their food, fighting,
preening their feathers, and in countless other ways.
The story of the bird’s foot has not half been told,

Feet and Legs 397

but enough has been said to arouse our interest in

this member and to put us on the watch for new
facts.

Fig. 313.—Fossil Dinosaur tracks, found at Middletown, New York.
(Courtesy of Prof. R. 8S. Lull.)

CHAPTER XV

TAILS

wa] have found that almost every organ of a bird’s
| body may be compared directly with the corre-
sponding structure in the body of a lizard or
of some reptile, and the tail is no exception: although
a lizard with a fan-shaped group of feathers sprouting
from the root of his tail would certainly be an anomaly;
and even if we substitute scales for the feathers, the result
would be ridiculous and unmeaning. But glance at the
photograph of the tail of our ancient, original-bird ac-
quaintance, the Archeopteryx, Fig. 315, which was taken
expressly for this purpose.

Take twenty feathers and arrange them as in Fig. 314 a,
representing the tail of Archzopteryx; then rearrange
them as in 3146, corresponding to the tail of modern birds,
and the whole matter will be clear. Archaeopteryx had
twenty bones in its tail, all separate, long and slender, and
arranged end to end, just as are the bones of a lizard’s
tail to-day. But in the case of the bird of olden time
a pair of feathers grew out, one on each side of the tail-
bone, making forty tail-feathers in all. As we have seen,

this bird was rather weak-winged and probably more
398

Fig. 314.—(a) Arrangement of 20 feathers, as in Archwopteryx; (b) tail-feathers
of a Sparrow in place.
399

400 he Bird

of a flutterer, or scaler, than a true flier, but as time went
on, and birds became more and more expert on the wing,
their wings grew stronger and their tails shorter and more
compact. We can readily see the reason for this, if we
imagine a ship which has been built with a rudder as long
as its whole deck. What an awkward thing such a rudder
would be! The waves would beat against it and great
force would be necessary to turn it and to steer the ship.
As long as a bird was content to climb a tree with its
hands and feet, and then scale, like a flying squirrel, to
the base of the next, a lizard-like tail would be all-sufficient.
So conspicuous and so unbirdlike was the long appendage
of the Archzopteryx that Saurura—lizard-tailed—has
been given as the name of the Sub-class which it occu-
pies all to itself.

When we look at the bones of the tail of a modern
bird, we find that many interesting changes have taken
place since the days of the lizard-tailed ancestors. Thus
in the common duck, for example, we find eight free
bones followed by a large upturned bone, which, from
its shape, is known as the ploughshare. It is this terminal
bone which supports all the tail-feathers of modern birds,
and in the duck it represents ten of the lizard-tail bones
all telescoped and fused into one. Some of the feathers
have been lost, as there are but sixteen in this bird’s
tail. This loss of tail-feathers is of no value in classifica-
tion, as it may vary within narrow limits. For example,
one species of cormorant has seven pairs of tail-feathers,
while a closely related species has but six. Not only
this, but the variation may be merely sexual, as in the

seum

Mu

British

yx im

&
eo
SS
SN
S
&
S
=>
=
S
Nn
x

HicGaois——eanlaon

402 They Bird

peacock, which has ten pairs, while the peahen has one
pair less.

The fusing together of these bones has resulted in the
drawing together of the feathers, so that, instead of the
long, unwieldy, paired affair, they are arranged in fan
shape, although still in pairs, and usually showing a slight
graduation reminiscent of the old-style tail. Some birds
have as few as four pairs of tail-feathers, while others

Fie. 316.—Tail-bones of Ostrich.

have as many as twelve. In the abnormal domestic breed
of pigeons known as fantails, as many as forty tail-feathers
are sometimes found. The cassowary and the emeu
have none at all, while the ostrich seems to have an in-
definite number; the tails of these two unrelated groups
of birds seeming, like their wing-feathers, to have lost
uniformity from little use. Besides these true tail-feathers
there are others, usually smaller, which grow from above
and below the tail, being known as upper and under tail-

Tails 403

coverts. Mention is here made of these because of the
important part they take in certain sham tails which
will soon be described.

In the embryos of most birds of true flight the tail-
tip of the back-bone is represented by six or ten separate
pieces, which, before the chick hatches from the egg,
fuse into the ploughshare bone. In the ostrich-like birds

Fig. 317.—Tail-bones of Bald Eagle, showing greater fusion and more
specialization than in Fig. 316.

these small bones never fuse, but remain separate through-
out life—a reptilian character persistent in these strange
birds (Fig.316). The ploughshare bone is seen splendidly
developed in such a bird of strong flight as the Bald Eagle.

Now that we have explained the origin of the tail,
let us consider what part it plays in the lives of the birds
about us. So diverse are the modes of life, and so varied
are the surroundings of this class of creatures, that we

A404 The Bird

Fig. 319.—Emeu, a tailless bird. (Courtesy of N. Y. Zoological Society.)

Tails 406

shall find many unexpected uses to which the tail is put,
and yet those which have been explained are a mere frac-
tion of the problems which still await solution.

The principal use of the tail-feathers in birds is, of
course, to perform the function of a rudder, and we find
that the arrangement of the bones perfectly carries out
the simile of a tail to the rudder of a ship; namely, a
broad, expanded surface which is closely hinged to the

Fre. 320. Fie. 321.
Tail of Barn Swallow, closed (320) and spread (321).

body by several movable joints. The real tail of a bird
is the small, fleshy protuberance which in our roast
chicken we call the “pope’s nose”; but In common par-
lance the word tail has come to be applied to the large
feathers which sprout from this structure. Thus, although
not comparable to the appendages of mammals, the so-
called tail of a bird is superficially more like the correspond-
ing organ of a whale than the tail-fin of a fish, since it is
expanded horizontally instead of vertically.

406 The Bird

One interesting analogy to the fin of a fish is found
in the tail of the Blue Duck of New Zealand. This bird
lives in swift mountain streams and when swimming carries
its long tail entirely submerged. By vigorous sidewise
flicks of these tail-feathers 1t can turn around, as if on a
pivot, without being carried down-stream, even when
in the centre of a rapid, swirling current.

Fig. 322.—Murre showing tail. (Compare with Fig. 246.)

It is interesting to compare this use of the tail-feathers
with the function of the tail in the flightless penguins.
In the Black-footed species, at least, the tail-feathers are
stiff and short, but the bones of the tail are unusually
elongated and the flesh which covers them is flattened
into a kind of vertical rudder. Strong muscles control

Tails 407

this, and by it the extremely quick dives and turns are
made possible. No feather would be stiff or rigid enough
to offer to the water the resistance which these feathered
seals require.

Exceptions to the rudder use in flying birds are found
in the murres—sea-birds which share the cliffs of our north-
ern coast with cormorants and gulls. The tail-feathers
of a murre are so short as to be useless for steering pur-
poses, so in flight the bird uses its webbed feet instead,
stretching them out behind, opening, turning, and twist-
ing them in harmony with the wings, with as satisfactory
results as could be desired.

The shape of the tip of the tail varies greatly in birds.
It may be square or rounded, or cuneate, or indented
in the centre, or swallow-tailed, as we appropriately call
the latter deeply forked condition. These conditions may
be paralleled or duplicated in many different Families of
birds. For example, the forked type is seen in our com-
mon Barn Swallow, in those dainty relatives of the gulls,
the terns—“Swallows of the Sea,’—and again in the
Forked-tailed Kite and the Scissor-tailed Flycatcher.
By closely watching a swallow as it courses swiftly over
a meadow, or shoots upward, buoying itself against the
breeze, we can appreciate the delicate adjustment of the
muscles which govern the tail-feathers. Each feather
seems vital with life, now sliding one over the other until
all are in a narrow line, then expanding, with less friction
than ever a fan opened, into a wide-spreading, gently
eraduated fork. The quartet of forked-tailed birds men-
tioned above are splendid fliers, but we shall see that skill

408 The Bird

in flight depends but little upon the shape of the tip,
when we consider certain birds with cuneate tails, or
those in which the central feathers, soft and not rigid,
are elongated, instead of the outer ones.

The Undulated Grass Parrakeet shows a condition
almost the opposite of the swallow. The Mexican long-
tailed jays, the magpies, and the tropic-birds are also
all of this type, the latter being especially fine fliers and
capable of remarkable aerial evolutions. Again, some

Fig. 323.—Tail of Grass Parrakeet.

of the flycatchers with moderate, rounded tails can exe-
cute most wonderful flight movements, steering in erratic
darts through the air, or darting aside at right angles
while at full speed, this being accomplished principally
by means of the tail.

A tail serves also an important use as a brake. When
a great pelican settles gradually toward the surface of
the water, or a duck momentarily hovers before alighting,
the tail, wide-spread and brought downward, gives effi-
cient aid in retarding the impetus.

Tails 409

We notice that birds which have very short tails are
unable to turn quickly and that their flight is very direct,
or even where there is a long tail, if it is principally for
ornament and not well muscled, it is of little use in help-
ing its owner to change the direction of flight. The
partridge-like tinamous of South America are good exam-
ples of the first-mentioned group. Their tails are small
and useless, and when once the bird launches itself into

Fie. 324.—Tail of Pelican alighting. Fig. 325.—Tail of Tern in flight.

the air, it can keep on only in a straight line and is at
the mercy of every cross-current of air. A more familiar
case, which any one may observe, is a Song Sparrow, or
other small bird, which, from accident or from some irregu-
larity of moult, has lost all or most of its tail-feathers.
Instead of rismg with the strong, darting flight with
which such a bird is accustomed to make its escape from
our path, its flight under such conditions is weak and
direct, like the trial efforts of a young bird.

410 adhe sird

Reserving the mention of partly ornamental tails until
the last, we may now consider the use of this member as
a prop or support to the bird as it clings to or makes its
way up vertical surfaces. Four groups of birds which
are thus distinguished are the woodhewers—a_ tropical

Fic. 326.—Chimney Swift clinging to wall, resting upon tail.

the creepers, woodpeckers, and swifts. These
birds really sit upon their tails, the feathers of which are

family,

adapted for this special use, while retaining perfectly the
rudder function in flight. The tail-feathers of the Chim-
ney Swift are peculiar in having the ends, for a short dis-

Tails AII

tance, free of barbs, the tips being thus composed of a num-
ber of bare spines which are admirably adapted to catch
in the irregularities of hollow trees, or, as now in their
recently adopted homes, in the roughness of chimney-
bricks. I one day caught a Chimney Swift and placed
it against a varnished wall composed of composition
bricks; and, smooth though the surface was, the bird’s
tail and toes held it firmly, not slipping even a quarter
of an inch. After photographing it, I watched it for
some minutes and saw the bird shift its position several
times, moving always with a certainty and surety of
grasp most inexplicable.

The tails of woodpeckers and creepers are not thus
denuded at the tip, but they are stiffened throughout
and are very elastic (Fig. 240). When a wocdpecker
brings up against a comparatively smooth tree-trunk, its
certainty of hold is a perfect bit of magic. Then when
it braces itself and sets to work to hammer a hole into
the wood, or to excavate its nest, how the tail-feathers
bend and spread, buttressing themselves against every
roughness, the elasticity of the feather-tips allowing them
to slip into every crevice!

In many birds the tail is a perfect index of the emotions,
doing much to compensate for the lack of facial expression.
Especially is this true of the wrens, those feathered bundles
of tireless energy and curiosity, whose tails, upturned so
high that they fairly tilt forward over the back, twitch
and jerk with every passing mood. Even the genetic
individuality of a species may be hinted at in the way
it carries its tail; quiet, soft-mannered birds holding it

412 The Bird

low, beneath the wing-tips, while active, nervous species
carry it more or less raised.

In certain of the flycatchers
the tail, which hangs demurely
downward, reacts with a jerk
to every note of the bird, as if
connected with the bird’s vo-
cal apparatus, as in our com-
mon Least Flycatcher at every
“*Che-bec’ !”

The jerking motion of the
tail seems to have become
a regular habit with many birds, and, curiously enough,

Fic. 327.—Tail of Chimney Swift.

Fic. 328.—Tail of Flicker.

especially with those which spend their lives chiefly along

Tails Aes

the borders of streams. We are all familiar with the tip-
ping of the tail in sandpipers, and, including the Green
Heron, we will see much the same motion in birds which
haunt the stream borders; even in the Water Thrush the
same habit prevailing, although, as we saw in the pre-
ceding chapter, this bird is closely related to the bright-
coloured warblers of our tree-tops. The wagtails have
received their name from this same habit, of which no
explanation has yet been offered.

The Road-runner, a ground cuckoo of the Western
plains, has a tail as long as its entire body, which is as
expressive as the gestures of a Frenchman. When sitting
quietly in the shade of a mesquite-bush in Mexico, I have
seen one of these birds dash into sight and drop, like an
arrow, upon a luckless lizard. At the moment of attack
all ten tail-feathers of the bird were wide-spread and
a-tremor, indicative of the extreme excitement attendant
upon the capture of the reptile. While eating what choice
parts were desired, the tail was folded and lifted out of
the way. Soon the bird spied some motion of mine, and
with the suspicion came the high extended neck, while the
tail turned up and forward, until almost touching the
bird’s head. A second motion on my part, and the tail
manceuvred to a line and trailed limply after the bird,
as it half-flew, half-leaped to a high rock and on out of
sight.

The white under sides of the tails of the wild rabbit
and the white-tailed deer have been explained as warning
signals to others of the family or herd: white guides
which the less experienced members may follow and so

414 The Bird

escape from danger. Again, the theory has been advanced
that these white patches merge with the sky when the rab-
bit or deer makes the first high frantic leap to escape an
assailant, the white spots thus tending to confuse the
creature making the attack. We are, however, far from
certain whether any such interpretations can be applied
to those birds, such as the Junco, the Meadowlark, and
the Vesper Sparrow, which have the lateral feathers of
the tail white; but in these
cases the first theory seems
at least more probable, as
these birds live in flocks and
in a more or less open en-
vironment, where such a sig-
nal would have the greatest
chance for use. When a
Junco is upon the ground,
its black and gray plumage

renders it very inconspicu-
Fig. 329.—Tail of Junco. ous, but the instant it takes
to wing, out flashes the white V in its tail.

We have seen that not a portion of the external parts
of the bird has escaped, in one species or another, being
utilized for ornament; generally, as well as we can tell,
as some decoration to attract or charm the female. Tails
bear even more than their share of adornment, which we
cannot pass by without mention, although, as dealing with
the psychological side of bird life, any discussion of this
question is outside the province of this volume. Some-
times it is only some slight addition to the feathers of

Tails A415

the tail proper, as the elongated middle feathers of the
male Pintail Duck and the Sharp-tailed Grouse.

Turning to a few of the more decorative tails in the
world of birds, we find a small Australian bird, known
as the Emeu-wren, bearing aloft a half-dozen long feathers,
so scantily clothed with barbs as to resemble somewhat
the plumage of the Emeu itself. These skeleton plumes,
for they are little else, while giving a striking appearance

Fig. 330.—Tail of Emeu-wren. (Cf. with Fig. 23.)

to the owner, must radically weaken its flight, as regards
steering capacity; since the open-work mesh of the vanes
can offer no resistance to the air. Indeed it is said of
this bird that it is such a poor flier that it 1s seldom seen
on the wing, but it runs rapidly and is able to leap into
the lower branches of trees. The penalty of danger from
weakened flight which the EKmeu-wren must pay for his
caudal decoration is paralleled by certain little whydah-
finches of Africa, the males of which at the breeding
season are decorated with several tail-feathers over five

416 ThevBird

times as long as their tiny bodies. When a heavy dew
falls during the night, drenching the plumage of these
birds, they become helpless and quite unable to fly. At
such times many are killed by their natural enemies;
and such indeed is their helplessness, brought about by

Fig. 331.—Male Paradise Whydah-bird showing tail.

this excess of nuptial dress, that a person can pick them
up in the hand without difficulty.

The beautiful tails of pheasants are in harmony with
the wealth of colour which many of these birds display
upon other parts of the body; the long graceful tail of the
Reeves being especially striking.

The folded, roof-shaped tail of the common rooster,

Fig. 332.—Japanese Long-tailed Fowls. (From a photograph provided by the
American Museum of Natural History.)
417

418 he Bird

and of his wild ancestors the Jungle-fowl, with the graceful
overarching feathers, is a type of tail found elsewhere

Fic. 333.—Roof-like tail of Jungle-fowl.

only in certain pheasants. In the Boat-tailed Grackle
the arrangement is reversed, the apex of the slope being

Fic. 334.—Decorative tail of Reeves Pheasant.

beneath instead of above. The possibilities of abnormal
feather growth are well shown in the tails of the Japanese

Tails 419

Long-tailed Fowl—a breed of birds in which, by artificial
stimulation, such perhaps as periodical pulling of the
feathers or else retardation of moult, has produced, in the
cocks, tails from twelve to twenty feet in length. This
process dates back, in Corea at least, to a.p. 1000, and
necessitates keeping the birds continually upon high
perches, or else wrapping the
feathers carefully in paper.
The arrangement of feathers
in this artificially induced
character is duplicated in
nature in the Paradise Why-
dah-finch mentioned above.
In both the male and fe-
male Peacock Pheasant the
tail is quite long and the
feathers are decorated with
beautiful iridescent “ eyes.”’
But in this bird usefulness ex-
ists as a corollary of beauty.
When the young chicks are
reared under a bantam hen,
they invariably keep close be- _ Fic. 335.—Useful tail of Peacock
hind their foster-mother, for eeaicas
no apparent reason; indeed this position often results in
their death, a kick from the bird’s foot generally being
fatal. The reason for this strange instinctive act is at
once clear when we see the chicks with their rightful
mother. They spend much of their time hidden beneath
the shelter of her long, sloping tail, coming out now

420 The Bird

and then to feed when she calls them, then hurrying
back to their snug shelter. Thus when she walks from
place to place, the tiny feet of the chicks may be seen
scurrying along beneath the beautiful tail-feathers, all

Fic. 336.—Tail of Lyre-bird.

but their legs concealed from view, giving a most re-
markable appearance to the mother bird.

Among ornamental tails assumed for show during the
breeding season, that of the Lyre-bird of Australia is
unequalled. The name is well given, since the outer
tail-feathers carry out the graceful, curving outline of

Tails a2

the classic form of a lyre; while twelve of the central
feathers, so scantily barbed that their stems are plainly
visible, hold positions corresponding to the strings of
that ancient instrument. The two elongated middle
feathers cross each other and curve outward, adding still
more to the decorative effect of
this strangely beautiful member.
Naturally we find that these
birds are better runners than
fliers. The females lack the or-
namental tail.

If we judge from analogy
with the human race, when an
inordinate amount of ostenta-
tious show is noticeable among
birds, we occasionally find that
it is, In a sense, a sham display;
although the analogy ceases when
we find that such a case among
birds is no less interesting than
where the phenomenon is really
what it appears to be. Upon
seeing a specimen of the beau-
tiful trogon commonly called

Fig. 337.—Tail-coverts of Quezal.

the Quezal, the involuntary ex-
clamation is, “What a magnificent tail!” And no wonder;
for, while the bird is only about the size of a small (one
behind it, for three and a half feet, there stream long,
iridescent green plumes, soft as down, brilliant as emeralds.
Yet the true tail is a short, squarish affair, completely

422 The Bird

hidden by the overhanging train of gorgeous plumes,
which are in reality the upper tail-coverts.

The same thing is true of the peacock, whose real tail,
while it has the power of spreading, consists solely of

Fic. 338.—Train of Peacock spread.

short, dull, brownish feathers, acting as a support to the
glorious train of ocellated plumes which springs from the
lower back. Indeed the tail-feathers of a turkey-cock
are far more beautiful than the real tail of a peacock.
This is especially evident when, after a peacock has moulted

Tails A232

his long train, he sometimes spreads the real, incon-
spicuous tail. Large and heavy as this decoration of
the peacock is, the birds fly with remarkable ease. In
such places as the New York Zoological Park, after roost-

Fic. 339.—Rear view of train of Peacock, showing real tail.

ing all night in the tallest trees, they sail down in the
early morning, the long train waving gracefully behind—a
sight which, once seen, is never forgotten.

We must leave unmentioned scores of beautiful and

424 The Bird

interesting types of tail-feathers—those of hummingbirds,
birds of paradise, and many others; but there is one which
deserves especial mention. These birds, of which there
are a number of species, are the motmots, abundant in
many parts of Mexico and southward. The tail-feathers
of the Mexican motmot, which are bluish green in colour,

Fig. 340.—Tails of Motmot: (a4) young male; (6) adult female.

have nothing peculiar about them, except the middle pair,
which are two inches longer than the others. Of this
extra length one inch is bare shaft, while at the tip the
barbs are normal, forming a racket-shaped extremity. The
fact which places this slight decoration above all other more
elaborate examples in point of interest is that the bards

themselves voluntarily produce the racket condition. Even
the youngest birds, of both sexes, when the long central

Tails 425

tail-feathers have grown beyond the others, instinctively
begin to pick at the vane, soon denuding the shaft so
symmetrically that the rackets are equal in size. The

Fig. 341.—Motmot swinging its tail.

photographs show this perfectly. Figure a is the tail
of a young male where the operation of ornamental de-
nudation has just begun; while b shows the condition
in an adult female. The photograph of the entire liv-
ing bird also shows the rackets, as well as the peculiar
pendulum motion of the tail from side to side, although

426 The Bird

the motion is more abrupt than is the motion of a pendu-
lum. The Mexican motmot is brilliantly coloured, yet in a
densely foliaged tree, among the bright spots of sunlight,
it becomes almost invisible. It is the motion of the tail
which most often betrays the bird.

In the tail marked a in Fig. 340 it will be noticed that,
where the barbs have not yet been picked off, the unmu-

tilated vane is considerably narrowed—an interesting fact
for the consideration of evolutionists, as it offers strong
circumstantial evidence, but by no means absolute proof,
of a ease of the inheritance of acquired characters, a much-
mooted question not many years ago among scientists. If
we choose to accept the evidence thus, we may presume
that if this habit is continued through a sufficient number
of generations, the vane will, at the point of continued
denudation, ultimately become naturally bare.

But, in any case, it is a fact which must hold the inter-
est of the most superficial bird student that here is a
bird which voluntarily tears away a portion of its plu-
mage. To the best of our present knowledge this is solely
to ornament itself, but the fact that both sexes equally
possess this habit makes such an explanation the merest
theory. The interest which this has for us here is not the
ultimate psychological significance of the habit, but the
fact that there is a bird which thus voluntarily mutilates
its plumage. As in so many other cases, we must
depend on future study of live birds in their natural
haunts to clear up the difficulty. It is this very com-
plexity of Nature’s problems which makes a naturalist’s
life ever one of enthusiasm and zest.

CHAPTER XVI

THE EGGS OF BIRDS

is the way in which she cares for her chil-

mae dren during the early part of their lives. The
story of seeds and eggs has not been half told. Think
of the tiny thistle-fluff which soars away, borne on the
lightest breath of air; of the great cocoanuts in their
husks, so hard that they will turn the edge of a knife;
of the burrs which ever patiently reach out for some
passing creature to carry them to a distant home; of the
cones of the forest, whose seeds may be transported by
birds, or dropped to the ground only to smother in the
shadow of the parent tree.

In that “mother of life” the sea, the wonder of
the first beginnings holds us spellbound. We see the
tiny hydroids, those animal plants, flowering and budding
on their waving stalks, and presently setting free their
“seeds ”—jelly-fish,—throbbing with life, drifting away
on the ocean currents. Again observe these jellies scatter-
ing behind them an untold host of eggs, as a rocket marks
its path with a myriad sparks. Think of the salmon
seeking her spawning-grounds in the uppermost reaches

of rivers, or the cod boldly playing for her offspring the
427

428 The Bird

chance in the lottery of life in the open ocean. Of her
nine millions of eggs, will one survive?

How strange is the four-tendriled, purse-like cradle
of the baby shark; how delicate the forms and patterns
of butterflies’ eggs! and was there ever a more model
parent than that frog which holds its eggs in its mouth
until the tadpoles grow up?

The white leathery eggs of turtles and lizards bring
us to our subject. Leading all in beauty and interest are
the eggs of birds. Precious stones have always exerted
a great fascination over mankind, and in appearance
birds’ eggs may be compared with gems; indeed the shell
itself is almost wholly composed of mineral matter. But,
far from being an inanimate crystal, an egg shelters one
of the marvels of the world—an embryo bird. The
gaudy sea-shell cloaks a slimy snail, but from the beautiful
egg of a bird emerges a greater beauty.

Reptiles lay white eggs whose shells are not brittle,
but, when broken, curl up like a celluloid film. Some
of these reptilian eggs are oblong in shape, but most are
spherical and the great majority are deposited in the
ground, or under bark, and are hatched by the heat of the
decaying vegetation or by the direct rays of the sun.
Thus we see that there is little need for variation in
shape or colour. Among birds, however, we find very
different conditions.

As we know that birds have evolved from reptiles,
we have a right to suppose that the early forms of birds
laid white, leathery eggs, perhaps in hollow trees; but
the power of flight has taken birds entirely out of the

Fic. 342.—Comparison of eggs of reptiles and birds.
(a) Egg of Hen. (6) Egg of Skate. (c) Egg of Snake. (d) Egg of Turtle.
(e) Egg of Alligator.

429

430 The Bird

reptilian horizon, and greatly altered all the conditions
of their life. The history of the egg of a bird, from the
time it is laid until it hatches, has an all-important effect
on its form, colour, and even upon the number of eggs
laid. This is not strange when we consider that every
minute of the bird’s life is open to many dangers, and
that the egg stage—that bridging over of generations—
is a most precarious period.

That which adds the greatest interest to anything is
the why of it, and a vast collection of eggs, beautiful
though they are, yet, if ignorantly looked at, is worse than
useless. Why one bird lays twenty eggs and another
but two; why one bird’s eggs are white, another’s of varied
colours, we will never learn from blown museum speci-
mens. Not until we have the patience and skill to watch
and to find the most deadly enemies which threaten the
nests and eggs of birds, their number and modes of attack,
can we hope for successful soiutions to the thousand and
one problems which offer themselves. What we know in
respect to eggs is fragmentary and rests on so slight a
degree of proof that every theory is attacked and re-
attacked in turn.

Supposing that the eggs of the early forms of birds
were round,—that being the most typical form of a single
cell,—we find many variations in shape among the eggs
of living species. Many of the eggs which are laid in
hollow trees still retain the primitive spherical form, per-
haps an advantage in keeping the eggs in a close group
in the centre of the floor of the cavity.

So characteristic of the eggs of birds is the pear-shape

The Eggs of Birds 431

—one end blunt and narrowing to the other—that they
have given to it its name: oval. In the eggs of certain
sea-birds which breed on the narrow ledges of perpendicular
cliffs this oval shape is carried to an extreme, and ap-
parently for an excellent reason, mechanical, but of ines-
timable value to the birds. Eggs laid in such positions

Fic. 343.—Egg of Murre.

are of course especially exposed to danger from the wind
or from some sudden movement of the birds, which gener-
ally nest very close together. Were it not that the eggs,
on account of their peculiar shape, describe an arc of
very small diameter when they roll, doubtless a far greater
number would roll off and be dashed down upon the
rocks below. Among the plovers, sandpipers, and phal-
aropes we again find a peculiarly pronounced pyriform

fae The bird

shape of egg, serving in these instances a very apparent
and useful end. These birds almost invariably lay four
eggs, which are of large size in comparison with the birds,
and their shape allows them to be fitted closely together,
each forming one of the four segments, their points all
but meeting in the centre. Thus the little body of the

Fig. 344.—Eggs of Killdeer.

parent is large enough to cover them all, which would be
impossible were the eggs arranged at random. The eggs
of grebes are peculiar in having both ends alike.

The number of eggs which a bird lays has been found
to bear a definite relation to the amount of danger to
which the species is exposed—a fact which holds good

The Eggs of Birds 433

in the young of many, if not all, other Phyla of animals,
and which is one of the most interesting provisions brought
about by the slow but sure working of evolution. We
may instance the few eggs of the voracious and masterful
sharks and the millions of spawn necessary to enable
the halibut and the cod to continue in existence.

Mr. Ernest Ingersoll has so admirably summed up
the matter of this relation of the number of eggs to the
corresponding danger that I cannot do better than to
follow his argument, quoting his words with a. slight
change here and there. This phase of the study of eggs
being so clearly understood, it is well worth a little detail
as an illustration of how interesting all the other problems
will become when we once get on the right road to their
solution.

Among the majority of birds the average number of
eggs in a nest is from three to six; we may take five as a
typical average. “Any considerable departure from this
normal number in a species or Family must then be ac-
counted for by some specific or tribal peculiarity in cir-
cumstances.

‘“ Beginning with the ostrichlike group at the bottom
of the list, we find ourselves face to face with an inter-
esting state of things, to which the number of eggs is
an index. Ostriches, rheas, and emeus incubate large
clutches—a dozen or more,—those inhabiting the conti-
nents of Africa and South America, however, producing
twice as many eggs annually as their relatives of Australia
and the neighbouring smaller islands.

“Immediately following and contrasting with them are

434 The Bird

the three groups characterized by the curious elephant-
footed, often gigantic moas, and similar birds of Mada-
gascar, Mauritius, New Zealand, and the Papuan region,
which have become extinct within the historic period,
except the kiwis, to be spoken of later. All of these,
so far as we know, laid only one egg at a time, which,
plainly enough, was sufficient to keep the race going in
the limited space afforded to each species by its island,
but which did not suffice to prevent an almost immediate
extinction of these species as soon as mankind discovered
that the birds and their eggs were serviceable. But Provi-
dence, or Nature, or natural selection, or whatever has
been the ruling influence in determining means and limits
for animal life, seems never to have taken man into ac-
count.

“Turning now to the sea-birds—penguins, gannets,
murres, puffins, auks, petrels, guillemots, tropic-birds,
and the like,—we find that none of them is in the habit
of laying more than one egg, as all breed on such remote
and inaccessible rocks, often in holes, that harm can
rarely happen to their young, and therefore a very high
percentage comes to maturity. Many of these breed in
companies, and are so unacquainted with danger that
they make no attempt to hide their eggs or to leave the
nest when the place is visited by some wandering natu-
ralist or egging party.

“The habit of the King Penguin deserves a note to
itself. This big Antarctic bird guards its one white egg
from harm by carrying it somewhat as a marsupial does
its young, in a pouch formed by a fold of the skin of the

435

Nest and eggs of Junco.

345,

Fia.

436 The Bird

body between the thighs. Both sexes are provided with
this contrivance during the breeding season, and relieve
each other of the burden at intervals.

“The gull tribe, however, are far more exposed to acci-
dent and to enemies, both in adult life and as to their
eggs and young, than are the penguins, petrels, and others
mentioned above; and here the rule is from two (skuas)
to four (gulls and terns) eggs in a nest. When we come

Fic. 346.—Eggs of Ostrich, Cassowary, Hummingbird, and Hen,
showing comparative size.

to the shore- and marsh-birds—the plovers, snipe, sand-
pipers, Jacanas, all of which nestle on the ground, usually
near the shore of the sea or lakes—we judge them to be
exposed to about the average of dangers, since their nest
complement is from four to six. The northern, tundra-
loving cranes need raise few young, and hatch only two
eggs; but when we come to the water-birds—the rails,
gallinules, ducks, and geese—we find an extensive group

The Eggs of Birds 437

whose nests average a dozen eggs in each set. Explana-
tions are ready for this: the birds themselves are exposed
to unusual peril, from weather as well as from active
enemies, since they mostly emigrate to the extreme North
and nest in the edges of marshes, where the sitting birds,

Fie. 347.—Nest of Laughing Gull.

eggs, and young are all subjected to freezings, floods,
and countless marauders that depend largely upon them
for food during the Arctic summer, so that a heavy annual
recruiting must be made to repair losses. Few birds are
liable to so many misfortunes and mishaps as the water-

438 dhe Bird

fowl, except perhaps the big and pugnacious swans, who
can take better care of themselves, and lay only five
eggs or fewer. The long-legged wading birds also, such
as the storks, ibises, herons, and the like, are fairly safe
in the breeding season, because they nest in trees, as
a rule, (lig. 356,) and consequently we here find only two

Fic. 348.—Nest and eggs of California Partridge.

to four young in the annual brood; so with the snake-
birds.

“This brings us to the game-birds—the world-wide
tribes of partridges, pheasants, grouse, turkeys, jungle fowls,
peacocks, and the like—which are of large size, run about
on the ground, and are of interest to sportsmen and epi-
cures. With few exceptions, these must put forth a

439

Fig, 349.—Nest and eggs of Mourning Dove.

440 The Burd

large complement of eggs (eight to twenty) in order to
bring to maturity enough young to replace the yearly
mortality, for the ground-built homes and huddling chicks
encounter a multitude of dangers to which birds in trees, or
even the small-sized ground-nesters, are not exposed. One
exception here singularly favours the rule. The Thibetan
Peacock Pheasant inhabits the heights of the Himalayas,
where it has to contend with only three or four nest-
robbers, instead of the countless foes that infest the lower
jungles; hence its ample breast warms but two eggs.

“The doves and pigeons lay only two eggs, and a few
lay but one; but this seems to be due to the fact that
their extraordinary powers of flight render them, as adults,
unusual immunity from capture and famine, rather than
to any special safety pertaining to their method of nidifi-
cation.

‘“ Hawks and owls in general have four or five eggs,
and as this is about the average number of the small
birds on which they largely prey, it seems evident that
their chances of life and the difficulty of sustaining it
are, on the whole, no less than are met with by their
victims. The owls, however, vary much among them-
selves in this respect; the Snowy Owls, whose home is in
the snowy north, where a nest in the tundra moss is acces-
sible to every marauder, and the Burrowing Owls, whose
underground homes are constantly robbed, being obliged
to lay twice as many eggs as the remainder of the family
in order to overcome the high percentage of casualties
due to these unfortunate situations.

“An odd feature in the nidification of some of the

ithe Begs of Birds AAT

Arctic-breeding owls, where the nesting must take place at
an unreasonably early and cold date in order to give the
fledglings time to reach mature strength before the suc-
ceeding winter assails them, is that these birds deposit
their eggs at intervals of a week or ten days. In this
way the mother can envelop in her plumage and keep
thoroughly warm one egg and a callow fledgling at a

Fig. 350.—Eggs of Screech Owl.

time, and is assisted, in respect to the later eggs and
fledglings, by the warmth of the older young in the nest.

“The parrots are a wide-spread and numerous tribe.
and none of the larger species need lay more than two
or three eggs, for they protect them in deep holes in the
earth or in trees, and are able to defend them; but some
of the smaller parrakeets lay as many as twelve eggs,
reflecting the greater dangers with which they have to

442 The Bird

contend. Toucans are able to get along with a pair of
eggs; while a hornbill, by sealing its mate up in its little
arboreal cavern during nidification, is so adequately
protected that one to three eggs in each family suffice
to keep the race going, since practically every young

Fig. 351.—Burrowing Owl at nesting hole.

bird is brought to maturity. Of the host of smaller and
weaker birds nesting in cavities, two to five eggs are the
usual quota. This brings us to the tribes of little singing
birds with which we started, whose average is about
five; but a few interesting exceptions may be noted.
Our whippoorwills and night-hawks, for instance, lay
only two eggs. These are placed on the ground in the

The Eggs of Birds 44.3

woods, surrounded by no nest, and are so precisely the
colour of the dead leaves that nothing but the merest
accident would lead to their discovery by the eye alone.
The same is eminently true of the bird itself. None of
the almost uncatchable hummingbirds needs to lay
more than two eggs in order to recruit the ranks of its

Fig. 352.—Nest and eggs of the Anna Hummingbird.

species to the full quota permitted it in the numerical
adjustment of bird life.

“T have gone into this matter somewhat at length,
though by no means exhaustively, because I am _ not
aware that the matter has ever been exploited, and be-
cause it embodies a general law or principle. Thus we
see that the nest complement of eggs of any bird is in
exact proportion to the average danger to which that

444 The Bird

species is exposed. I believe that this factor is fairly
constant for species or tribes of similar habits, and that
exceptions indicate peculiarities of circumstances which
in many cases we can easily perceive, because I believe
that Nature is strictly economical of energy, allowing
no more eggs to be laid, and consequently young to be
produced, than the conditions justify in each case. Thus
the uniformity of avine population—the balance of bird-
life—is maintained.”

When a bird’s nest and eggs are destroyed, she will
often lay another setting, and some birds raise two and
even three broods in a season under normal conditions.
If the eggs of a bird are removed as fast as they are laid,
the bird will sometimes continue to lay, one of the most
remarkable instances of this in an uncaged bird being
a Flicker which laid seventy-one eggs during the space
of three-and-seventy days. A tiny African Waxbill in
captivity has been known to rear fifty-four young in the
course of a year, during the same period laying an addi-
tional sixty-seven eggs! The domestic hen has become
a veritable egg-laying machine, thanks to careful breed-
ing in the past, since the wild Red Jungle Fowl from which
all varieties of poultry are descended, lays only one nestful
of seven to twelve eggs once a year.

Many birds still hold to the old style of nesting in
hollow trees and such concealed places. Whether they
hunt around until they find a cavity ready-made by the
elements, or whether, like the woodpeckers, they pro-
ceed to excavate a home in a dead branch, or, kingfisher-
like, to tunnel deep into a sand-bank, their eggs are almost

The Eggs of Birds 445

invariably white. Many indeed have such glossy, highly
polished shells that, were they laid in exposed situations,
their shining surface would be a sure guide to hungry

Fic. 353.—White eggs of Hairy Woodpecker in hollow tree.
(Bowdish, photographer. )

egg-eaters. Among such birds may be mentioned the
owls, woodpeckers and parrots, trogons, motmots, king-
fishers and puffins, besides many others which hide their

446 The Bird

eves in domed nests. On the other hand we find a num-
ber of birds laying spotted eggs in concealed nests, and
white eggs in open places; so that no universal law can
be framed to account for the varied colouring. This 1s
not surprising when we think of the great difference of
conditions under which each species lives. Take for ex-
ample the two species of marsh wrens which live so happily
among the reeds of the marshes of our Eastern States.
Both birds build globular mouse-like nests, both hide their
treasures deep in the interior, but the eggs of the Long-
billed species are dark chocolate-brown, while the Short-
pill’s eggs are like pearls. We do not know why this
difference exists, but that need not deter us from accept-
ing the facts to which the majority of eggs seem to point:
that eggs which are concealed, having no need for colour-
ing, are white like those of reptiles. If, as many writers
have suggested, the colours of eggs are only meaningless
by-products, there is no reason why these hues should
not run riot upon each egg or nestful of eggs, as is the
case in one or two interesting isolated cases to be men-
tioned shortly.

Perhaps the most marked exceptions to the theory
of the protective coloration of eggs is to be found in
doves and pigeons, which lay white eggs in open nests
(Fig. 349); with the exception, curiously enough, of the
Rock Dove, the wild progenitor of our domestic birds,
which places its nest in inaccessible caverns in the face of
cliffs. The almost total extermination of the Passenger
Pigeon has been instanced as an example of a “mistake”
of Nature in allotting to it white eggs; the absurdity of

The Eggs of Birds 447

which statement is apparent when we consider that the
havoc was wrought upon the adult birds and by man!

Wallace has suggested that the nests of doves are so
loosely and so flimsily built—being in reality mere plat-
forms of sticks—that, looking up at them, the eggs simu-
lated the colour of the sky beyond and so became incon-
spicuous; but unfortunately that argument is so decidedly

Fig. 354.—Nest and eggs of Mallard Duck.

suggestive of human presence that it loses much of its
value when we remember that egg-hunters among the
mammals and birds do not stand on the ground to take
observations, but either climb the trees in search of nests
or fly low above the branches.

The eggs of ducks and grouse are white or very light-
coloured, and are laid in open nests upon the ground.
The mother duck’s plumage is the very essence of the
mottled lights and shadows among the reeds, and when

448 the Bird

she leaves her eggs she backs carefully away, drawing
over them, at the same time, a coverlet of beautiful down,
the protective colouring of which is ample to shield the
eggs. Ordinarily this coverlet is rolled up at the edge
of the nest. It is to such a habit that the eider-down
hunters owe their supply. A grouse does not pluck the
down from her breast, but in devotion and ability to
remain close upon her eggs she has few equals. It 1s
rare indeed to find the nest of a grouse unguarded, and
the mother bird will all but wait until your hand is upon
her before leaving her eggs exposed.

The many species of hummingbirds lay the whitest
of eggs, but here it is the nest which is protected,—fash-
ioned of dull-hued plant-down, with beams and rafters
of cobweb, covered outside in our Eastern species with
lichens exactly like those which are growing upon the
limb to which the tiny air-castle is attached. The nests
of vireos, also, are much like their surroundings.

Herons and egrets, pelicans, cormorants, storks,
swans and geese, all lay white or whitish eggs in open
nests; but obviously these birds require little protection, all
being able to defend themselves with beak or wing. Some
of them nest, too, in large colonies, adding the advantage
of numbers. The constant need of vigilance in protect-
ing eggs thus exposed is at once evident when mankind
—that disturber of Nature for whose intrusion she seems
never prepared—comes upon the scene. If we make our
way into the heart of a Florida rookery of herons, ibises,
or cormorants, many of the birds will be frightened from
their nests and the Fish Crows take instant advantage,

6tb *palq SUTULUAN FY payeoryy-Aquy jo Ss59 PUB JSAN—"GGE “DIG

450 The Bird

swooping down one after another upon the nests and
each impaling an egg upon its beak and flying off with it.
They would never dare such open villainy were the herons
undisturbed.

Pia. 356.—Colony of Great Blue Herons.

Many of the more isolated cases of exposed white
eggs are to be explained, I think, by the fact that the
habits of birds often change rapidly, while their structural

The Eggs of Birds 451

adaptation follows more slowly. For example, let us
take the group of owls. The majority of these birds nest
in hollow trees, but even these occasionally make use of
an open hollow or a very shailow one, and individual,
radical departures from the conventional owl-habitation
are doubtless not uncommon. But these exposed eggs
are soon destroyed; for no crow, Jay, or squirrel could ever
resist any opportunity to avenge himself for the wrongs
inflicted by his ancestral enemy, the owl. But when,
urged on by that impulse which ever tends to make birds
vary their habits in all directions, some owl, such as the
Short-eared, finds good feeding on marshes and open,
treeless plains, it naturally takes to nesting on the ground,
in nests but partly concealed by the overhanging grasses.

Three things might now happen. If sufficient varia-
tion occurred and the conditions demanded it, natural
selection might bring about a protective colour on the
shells of the eggs; if enemies were few and easily over-
awed, the eggs might remain white; while, on the other
hand, the enterprising race might be wiped out of exist-
ence for no more reason than the colour of the egg-shells.
The second result seems to be the good fortune of the
Short-eared Owls. All of these fates have undoubtedly
overtaken birds again and again, and it is by the inter-
action of such condition , combined with an ever-chang-
ing environment, that many phenomena are brought about.

It was by reason of the general similarity in colour
which the eggs of related groups of birds tend to show
to each other that odlogy, or the science of egeg-shells,
was able to initiate an important scientific discovery.

452 The Bird

At one time the sandpipers and plovers were classed as
wading birds, and the gulls and terns in an Order placed
at a remote distance in the scheme of classification from
the former birds; no one suspecting that the two groups
were in any way related. The striking resemblance
which their eggs showed, however, suggested an affinity

Fig. 357.—(a) Egg of common Tern compared with (b) egg of Black-necked Stilt

which was later perfectly confirmed by anatomists and
embryologists.

The few thousands of years during which our race
has risen to inheritance of the earth is all too short
a time, geologically speaking, for us to flatter ourselves
that any of the protective colours of animals were de-
veloped on our account; but in many instances we,
sharing the same five senses of animals, may put our-
selves in their position. Imagining ourselves egg-hunting

454. The Bird

animals, let us consider some of the more patent cases
where eggs are coloured for protection— where they
mimic their surroundings so perfectly that only the most
careful search reveals their whereabouts. Ostriches and
Cassowaries are two interesting examples, the former
bird laying its white eggs upon the white sands of the
desert; while the cassowary, in the depths of its jungle
home, incubates a nestful of eggs of the most exquisite
emerald hue, matching perfectly the green moss upon
which they rest. I knew of one of these birds confined
in a small paddock of green grass, whose splendid eggs,
measuring three by six inches, once remained undiscov-
ered for weeks, although laid openly upon the ground.
Special search was necessary to find even these great eggs.

If we walk in the woods in June and happen to flush a
night-hawk from the ground, the most careful scrutiny of
the place where the bird rose will often fail to reveal to
our sight what at last our fingers detect—two eggs, their
shells imbued with the colours of the forest floor. I have
led persons to a spot on a beach of shells and sand,
told them that there were twenty-one good-sized eggs
within a radius of fifteen feet, and seen them utterly baffled.
The olive-gray, blotched shell of a tern’s egg rests among
dark pebbles, or more often upon a wisp of seaweed, into
whose irregularities the hues of the eggs melt and mingle
perfectly. The Black Skimmer, that most interesting
bird of our coast, lays its eggs upon the bare sand among,
or sometimes in, the large clam-shells which the storms throw
up in windrows. Against man’s systematic search their
wonderful assimilative colouring is of course often useless,

The Eggs of Birds 455

but sharp as is the eye of passing crow or beach-patrolling
bear, the eggs to them would appear but bits of sand and
shadow.

And thus we might go on with many other examples
of protection derived from the pigment on the shells—
protection which in a hundred instances might prove

Fia. 360.—Eggs of Night-hawk.

futile, but which in the great summing up and balancing
of Nature’s profit and loss is of inestimable value to the
race.

We find an unusual condition in the colouring of the
eges of sea-birds,—of certain of those species which nest
on inaccessible cliffs. If pigment was developed in the

456 ihe Bird

eges of the ancestors of these birds for the sake of protec-
tion, all need for it is now lacking, and as an apparent
result the various hues seem to have run riot. One may
place a hundred murres’ eges side by side and find no two
alike, while the extremes would never be recognized as
belonging to the same species of bird.

Fia. 361.—Nests of Tern and Skimmer.

Another instance of extreme variability in the colour
of eggs and an instance of intensely interesting import is
found in the English Cuckoo, which may be taken as an
example of species which are parasitical,—in the sense
that the females make no nest of their own, but deposit
their eggs in the nests of other birds, the young being thus

LSV ‘ULd], UOWIMIOD JO ss50 puT JSAN—’ZOE “DIT

458 The Bird

hatched and reared by foster-parents. Such an unusual,
almost unique habit has brought about a considerable
modification of the eggs. Anything which would tend to
deceive the greatest number of intended victims would,
of course, greatly redound to the advantage of parasitical
birds.

The remarkable similarity of the English Cuckoo’s egg
to those in the nest in which it is laid has been explained
as due to each individual bird being accustomed to lay its
ege in the nest of the same species favoured by its parents
and its more distant ancestors; its eggs in course of time, by
natural selection, thus coming to resemble the eggs of that
particular species. Other adaptations are the extremely
small size of the egg in comparison with the parent bird,
and also the unusual strength and weight of the shell.
This last is doubtless of great value; for, strange as it
may seem, the bird first deposits its egg upon the ground
and then picks it up in its beak and places it in the nest
selected. Thus a strong shell is a very necessary require-
ment.

The colours of eggs have been carefully examined with
the spectroscope and are found to consist, chemically, of
seven pigments: a brownish red, two delicate blues, two
clear yellows, a peculiar brown hue, while the seventh is a
rather indefinite shade, known as lichenixanthine—most
interesting of all as being identical with a colour substance
common in plants and especially in lichens and fungi.
These substances somewhat resemble those found in the
blood and the bile. They are deposited on the shell while
the ege is passing down the oviduct, and it is to the circular

The Eggs of Birds 459

or erratic motion of the egg that the curious scrawls and
blotches upon some eggs are due. The shell is deposited
in successive layers, and from the dim, clouded appearance
of many colours we judge that the pigment is often partly
concealed by the outermost layers of the shell.

Fig. 363.—Nest and eggs of Skimmer, showing the remarkable variation in colour
cee eggs in a single nest, heightening their resemblance to pebbles or sea-
Occasionally, in the eggs of birds which number only
two in a nest, one ege will be almost white and the other
coated with an abnormal density of pigment. In certain
species of small birds which lay four or five eggs, one egg

always differs remarkably from the rest. Can we not

460 The Bird

account for this latter condition on the hypothesis that an
actual change—an increase—is slowly taking place in the
number of eggs of this species, the abnormal shell reflect-
ing the as yet only partial readjustment of the pigment-
gland to meet the extra demand?

The carbonate of lime, of which the shell is chiefly
composed, varies in its composition, being sometimes so
fine that the surface has a high gloss, the eggs of wood-
peckers being a good example, or again loose and chalky,
as in cormorants. In tinamous the glossiness is carried
to an extreme, their eggs resembling ovals of highly
burnished metal, green and purple in colour.

The shells of ducks’ eggs are impregnated with an oily
substance, which must be of great use in resisting the
dampness and moisture of their surroundings.

The eggs of some entire Families of birds are easily
recognized by the resemblance of the grain of the shell;
while, on the other hand, this microscopic appearance in
the eges of individual species may differ considerably,
as in the case of the eggs of the Mute and Whooping Swans.
The eggs of the North African Ostrich have a surface
smooth as ivory, while the eggs laid by the South African
birds are deeply pitted. The beautiful eggs of the casso-
wary show an extreme condition, the light green surface
of the egg being covered with raised irregularities of a
darker green colour.

The thickness of the shells of ostrich eggs is remarkable,
and their strength permits their use as water-bottles—an
invaluable boon to the Arabs of the desert.

With the relative size of the egg and the bird which

The Eggs of Birds 461

lays it we will not here concern ourselves, except to remark
that the largest egg in proportion to the size of the bird
is that of the apteryx. If we imagine a rather smallish
hen laying an egg 35 inches in size, we will get a vivid
idea of this bird’s ability, and it lays two at a setting!
The smallest of all eggs is that of the hummingbird, while
the largest is the egg of the extinct giant Apyornis of
Madagascar, the shell of which measures 9X13 inches.
In some cases the fossil egg is all that is left to us to hint
of the existence of these great feathered creatures. Many
of these shells have been found buried with some old
native chief, the whole egg placed beside him to furnish
food for the long journey after death.

Whether we look at eggs from the standpoint of an
artist’s delight in harmonious and delicate colouring, or
from the wonder of their scientific composition, or even
from the point of view of a hungry man sitting down to
breakfast, we must admit that they deserve all the appre-
ciation which their beauty and their utility demand.

CHAPTER XVII
THE BIRD IN THE EGG

HE embryology, or life of the bird in the egg, is
the most mysterious and wonderful part of the
entire physical aspect. Many of the lesser de-

tails of growth are very difficult to study without the

use of microscopic sections and wax models; but a little
knowledge of the subject is more interesting and simple
than one would imagine.

The very best way to begin our study of the life in the
eve will be to go to the nearest pond or marsh, if it is spring-
time, and bring home a pailful of freshly laid frog’s eggs
—those queer, gelatinous masses filled with black dots.
Place them in a flat, white basin, and into a smaller saucer
near by break a fresh hen’s egg, being careful not to injure
the yolk. Separate one of the frog’s eggs with a spoon
and put it beside that of the fowl. Now examine them
carefully with a good dissecting-microscope or even with
a hand-lens.

We see a large, round, yellow yolk in the case of one
ege, and a tiny speck of black and white in the other,—
both apparently inanimate bits of matter, but which,

merely by the application of heat in the one instance
462

The Bird in the Egg 463

and the presence of water in the other, will slowly take
on the semblance of living creatures; the one eventually
to swim forth, live the life of a fish for a time, then to
leap upon the land and croak among the reeds. The
other yolk would have evolved into a downy, yellow chick.
We cannot hope to solve the mystery of life, but there
is a fascination in seeing how near its beginnings we can
approach.

Fic. 364.—Egg of Hen, opened to show a 3-day embryo in position on the yolk.
(Slightly enlarged.)

If we have ever watched under the microscope the strange
little creatures which live in the mud at the bottom of
ponds, we will have realized the wonderful possibilities of a
single drop of living matter,—a single cell,—from the
amoeba with its ever-changing shape to the swiftly moving
slipper paramecium and the beautiful animal vases,—the

464 The Bird

vorticella, on their queer little corkscrew stems. All these
are made up of but a single cell, and in the beginning all
seeds of plants and all eggs of animals likewise consist of
one cell.

If we examine a chicken while it is being dressed for the
table, we can easily find the ovary, a mass of hundreds
of tiny golden spheres,—eggs which would have been
laid during the coming years. So we realize that the most
essential part, in fact the real egg, is only the yolk; all
else being merely protective. The shell protects the yolk
while the chick is developing during incubation, and
although formed of crystals of lime, yet it is so porous
that oxygen can enter and carbonic acid gas escape. The
viscid white, or albumen, is nutritious as well as protective,
while the yolk itself is the real food of the embryo and also
acts as a support to the developing chick. If we look
carefully, we will see two whitish, twisted strands which
extend from the yolk through the white. These two strands
have whitish opaque knots strung along them, and from a
fancied resemblance to hailstones they are called chalaze.
These act as pads to protect the yolk from sudden jars,
but they do not act as suspensories. A hen never turns
her eges, as many people imagine, to warm the different
sides equally, for the germ-dot—the position of the future
embryo (of which we will speak presently)—is always
on the lightest side of the yolk, and whichever way the egg
is turned it always swings uppermost, nearest the heat
from the body of the sitting hen. The turning, however,
may be of advantage in allowing moisture to act upon a
greater surface of shell.

The Bird in the Eee 465

Now let us examine closely the egg of the frog. It,
too, has a protective gelatinous outer coating. Before the
egg was laid it was enveloped with several very delicate
membranes, which were sponge-like in their property of
absorbing water, and when deposited in a pond _ they
immediately swelled up to the present gelatinous con-
sistency. If the egg has been deposited but an hour or
two, it will show a perfectly smooth surface under the
lens, but look at it intermittently for a half-hour, or even
longer, and you will be well repaid. Slowly but surely,
as the shadow of an eclipse darkens the face of the sun,
a tiny furrow ploughs its way over the surface of the dark
end of the egg. It lengthens and deepens and soon divides
the egg into two equal halves.

Let us stop a minute and realize what we have seen.
It is all but the beginning of life, the first hint of a higher
order of things than those one-celled creatures which we
dredged from the mud,—than the life which, untold ages
ago, was all that the earth boasted. The original cell of
the ege has, before our eyes, divided into two! But
while we have been lost in wonder and awe,—for the lover
of Nature must indeed be stolid if the first sight of such a
happening does not stir his deepest emotions,—the life
has ceased its progress never an instant. A new furrow
appears, crossing the first at right angles, dividing the egg
into quarters; then other furrows dividing it into eighths,
then cross-furrows, and the count is lost; the multitude of
cells repeating themselves hour after hour, day and night,
arranging themselves, each in its right position, obeying
some inscrutable law, until at the end of about 300 hours

466 The Bird

the tadpole wriggles his way through the cloudy mass of
gelatine and swims into the water.

The first steps of this dividing or cleaving of the original
single cell is similar in all eggs. The deep significance of
the equality of the first two cells may be better appre-
ciated when we know that if one of these be destroyed by
a touch from a red-hot needle, a perfect hal/ tadpole will
develop from the other unharmed twin cell. If we observe
the cleavage of the whiter portion of the frog’s egg, we will
notice that the furrows, though ultimately extending all
the way around, yet grow very slowly in that portion. This
is because much of the white part consists of yolk, or true
food-matter, the more active formative material being
confined to the black portion.

If we follow this segmentation of the cells for some
time, the egg of the frog will come to look like a diminutive
blackberry—a single layer of cells thickly covering its
entire surface, like the rounded protuberances of the berry.
Now a curious thing happens. <A tiny nick appears in one
side, which gradually deepens and widens until it extends
deep into the egg, pressing two rows of cells into close
proximity to each other. This will be perfectly clear if
we take a small rubber ball and squeeze it until one hollow
hemisphere is pressed into the other. This stage of em-
bryological life is called the gastrula, and is of the greatest
significance, as we shall soon see.

Without further comment at present, let us now leave
the frog’s egg and consider that of the fowl. When the
yolk or egg has but just left the ovary a tiny dot is visible
on one side,—the germinal vesicle, which after fertilization

Fig. 365.+-Stages in the development of frog’s egg, from first division into two
cells up to well-formed larval tadpole. (From original drawings by the author.)

467

468 The Bird

immediately begins to divide into numerous cells, as in
the case of the frog’s egg. This goes on until the egg is
Jaid, and when we break the shell, we see at the uppermost
part of the sphere of yellow yolk a well-defined portion,
in appearance a tiny ring of cloudy, opaque matter enclos-
ing a transparent circle. So now we see the use of begin-
ning our investigation with the frog’s egg, that of the fowl
having reached quite an advanced stage before it is laid.

The ring and circle of the embryonic spot on the yolk
consists of a layer of small, even cells, like cobblestones.
These are spread over the top of the yolk, while just be-
neath is a jumbled mass of many larger cells. The opaque
ring is caused by a thicker, denser concentric layer of these
lower cells. When heat is applied, this outer layer begins
to segment rapidly, the new cells spreading down over
the surface of the great ball of yolk; a curving depression
dimples the surface of the little transparent circle, pushing
in deeper and deeper; and behold! we have the very same
condition—the gastrula stage—which we saw in the frog’s
ege. To make this stage in the egg of the hen more real,
squeeze the rubber ball into a hemisphere and clap it
upon an orange so that the two layers of rubber fit, cap-
like, upon the fruit.

This is all very wonderful, but what special significance
has it? What particular point upon which we may sus-
pend it in our memory, so that it will always return to us
with a thrill of interest and wonder whenever we see an
ege? Just this. When we first examined the frog’s egg,
and when the egg of the chick was still attached to the
ovary, they were comparable to the one-celled creatures

The Bird in the Egg 469

living in the mud of the pond, which are the most lowly
organized beings in the world. The gastrula stage—the
double-walled cup, into which the real egg-part of each

Fic. 366.—Third-day stage of embryo chick. (See Fig. 364.) Greatly enlarged.
M, Muscle-plates (false vertebree).

yolk forms itself, is comparable with the next higher class
of living creatures, the sponges. For the simplest of
these are nothing more than a cup of cells, two layers deep

470 m@he Bird

(these layers being known as the ectoderm and endoderm,
or outer skin and inner skin). The name gastrula, or little
stomach, is certainly most applicable, for an animal of
this kind consists of hardly more than stomach and mouth.

But the embryo of the frog’s egg does not long remain
in this sponge-like condition; for almost immediately a
third layer, the mesoderm, or middle skin, appears between
the other two. From these three layers of cells all the
parts of the body of the future chick arise, by the continued
dividing of the cells. The details are far too involved to
be followed without going into technicalities.

Suffice it to say that in the development of the embryo
chick we have one of the surest proofs of the truth of the
theory of evolution,—of the gradual evolving of each of
the higher groups of animals from some lower, more
generalized form, until all are originally derived from an
organism consisting of a single cell, with its tiny germ-
spot. The dividing of this ge:m-spot in the dawn of
creation was the beginning of that wonderful unrolling
of life which to-day culminates in birds and the higher
mammals,—even in man himself.

It would be too much to expect that the growing
embryo chick distinctly reflects in its successive stages of
erowth, during a short three weeks, the embryonic states
of all its unnumbered generations of ancestors. The record,
like that of paleontology, is imperfect. Many important
phases are slurred over or apparently entirely omitted;
in order, evidently, to give freer play to the development
of organs which will be of vital importance in the future
active life of the bird. Now and then, however, a gleam—

The Bird in the Egg 471

a spark of life reflected from the far-distant past shines forth
so vividly as to hold us spellbound, almost instantly to
fade out forever, having no part in the actual life of the
chick. Like the finding of the Archzeopteryx, these dim
reflections seem to have been preserved by some kind
Providence, especially to aid our groping efforts to find
the truth of ages that are past. Were it not for these
we should never dare to voice such an incredible theory
as the story of evolution would be, were it not supported
by unanswerable proofs. The question which interests
scientists to-day is not whether evolution is true, but how
its processes and changes have been brought about.

The difficulty of seizing upon these evanescent bits of
realism of the past will be appreciated when we know
that while, in the case of the hen’s egg, three weeks are
required before the chick is ready to break the shell, yet
when incubation has proceeded but eighteen hours, a tiny
rod of cells shows where the notochord will be formed—
that gelatinous foreshadowing of the back-bone. Thus a
character, found first in living organisms as high in the
scale of life as fish and primitive fish-like creatures, makes
its appearance in a few hours, giving but the scantest
opportunity for the passing in review of embryonic features
of the great group of invertebrates, or those animals, like
starfishes, crabs, worms, and insects, which lack a back-
bone.

The simplest way to study the growing embryo is to put
a number of eggs in an incubator, or under a hen, and
examine one on each successive day. If the egg is held

firmly, by pressing it down into a box of loose sand, the

472 The Bird

upper part of the shell may be carefully picked away with
a pin and the little embryo exposed to view.

When thirty-six hours old it measures almost one
quarter of an inch in length and shows many interesting
things. The embryo is set off from the rest of the yolk,
much as one’s hand is if placed under a piece of cloth, the
latter then being tucked in beneath the palm in all direc-
tions, until the gathered portion is closely constricted.
We are able with a good lens to make out which is the
head and which the tail end of the future chick, the former
being broader and showing the beginning of the two tiny
swellings—the future eyes. Behind these, four faintly
outlined enlargements along the central line show the
anlagen of the various parts of the brain. These take up
about one third of the entire length of the embryo, showing
the importance of the organs of the head. Still farther
back are two rows of little segments strung along the

centre line—the false back-bone, hinting of the worm-like

series of muscles, of which we have already spoken (page
69).

A heart is even now hinted at, but is seen better in a
later stage. An interesting thing about it, however, is
that, at this stage, it is really in the head region, vividly
recalling the condition existing in fishes, where it is very
far forward in the body, in fact only just behind the gills.
At this period in the chick embryo the heart, instead of
being a complicated organ, divided into four complete
cavities, is very similar to that organ in our old friend
Amphioxus, that lowliest of all fishes, where it is nothing
but a slightly enlarged, contractile blood-vessel. In this

The Bird in the Egg 473

latter creature there have been found as many as a hun-
dred and eighty pairs of gill-clefts, such a remarkable
number aerating the blood with but little necessary pro-
pulsion, but when in the higher fishes the number of gills
in many species is reduced to four, we realize at once the
need for a stronger engine to force the blood through the
lessened number, this accounting for the increased com-
plexity of the heart.

Up to about the twelfth day the tiny foreshadowings of
bones are cartilaginous, like those of the shark, but at this
time real osseous, or bony, tissue begins to be deposited
in spots which spread rapidly. In the various portions of
the skull these bony centres spread until the bones are
separated only by narrow sutures, and in the adult bird
even these are obliterated, unlike the condition in the
skull of a cat or a dog.

The bones of the adult bird are so neatly joined together,
and are so mutually dependent, that we might easily
imagine that they were formed in the order of size or
importance, or in a regular series, following their connection
with one another; but this is not true. The ribs, for
example, are formed between the segments of the primitive
sheets of muscle, independently of the back-bone, and
only later become attached to it. There is no trace of the
great keel-bone, or even of the sternum of the adult fowl,
until after the ends of the ribs have met in the middle line
of the body, when they grow together and give rise to the

a structure not found in fishes. We have
learned that the repetition of similar structures (as the
ribs) is a sign of a low degree of organization, and the truth

sternum

474 The Bird

of this is emphasized in the development of the embryo,
during which process a number of additional ribs dis-
appear. The abortive ribs of the neck-bones are especially
noticeable during the egg-life of the bird, so that in some
species we can make out traces of as many as fifteen ribs
all told.

On page 97 a short account was given of the origin of
the wings and feet, in the case
of the chick—from a_ primi-
tive fin-fold in some general-
ized aquatic ancestor. About
the fourth day of incuba-
tion, sections of our embryo
chick will show a low, round-
ed ridge, extending the whole
length from the neck to the
tail. While we can never be
absolutely certain that perfect
homology exists between the
two, yet it is very significant

that soon after its develop-
Fic. 367.—Early embryo of Canada ment it dwindles away, leay-

Goose, showing fin-like limbs. ? 5
: ing four conical, isolated
buds—the beginnings of the limbs of the bird. Within
two or three days after the appearance of the limbs, faint
streaks become visible upon the tips of the extremities,
and these hints of the bones of fingers and toes, for such
they are, soon push out beyond the edge, still bound
together by their transparent membrane, and for some
time they present the appearance of webbed paws or

The Bird in the Egg 475

radiate fins. But as early as the tenth day, except for
the absence of feathers and claws, the limbs are, in appear-
ance, very perfect wings and feet. The most interesting
fact in connection with the limbs is that their develop-
ment begins superficially and works inward, not, as would
be thought, starting at the shoulder and ending at the
digits.

Even the deep-seated shoulder- and thigh-girdles of bone
(pp. 85 and 89) are not derived from the axial skeleton.
The former, in the long ago, was gradually pushed inward
from the surface by the deep-reaching rays of the fin-like
fore limbs, and it is believed that the pelvic girdle had
its origin in the spliced scales of some fish-like ancestor
of old, which had scales like those of some of the fossil
ganoids. These probably covered over the cartilage girdle
and then sunk in.

An example of one out of many reptilian structures
which appear for a time and then vanish, 1s found in the
procoracoid bone which has apparently much to do with
the development of the typical coracoids, but which is
absent or reduced to a mere process in the adult bird.*
Strangely enough, in the embryo of the common chick
the coracoid and scapula fuse together at an early stage,
being then in a condition comparable only to that found
in the full-grown ostrich. Later this inexplicable fusion
is dissolved and the bones complete their development as
they began,—two wholly independent structures.

Again, in the embryo of a tern, faint vestiges of teeth

* This process is quite pronounced in the case of the Ostrich.

476 The Bird

have been observed, instantly bringing to mind that some-
what gull-like, toothed bird of old—IJcthyornis.

The origin and subsequent changes, in the embryo chick,
of the vascular system, including the heart, nerves, and
arteries, are more intricate than the development of any
other system of organs, and for an excellent reason. We
know that the frog’s egg hatches as a tadpole, which breathes
by means of gills and lives, for a considerable time, in the
water. We learned in Chapter IV that important parts
of the head and sense-organs of birds are derived from
metamorphosed gills; so the inference is that all the changes
in the blood-channels, which in the tadpole and frog take
place during several months, are in the embryo chick
gone through with in a period of a few days.

The blood in the heart of a fish 1s sent from the single
ventricle to the gills, and from there it is distributed all
over the body. In the gills it passes through the paired
series of red fringes and is oxygenated by the water. Now
in the chick there are six pairs of these gills, or paired
blood-vessels (although not more than three or four are
found at one time). The chick breathes by means of a
membranous sheet of blood-vessels spread out just beneath
the shell, and even the lungs are not brought into use until
just before the bird hatches. But strange to say, although
there is no water to supply the gill-channels with life-
giving oxygen, yet blood actually flows through them, in
obedience to the long-forgotten ancestral life-habits—
useless these many millions of years.

Of all the gill-channels, but three remain in the adult
bird. The great aorta, which springs from the heart and

Fic. 368.—Pineal eye in Lizard

477

478 The Bird

turns to the right (in ourselves, the left-side gill-channel
forms this aortic arch), is what is left of the fourth pair
of aortic gill-arches, while the two arteries which, in all
higher animals, leads to the right and left lungs. are the self-
same channels which in the creatures of olden time encircled
the sixth pair of gill-bars.

Although the eye of the bird is far superior to that of
a fish in seeing ability,
yet in actual structure
there is not very much
difference, except that
the bird has gained
eyelids, — tear-glands,
and a few other struc-
tures. Fishes, frogs,
lizards, birds, and
mammals, through all
the ages, have depend-
ed on these two eyes
and have found them
all-sufficient ; but there
are hints that once,
long ago, the ancestors of all the higher animals had a sense-
organ, probably of sight, situated, like that of the mythical
Polyphemus, in the centre of the head. In lizards this
vestigial organ is sometimes quite well developed, having
a nerve which leads up from the centre of the brain to a

Fic. 369.—Pineal eye in Chick (P. E.).

kind of translucent, lens-like scale which lies among the
other scales of the skin, upon the centre of the forehead.
In the long-extinct Ichthyosaurs this median eye was prob-

The Bird in the Egg 479

ably functional. In an embryo chick of even the third
day this organ is remarkably prominent; but although
traces of it always remain, yet it fades away to a vestige.
Look with a hand-lens at the head of a polywog, and
see the whitish dot between the eyes; or when you touch

Fig. 370.—Forty-day embryo Ostrich, showing position in the shell.

the “soft spot” on the head of a human baby, let it recall
the strange third eye which is its cause.

And so we might continue to tell of the wonder of
embryo life: how up to the sixth day the little being
might be mistaken for the embryo of a reptile or a mammal,
but from this day onward the bird characteristics become
more and more noticeable. On the ninth day feathers

480 The Bird

begin to be seen, looking, however, more like tiny cones
than anything else (Fig. 11). The muscles and the cartilage
skeleton are well defined on the fourteenth day, and about
this time the tiny beak with its white egg-tooth is pressed
against the membrane of the air-chamber at the large end
of the egg. Reptiles also show this tiny bit of sharp lime
upon the head, which drops off soon after its function 1s
completed. Not until almost the last day is the mem-
brane pierced and the first gasp of air breathed into the
little lungs. By an instinctive moving of the head back
and forth the shell is filed through and cracked, and the
chick rolls out into the world, weak and helpless and for
a while absolutely dependent upon warmth and the care
of its mother, before it is fit for its future life. (Figs. 18
and 19.)

Thus do all wild birds begin life, passing through
similar phases within the egg; and although we so often
admire a nest full of eggs, yet how seldom do we give
thought to the tiny creatures within,—their hearts even
at that very minute, perhaps, giving their first fluttering
beat!

The instant that its eyes have cleared and its shaky
legs have gained strength to support its body, the chick
begins to use its senses and to store up experiences, taking
note of this sound and that taste, learning to fear or to
ignore, to flee or to pursue, to call or to remain silent.
And thus does the brain of the chick and of all wild nestlings
begin to act and its psychological life commences, with
intermingled perceptions, instincts, and gleams of intelli-
gence. Here belong the making of nests and journeys,

Qh (doydersojoyd ‘uoysMeg) sBuryo ey syorqo yourIsQ— [LZ ‘D1q

482 The Bird

courtship and songs, the rearing of young birds, the avoid-
ing of enemies, the selection of food and suitable haunts,
and, lastly, the encountering and overcoming of dangers, —
new and wide-spread,—which are now affecting the environ-
ment of every creature of this world. Of greater impor-
tance than ever before is this adaptation to new con-
ditions; since man and his traps and his guns have come
upon the scene, upsetting all the world-old order of
Nature and slowly, surely, claiming the whole earth for
himself.

May the naturalists of to-day realize their opportunity
and do their best to preserve to us and to posterity what
is left to us of wild life! If not, let us pity the Nature-
lover of two hundred years hence!

APPENDIX

A FEW EXCELLENT BOOKS RELATING DIRECTLY OR
INDIRECTLY TO ORNITHOLOGY

EVOLUTION

ORIGIN OF SPECIEs.
Charles Darwin. Appleton & Co., New York.
FROM THE GREEKS TO DARWIN.
Henry Fairfield Osborn. Maemillan Co., New York.
OreGANIC EvoLution.
M. M. Metcalf. Macmillan Co., New York.
VARIATION IN ANIMALS AND PLANTS.
H. M. Vernon. Henry Holt & Co., New York.
BOOKS FOR THE IDENTIFICATION OF NORTH AMERICAN BIRDS
GuIDE TO THE Birps oF New ENGLAND AND EASTERN NEw York.
Ralph Hoffmann. Houghton, Mifflin & Co., Boston.
HANDBOOK OF Brirps OF EASTERN Norru AMERICA.
F. M. Chapman. Appleton & Co., New York.
HANDBOOK OF BIRDS OF THE WESTERN UNITED S?TarTEs.
Florence M. Bailey. Houghton, Mifflin & Co., Boston.
Key to Norra AMERICAN Birps (2 vols.).
Elliot Coues. Dana Estes & Co., Boston.
Birps oF NortH aNp MrippLe America (3 parts; others to follow).
Robert Ridgway. Bulletin of the United States National Museum,
No. 50, Washington, D. C.
History or NortaH AmerIcAN Lanp Birps (3 vols.).
Baird, Brewer, and Ridgway. Little, Brown & Co., Boston.

483

484 Appendix

' BIRDS IN GENERAL

DicTIONARY OF Brirps.

Alfred Newton. <A. & C. Black, London.
RiversipE Naturat History, Vol. IV. Birds.

L. Stejneger. Houghton, Mifflin & Co., New York.

MISCELLANEOUS

Birps or Essex County, MASSACHUSETTS.
C. W. Townsend. Memoir of Nuttall Ornithological Club, No. III,
Cambridge, Mass. (A type of a local bird-study )
THE WOODPECKERS.
Fannie H. Eckstorm. Houghton, Mifflin & Co., Boston. (A popu-
lar study of a single group of birds.)

INDEX

Figures in heavy-faced type indicate illustrations.

A

Abdominal ribs, 79

Adaptation of feet, 361, 362

Adaptative Radiation, 15-18; in war-
blers, 361-367

Adjutant, head of,
from neck of, 276

Apyornis, com. size of egg of, 461 .

Aftershaft, 36

Aggressive coloration, use of, 308;
in Arctic fox, 309; in Cuckoo, 311;
in Gyrfalcon, 309, 312; in Ivory Gull,
309, 311; in Penguin, 309, 310;
in pickerel, 310; in Snowy Owl, 309,
313

Air-saes, ef. with respiratory system
of insects, 173: extent of, 173;
function of, 174, 177; in Prairie Hen,
LAE

Albatross, wing of, 320, 321, 325, 332

Albinism, 314

Alligator, egg of, 429; foot of, 354;
nictitating membrane of, 215; re-
lation to birds, 9; skull of, 105

Altricial nestling, 30

Amoeba, 185, 186, 463

Amphioxus, 66; gill-clefts in, 473;
notochord of, 66; segments of, 78;
trachea of, 169; breathing motions
in, 180

Anaximander, 12

Ancestors of birds, 1-18

Aorta, 476

Apoplexy in birds, 202

Apteryx, ody-feathers of, 289; eyes
in, 254, 255, 256; sense of touch in,
219

Archeopteryx, as parallel branch, 10;
as ancestral type, 10; foot of, 353;
general description of, 7; in Berlin
Museum, 11; in British Museum, 8;
probable habits of, 12-13; restora-
tion of, 14; tail of, 398, 399, 400, gor

Aristotle, ef. with Darwin, 12

273, 276; hair

Artery, 182

Arteries, course of vertebral, 79

Atlas of Jabiru, 72

Auk, wing of Great, 339, 340; wing of
razor-billed, 339, 340

Avocet, bill of, 237, 239

Axis of Jabiru, 72

B

Back-bone, of Amphioxus, 66;
tion of, 64-70; of shark, 68
Barbs, of Condor’s feather, 32
Barbicels, 32, 34
Barbules, 32, 34
Bats, keel of, 83-84; used as food, 158
Beak, see Bill
Beaks and Bills, 223-251
Bear, feet of, 102
Bellbird, wattles of, 273
Biil,
function of, 223, 224, 250, 251
of Avocet, 237, 239; Archzopteryx,
226; Cormorant, 227, 228; Cross-
bill, 24, 249, 245; Crow, 226;
Shoveller Duck, 233, 235; Purple

evolu-

Finch, 249; Golden Eagle, 242;
Flamingo, 128, 234, 235, 236;
Gannet, 227, 228; Boat-billed

Heron, 237,238; Great Blue Heron,
237; Night Heron, 237; Huiabird,
248, 249, 250; Hummingbirds, 244,
245, 246, 247, 248; Ibis, 237, 239;
Shell Ibis, 240; Merganser, 233,
234; Nuthatch, 245; Owls, 242;
Oyster-catcher, 238, 240; Parrots,
JAD Relicanw 2285 9220.) 230%
Crook-billed Plover, 240, 241;
American Raven, 225; Black Skim-
mer, 231, 232, 236; Snakebird,
228, 229; Dowitcher Snipe, 241;
Spoonbill, 220, 2386, 239; Stilt, 237;
Chimney Swift, 244, 246, 245;
Tailor-bird, 245; Tern, 231, 232;
Toucans, 243, 244; ‘Triceratops,

485

486

226; Woodcock, 219,
Woodpeckers, 245
Blackbird, down on nestling, 26
Blood, circulation of, 182, 183, 184;
compared with amoeba, 185; red
corpuscles of, 184, 185; white cor-
puscles of, 185
Bobolink, cause of colour
spring, 297
Bob-white, effect of climate on, 293
295; moult of, 43
Body, of Herons, 286; Petrels, 286

22222

change in

Body-feathers, of Apteryx, 289; Cas-
sowary, 288; Snowy Egret, 305,

322; Emeu, 36, 289; Ostrich 236,

288; Scaled Partridge, 289; Pen-
guin, 289; Rock-jumper, 288;

Snake-bird, 289

Boltenia, notochord of, 67, 67

Bones, of embryo chick, 473; hollow-
ness of, 175, 176; of mammal skull,
103; relation to flight, 176; of skull,
107

Breast-bone, 79-84; evolution of, 79

Breast ornament of Wild Turkey, 280

Brain, of bird compared with that of
crocodile, 200; with that of Tricera-
tops; 200; with that of Walrus, 200;
embryo, thirty-six hours old, 472;
great size in birds, 199, 200, 201;
importance of, 198; nerves of, 202;
protection of, 196

Bulk, birds of largest, 285

Bustard, echin-feathers of Great,
weight of, 285

Butterfly, eggs of, 428; torn by birds, 147

Buzzard, ~Black-breasted, feeding on
Emeu eggs, 159

267;

C

Canals, semicircular, 218
Caracara, head of, 271, 272; foot of, 378
Carp, compared with Scaled Partridge,
289, 290
Carrion Hawk, Chimango, food of, 162
Cassowary,
body feathers of, 288
eggs of, 436, 453; colour of, 453, 454;
character of shell of, 460
helmet of, 275, 288; lack of tail of,
402; tracks of, 396; wing of, 321,
337, 338
Catbird, use of wing in young. 322
Caterpillar, used as food by birds, 146
Cells, of blood, see Blood; of feathers,
34; of muscle, see Muscle
Cerebellum, 201 y
Chewink, foot of, 367
Chicken, stomach glands of, 135

Index

Chuck-will’s-widow, comb on toe of, 369
Circulatory system of pigeon, 183
Classification, based on toes, 354, 555
Clavicle, function of, 85; of Hoatzin, 86;
in mammals, 86
Claws of foot, 368
three on wing of, Osprey, 322; Ostrich,
338, 339; Swan, 322
Climate, effect on plumage of, Bob-
white, 292, 295; Song Sparrow, 292,
295; South American Pipit, 295, 296;
Turkey Vulture, 322; White-throated
Sparrow, 291, 294; Wood Thrush, 294
Cockatoo, feet of, 371; Leadbeater,
crest of, 260
Cocoon, as food, 146
Cod, eggs of, 428
Collar-bone, see Clavicle
Colour,
of birds, 287; of young birds, 316, 317;
blindness, 301; breast of Bleeding
Heart Pigeon, 306, 308
change in moulting of Bald Eagle,
296; Scarlet Tanager, 294, 297;
Siberian Black Lark, 295, 297
of eggs, 480
of feathers, 53-61; causes of, 54-56;
patterns of, 56-60
in mammals, 287; phases, double, 314;
relation to haunts, 296-314; use of,
322
Coloration, aggressive, see Aggressive
coloration; protective, see Protec-
tive coloration
Columella, of Owl, r1ro, 109
Comb, of Condor, 271; Domestic Cock,
274; Heron, 387, 388; on toe of
Chuck-will’s-widow, 369
Condor, feathers of, 36; flight of, 324,
326; wattles of, 271
Condyles of skull, 108
Coot, foot of, 387
Coracoid, function of, 84; in man, 85;
in reptiles, 84
Cord, spinal, 202
Cormorant, bill of, 227, 228; character
of egg-shell of, 460; gullet of, 133;
iris of, 256; method of fishing of, 154;
tail feathers of, 400
Corpuscles, see Blood
Courlan, food of, 153
Cuckoo, aggressive coloration of, 311;
colour of eggs of English, 456, 458;
foot of, 372
Curassow, Banded, crest of, 261
Crab, used as food, 149

Crane,
Crowned, crest of, 264; head of, 252,
265

Demoiselle, crest of, 267, 295

Index

Crane, trachea of, 170, 171

Cranium, see Skull

Creeper, Brown, protective coloration
of, 303, 304; food of, 150; tail of,
410, 411

Crest of, California Partridge, 259;
Cock-of-the-Rock, 270; Condor, 271;
Crowned Crane, 264, 265; Crowned
Pigeon, 260, 261; Banded Curassow,
261; Demoiselle Crane, 265, 267;
Domestic Cock, 274; Double-crested
Pigeon, 270; Eared Pheasant, 268;
Harpy Eagle, 262, 264; Hooded
Merganser, 263; Hummingbirds, 267;
India Peacock, 259; Java Peacock,
258; Kingbird, 260; Ruby-crowned
Kinglet, 260; King of Saxony Bird
of Paradise, 269, 270; Laughing
Thrush, 263; Leadbeater Cockatoo,
260; Mandarin Duck, 263; Night
Heron, 259; Plumed Partridge, 259;
Six-shafted Bird of Paradise, 267;
Snowy Egret, 260; Umbrella-bird,
264, 266; Woodpeckers, 264

Crests, use of, 258

Crocodile, brain of, 200; gizzard of, 138;
gullet of, 134; heart of, 181

Crop, 127-134; of Caracara, 134; capa-
city of, in Wood Pigeon, 130; ejection
of food-pellets from, 132, 133; of
English Sparrow, 129; extreme devel-
opment of, in Pigeon, 130; in Hoatzin,
130, 131; oil in Petrel’s, 131

Crossbill, bill of, 245, 248, 249

Cross-fertilization by birds, 144, 145

Crow, brain of, compared with that of
Hesperornis, 6; Fish Crow, stealing
eggs of herons, 448, 449; foot of,
356; method of feeding on shell-fish,
153; pterylosis of nestling, 39

D

Darwin, evolutionary theory of, 12

Decorations, use of, 322

Deer, nostrils of, 204; spots in young,
316, 317, tail of, 413

Dermis, 21

Dinosaur, relation to birds, 9; thigh-
girdle of, 90; tracks of, 396, 397

Distribution of birds, 361

Dogfish, see Shark

Donkey, foot of, 39, 395

Dove, colour of eggs, 446; nest of
Mourning, 439; position of eyes in,
252, 253, 204

Down, development of, 23; from head
of young Bobolink, 26; magnified
from young Song Sparrow, 27;
models of develoomsnt of, 24, 25;

437

of adult Crested Screamer, 29;
Duck Hawk, 27. of

Duck, colour of eggs of, 447; oddities
of diet of, 160-163; eggs of, 447;
food of, 147; crest of Mandarin,
263; nest of Mallard, 447, 448;
position of feet in, 382, 389, 390;
Side-wheel, see Steamer Duck; _ bill
of Shoveller, 233, 234; gradual loss
of flight in Steamer, 337; tail-feathers
of, 400; tail of Blue, 406; tail of
Pintail, 415

K
Eagle, Bald, iris of eye of, 256; foot
of Golden, 374, 376; foot of Harpy,
375; Golden, 242; Harpy, 262, 264;
Hyoid of, 114; nictitating membrane
of, 214; sight of, 208
Kar, canals of, 218; in owls, 216, 217;
structure of, 217, 218
Eclipse plumage, 48, 49
Edible birds’ nest, see Swiftlet.
Kggs,
abnormal number laid by African
Waxbill, 444; domestic Hen, 444;
Flicker, 444
of Apyornis, 461; alligator, 429;
Anna Hummingbird, 443; Arche-
opteryx, 13; butterflies, 428; Cali-
fornia Partridge, 438; Cassowary,
436, 453
character of surface of, in Casso-
wary, 460; Cormorant, 460; Duck,
460; North and South African
Ostriches, 460; Tinamou, 460;
Mute and Whooping Swans, 460;
Woodpeckers, 460
of cod, 428
coloration of eggs, 480; of Casso-
wary, 453, 454; causes of, 458, 459;
Doves, 446; Ducks, 447: English
Cuckoo, 456, 458; Goose, 448;
Grouse, 447; Herons, 448; Long-
billed Marsh Wren, 446; Murres,
456; Nighthawk, 454, 455; Ostrich,
453, 454; Owls, 451; Parrots,
445; Pelicans, 448; Sea-birds,
455; Short-billed Marsh Wren, 446;
Skimmer Black, 454, 455, 456, 4590;
Tern, 454, 456. 457; compared
with stilt, 452; variability of, 456,
457, 459; Woodpecker, 444
comparative size of eggs of Hum-
mingbird, 461
of Emeu, devoured by Buzzard, 159;
Fowl, 429, 436
of frog, 428, 465; development of, 465,
466, 467; for embryonic study, 462
of Grebe, 432; Hairy Woodpecker, 445;

488

Eggs,

of Hen, development of, 466; for
embryonic study, 462; structure of,
464

of Hummingbird, 436; Jellyfish, 427;
Junco, 434; Isilldeer Plover, 431,
432; Mallard Duck, 447; Mourn-
ing Dove, 439; Murre, shape of,
431

number laid by, average bird, 433;
Doves, 440; Game-birds, 438;
Gulls, 436; Hawks, 440; Hum-
mingbirds, 443; Jungle Fowl, 444;
King Penguin, 435; Moas, 435;

Nighthawk, 442; Ostrich, 433;
Owl, 440; Parrots, 441; Peacock
Pheasant, 440; Rhea, 433; Sea-

birds, 435; Shore-birds, 486; Wad-
ing birds, 438; Water-birds, 436,
437, 438
relation of number to danger,433—444;
relative size compared with bird,
460, 461
of reptiles, 428, salmon, 427; show-
ing relation of orders, 452; skate,
428, 429; snake, 429
Egg-tooth, of embryo
reptiles, 480
Egret, crest of Snowy, 315, 322; neck
curves of, 73; use of wing of, 350
Embryo,
aorta, 476, 478
development of limbs, 474, 475; of
girdles, 475; of three toes, 475
drawing of third-day embryo, 469
feathers of, 479, 480; twelve-day
chick, 22; forty-day Ostrich, 479
gastrula stage of, 466, 468; gill-clefts,
476; hatching of, 480; hatching of
egg-tooth of, 480; hatching of
Ostrich Chicks, 481; illustrating
evolution, 470, 471; limbs of, 97;
lung in, 178, 179; method of study-
ing, 462, 471; muscles of, 480;
muscle-plates of, 69, 70; pineal
eye in chick, 478, 479; precoracoid,
475; respiration of, 476; ribs, 473,
474; segmentation of Chick, 466,
468; segmentation of frog, 465,
466, 467; sixth-day chick com-
pared with reptile and mammal,
479; tarsus of, 99; teeth in tern,
476; third day in egg, 463
thirty-six hours, 472; brain in, 472;
eyes, 472; false vertebre, 472;
heart, 472
twelfth-day, 473
Emeu, body-feathers of, 239;
of, 36; lack of tail in, 402, 404
Emeu-wren, tail of, 415

chick, 480;

feather

Index

Environment, relation of birds to, 480.
482

Epiclavicle of fish, 86

Evolution, of bill of Flamingo, 235, 236;
bill of Skimmer, 231, 232, 236;
breast-bone, 79; Class of birds, 15;
colour patterns, 58-61; embryo chick,
470, 471; foot, 353, 358, 361; gill-
arches, 114, 115; gizzard, 138; heart,
180, 181; history of theories of, 12;
lung, 178, 179, 180; Penguin’s wing,
341; ribs, 78; shoulder-girdle, 86,
87; skull, 104-106; tail, 398, 399,
400, 402, 403; tree (of birds and

reptiles), 10; warblers, 361-367;
wings, 91-97

Kye,
Apteryx, 254, 255, 256; compared

with camera, 207, 208; iris of, 210

lashes of Hornbill, 257; Ostrich, 257;
Serlema, 257

lids of, 214, 215; Brown Thrasher,
212, 213; Woodcock, 221, 256

mammals, 209, 254; nocturnal birds,
254

pineal eye in, embryo chick, 478, 479;
child, 479; lizard, 477, 478; polly-
wog, 479

position of, in Dove, 252, 253, 254;
Owl, 252, 253, 254

structure of, 207-210;
hour embryo, 472

Expression of face of birds, 252

thirty-six-

F

Faleon, Peregrine, see Duck Hawk.
Family, habits of Warbler, Black-and-
white Warbler, 366; Black-throated
Green Warbler, 166; Magnolia, 366;
Maryland Yellow-throat, 362; Myrtle
Warbler, 364; Ovenbird, 366, 375;
Pine Warbler, 366; Redstart, 365,
364; Yellow Palm Warbler, © 363;
Water Thrushes, 364, 365; Worm-
eating Warbler, 363
Fat, of Penguins, 286; Petrels, 286
Feather, aftershaft of, 36; barbicels of,
32, 34; barbs of, 34; barbules of, 32,
34; cells of, 34; divisions on wing,
320; growth of Ostrich, 28; model
of structure of, 33; pattern on, 58-61;
structure of, 31-388
Feathers, arrangement of, 38-40; in
tail of Archwopteryx, 398, 399
400, 401; in modern bird, 399, 400
of Cassowary, 338; colour of, 53-61;
of Condor, 36, 336; development
of, 17-38; downy condition of, 35;
of embryo bird, 479, 480; of

Index

Feathers (continued),
Emeu, 36; of embryo of twelfth-
day. 22: moult of, 40-53
number of, in tail, of Archxopteryx,
400; of ‘Cormorant, 400; of Duck,
400: of Ostrich, 402; of Peafowl,
402; of Fantail Pigeon, 402
of Ostrich, 35, 336; papillee of nestling,
21; powder-downs, 37, 38; ptery-
losis, 39; sheaths of, 26; sheaths
of young ’ Kingfisher, 29; texture of,
287-289; function of, in Puff- back
Shrike, 287; of wing, 320-352;
worn-oué Hummingbird’s breast, 44
Feather-ears, of owl, 267, 268
Feather-tips, in Bobolink, 2975 in
Black Lark, 295, 297; in Snow-
flake, 297; in English Sparrow, 52,
53; wearing off of, 52, 53, 297
Feeding, method of, in Flamingo, 128;
in Woodcock, 222
Feet, adaptation of, 361, 362;
cation based on, 354, 355;
tion of, 353, 358, 361
Femur, 98
Fibula, 98
Fighting, method of, in Ruff, 277, 279,
280
Finch, 143; bill of Purple, 249; colour
change in Purple, 293
Fins, origin of paired, 96
Fish, used as food, 153;
muscle-flakes of, 78
Fishing, method of, in Cormorants, 154;
Frigate-birds, 154; Herons, 156;
Kingfishers, 154; Ospreys, 154; Peli-
cans, 152; Penguins, 154; Snake-
birds; 154; Terns, 154
Flamingo, bill of, 128, 234, 235; colour
change in, 293; foot of, 388; neck of,
73, 281; sternum of, 80; tongue of,
126, 127; trachea of, 168, 169
Flicker, abnormal number of eggs laid
by, 444; hyoid of, 123, 124; protec-
tive colouring in young, 302, 303, 304;
tongue of, 123, 124
Flight, ef. with swimming, 327; Condor,
324, 326; Steamer Duck, 337; cer-
tain Flyeatchers, 324, 326; Gold-
finches, 329; Grebes, 341; Gulls, 328;
Hummingbirds, 329; Owl Parrot, 333;
Pheasant, 323, 324; Crested Screamer,
329; Sparrows, 328; swiftness of, in
Pigeon, 350; swiftness of, in Swallow,
352; of Tinamou, 333-336; of Wood-
peckers, 329; of Vultures, 328, 330,
B3Toon
Flipper, of Penguin, 341, 342, 343
Flycatcher, feet of, 360; flight of, 324,
326; tail of Least, 412

classifi-
evolu-

heart of, 181;

489

Food, affecting structure, 164; indu-
cing intoxication, 163; of Apteryx,
147; Buzzard, 159; Courlan, 153;
Creepers, 150, Crows, 153; Ducks,
147, 153; Bald Eagle, 148; Gulls,
161; Carrion Hawk, 162; Duck
Hawk, 159; New Zealand King-
fisher, 161; Locust-birds, 150-152;
Osprey, 155; Barn Owl, 158; Bur-
rowing Owl, 162; Elf Owl, 158;
Strenuous Owl, 158; Oyster-catcher,
153; Kea Parrot, 161; Penguins,
153; Ptarmigan, 144; Raven, 158;
Road-runner, 157; Sea-birds, 148;
Sea-eagles, 157; Secretary-bird, 157;
Red-winged Starlings, 162, 163;
Storks, 157; Sugar-birds, 144; Sul-
phur Tyrant, 161; whales, 148

Food-pellets of Owl, 132, 133

Foot, claws of, 368; tendons of, ror,
192; of alligator, 354; Archeop-
teryx, 353; bear, 102; of bird cf. with
man, 99, 100; Caracara, 378; Casso-
wary, 394, 396; Chewink, 367; Chuck-
will’s-widow, 369; Cockatoo, 371;
Coot, 387; Crow, 356; Cuckoo, 3725
Donkey, 394, 305; Duck, 382, 389,
390; Golden Eagle, 374, 376; Harpy
Eagle, 375; Flami-go, 388; Fly-
catchers, 360; Gallinule 385, 386,
387; Grebe, 391; Ruffed Grouse, 380,
381; Rough-legged Hawk, 389; Heron,
387, 388; Hummingbirds, 368; Wood
Ibis, 102, 385; Kangaroo, 394, 395;
Horned Lark, 367; European House
Martin, 381: Nuthatch, 359; Oriole,
360; Osprey, 375; Ostrich, 394, 395,
396; Burrowing Owl, 373; Snowy
Owl, 375; Owls, 373, 374; Parrots, 372;
Passeres, 358, 359; Peacock, 383;
Brown Pelican, 355; Penguin, 391,
392; Pheasant, 380; Phalarope, 384;
Pipit, 367, 368; Plover, 384; Ptar-
migan, 381; Quail, 380; Raven, 356;
Rhinoceros-bird, 357; Road-runner,
373; Rock-jumper, 393; Sand-grouse,
383; Semipalmated Sandpiper, 384;
Secretary-bird, 378, 379; Snakebird,
391; Swallow, 360; Black-necked
Swan, 390; Swift, 368, 369; Vulture,
377; Woodpeckers, 370

Fowl, egg of, 429, 430; Japanese Long-
tailed, 417, 419; number of eggs laid
by Jungle, 444; spurs of, 382; tail of
Jungle, 418

Fox, aggressive coloration in Arctic,
309

Framework, 62-102

Frigate-bird, method of feeding of, 154

Frog, egg of, 428; fresh egg of, 462.

490

gastrula of egg of, 466; segmentation
ot egg of, 467; used as tood, 157

G

Gallinule, foot of, 385, 386, 387
Game-birds number of eggs laid by, 438
Gannet, bill of, 227, 228
Gastrula, 466, 468; compared
sponge, 469, 470
Gill-arches, of chick, 114; evolution of,
114, 115; ultimate distribution of, in
chick, 114, 115
Gill-bars of shark, 113
Gill-basket of lamprey, 112
Gill-clefts in Amphioxus, 473;
chick, 476; fishes, 473
Giraffe, neck-vertebre of, compared with
those of bird, 73, 75
Girdles, embryonic development of, 475
Gizzard, 134-140; change in structure
of, 137, 138; function of, 135; of
Fruit Pigeons, 138; of Hornbills, 139,
140
stones of Cassowary, 136; crocodiles,
138; extinct Moas, 136, 137
of pigeon shown by X-ray, 63
Glottis of nestling Robin, 166;
can, 166
Goat-sucker, West African,
ments of, 349
Goldfinch, flight of, 329; tongue of, 125
Goose, Canada, embryo of, 474; colour
of eggs of, 448; muscle of skin in, 188;
sense of hearing in, 216; Spur-wing,
wing of, 346, 347; use of wing in
young Canada, 322
Grackle, tail of Boat-tailed, 418
Grebe, eggs of, 432; flight of, 341;
of, 391
Grouse, Black, moult of, 48; colour of
eggs of, 447; Ruffed, ruff of, 277;
Ruffed, use of wing of, 547; toes of
Ruffed, 380, 381
Guinea Fowl, Vulturine, evolution of
colour pattern on wings of, 58, 59,
61
Gullet, of Cormorant, 133; crocodile, 134
Gull, change in gizzard of, 137, 138;
flight of, 328; food of, 161; Her-
ring, wing of, 328
Ivory, aggressive coloration in, 309,
311; protective coloration in 309,
311
Laughing, nest of, 437;
coloration of, 309, 312;
eggs laid by, 436
Gyrfaleon, aggressive coloration in, 309,
312

with

embryo

Peli-

wing orna-

foot

protective
number of

Index

H

Hatching of embryo Chick, 480; Os-
trich, 481

Hawk Duck, food of, 158; head of, 211;
teet of Rough- legged, 389; mimicked
by Cuckoo, 311, 312; ‘number of
eggs laid by, 440; skull of, compared
with that of Heron, 199, 200

Heads and necks, 252-284

Head of, Adjutant, 276: Apteryx, 254;
256; Barn Owl, 253; Bell-bird, 273,
Caracara, 271, 272; Eared Pheasant,
267, 268; Condor, 271; Crowned
Crane, 252, 265; Domestic Cock, 274;
Dove, 253; Duck Hawk, 211; Java
Peacock, 258; King V ulture, 272,
Zilles Seriema, 257; Sloth, 210;
Wild Turkey, 273, 275

Heart, beats of that of bird, 182;
chambers of, 182, 184; of eroco-

dile, 181; of fish, 181; of embryo
36 hours "old, 472; evolution of, 180,
181; position of, in vertebrates, 181

Helmet of Cassowary, 275, 288; Horn-
bill, 278

Hemispheres, cerebral, 200

Hen, abnormal number of eggs laid by
domestic, 444

Heron, a still hunter, 156; Boat-billed,
237, 238; body of, 386; cause of
downiness in feather of, 35; colony
of Great Blue, 450; colour of eggs
of, 448; comb on toe of, 387, 388;
divisions of feathers in wing of young
of, 320; Great Blue, 237; in sleep,
344; Night, 237; Night, crest of,
259; skull of, compared with that
of Hawk; 199, 200; standing on
toes, 101; tail of Green, 413; use
of wing in young Green, 323; wing
of Great White, 321

Hesperornis, habits and structure, 3-6;
restoration of, Frontispiece

Hoatzin, clavicles of, 86; crop of, 130,
131; keel repressed by crop, 132

Honey Creeper, tongue of, 127, 129

Hornbill, casque of, 275, 278: eye-
lashes of, 257; feeding mate from
its gizzard, 137, 138

Horse, toes of, 358

Hudson, quoted, 329, 333

Huia Bird, bill of, 248, 249, 250

Humerus, 92, 96

Humidity, effect on plumage of, Bob
White, 293, 295; Song Sparrow, 292,
295; White-throated Sparrow, 291,
994: Wood Thrush, 294 ;

Hummingbird, Anna, nest of, 443; eggs
of, 443; bills of, 244, 245, 246, 247,

Index

248; crests of, 267; eggs of, 436, 461;
feet of, 368; flight of, 329; flight of,
compared with that of insect, 165;
length of intestines in, 140; nest of
Ruby-throated, 449; number of eggs
laid by, 443; tongue of, 127; wing
of, 320, 321, 325; wing-strokes of,
82; worn-out breast-feather of, 44;

Huxley, definition of paleontology, 2;
Thomas, quoted, 2

Hyoid, 111; of eagle, 114

I

Ibis, 239, 237; feet of Wood, 385;
Indian Wood, beautiful feathers of, 61;
Wood, resting upon whole foot, 102;
Shell, 240

Ichthyornis, lower jaw, 5; restored
skeleton of, 3; structure of, 4

Icthyosaurus, eye-plates of, 213

Ilium, 89, 90; function of, 89; of bull-
frog, 91

Ingersoll, Ernest, quoted, 433

Insects, use as food of birds, 148-152

Intestines, function of, 141; length in
Hummingbird, 140; length in Ostrich,
140; in alligator, 141

Iris of eye, 210; of Bald Eagle, 256;
Cormorant, 256; Owl, 256; Puffin,
256; Towhee, 256; Vireo, 256

Ischium, 89, 90

J

Jabiru, atlas and axis of, 72
Jaguar, standing on toes, Ior
Jelly-fish, eggs of, 427
Juneo, eggs of, 434; nest of, 434; tail
of, 414
K

Kangaroo, feet of, 394, 395

Keel, in Flamingo, 80; Hoatzin, re-
pressed by crop, 132; model com-
paring various, Albatross, Humming-
bird, Pigeon, 83; value in classifica-
tion of, 82

Kingbird, crest of, 260

Kingfisher, method of fishing of, 154;
nest of, 444; New Zealand, food of,
101

Kinglet, Ruby-crowned, crest of, 260

L

Lacrymal glands, 211

Lamprey, gill-basket of, 112

Lark, foot of horned, 367; tail of
meadow, 414; cause of colour change
in Siberian black, 295, 297

491

Layers of cells in embryo, 470

Leg, correlation with neck in Flamingo,
281; in Swan, 282; framework of,
98-102; function of, 98; of Ostrich,
100; skeleton of Ostrich, 99; human,
99; scales of, 368; spurs on, 382, 383;
of Bald Eagle, 375; of Cassowary,
394; of Flamingo, 388; of Golden
Eagle, 375; of Secretary-bird, 378,
379

Life in the egg, 462-479; post-embry-
onic, 480

Limbs, origin of, 96, 97; evolution of,
96, 97; of embryo chick, 474, 475

Lobed toes, of coots, 387; of phalaropes,
384
ocust birds, method of feeding, 150-
152; relation of habits to food, 152

Loon, in winter haunts, 6; neck of, 277

Lory, tongue of 125

Lungs, eévolution of, 178, 179, 180;
character of, 174, 175; ef. with those
of chameleon, 177, 178

Lyre-bird, tail of, 420, 421

M

Mallard, eclipse plumage of, 48. 49;
tongue of, 122; trachea of, 168;
syrinx drum of, 168, 170

Mammals, used as food, 159

| Mankind vs. birds, 18

Maoris, legends of, 13

Martin, feet of European House, 381

Merganser, bill of, 233, 234; crest of
Hooded, 263

Mimicry, of Hawk by Cuckoo, 311, 312;
of Hawk by Hawk, 312

Moa, ef. with Ostrich, 13;
eggs laid by, 435

Monkeys, toes of, 358

Motmot, protective coloration of, 303;
tail of Mexican, 424, 425, 426

Moult, 40-53; of Black Grouse, 48;
of Bob-white, 43; of Brown Pelican,
41; causes for, 42-50; of body-
feathers of English Sparrow, 52, 53;
of wing-feathers of English Sparrow,
46; of feathers, 41; of feather-tips,
52, 53; of Mallard Duck, 47, 48, 40;
of mound-builders, 44, 45; of Pen-
guin, 51; of Ptarmigan, 48, 50, 51, 52;
of reptiles, 40; of Robin, 43; in
spring, 45; time of, 42-47

Mouse. used as food, 157

Murre, colour of eggs of, 431, 456; tail
of, 406, 407; shape of eggs of, 431

Murrelets, wing of, 339, 341

Muscle-plates, of embryo chick, 69, 70

Muscles, of body, 189, 190; celis of,

number of

492

189; cf. with reptiles, 193, 194;
of embryo chick, 480; energy of, in
Hummingbird, 83; impressions on
bones, 194; pectoral, 190; of skin
in Goose, 188; of skin in Penguin,
188; structure of, 193; of wing and
breast of Pigeon, 190; of wing in
Owl Parrot, 333

N

Neck, of Flamingo, 281;
Loon, 277; Snake-bird,
Swan, 282

Neck vertebre, cf. with Giraffe, 73, 75;
ef. with man, 72; cf. with reptile,
73

Nerves, action of, 198; cerebral, 202

Nervous system, 196, 198; of Pigeon,
197; reflex, 197, 198

Nest, of Mourning Dove, 439; Mallard
Duck, 447, 448; Laughing Gull, 437;
Great Blue Herons, 450; Humming-

Heron, 281;
2825 Zo 30

birds, 448; Anna Hummingbird,
443; Ruby-throated Hummingbird,

449; Junco, 434; Kingfisher, 444;
Nighthawk, 455; Ostrich, 453, 454;
Burrowing Owl, 442; California Part-
ridge, 438; Black Skimmer, 454,
450, 459; Tern, 453, 456, 457; Hairy
Woodpecker, 444, 445

Nictitating membane, of alligator, 215;
Eagle, 214; human eye, 215; Brown
Thrasher, 213

Nighthawk, colour of eggs of, 454, 455;
nest of, 455; number of eggs laid
by, 442; protective coloration in,
296, 301

Nostrils, of bird, 204; of deer, 204

Notochord, of Amphioxus, 66; of
Boltenia, 67

Nuthatch, bill of, 245; foot of, 359

Nutrition, 116-141

O

Odour in birds, 287

Oil-gland, 286, 287

Oology, 451

Orbit, of Apteryx, 255; of Owl, 255

Oriole, foot of, 360

Osprey, food of, 155, 156; foot of, 347;
method of fishing of, 154; use of
wing in young, 322; wing of, 351

Osteology, 62

Ostrich, body-feathers of, 288; cause of
downiness in feather, 35; colour of
eggs, 453, 454; compared with Moa,
13; cross-section of wing-bone, 175;
eggs of, 436, 453; embryo (40-day),

Index

479; eyelashes of, 257; leg of, 100;
length of intestines, 140; neck and
vertebrie of, 69, 71; nest of, 453, 454;
number of eggs laid by, 483; pro-
tective position of, 306, 307; skele-
ton of leg, 99; specific difference in
eggs, 460; sternum of, 81; tail of,
402; toes of, 358, 394, 395, 396;
wing of, 321, 337, 338, 339

Owl, aggressive coloration of Snowy,
309, 313; cause of downiness in
feathers, 35; colour phases of Screech,
314; eggs of Screech, 441; food of
Barn, 158; food and feeding habits
of Burrowing, 162; food of Elf, 158;
food of Strenuous, 158; food-pel-
lets ejected by, 132, 133; foot of
Burrowing, 373; foot of Snowy, 375;
iris of eye of, 256; nest of Burrow-
ing, 442; orbit cf Barred, 255; posi-
tion of eyes in Barn, 252, 253, 254;
sight of Barred, 211

Owls, bills of, 242; colour of eggs of,
451; foot of, 373, 374; number of
eggs laid by, 440

Ovary of fowl, 464

Ovenbird, 365, 366

Oyster-catcher, bill of, 238, 240; food
Olmos

12

Palate, 111

Paradise, King of Saxony Bird of, 276;
269; Six-shafted Bird of, 267, 269,
Superb Bird of, 277; ‘Twelve-wired
Bird of, 348

Parallelism, in feeding habits, 163, 164

Paramecium, 463; keels, 83, 84

Parrakeet, tail of Grass, 408

Parrot, bill of, 242; colour of eggs of , 445;
flight of Owl, 333; food of Ixea, 161;
foot of, 372; number of eggs laid by,
441; use of wing in, 322

Partridge, California, crest of, 259; nest
andeggs of, 438; Plumed, crest of,
259; Scaled, feathers of, 289, 290

Passeres, foot of, 358, 359

Peacock, feather of, 20; India, crest of,
259; Java, crest of, 258; ribs of, 78;
spurs of, 382, 383; tail of, 422, 423;
train of, 422, 423

Peafowl, tail of, 402

Pectoral girdle, see Shoulder-girdle.

Pelican, bill of, 228, 229, 330; colour
of eggs of, 448; downy stage of, 54;
foot of, 355; full-grown, 59; glottis
of, 166; half-grown, 57; method of
fishing of, 152; nestling of Brown, 21;
newly hatched, 30; tail of, 408, 409;
tongue of, 120, 121

Index

Pelvic girdle, see Thigh-girdle.

Pelvis, compared with that of reptiles,
74; vertebree in, 74

Penguin, aggressive coloration in, 309,
310; body-teathers of, 289; eggs of,
435; fat of, 280; food of, 153; method
of fishing of, 154; moult of, 51; skin-
muscles in, 188; tail of Black-footed,
406; wing of, 321, 341, 342, 343

Pepper, etfect on plumage of, 292

Petrel, body of, 286; ejecting oil from
crop, 131

Pickerel, aggressive coloration in, 310

Pigeon, Blood-breasted, 306, 308; cir-
culatory system of, 183; Crowned,
crest of, 260, 261; Double-crested, 270;
extreme development of crop of, 130;
gizzard of Fruit, 138; nervous system
of, 197; number of eggs laid by, 440;
symptoms of flight in, 350, 352; tail
of, 402; tail of Fan-tail, 404; wings
and breast-muscles of, 190; wing-
feather of, 35; X-ray photograph
of, 63

Pigment, colour caused by, 54, 55

Pipit, effect of climate on, 295, 296;
foot of, 367, 368

Phalarope, feet of, 384

Pheasant, Argus, colour pattern of, 58;
Eared, head of, 267, 268; feet of, 380;
flight of, 323, 324; number of eggs
laid by Peacock, 440; ruff of Lady
Amherst, 277, 278; spurs of Peacock,
383; tail of Peacock, 419, 420;
tail of Reeves, 416, 418; wing of, 327

Phororachus, skull of, 16; structure of,
13, 14

Plantain-eater, green pigment in, 55

Ploughshare-bone, 400, 402, 403

Plover, Crook-billed, 240, 241; feet of,
384; nest and eggs of Killdeer, 431,

432

Pollen, used as food, 144, 145

Powder-down, 38; of Great White Heron,
37

Prairie hen, use of air-saes in, 117

Precocial nestling, 30

Precoracoid in embryo, 475

Primaries, moult of, in Bob-white, 43;
English Sparrow, 46; Mallard, 47;
Robin, 43

Primaries, of Albatross, 320, 321, 325;
Cassowary, 321, 337, 338; Hum-
mingbird, 320, 321, 325; Ostriches,
321; Penguins, 321

Protective coloration, in Brown Creeper,
303, 304; Flickers, 302, 303, 304;
Ivory Gull, 309, 311; Laughing Gull,
304, 306; Motmot, 303; Nighthawk,
296, 301; Ostrich, 306, 307; Ptar-

493

migan, 298, 300, 309; Quail, 299,
300; Sandpipers, 299; Sparrows, 299;
Black-necked Swan, 305, 306; Sooty
Tern, 300, 303; Thayer’s experiments
in, 299; of eggs, 446-459
Proventriculus, 135
Ptarmigan, feet of, 381; food of, 144;
moult of, 48, 50, 51, 52; protective
coloration in, 298, 300, 309
Pterodactyls, 2,9; weight of, 285
Pterylosis, 39, 40; of nestling Crow, 39
Pubis, 89, 90; in embryo bird, 90
Puttin, iris of eye of, 256

Q

Quadrate, 109, 110; in reptiles, 111

Quail, feet of, 380; protective colora-
tion in, 299, 300

Quezal, sham tail of, 421, 422

R

Rabbit, tail of, 413

Radius, 92

Ratite, 82

Raven, bill of American, 225: feeding
on ostrich-eggs, 158; foot of, 356

Redstart, life-habits of, 363, 364

Reptiles, causes of colour in, 56; eggs
of, 428, 429; trachea of, 169

Respiration of embryo chick, 476

Rhea, number of eggs laid by, 433

Rhinoceros-bird, foot of, 357

Ribs, 77-79; abdominal, of Archzop-
teryx and of reptiles, 79; embryo,
473, Av4) ~ function Jot, im 792
Hatteria Lizard, 77; Screamer, 77;
significance of numerous, 78

Road-runner, food of, 157;
3/3; tail of, 413

Robin, glottis of nestling, 166; moult.
of, 43; spots in young, 316, 317

Rock-jumper, body-feathers of,
feet of, 393

Ruff of, Lady Amherst Pheasant, 277,
278; Ruff, 277, 279, 280; Ruffed
Grouse, 277; Superb Bird of Paradise,
277

Ruff, feather cloak of, 277, 279, 280

foot of,

288;

,

S)

Salivary glands, original function of,
117, 118; in Swiftlets, 119; Swiits,
119; Woodpeckers, 118

Salmon, eggs of, 427

Sandgrouse, feet of, 383

Sandpipers, protective coloration in,
299; semipalmated, feet of, 384

494

Sapsucker, tongue of, 124

Scales, of carp, 289, 290;
birds, 356, 368

Scapula, 84; position in various ani-
mals, 88

Scent-glands, of birds, 286, 287; of
mammals, 286

Screamer, Crested, 330; flight of, 329

Sea-birds, colour of eggs of, 455

Sea-eagles, food of, 157

Sea-urchins, used as food, 145

Secondaries, number in Albatross, 320,
321, 325; in Hummingbird, 320, 321,
325

Secretary-bird, 378, 379; food of, 157

Seeds, 427

Segmentation of egg, 465-470

Senses,
hearing, 215-218; in Geese, 216
sight, 207-215; in Barred Owl, 211;

Eagle, 208; Woodcock, 208
smell, 203-206; in Vultures, 205
taste, 218, 219
touch, 219, 222; in Apteryx, 219;
Woodcock, 219, 220, 222

Seriema, 17; eyelashes of, 257; habits
of, 15; relation to Phororachus, 15

Shark, back-bone of, 68; gill-bars of,
113; skull of, 104; tooth of, 20

Shore-birds, number of eggs laid by,
436

Shoulder-girdle, 84-88, 85; bones com-
posing, 84; evolution of, 86, 87;
of fish, 86, 87

Shrike, Puff-back, feathers in, 287

Size, as correlated with distribution,
295

Skate, egg of, 428, 429

Skeleton, of man, leg of, 99; Ostrich,
leg of, 99; Pigeon, shown by X-ray
photograph, 63; Rooster, compared
with contour of body, 65; ways of
preparing, 64

Skimmer, bill of, 231, 232; Black, nest
and eggs of, 454 456, 459; colour
of eggs in Black, 454, 455, 456, 459

Skin, layers of, 19; products of, 20

Skull, 103-115; bones of, 107; evolu-
tion of, 104-106; origin of, 103-104;
section through, 201; alligator, 105;
Eagle, 106; Hawk, 199, 200; Heron,
199, 200; shark, 104

Sleep, birds in, 344, 355

Sloth, head of, 210

Snail used as food, 148, 453

Snake, egg of, used as food, 157, 429

Snakebird, bill of, 228, 229; body-
feathers of, 289; foot of, 391; method
of fishing of, 154; neck of, 282, 283;
stomach of, 139

on legs of

Index

Snipe, bill of Dowitcher, 241; fighting,
see Ruff.

Snowshoes of Grouse, 380, 381

Snowflake, colour of change in, 297

Sparrow, albinism in English 314;
crop of English, 129; effect of cli-
mate on song, 292, 295; effect of
humidity on White-throated, 291,
294; flight of, 328; moult of wing-
feathers of, 46; moult of body-
feathers of, 52, 53; neck of White-
throated, 74, protective coloration
in, 299; stomach-glands of, 135;
tail in moult of, 409; tail of Vesper,
414

Specialization of feet, 358

Spoonbill, bill of, 236, 239; use of wing
in a, 350

Spurs of fowls, 382; of Peacock, 382,
383; Peacock Pheasant, 383; struc-
ture of, 382

Squid, used as food, 150, 153

Starling, food of Red-winged, 162, 163;
Wattled, see Locust-bird

Sternum, function of, 81; value in
classification of, 80; of Flamingo, 80;
Ostrich, 81

Stilt, 237

Stomach, 134-140; of Chicken (young),
135; English Sparrow, 135; Snake-
bird, 139

Storks, food of, 157

Sugar-bird, food of, 144

Sulphur-tyrant, food of, 161

Swallow, food of, 360; tail of Barn, 405,
407

Swan, foot of Black-necked, 390;
neck of, 282; protective coloration
in Black-necked, 305, 306; sleeping
position of, 345; specific difference in
egg-shells, 460; trachea of Trumpeter,
170; weight of ‘Trumpeter, 285;
wing-bone of Black, 175; use of
wing in defence, 346

Swift, bill of Chimney, 244, 245, 246;
foot of, 368, 369; nest of, 118; tail
of Chimney, 410, 412; wing-feathers
of, 42

Swiftlets, nest of, 119; use of nests,
yy)

20
Swim-bladder of fishes, 178, 179
Swimming compared with flight, 327
Syrinx, drum of Mallard, 168, 170;
structure of, 172

‘a
Tail, of Archeopteryx, 398, 399, 400,
401; evolution of, 398-403; feathers
of, 402, 403; lack of, in Emeu, 402,
404; in Cassowary, 402

Index

Tail,
number of feathers in Archeopteryx,
400; Cormorant, 400; Duck, 400;
Ostrich, 402; Peatowl, 402; Fan-
tail Pigeon, 402
ornaments of, 414-421; ploughshare-
bone of, 400; sham, of Quezal, 421,
422: sh m, of Peacock, 422, 423
vertebre of Bald Eagle, 403; embryo
bird, 403; Ostrich, 402
use of, 405; voluntary decoration of,
424, 425, 426; of creeper, 410, 411;
deer, 413; fPin-tail Duck, 415;
Blue Duck, 406; Emeu-wren, 415;
Least Flycatcher, 412; Japanese
long-tailed towl, 417, 419; Jungle
Fowl, 418; Boat-tailed Grackle,
418; Green Heron, 413; Junco,
414; Meadow Lark, 414; Lyre-
bird, 420, 421; Mexican Motmot,
424, 425, 426; Murre, 406, 407;
Grass Parrakeet, 408; Peacock, 422,
423; Pelican, 408, 409; Black-
footed Penguin, 406; Fan-tail Pigeon
404; Peacock Pheasant, 419, 420;
Reeves Pheasant, 416, 418; Rabbit,
413; Road-runner, 413; Sparrow
in moult, 409; Vesper Sparrow,
414; Barn Swallow, 405, 407; Tern,
407, 409; Chimney Swift, 410, 412;
Tinamous, 409; Wagtail, 413;
whale, 405; Paradise Whydah-
finch, 415, 416; Woodhewers, 410;
Woodpeckers, 410, 411, 412
Tail-coverts of Quezal, 421, 422; of
peacock, 422, 423
Tailor-bird, bill of, 245
Tanager, colour change in moult of, 294
Tarpon, scale of, 20
Tarsus, 99
Teeth, in embryo Tern, 476; origin of,
23, 114
Temperature, of bird, 186; of man, 186
Tendons, of foot, 191, 192; strength of,
illustrated, 193; use in perching of,

195

Tern, bill of, 231, 232; colour of eggs of,
454, 456, 457; eggs of Stilt and, 452;
method of fishing of, 154; nest of, 453,
456, 457; protective coloration in
Sooty, 300, 303; tail of, 407, 409;

teeth in embryo, 476; wing of, 352 |

Thales, 12

Thayer, experiments of Abbott, -

Thigh-bone,, see Femur

Thigh-girdle, 88-91; bones composing,
88, 89; of embryo bird, ef. with Dino-
saur, 90

Thrasher, eyelids of Brown, 212, 213;
nictitating membrane of, 213

aio)

Thrush, crest of Laughing, 263; effect
of humidity on Wood, 294

Tibia, 98

Tinamou, 334; egg-shell of, 460; flight
of, 333-336; tail of, 409

Toes, of Cassowary, 394, 396; Chuck-
will’s-widow, 369; Coot, 387; Donkey,
394, 305; embryo, 474; Ballinule,
385, 386; Grebe, 391; Ruffed Grouse,
380, 381; Heron, 101; comb on
Heron, 387; 388; perching function
of hind, 359; horse, 358; Wood Ibis,
385; Jaguar, Ior; young kangaroo,
394, 395; Kuropean House Martin,
381; monkey, 358; number of, 353;
Osprey, 374; Ostrich, 358, 394, 395,
396; Snowy Owl, 375; Penguin, 391,
392; Plover, 384; Phalarope, 384;
Ptarmigan, 381; Rhinoceros-bird,
357; Sand-grouse, 383; Semipalmated
Sandpiper, 384; Snakebird, 391;
Vulture, 377; Zygodactyl, 369, 370,
Sill, 372

Tongue, of Cockatoo, 125; Ducks and
Geese, 120, 121, 122; Flamingo, 126,
127; Flicker, 123, 126; function of
fleshy teeth on, 120; Goldfinch, 125;
Honey-creeper, 127, 1209; Humming-
bird, 127; Lory, 125; Owls, Larks, and
Swifts, 122; Pelican, 120, 121; Sap-
sucker, 124; Toucan, 126; Wood-
peckers, 122

Toucan, bill of, 243, 244; tongue of, 126

Towhee, iris of, 256

Trachea, of amphibian, 169; of cranes,
170, 171; cf. with cesophagus, 167;
of duck, 168; of flamingo, 168, 169;
of reptiles, 169; of Sparrow,169; struc-
ture, of, 168, 169; of Trumpeter Swan,
170

Tracks, of Cassowary, 396; of Dino aur,
396, 397

Triceratops, beak of, 226; brain of, 200

Turbinal bones, 205

Turkey, breast-ornament of Wild, 230

Turtle, beak of Snapping, 224; egg of,
428, 429

“Two Bird-Lovers in Mexico,” quota-
tion from, 301

U

Ulna, 2

Umbrella-bird, crest of, 264, 266

Uncinate processes, 77

y
Vegetable feeders, 143, 144

Vertebre, of Bald Eagle, 403; bird,
cervical of, 71-74; embryo, 403;

496

Vertebre (continued)
function of, 196; Jabiru, neck
vertebrie of, 72; Ostrich, 69, 71;
Ostrich-tail, 402
pelvic, of American Flamingo, 76;
alligator (young), 76; Bald Eagle, 76
of shark, 68; of tail, 75
Vireo, 144; iris of eye of, 256
Vorticlla, 463, 464
Vulture, colour in young Turkey, 317;
flight of, 328, 330, 331, 332; King,
head of, 272, 273; sense of sight in,
205; toes of, 377; Turkey, in flight,
331

W

Wading birds, number of eggs laid by,
438

Wagtail, tail of, 413

Walrus, brain of, 200

Warbler, life-habits of Black-and-white,
366; Black-throated Green, 366; Mag-
nolia, 366; Myrtle, 364; Pine, 366;
Worm-eating, 163; Yellow Palm, 363

Warbler-bush, wings of, 347

Warblers, evolution of, 361-367

Water-birds, number of eggs laid by,
436, 437, 438

Wattles, of Bell-bird, 273; Condor, 271;
Wild Turkey, 273, 275; King Vulture,
2725 Ze

Waxbill, African, abnormal number of
eggs laid by, 444 ‘

Web of toes, of Flamingo, 388; Sea-
birds, 389; Semipalmated Sandpiper,
384

Weight of birds, 285, 286;
dactyls, 285

Whale, food of, 148; tail of, compared
with that of bird, 405

Whydabh-finch, tail of Paradise, 415, 416

Windpipe, see Trachea

Wing, bones of, 95; change of function
in, 337; compared with arm of man,
94; evolution of, 91-97, 319; feather
divisions of, 320; framework of, 91-
97; noise of, 345, 347; spurs of, 346,
347; strokes of Hummingbird, 82;
use of, in defence, 337

of Ptero-

Index

Wing of, Albatross, 320, 321, 325, 332;
Great Auk, 339, 340; Racor-billed
Auk, 339, 340; Cassowary, 321, 337,
338; Young Catbird, 322; Condor,
324, 326, 332; Steamer Duck, 337;
Snowy Egret, 350; West African
Goatsucker, 359; Canada Goose, 346;

Young Canada Goose, 322; Spur-
winged Goose, 346, 347; Rvffed

Grouse, 347; Herring Gull, 328; Young
Green Heron, 320, 323; Great White
Heron, 321; Sleeping Heron, 344;
Hummingbird, 320, 321, 325; Mallard,
47; Murrelets, 339; Young Osprey,
322, 351; Ostrich, 321, 337, 338, 3305
Twelve-wired Bird of Paradise, 348;
Parrot. 3225) earroteOwleoso se ben=
guin, 321, 341, 342, 343; Fheasant,
323, 324, 327; Screamer, 346; Black
Skimmers, 324; English Sparrow, 46;
Spoonbill, 350; Trumpeter Swan, 346;
Tern, 352; Bush Warbler, 347; Wood-
cock, 348, 349; Turkey Vulture, 331

Wish-bone, see Clavicle

Woodcock, bill of, 222; eyes of, 221, 256;
sense of sight in, 208; sense of touch
in, 219, 221, 222; wing-song of, 348

Woodhewer, tail of, 410

Woodpecker, tail of 410, 411, 412;
nest and eggs of Hairy, 445; char-
acter of egg-shell of, 4€0; colou- of
eggs of, 444; function of saliva in,
118; tongue of, 122; bill of, 245;
crest of, 264; flight of, 329; feet of,
370

Wren, Marsh, colour of eggs of, 446;
tail of, 411

Wrist-bones of bird, 92; of man, 92

xX
X-ray photograph of Pigeon, 63
Y
Yellow-throat, life-habits of Maryland,
362 3

Zygodactyl toes, 369, 370, 371, 372

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