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Full text of "The bird, its form and function"

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FORTHE PEOPLE 

FOK EDVCATION 

FOR SCIENCE 






LIBRARY 

OF 

THE AMERICAN MUSEUM 

OF 

NATURAL HISTORY 





Bound gr 



THE BIRD 



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iuL'ii iiiiiaLited 



Hesperoriiis,— a wiuylt-^^. tuolht-a. ._ii\iLig una. aiMHU il\ l- R^t in l<ni^l 

the great seas during the Cretaceous period, some four miUious of years ago 



iamrrican j^aturr ©cries 

Group IIJ The Functions of Nature 



THE BIRD 

ITS FORM AND FUNCTION 



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 l^ciences 

Author of " Two Bird- Lovers in Mexico" 



WITH OVER THREE HUNDRED AND SEVENTY ILLUSTRATIONS 

CHIEFLY PHOTOGRAPHED FROM LIFE 

BY THE AUTHOR 




NEW YORK 

HENRY HOLT AND COMPANY 
1906 



Copyright, 1906 

BY 

HENRY HOLT AND COMPANY 
Published September, 1906 



ROBERT DRUMMOND, PKINTEB, VEVT YORK 



DEDICATED 
IN GRATITUDE AND ESTEEM 

TO 

professor "fccnrg jfalrfiel5 ©sborn 

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. 

1 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 



viii 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 ix 

In my treatment of the various phases of the bird's 
physical Hfe 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. William 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 m.emorable 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. 



X Preface 

A few chapters of this volume have ah-eady appeared 
in print in ''Outing," "Bird-Lore," and the ''New York 
Evening Post." 

C. W. B. 

New York Zoological Park, May, 1906. 



CONTENTS 

•CHAPTER PAQB 

1. Ancestors 1 

II. Feathers 19 

III. The Framework of the Bird 62 

IV. The Skull 103 

V. Organs of Nutrition 116 

VI. The Food of Birds 142 

VII. The Breath of a Bird ] 65 

VIII. Muscles and Nerves 188 

IX. The Senses 203 

X. Beaks and Bills 223 

XI. Heads and Necks 252 

XII. The Body of a Bird 285 

XIII. Wings 319 

XIV. Feet and Legs 353 

XV. Tails 398 

XVI. The Eggs of Birds 427 

XVII. The Bird in the Egg 462 

Appendix — Brief List of Useful Books 483 

Index 485 




THE BIRD 

CHAPTER I 

ANCESTORS 

JiTH the exception of Astronomy, the science 
which most powerfully dominates our imagina- 
tion is Palaeontology, 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 Palaeon- 
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, 
milHons of years before the first being awakened into 
human consciousness from the sleep of the animal mind. 

Until recently, Palaeontology^ 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, " Palseontolog}" 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 thaa 
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 chmate 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— tapped 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 Ichthyornis and Hesperorriis. The 



Ancestors o 

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 




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



West, "was a tv^ical 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 sue- 



4 The Bird 

session 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 Ichthyornis ('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 
^roup 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 
Iiumerus, 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 

literalh' fly through the water by means of their flipper- 
Hke wings. 

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



_____ „... ^ iL. i , ^,1 ,. > i.mnK mmmmmmmmmmm 




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




Fig. 3.^IiOwer jaw of Alligator. 1/6 natural size. The teeth are set in distinct 
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 unceasingl}' at 
work. 

When we examine the skull of Hesperornis we get a 
clew to the reason why this great creature, nearl}^ 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- 
pHed 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. 

AVhen Hesperornis passed, it was succeeded b}^ 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 
Iguanodonis and Megalosaurs lived, long before the first 
serpents had evolved and about the time when the first 
timid forenmners 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 Archce- 
opteryx (ancient-winged-creature). From 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 frorri each of the twenty joints. 
The wings were not large, and instead of the fingers being 
concealed by feathers, there were three entirel}' 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 wdngs and tail, showing that perfect 
feathers were in existence at least six millions of j^ears 
ago. 

In the rocks deposited in very ancient epochs are 
found many footprints w^hich 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 The 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-necessar\^ feather-ideal; Dinosaurs began at 
the wrong end, learning to stand on their hind feet and 
to hop, but never the delights of fUght. These offshoots 
sooner or later were forced to the wall, but Archceop- 
teryx seems to have been ver}' 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-extinct 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 




9 



lo 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 Archce- 
opteryx as resembling closely the tj'pical original bird- 
tN'pe from which all others have at least indirect!}' evolved ; 
and thus having obtained a definitely fixed starting-point, 
we may consider how some of the more representative 
birds of the present dav came to acquire their widely 
differing structure and characteristics.* 

The tree of evolution of reptiles ma}' 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 Archcen-pteryx as merely 
the tip of a parallel branch, but one sprouting close to the base of the avian 
tree. 




^''^■fo;"Ii-'^7^""'^i'fl^-^uPr'^f'*'^ ^" ^he Berlin Museum. The skull vertebrae 
forehmbs and flight-feathers are re.nnrU-^hKr H,-.t.„„f i /o „„:._,' __>e/^eDrae, 



ght-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 Archceop- 
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 
scaling 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 pr}' 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 alread}^ 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 







Fig. 6. — Restoration of Archoeopteryx (adapted from Smit). Notice the teeth, 
three fingers, and hzard-hke 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, leather}^ 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 INIaoris 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 pre}', 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 1 5 

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 m}^ office and, coming close to my 
desk, watch me closely. It has most beautiful gray- 
blue e3'es, with long eyelashes (Fig. 199), and if the 
birds of past ages were as comel}^ and as lovable as this 
interesting species, I regret that only their fossil bones 
are left to us. As the Seriema nms 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. 



i6 



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, 
j-Si 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 




Fig. 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 




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

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



I 8 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 pitifull}^ 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 harmon}^ 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 w^orld 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 marv^el 
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 tw^o 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 w^ould be yery 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, 




Fig. 9. — Tarpon-scale, 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 papilla^ 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. 



2 2 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 wa}' 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 sa\^ that 



Feathers 



23 



in sharks, which are among the most primitive forms of 
fishes, the skin is covered with tin}^ 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 
liomologous 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 dr\^ 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 hfted clear 
of the skin, being supported on the new structure, and 



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




Fig. I2a. — 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 bab}' plumage is shed and replaced 



Feathers 25 

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




Fig. 12?).^Last stages in the fonnation 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. 




Fig. lo. — 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 horn}^ 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 3'oung cuckoo 



Feathers 



27 



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







-■^^s 


. ,^^, |l 






-^jpIIp^ 


^^P^^^^ \ oi 








^pjakj^^ik-^ 


^IS^^j^^^^p 


i^rT*^*;7-"'ir iiji^i^ 




it^^^^hi 


i^^^^^aSlSf^l^S 




^r^<^^^ 


^^^^^^^I^H 


^SSBS^^t^^ 


^^f^'TiJi 


f. r -:^3^^ 


^^^^ 


^^^ 




'"^'V 


^^P 






■■■ _^ 


^^3fe> 



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




Fig. 1.1. — 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, 



•H% 




Fig. 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 




Fig. 17. — Nestling Kingfisher ^vith 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 Archceopteryx. 

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; hnk left. 



• .'_,.^lv-r' 


. '^ 'v. 1 


*" T - ■ - ^^ _ ■'''*^^^ " " r' -' ' "fc."" 1 








iJr ^--"^ 


': ^-^ ' 









Fig. is. — Young Brown Pelicans; hatched naked and heliiless (altricial). 
1 4 natural size. 




Fig. 19. — Young Red Jungle Foul 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 Archceopteryx 
still retained reptile-like teeth, fingers and tail, it had 



Feathers 31 

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 close!}', 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 




Fig. 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 cassowar}^ We might 
naturally think that feathers stiffened b}^ so manj^ close 
rows of interlocking barbicels would be useful in many 
w^ays beside flight. But flufl"y 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 hnes 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 




Fig. 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 



2^ 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- 
Ijdng 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 enabUng 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 sa}' 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 tweh'e 
hundred of these little side featherlets. One of these, 
from a narrow part of the vane, will shc^v under the micro- 
scope about two hundred and seventy-five pairs of bar- 
bules, which multiplied b}' the number of barbs on that 
side amounts to three hundred and thirty thousand. 
Making a Yery 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 




Fig. 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. (6) Under wing-covert of a Great Blue Heron; downy portion was over- 
lapped by the adjoining feather, (r) 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 



3^ 



The Bird 



finer hooklets, and then the number of feathers on the 
pigeon's body, we can echo the exclamation of Solomon: 
''The wa}" of an eagle in the air" is ''too wonderful for 
me!" 

Another beautiful adaptation to flight is seen in our 




Fig. 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 
perfecth" 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 obliquel}^ forward direction 
in which the barbs grow, the change in shape of the 



Feathers 



37 



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. — Puwder-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 ordinars^ 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 constanth^ 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 w^e 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- 




FiG. 25. — Nestling Crow, showing feathered and infeathered portions of the body 
(pterylae 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 w^hich 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 dow^i 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 supphes 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 l)e 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 papillae (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 wdngs 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 rieh-hued breeding 
plumage (Fig. 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 




Fig. 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 nurserv^ 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 
m 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 Uttle 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 




Fig. 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 w^arns 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 passivels' await the development of 
plumes, gorgets, spots and splashes of colour w^hich, 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 ail 



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. 2S. — Wings of Engli.sh 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 











■ ' k 


^J^ 


"'"^ ^ffa 


k "^ 


^ 


^^ 


T " 


% 


i*«aai«spr-,r~-^ 




/■•j^5S b' 






^^^^'^^^■■F^ 


■■.* ■,-' 


'mm 


^H^EI 


^ • ^'^ 


|l^^ 


m 
J 


i 




^ 



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 brilliant 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 
\Nith the colour of the birds' surroundings. Ptarmigans, 
w^hich are species of grouse living in the far North, moult 



Feathers 



49 




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




Fig. 31. — Male in eclipse plumage during moult of wing-feathers. 




Fig. 32.— Female Mallard. 



5° 



The Bird 



after the breeding season into a special gra}' or dark 
phimage, 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 featlier.s l)t'ginning 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 j'ear, but when the wings are 



Feathers 



51 



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 




Fig. 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. 
Unlike 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. 



52 



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 




Fig. 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 



53 



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 is 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 raA's — 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 ^^ 

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 })ound 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 d3'ed the birds artificially, 
as when these birds were kept captive, the magnificent 
scarlet patch on the wing would gradualh^ fade and 
become a dull gray. It is a fact that this colouring- 
matter washes out when the feather is washed in alkaline 
water. Even ordinary water will be slightl}- 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 Httle ridges extending down the sides, 
and in some wa}', 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 delicac}^ and fluffiness which the bird's plumage 
as a w^hole 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 nevef 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 whifte 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 





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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 w^onderful 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 w^hite 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- 




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

59 



6o 



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. 




Fig. 39.— Evolution of a colour pattern upon two feathers of a ultunne Ciuirea- 
fovvl; 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. 



f'eathers 6i 

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 aesthetic 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 onl}^ to show the 
possibilities of a little feather-study. Even our common 
Ph'mouth 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 ^luch we usually pass by un- 
noticed. 




CHAPTER III 
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 
3'et the history of the lower part of a sparrow's beak 
opens a vista so far-reaching that the mind of man faUers 
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 wa}^ 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, j^et there is 
sufficient gradation among living creatures to give us 




Fig. 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. 

6? 



66 The Bird 

hints of the way it originated. In the lowest of fish-Uke 
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 lies 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 histor}', is 
not altogether a majestic upward evolution; it has its 
tragedies and set-backs, its hopes and failures. In the 
W'aters 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 a stem. 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 w^hich 
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 




Fig. 44.— Back-bone of Dogfish, with simple cartilaginous vertebra-. 

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 unknowii to us 
forever, and resembling some of these other living Classes at least in the pos- 
session of gills, scales, etc. 



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 




Fig. 45.— Neck vertebra 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 embr^^o lying on 
the 3'olk within will show a double series of tiny squares 
extending down the long diameter of the bod3\ 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 bod}' of a beetle, butterfly, or earthworm. 
In a short time all the squares will fuse together, and not 
until later will the}' 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- 




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

esting to note that the vertebrse of the embryo chick 
pass through a stage w^hen they are biconcave, — a condi- 
tion found both in Amphioxus and Archseopteryx. 

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 vertebrae 
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 beautifulh^ they saddle end to end, 
every convexit}' 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 little more than a simple ring * of bone, and is called 
the atlas, after the mythological giant who held up the 
heavens upon his shoulders; named very aptly too, for 





Fig. 4S. — Atlas and axis of Jabiru, separated. 



Fig. 49. — Atlas and axis of 
Jabiru, joined. 



this tin}^ 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 
a pivot on which the head turns, hence its name, — the 

axis.f 

Let us compare the neck-bones with those of a reptile 

and a man. Although, as a whole, the bones of the 

* This lx)ne is formed chiefly of two intercentra, whit-h are .■small hones, 
very characteristic of reptiles (chevron-bones of the tail) and are not uncom- 
mon among the lower Orders of birds. 

t Tn Hornbills the atlas and axis are fused together. 



The Framework of the Bird 73 

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 




Fig. 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 vertebrae, those of the upper and lower 
back, are ver}' 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 




Fig. 51. — White-thioated Sparrow, three inches tall, with lourteen neck vertebrae. 

(Compare with Fig. 52.) 



rigid body-frame. In reptiles and in the embr\^os of 
birds only two pelvic vertebrae 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 



7S 



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 




Fig. 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- 
brae 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 vertebrae of young Alligator. 




Fig. 54. — Pelvic vertebrse ot American Flamingo. 



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WUm 






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



The Framework of the Bird 



11 



hence the separate bones which unite it to the vertebrae 
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 vertebrae 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 will be seen. From near 
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 



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li'^ - 


kHiklLJll 


iL^lmii^^ 


r'/^/'' 






a'"" ^ \-': -. ■'*'^' 


/ -/ v< 


msk 


'/. 


'''/// 



V\Q,. 56. — Ribs of Hatteria Lizard, 
with uncinate processes. 



78 The Bird 

around toward the breast-bone — hints of something 
which perhaps has never occurred to us. We spoke of 
the worm-hke 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 everj^ 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 Archceopteryx (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 



8o 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 




Fig. 57. — Ribs and sternum of Flamingo; notice what a complex box of bone 
is formed by the vertebrae, 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 



8i 



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. 



I^^^H^^^^fa 


^v ^UH ^m 


^f^^ 1 >~ -'^^^■B 


191 




1 hhh m^ ^^ 






Sm 


^^^k H 


'i8r?! 


^SnFM 


Bl 




iM 



Fig. 58. — Ribs and sternum of Ostrich; notice absence of keel correlated with 
lo.ss 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 
cassow^ary, and it is the character which has given a 



82 The Bird 

name to two great divisions of birds : Rati' tee (those with 
flat breast-bones, raft-Uke), including the ostrich, rhea, 
emeu, cassowary, and apteryx; and Carina' toe (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 w^e 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 



83 



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 the}' 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 ver}' 
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. 




Fig 60. — Pectoral girdle of bird (scapulas, coracoids, and clavicles); compared 
with the scapula and coracoid ot 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 oesophagus 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 Hmbs, 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 contirme 
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 
Ave realize that a shoidder-girdle of bones is of no use 
without a limb. Therefore we find the first hint of the 
shoulder-girdle in sharks, in w^hich we also find the first 
limbs, or fins. In these fishes it is 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 




Fig. 61.— Ciirdle 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 ver}- 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 w^e 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 strongh' attached to the sternum, 
and this in turn joined to the back-bone b}^ 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 

* Thov were separnto also in Archcpupteriix. 



The Framework of the Bird 89 

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 vertebrae more distinctly — 
fourteen or fifteen of them. The two deep depressions 
in which the kidneys of the bird were located are also 




Fig. 62. — Pelvic 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. 

Each 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 



90 



The Bird 




Fig. 63— Pelvic arch of a Dinosaur 



bone extending backward from the thigh-socket, sepa- 
rated from the ischium 
(except at the extreme 
end) by a long open sHt. 
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 vertebrae, 
is directly connected with 
two-legged erect locomo- 
tion. A parallel condition 
is found in some Dinosaurs 
— those extinct giant rep- 
tiles — certain of which 
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 




Fig. 64. — Pelvic arch of an embryo bird, 
to show similarity ot the two as 
contrasted with Fig. (5. 




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



The Framework of the Bird 



91 



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 
been found no ''missing Unks" 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-raj^s 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 Hzards, 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 ver\' 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, teathered. 




Fig. 68. — Wing of Pigeon, bare, compared with Fig. 69. 




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. f 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. AVe 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 

* Some morphologists homologize the fingers of a bird's wing with the 
second, third, and fourth digits of a pentadactyl hand. The question is still 
a mooted one. 

t In the embryos of some birds, traces of a fourth finger have been found. 




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




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

95 



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 evers^where in Nature. 

The proportionate length of the various parts of the 
fore limb of a bird forms an interesting coiollary 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- 



yX:i*»i 



i^^0^^!^P .>iSW:> A5;>i^J^ 

f .. .v.: .:.:; "^'i^'-. — ■■::^'-:::^m^w^ . • • • ■ 

Fig. 72. — Diagram showing the origin of 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 embiyos of sharks we get a hint of what the first 
^eat 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 Hke 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 embrj^o 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 w^as 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, w^e 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 usualh' 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 low^er 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, is 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, w^hich 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. 





¥iG. 73. — Skeleton of an OstricJi Fig. 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. 



lOO 



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 




Fig. 75. — Living 0.strich, showing entire leg; notice the knee ahiiost 
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. 76. — Heron, standing naturally upon its eight toes. 




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

101 




Fig. 78. — Wood llj's, resting temporarily upon its whole foot, 
(Sanborn, photo. Courtesy of N. Y. Zoological Society.) 




Fig. 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 morphol- 
ogy; in its mutely eloquent lines may be traced 
the rhythmic rhymes of the myriad amoebiform animals 
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 a 
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 




Fig. 80. — Cranium ot 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, yet 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 




Fig. 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. 
AVe 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 



io6 The Bird 

few thousand years during which man has reigned seems 
but a da}'. 

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 hving creature — a shark — with 




Fig. 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 munber 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 




Fig. 83. — Skull of Fowl, showing orbit, brain-case, ear, lower jaw, premaxillary 
{Pmx.), maxillary {Mx.), vomer (Vo.). lacrymal (Lc), jugal (Ju.), palatine 
(Pal.), pterygoid (.Ptg), quadrate {Qd.), and supra (Sup. occ), ex {Ex. 
occ), and basioccipital 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 



io8 



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 a man, 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 manmial, 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 109 

know them b}' then- 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 ma}' be seen 
beneath, extending backw^ards 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 



I lo 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 III 

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 onh' 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, 3'et the radical differ- 
ence shown by the palate bones in the two groups is 
reliable evidence of their earl}^ 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, is 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 verj^ 
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 embr^^ology, 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- 
FiG. 86,-Giii-basket of Lamprey. ^^^^^ net-work protecting and 

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 lampre}^ is because 




The Skull 



113 



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 




Fig. 87.— C.ill-hars of Shark. 



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

All this may be very true, sa}^ 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 o\er the 
edge, and the bony scales in the skin, standnag up on 
end, have become teeth. 

And now to our bird. In the embryo chick four 
gill-arches are at first distniguishable, 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- 




FiG. 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 



115 



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- 




FiG. 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 — Karl 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 

|N other pages we shall consider some of the things 
upon which birds feed, and shall see how surely 
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 ma}' notice something which we did 
not before know. 

In the first place the bill of a bird is, of course, a 
primar}^ 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 

Ii6 



Organs of Nutrition 1 1 7 

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 
bod3^ 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- 
stantl}' 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, 



ii8 



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 sahva has but Httle 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 




Fig. 90 — Nest of Chimney Swift; twigs glued together with sah'va. 

an organ or special tissue by the elaborate synthesis of 
evolution, confines its use to an}^ 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 w^hich covers the long, many-barbed tongue and is 
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 
fuciphaga) 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 



I 20 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 i 2 i 

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 




Fig. 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 w^ith 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 vrorth examining. The use of 
such a complicated organ in a bird of so sim.ple feeding 
habits as the duck is hard to explain. 

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








-^ 




f ' 





Figs. 03 and 94. — Top and side views of the tongue of a jMallard Duck, showing 
complicated structure in the tongue of a bird which sifts its food from the mud. 

tion as the remaining portions. In mam^ 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 P'licker, 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 ot the tongue is 
visible beyond the tip ot 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 



I 24 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, h'ing 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 



125 



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

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 papillae, 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- 
v.r. n-7 Tu- I fl u . t n ^ , i^g ^^ admirable seed- 

tiG. 97. — Ihick fleshy tongue of Cockatoo. ^ 

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. 




Ftg 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 
reflecting its crookedness. The upper edges of the man- 




jTjG 9q___ 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, forcilily lifted above mandible, show- 
ing fieshy 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 oesophagus, through which the food 



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 




Fig. 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 sahva 
in birds, we had to refer to a swift, Hving in caves in 
islands of the Mahi}' 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 di\'ided 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 j^oung leave the nest, we will discover a func- 
tion of this organ which would otherwise ne\'er 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 probabh' 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 onh' 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 131 

squeeze out the juice of the thick leaves of the Arum 
arborescens which forms its food. Thus it has a gizzard- 
Uke function, and has become so important in the Hfe- 
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- 
vent riculus 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 \'ultures have gorged them- 
selves to repletion on the flesh of any animal, the}^ 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 fish}^ meals when frightened. Petrels and many 
fish-eating sea-birds appear to have a suppty 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- 



I -^2 



The Bird 



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 




Fig. 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 convenientl}^ to get 
rid of the indigestible portions of its food, this habit 
seems to be necessarv to the health of the bird. In 



Organs of Nutrition 



133 



captivity, owls and hawks are never so healthy and active 
when fed on flesh}^ 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, 




Fig. 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 tr}^ to eat the 
straw on the floors 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 



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

The typical bird-stom- 
ach, however, is compound, 
or formed of two more or less distinct parts. The first 




Fig. 105.- 



-Caracara, showing crop dis- 
tended with food 



Organs of Nutrition 



135 



portion — known as the proventriculus — is the smaller, and 
contains very active digestive glands, sometimes ar- 
ranged in patches, but more usualh' forming a band. If 
the lower part of the oesophagus 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 w^alls 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 
upon chemically by the secre- 
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, 




Fig. 106. 



-Glands of the stomach of a 
young chicken. 



I 36 The Bird 

in a chicken, is in shape Hke 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 man}' 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 da}', 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 hea^'ier 
bones. In all cases they were in distinct groups; even 



Organs of Nutrition 137 

where they had become scattered, each group covered 
only a few square yards of ground, and in that space 
hiy thickly strewn. . . . The peculiar feature of the 
stones was that they were almost all opaque, white quartz 
I)ebbles. In one place I found a small group of small 
j)ebbles 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. 

"I 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 1 collected 
three sets of pel^bles, 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 lb. 9 oz.; 
No. 2 weighs 4 11).; while No. 3 weighs no less than 5 lb. 
7 oz.! 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 

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 onl}^ 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 probabl}' 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 i 39 

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 an)' 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 Hning the entire organ, but 
these are in reality only the hairs of caterpillars upon 



^^^^lp^^ 






^^K 


./ 


X. 


^ 


"'^'^^^^H^ 


v^ 



Fig. 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- 



140 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 deficate 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 is very simple, much like the condition 
to be found in alligators. 




CHAPTER VI 
THE FOOD OF BIRDS 

5|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 memorj^ 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 waj^s 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- 




FiG. 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 
the}^ alone would offer an interesting field for stud}^, 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. 




Fig. 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-Hke 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 



^^ 


'ST'"' .-" 




<■*- -* . 7 - , 


^ 1 


m 


J 



















Fig. 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 




Fig. 112. — Cocoon. 



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



The Food of Birds 



H7 



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- 





^ 




\ 


1 

/ 

1 

r 






:^m 




! 



Fig. 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. 

Roundw^orms, 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 Hghted 
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 carr}' 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 
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 larvae 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- 



F'lG. 114.— Snail. 



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 




Fig. 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 reaUzed the fact that 
to each is apportioned certain phases of insect Hfe, 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- 




FiG. 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 



151 



ing is influenced by the presence or absence of these in- 
sects. ''When pursuing a flight of mature locusts these 
starUngs 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 
starlings gradually fill up the 

hollow of the cylinder until they again assume their *balP 
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 




Fig. 117.— Rattlesnake. 



152 



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 




Fig. 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 3'oung, 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 153 

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 w^ith 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 probabl}^ many other birds also feed upon 
them. Even deep-water snails and crabs are not safe, 
as the sturd}' sea-ducks will sometimes dive to a depth 
of one hundred and fifty feet to feed upon them. 

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



154 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-circle and driving them ashore or into shallow water. 




?5 



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 




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



at a hair-trigger poise. So w^e 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 



^57 



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. 





/ r ''mj^^^^^^mjjl^ 


K ■ . -A 1 . -^ "^ ,.-:"'■ 


iHHI 


^■■iiW' 



Fig. 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 pre}^ frenzied with hunger. In 
certain districts eagles and hawks have been shot 
smelling strongly of skunk, but w^hether 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 bj' 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 



i6o 



The Bird 



surprising in its numbers and 
extent. Every class of living 
beings appears, at certain ])hases 
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 
the effects of accumulated 
events no more important than this are felt around the 
world, so delicate is the balance of Nature. 




Fig. 122.— Red-tailed Hawk 
(the watcher) an active 
hunter. 



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 

Fig. 123. -Red Squirrel (the watched), of giving lip and becoming 
food of hawks and owls. < • j. -. • ;n 

(R. H. Beebe, photographer.) extmct, a Certain race will 




The Food of Birds 



i6i 



instantly accept changed conditions and flourish under 
the new regime. 

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 man}^ 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 Tj-rant and 
several others readil}^ 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 
battered out. Certain small king- 
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 




Fig. 124. — Texas Kingfisher 
fi.shing for insects. 



1 62 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 larvae 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 




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

fruit of the sjTinga-tree, "on which the}^ 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 solety to similarity in method of seeking their food 
that the likeness is due. 




CHAPTER VII 

THE BREATH OF A BIRD 

^IJHINK of a mite of a hummingbird shooting 
|J 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 or a 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 



1 66 



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 mellow 
mouth of a nestling robin this 
may be seen to excellent advan- 
tage, and watched as it widens and 
narrows wnth 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 
3^ou ma}^ eject a stream of water 
from a medicine-dropper into the ^-, ,^^ ^ w,- . 

^ '^ Fig. 126— Open glottis ot 

bird's mouth, reflex action will ^ 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 oesophagus, 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. 

Comparison of the two 
tubes which traverse the 




Fig. 127. — Windpipe and oesophagus of 
bird compared; the former always dis- 
tended; the latter soft and collapsed. 



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 oesophagus 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, 



i68 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 





Fig, 12S. Fig. 129. 

Fig. 128. — Windpipe of Flaminpjo, extended and contracted, showing delicate 

mechanism of supporting; rings. 
Fig. 129. — Syrinx-drum of Mallard Drake; the windpipe ahove; the bronchi 

below leading to the lungs. 

immediately back of the glottis, nnd 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 (T have in my hand an inch of 
the windpipe of a flamingo, but the general structure 



The Breath of a Bird 169 

is common to all l)irds) 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 an}- 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 tlie kings, 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 \'eritable 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 j^ears 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. 




Fig. 131.-Breast-bone of Whooping Crane, showing convolutions of trachea 

withui the keel. 



172 The Bird 



The Syrinx 

This organ is pecuhar 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 
magi^ie or crow to "make it talk" is as unnecessary as 
it is inhumanly cruel. 

The sjTinx is singularly uniform among birds, and 
this seems the more remarkable when we consider the 
great 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 173 

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 sj^s- 
tem of tubes ramifying throughout the bod}^ 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 laver 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 ma}' compare the body of a bird to a submarine 
boat with mam' 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 bod}', 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 vitaUzing the entire body. If 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 



^7S 



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 




Fig. 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 sev- 
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 w^ho 
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 177 

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 an}' 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 
a-. the ancestors of birds were once 

A. ^H ^ aquatic and fish-like. But how about 

;f; -'^v-r"'^:^ lungs? Fishes have none, and indeed 
vv : >: ;j in their aquatic life such organs would 

r' ; - '"^ be useless. Nevertheless, as we shall 
1^ • see, the lungs of reptiles, birds, and 

# mammals are legacies from the crea- 

i^;^ ^^ V "^ tures of the sea. 

sf - . ■ • 

^■. . , X ■ ... 

f^^ ^ ; Many fishes have withm their 

-■"^y -%l 11 bodies a thiin-walled sac, known as 

y ■ % : ^ the swim-bladder. This is filled with 

:; gas, and as the fish ascends to the 

-I iy^i-pi surface, or dives to where the pres- 

. i%^y^^ J ^M sure of the water is very great, the 

"*/ %^ H^ amount of gas varies; so that the 

1% ^ specific gravity of the fish changes 

i 4 ^ with that of the water. This swim- 

®| bladder is generally connected with 

^ the throat by a delicate tube; and 

Fig. 133. — Lune of Ohame- . ,1 , , , 1 ,1 

leon, foreshadowing con- m these two structures we have the 

dition in bird. , , r j.i i • 1 > i 1 

homologues oi 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 oesophagus, 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 
canal, 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- 







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



i8o 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, w^hich 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 i8i 

is the ease 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 lies 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 fairl}- 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 wath birds and the w^arm-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 



I 82 The Bird 

in birds. Here we find an organ remarkably large in 
proportion to the size of the bird's body— a conical knot 
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 w^hich 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 twdg near its nest mur- 
muring its sweet warble; a Wood Pew^e, half hidden 
in the shadows of some dense, moist forest, speaks to 
us in its sad dream}- 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 ot the body. 



183 



I 84 The Bird 

the tree merges into hmbs, and these into branches, twigs, 
stems, and at last into the dehcate fohage. 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 W'hat occurs in the course of the blood. The capil- 
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. From 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, w^e shall 
see thousands upon thousands of oval discs, 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. Scat- 
tered among these oval bodies will occasionally be seen 
others of indefinite shape and white in colour. As we 
w^atch one of these tin)^ cells, the thought suddenh' comes 
over us, — w^hat are birds indeed but collections of untold 



The Breath of a Bird 



.85 



millions of one-celled animals! For here before us we 
have what is almost exactly like the little flowing drops 
of jelly called Amoebae 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 




Fig. 136. — Blood-corpu.scles 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 carr}^ 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 



i86 



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 98^°; 
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°! 




Fig 137. — Amoeba, 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 Httle 
laboratory concealed in his mite of a body; w^hich his 
wings bear up with so little effort, which his tiny legs sup- 



The Breath of a Bird 



187 



port, now hopping along a branch, now suspended from 
some worm}' 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 w^hich 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 w^hose tiny 
brain can generate a sympathy, a love for its mate, which 
in sincerity and unselfishness suffers little when compared 
with human affection. 




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 immediateh' be- 
neath the skin, which ser^^e to raise or otherwise move 
the feathers. 

In a penguin the muscles immediately beneath the 
skin are unusually well developed, and for an excellent 
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 wdth many important back-muscles. 
But if we have ever carved a chicken, w^e 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 



I 90 



The 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- 




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

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 w^ould instantly overbalance the bird. 
If we remove the skin from the upper arm of a bird, 



Muscles and Nerves 191 

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. 




Fig. 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 



wa\y 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. 



HMHIH 


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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 (m 
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 
man}' 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- 



196 The Bird 

bone supports the entire body and gives a point of at- 
tachment for the hmbs, but long before hmbs 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 it was the original, function of our vertebrae. 
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 
leading to wings and legs. 

197 



198 The Bird 

this is the sympathetic or reflex S3'stem. It is a very 
wonderful thing, this not having to think about the heart 
beating or the kings expanding. 

\\e 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 
e^'e 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 quickl}' 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 sa}^ 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 carefiill}^ remove the upper part of a bird's 
skull, we find that the brain occupies the whole interior, 




Fig. 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 
timid heron and say, ''phrenologically/' in the first we 
have the bump of combativeness well developed, analo- 
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 Archceopteryx (which had a typical bird- 
brain), the monster Dinosaur, Triceratops, 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-j^ear-old child, and when 
we compare the wonderfully varied life of birds, and 



Muscles and Nerves 



20I 



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 




Fig. 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 vitce — 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. 
Each 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 it must be confessed that 
the effect of this in the immobile face of a bird is not 
especial!}' 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 

E 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 



205 



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 
vultures perceive their 
prey by sight or smell has 
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 
slight 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 apterj^x of New Zealand, probably have the 





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Fig. 149. — Turbinal scrolls of dog. In a 
bird these bones are far more simple. 



2o6 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 




Fig. 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 



2o8 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 
sk}" expanse. He is far-sighted, and, scouring the earth 
below, descries an object much smaller than himself, 
w^hich 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 w^ell 
how to complete the bloody work begun. A humming- 
bird darts so quickly that our e3'es 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 3'ards awaj'. 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 an}' 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. 



2IO 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 




Fig. 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 



21 I 



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 the stars. In Nova Scotia I have 
noticed Barred Owls flying about and feeding at noonday. 




Fig. 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 Ichthyosauri. All we know of them we 
have learned by stud}^ of their fossil bones which, through 
the ages, have been preserved in rocks. One notable 




Fig. 153. — Brown Thra.sher with ej-es 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 bonj' 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 




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




Fig. 15.5. — Same with eyelids closed. 



214 'T^^ Bird 

shutter, and in fact our bird has not one, but three — 
eyeUds 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 aw^are 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 usuall}^ 
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, lies 
snugly packed aw^ay in folds at the inner corner of the 
eye, held back out of sight by its own elasticit3\ It is 
drawn across the front of the eye by a slender thread of 
tendon which is suspended, pullejMike, from a muscle 
which keeps it from pushing against the optic nerve. 

AMien 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 3^et 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 monke3^s. 



The Senses 2 i 5 

although usually much less perfectly developed than it 
is in birds. Alligators, however, have it fully functional. 
In the inner corner of our own e3'es 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. 



"~ " J^i^Av -:-;■■•■•;•■■ \ 




t 



Fig. 156. — Vestige of nictitating membrane in a human ej'e. 

The Sense of Hearing 

"The Gauls," says LiAy, "having discovered that the 
rock Carmentalis was accessible, one night when it was 
pretty clear, sent a man to examine the wa}^ without 
his arms which were afterward handed to him. Others 
followed, lifting and assisting each other, according to 
the difficulties which the}' 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 



2i6 The Bird 

their cackUng and beating their wings, they roused Mar- 
cus ManUus, 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, iElian, 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- 
criminating. 

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 ow4s 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 




Fig. 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- 



21 8 The Bird 

ated in the inner ear — which occupy the three planes of 
space, — exercises a most important function, that of equi- 
libration. The}' 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 sidewaj's 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 
continualh' falls backw-ard. 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 veiy apparent. 

The Sense of Taste and Touch 

"The hands of birds being hidden in the feathers 
W'hich envelop the whole body, — their feet and their lij^s 
and usuall}' 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 wa}' through the 
pores of the bill and tongue are more properh' 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 
w^ould be useless. Parrots and ducks, with their fleshy 



The Senses 2 1 9 

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 facult3\ 

But from no bird is taste entirely absent, as we may 
easily see by presenting some nauseous insect, which 
will be instantly rejected with ver}^ 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 
feather}' and horn}" 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 



The Senses 22 i 

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 Fig. IfiO 

Fig. 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 surve}' 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. 




_ N 




CHAPTER X 
BEAKS AND BILLS 

TE a man's hands and arms tightly behind his 
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 
w^ays 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 vohime could be filled with in- 
teresting facts about the bills of birds and the uses to 
which the}^ 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 





fclH i^^iiM 




1 

4 




^' 




^^^ii^PIIPHH 


©"■_ 



Fig. 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 identif}' 
structures among the creatures which rank below us 
wuth portions of our own anatomy corresponding onl}^ 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 



225 



reaching about, or for ])rogression 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 universalh' 




Fir.. l(v). — Rill nt 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 horn}", 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-extinct Dinosaurs, such as 



226 The Bird 

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

Starting with the generalized beak of the Archce- 
opteryx, which, we remember, was furnished with teeth, 
we are almost at a loss in which direction to turn, 
so man}^ 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 stricth' 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 cariying great 
quantities of sticks, which they use in the constniction 
of their nests. These birds are so skilful with their 



Beaks and Bills 



227 




Fig. 164.— Beak of Gannet. 




Fig. 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 w^ith 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 




Fig. 166. — Beak of Snake-bird. 




Fig. 167.— Beak of Pelican. 
Birds related to each other and to Figs. 164 and 16.5, but with difTerent 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 




Fig. 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 



231 



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




Fig. ] (59.— Bill of Tern. 




Fig 170— Bill 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 



232 



The Bird 



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 

bkd. It is long 

and high, and 

the lower man- 




FiG. 172.— Two-year-old Skim- 
mer, reared in oaptivity, 
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 veiy close to 



Beaks and Bills. 233 

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. 




Fig. 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 radicalh' in respect to their 
beaks. The fish-eating merganser has perhaps, of all 
living birds, the nearest resemblance to a toothed beak. 



234 The 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 w^orms 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 
a 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 IX THE DEVELOPMENT OF THE BILL OF THE 

FLAMINGO. 




Fig. 17.5. — Youna; bird in down. 




Fig. 177. — Young in gray plumage, later stage. 




Fig. 178. — Adult living bird. 



235 



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, 3'et 
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 6f 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 



237 



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- 
shore, offer sumptuous 
feasts to birds furnished with beaks adapted to pr\ang 
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 




Fig. 179.— Bill of Great Blue Heron. 



23 



8 



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 rashl}'- pecked at the sweet flesh, when the two tight- 
fitting doors have suddenly closed, pinning the bird help- 




FiG. 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 j^ears 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 




Fig. 181. — Spoonbill, with spatulate 
mandibles. 



Fig. 182. — W hite Ibis, showing 
curved bill. 




Fig. 1813. — Bill of Avocet, recurved for probing. 



240 The Bird 

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 oj^'sters 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 




Fig. 184. — Bill of Oyster-catcher; used for prying open the shells of moUusks. 

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 




Fig. 185. — Bill of Crook-hilled Plover, for probing under stones. 



in the Dowitcher Snipe, the extremit}' of the upper man- 
dible can be raised some distance (Figs. 159, 160). This 
extreme sensitiveness is especially necessarv^, as the e3'es 
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 ofTer, 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 hnear sequence. The ma- 
jority of those birds which have their beaks armed with 
a strong hook feed upon Hving 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 
w^hose 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 243 

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 




Fig. 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 vertebrae 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 




Fig. 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 
tw^o bills more unlike be imagined? In very young hum- 
mingbirds the bill is short and broad, very like the swift 
tj'pe, 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 w^hich there are none to dispute with 



246 



The Bird 




Fig, 189. — Bills of adult Hummingbird and Chimney Swift, showing great dis- 
similarity in form, due to different methods of procuring food. 




Fig. 100. — Bills of young Rufous Hummingbirds, showing swift-hke character. 
(Photograph by Finley & Bohlman.) 




Fig. 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. 




Fig. 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 ver}" different in 
form and use, and complement each other's methods. 
Concerning the peculiar use of the bill in the Huia birds, 




Fig. 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 decaj^ed 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, dr}'ing them, and, most important 
of all, in pressing out the oil from the gland on the lower 
back, and with it carefulh' dressing all the feathers, giv- 




-^w^l^^W-V^V-ffijiM 




Fig. 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, literall}' like " water off a 
diick'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 251 

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 playfuhiess! 




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, is made apparent by the dilating 
e3^es 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 ail 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, 





Fig. 195. 



Fig. 196 



Fig. 19o. — Head of Dove, with eyes at side 

Fig. 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 carr}- a mousing owl over 



254 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 eyes 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 




P"iG. 197.— Skull of Owl. 




Fig. 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 e3'e 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- 
tw^een 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 Axllow. 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 



'^Sl 



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- 




FiG. 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 milad}' is by way of wonderful and strange 
creations; but withal feathers are really beautiful only 



258 



The Bird 



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. 




Fig. 200. — Crest of Java Peacock. 



Most, if not all, plumes and crests are probablj^ 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 ma}' 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 has a tiny, 




Fig. 201. — Californiti 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, 



26o The Bird 

forming a slender tube. The glon' 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 w^hiteness. 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 finall}" 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. 




Fig. 202. — Crest of Banded Cvirassow (female). 




Fig. 203. — Crest of Victoria Crowned Pigeon. 




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 entirel}' bare of feathers, and 
the lower half suffused wuth 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. From 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. 




Fig 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 




Fig. 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 veiy difficult of 
detection when it is 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 b}^ the Dem- 
oiselle Crane (Fig. 207), some of the Puffins, and the Man- 
churian Pheasants (Fig. 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 brilliancv 




Fig. 209.— Head of Eared Pheasant. 




Fig. 210. — Head of Great Horned Owl. 



268 



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 Paradi.se (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-Hke, they are best described 
as a series of thirt}' or fort}' tin}^ 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. 




Fig. 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 



271 



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 




Fig. 21.3. — 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 



272 



The Bird 




Fig. 214. — Caracara partly vulturine in habits. 




Fig. 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 
highh' 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- 
waries 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 wath 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 
absolutel}' 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 ! 




Fig. 216. — Head of domestic cock. Extreme development of comb. 




Fig. 217. — Head of domestic cock. Extreme development of crest. 

274 



Heads and Necks 



275 



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 ])urel3' 
ornamental. But the impressive helmets of the cassowaries, 



■M 




1 
i 


P-'^.^ 


'-""v 




'* *-.-* 


L:'^"^'-"' 










/■ /'■ . 






?,, 




m/m 




' '« ^X^hM^^^^I 


^Ism^Sl^^^^b 




'^ij^pfH 


^^^^H 




,,s -^jT^^U 


^^^HM 




'^l^gl 


HK 



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 



2/6 



The Bird 




Fig. 219.— Head of Adjutant. 




Fig. 220. — Ringlet of hair from the neck of an Adjutant. 



Heads and Necks 



'^11 



and shunts off the hanging Hanas 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 
rufl's 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 wavmg ear-plumes are also independent 
in colour, varymg 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 Hornhil 



Heads and Necks 279 

We can only compare these little Joseph-coated l)irds 
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 gra}^, dotted gray, 
chestnut barred with black, and a rich golden rufous. 
Though no females were present, 3^et 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 w^hole body. Now and then one of the fencers 
would make a vicious dash, sending his bill through the 



28o 



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 ph3'sical 




Fig 224.— Breast ornament of a Wild Tnrkeycock. 

life of the bird, yet I mention them to show to what prac- 
tical, as well as aesthetic, uses the development of some 
portion of the bird's plumage ma}' be devoted. 

What a contrast to the cloak of the Ruff is the pectoral 
decoration of the Wild Turkey cock: a great tuft of 
coarse, black hair-Uke feathers, like the tail of a horse 



Heads and Necks 



281 



in miniature, growing almost a foot in length from the 
centre of the l^reast ! 

The length of the neck of hirds is often correlated 
with that of the legs, — a long-legged bird of necessit}' re- 
quiring a long neck to permit its hill to reach the ground. 
Geese and swans are an exception, and in their case we 




Fig 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 the}" 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 




Fig. 226. — Swan. Correlation of long neck and short legs due to feeding habits. 
(Sanborn, photographer.) 

adaptation of three of the neck-bones, become a veritable 
trigger, b}' 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 monoton}- 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, 




Fig. 227. — Snake-bird, showing crook in neck. 

which in its turn is one of the most important and interest- 
ing corollaries of the psycholog}^ of these beings. Whether 
female birds have highly developed aesthetic 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 cassowar3''s 
horny hehnet, the feather shield of the Ruff, perhaps the 
crest of the kingbird, and many others as }et 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- 
f'x^i^\ ance, and among birds there seem to be certam 
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 seem.s to reach the acme of perfec- 
tion. But the flying birds of actual heaviest bulk are 
perhaps the Wild Turke}', the Great Bastard, 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 w^ater 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, oil}' 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 
wdck, 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 call-notes 
which are so characteristic of these birds. One exception, 
however, may be noted, that of the apteiyx, 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 man}" 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 X. 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 aptervx 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 weaving them to and fro. 

The feathers of the penguin are small, flat, and rigid, 
approaching in these respects the scales of fishes — an 
interesting reacquirmg 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 briefl}' 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 an}- 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 




Fig. 229. — Breast of Scaled Partridge. 




Fig. 230.— Carp, a fish with distinctly marked scales. (Keller, photographei.) 

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 



291 



than we now possess of the hfe-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 




Fig. 231. — White-throated Sparrows. The hght-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, etc., 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 captivit}', 
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 
w^iich 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 
mixing with their food 
a quantity of some 
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 ma}^ be noticed in wild birds as well as in 
those in captivity. In regions which have a very dry 




Fig. 233.— Effect of environment on Bob- 
white, shown by specimens from Min- 
nesota, Florida, and Cuba. (From a 
photograph provided by the American 
Museum of Natural History.) 



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 readil}^ evapo- 




FiG. 234. — Male Scarlet Tanagers, showing niovilt from the scarlet summer dress, 
(a), through the parti— coloured garb (6), into the green winter plumage (c). 

rate. In such 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-houvse where the air 
was constantly moist. Correlated with the effect upon 
colour is often a difference in size, and in man}- 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 ven* pale individuals live within 
a few hundred yards of each other, in dry and swamp}^ 
situations respectively, each, it is said, keeping entirely 
to its own little beat. 

We are all fan iliar with the changes of colour due to 




Fig. 236. — Nighthawk peiching 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 3'oung 
birds and the adults, and very good evidence of the gradual 
evolution which must have preceded these changes is 



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 brow^nish 
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. 



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; w^hile the birds w^hich 
spend their lives higher up among the branches of trees 
are greenish, or at least more brightl}' 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 tw^o 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 
wath the upper parts of the second decoy, makmg its 
back darker than the surroundmg 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; w^hile number tw^o 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 light; while if the entire bird be unshaded, although 




Fig. 238. — Sooty Tern on her nest. 

coloured like the environment, the dark shadow beneath 
will reveal it clearl}^ 

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 




Fio. 239.-Seven young Flickers clinging to a tree. (R. H. Beebe, photographer.) 



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- 
vanced, that it is better, for the most part, to go to Nature 
without a 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 man}^ m.en 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 j^ears had been appar- 
ent to me, l3ut unexpressed until Mr. Abbott Tha^^er 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 volurre 
''Two Bird-lovers in Mexico," I say: "I have often 



The Body of a Bird 



303 



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- 
tion baffles the eve. If 




Fig. 240. 



-Brown Creeper circling up the 
trunk of a spruce. 



the Sooty Tern, Fig. 238, were totally black, it would 
be conspicuous even against a patch of dark-coloured 
mottled shingle. But the transverse lines of white across 
the back totally destro}' 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 clingmg to 
their natal stump. As the warriors of Jason sprang forth 
from the ground full}^ armed, so the ver}^ bark, mottled 



3^4 



The Bird 



with spots of hchen and sunhght, 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 










1*^ 



Fig. 241. — Laughing Gull on nest. 

rump blazes forth. At such moment no protection is 
needed; but in these young Flickers 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. 



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, w^e 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 ma}^ swim closely 
along in full view near the opposite bank of a pond, and 
yet be totally unrecognizable; showing to the e3^e 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 al)ove the earth, 
becomes naught but a dark ant-hill, which the photo- 
graph picks out clearly, but which in the desert, dotted 
with ant-hills, would seldom be noticed even b}' 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 w^here it seems to answer every 
requirement of the case. Few^ fields offer such opportuni- 
ties for original work of the most delightful character. 
As one example out of untold numbers, what explanation 
can 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 




Fig. 243. — Group of Ustriches on the run. (Cawston, photographer.) 




Fig. 244. — Ostrich as it hides from an enemy. 



3o8 



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 b}^ 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 




Fig. 2-1o. — Bleeding-heart Pigeon. 

have been considering. The colours which we are now 
to mention have been aptly called aggressive colours, as, 
b}' 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 trvang 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 it 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 wdth these lives the Ivory Gull, 
immaculate as the ice-floe over which it flies, and in its 
whiteness w^e can perhaps read two purposes: a better 
chance to elude the fierce Gyrfalcon, and a better chance 
to float cloud-like unperceived over the unsuspecting fish 
which it seeks for food. 




Fig. 246. — Black footed Penguin. 




Fig. 247. — Pickerel. (Keller, photographer. From life, swimming.) 

PREDACIOUS, AQUATIC ANIMALS, SHOWING AGGRESSIVE 
COLORATION. 

310 



The Body of a Bird 311 

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 



312 



The liird 



to deposit an egg. A few other instances are known, as 
where a fierce, bird-kilhng hawk resembles a harmless, 

insectivorous species, 
perhaps b\' 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 
which compose its diet. 
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, 




Fig. 249. — Ciyrfalcon. Aggressive coloration 
in an Arctic Hawk. 



The Body of a Bird 



3' 3 



in this and in many other so-called protectively coloured 
birds, other factors, such as the direct effect of light on 




Fig 250. —Snowy Owl. Aggre-ssive 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 



3^4 



The Bird 



Pamilies of birds; but white blackbirds and such freaks 
of Nature have but sKght chance for Hfe 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 
Screech 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- 
can Robin, whose lower parts, from throat to flanks, are 




Fig. 252. — Young Robin. 




Fig. 253. — Fallow Deer fawn one day old. 
BOTH SHOWING SPOTS WHICH ARE ABSENT IX THE ADULTS. 

316 



The Body of a Bird 3 i 7 

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 



3i8 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 majorit}^ 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 
aesthetic 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 w^hich 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. 



Mw^ 



CHAPTER XIII 

WINGS 

EFORE the front limbs of any creature had be- 
come adapted to flight 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 j^'oung heron's wing shows 

319 



3 



20 



The Bird 



the two principal divisions into which the flio:ht-feathers 
are divided: the primary feathers, or those growing on 
the fingers and wrist-bones, and the secondaries which 
sprout from tlie 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, 



Wings 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 



'!•: W.'-nKPiVKBBB^J^^^^^^^^^^HRK' ^-? < 




-^.r'tifm}. 'mimmv^^ ^^- 




^fl 


^r'^PI^^^^ 




..•4* 


■ ■"■:. i 



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. 



322 



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 fours. A young Canada Goose, when climb- 
ing about its nest, or a Fish Hawk in the downy nestling 




Fig. 257. — Nestling Catbird, supporting itself, lizard-like, on all four limbs. 

plumage, does the same thing, and 3'oung birds of many 
species, when too 3'oung 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 



w 



ings 



323 



wings are put, we will look at certain birds whose flight 
can teach us something niteresting. 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. 25s. — 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, 
tne 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 



The Bird 



we should see that this burst of speed would end in 
a long, slowly descending sail, and with wings held mo- 
tionless the bird w^ould 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 w\aits 
until a breeze is blowing and then, facing the dn^ection 
from which it comes, he runs with all his might, flapping 
awkwardly until sufficient headway is 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 



325 




Fk;. 259. — Wing of Eluininiiighiid with 1(1 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 rismg 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 \'ividl}' than from any amount of descriptions and 
diagrams. 

The under surface of a bird's wing is concave; and 




Fig. 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 329 

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 m mid-air. 

When ornithologists think that the}^ 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 efl'orts, 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 laboriousl}^, 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 ultimatel}' 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 



33' 



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. 




Fig. 264. — C're.sted 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 hurros lay 
dead upon the plain. This we knew yesterday, and here 
were the scavengers. Never had we seen Vultures more 



Wi 



ngs 



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 




FKt. 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 



332 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 oblique 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 333 

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 mocker}-. The wings of the Owl Parrot 
of New Zealand are of full size, but the muscles are so en- 
cased 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 Flj'ing 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 ordinarj^ balloon, who 
is at the mercy of the wdnd 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 j^ards, 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 




Fig. 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 335 

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 verj^ 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 agamst 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 ^'iolently, 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 ver}^ 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 



1 -^ A 



The Bird 



itself and start off in a fresh direction. The tinamou, 
when launched on the atmosphere, is at the mercy of 




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 



Wings 337 

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 primarv^ 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-w^ork 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 w^ould 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 rehc ! 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 extmct 
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 The 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 flj'ing 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 -feat hers 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- 
scales, and the rigidit}^ 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 mLxed 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 




m in 

ac o 















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 




Fig. 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 fuH 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! 



Wings 



343 




Fig. 272. — Wing of Black-tooted Penguin, top view. 




Fk;. 27.'!. —Wing of Black-footed Penguin, side view. 




Fig. 27-4. — Wing of Black-footed Penguin, inidei siuface 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 l)ehind 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 




Fig. 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. 



34^ 



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 




Fig 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 



347 



spurs are not claws, but correspond in structure to the 
ordinary spurs on tlie 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- 




FlG. 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 Ueu 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, 




Fig. 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 onl}- 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 wdth 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 upo7i 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 ninet}^ 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 Compiegne to Antwerp, — a dis- 
tance of one hundred and forty-eight miles, — and with the 
pigeons he Uberated a swallow captured on her nest under 
the eaves of his house in Antwerp. The swallow, which 




aq 



35^ 



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 tlie journey. 




Fig. 282. — Terns in flight. (Photograph provided by the American Museum 
of Natural History.) 




CHAPTER XIV 
FEET AND LEGS 

ARRIED far and wide by the power of flight, 
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, w^hether 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 tj-pe of avian foot is that in w^hich 
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 Archceopteryx, 
and for perching birds, as well as for many others with 
very different habits, it has stood the test of six millions 

353 



:54 



The Bird 



of 3^ears, or thereabouts, since the days of its venerable 
prototype. 

This is the kind of generahzed 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 jDut 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 



355 



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 




Fig. 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 cUmbing 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 b}^ 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 
standmg ver}^ near the top of the scale of bird life, yet 
which has found it good to hold to the t3"pical 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 357 

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 livel}' 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 Umbs 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 Archseopteryx-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, 
clinging upside down. 



Fig. 287. — Nuthatch clinging to a gloved 
hand. (Bowdish, photographer.) 



The creepers, Fig. 240, are passerine woodpeckers 
in habit and forever wind their spiral paths about the 
tree-trunks. But the nuthatch is the marv^el 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 




Fig. 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 Families 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 haimts 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 w^hich 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 3'et 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, yet 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- 
catching 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 flycatchers. He may imitate their meth- 
ods of actual capture, bagging his game on the wing, but 



364 The Bird 

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 pre}^ 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 bay berries are not only 
an occasional welcome variety to the everlasting diet of 
insects, but that a warbler can comfortably hve 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 365 

the brim, now wading in a short distance, then leaping 
to a soft rim of clay, everywhere finding the most dehcious 
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 sill}^ 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 sm.all edible things among the cracks and crevices 
of the bark, no matter how vainh' 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 sam.e 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 volum.e, 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 awa}^ 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 ke}-. 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 peculiarit3\ 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 tim.e their claws become long and 



368 



The Bird 



curved, and in a neglected aviar}^ 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. la 
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 horn. 
The cause of this coalescence yet 
remains to be discovered. 

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 ordinarv^ 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 safel}'. 

Some species of swifts have all four toes pointing 




Fig. 289. — Foot of American 
Pipit. 



Feet and Legs 



369 



fonvard, 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 




Fig. 290. — C'oinl) on toe of Chufk-will's-widow. 

not only are the toes sm.all 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. 



37° 



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 371 

Parrots use their feet for more different purposes than 
do any other birds : they are the monkeys of the feathered 




Fig. 291. — Cockatoo perching with one foot and holding food with the other. 

world. They cUmb 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 



372 



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. 




Fig. 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 073 

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 



374 



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, Uke the owls, reverse 
its outer toe, but all typical hawks and eagles have the 




Fig. 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 375 

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 : 



37^ 



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 



377 



clearl}'^ 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 




Fig. 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. 

WTien 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 
claw^s 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 
carr}dng up the object in its beak, and then reaching for- 
ward 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 
b}^ 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 w^ould pass 
for a very long-tailed species of hawk ; it is really a haw^k 
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 t^-pe 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 







'^•f ^l^^^k^ 




S, ^1|^^^^ 




' \;,.^|^^^^^ 




• ■\l^^ 


i 






.'ijL '■ii 



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 finalty seizes it near the head with his bill, and hold- 



38o 



The Bird 



ing the body down with one foot, proceeds to swallow it. 
In case a snake proves unusuall}' hard to manage on 
the ground the dauntless bird watches his opportunity, 
seizes his adversary close to the head, and, %ing aloft 
to a considerable height, lets it drop on the hard ground, 
which is usually sufhcient 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 ver}' 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 -^Si 

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 
difhcult to keep from being buried at each step. So 
Nature provides him with snowshoes. From each side of 
each toe a broad, horn}^ 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 scarcel}^ 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 
cliffs of Persia and southern India. 



382 



The Bird 



If we watch a duck as it settles itself for the night 
upon the snow, we wdll 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 fowds, 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 w^hich are content to wade along the shallow 
margins of ponds and streams require long legs and long 



384 The Bird 

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, j^et 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, 
miake use of their toes to stir up the bottom mud of shal- 




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.- Gallinule 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 
galUnules 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 
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 3-et we have no clue to its use. Although 
differing so greatly from hawks in their method of feeding, 




Fig. 303.— Foot of Coot. 



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 




Fig. 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-hke 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 
observ^ed in captive ducks and several times in wild ones, 
of swimming thus with one foot when both eyes are shut 
and the bird is apparentl}^ fast asleep. But, in such a 



390 



The Bird 



case, no attempt is made to proceed in a straight Hne. 
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 



1 




■ 






■ 


1 


N 


1 


M 


■Bp/'. 


^^^H 


1 


1 


1 ^ 


'<j|g*^^gj 


^^^^^^1 


1 


1 


1 


1 -- 


^^ 




9 


1 


1 


■ 


n 


d 


H 



Fig. 306.— Foot of Rlark-nopked Swan. 

can imagine 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 
swdm 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 w^as constantly grasping something tangible 
in the w^ater 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 fundam.ental and thorough that even 
the claws are broadened and flattened until they resemble 
finger-nails. On land, grebes are absurdly aw^kward, 
although they can walk upright even up a slight incline. 
But they are pow^erless to rise from the ground, even 
with the aid of the wind,— needing the greater speed which 
a swnmming 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- 




FiG. 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 mterval 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 a single 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 rrentioned. 

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 
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 




Fig. 308. — Feet and legs of Cassowary. 



Feet and Legs 



395 





Fig. 309.— (a) Front and (b) side view of foot of Ostrich. 



'#^1 



S-.l^. 




Fig. 310. — Feet of Donkey. 



Fig. 311. — Feet of young Kangaroo. 



39^ 



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 lies 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. 

Thus in our brief review we have 
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, 




Flu. 312. — Iracks ol' C'ii,s80 
wary in soft clay. 



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. S. Lull.) 




CHAPTER XV 
TAILS 

E 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 Archseopteryx, Fig. 315, which was taken 
expressly for this purpose. 

Take twenty feathers and arrange them as in Fig. 314 a, 
representing the tail of Archseopter^^x ; then rearrange 
them as in 314 6, corresponding to the tail of modern birds, 
and the whole matter will be clear. Archseopterv^x 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 




V,a 314 -W Arraugement ot 20 feathers, a, in Arck^opUnj. ; (6) tail-feathers 
Fig. 314. (a) au^ ^ ^^ ^ Sparrow m place. 



400 The 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 w^hich has been built with a rudder as long 
as its whole deck. What an awkward thing such a rudder 
w^ould be! The waves would beat against it and great 
force W'Ould be necessary to turn it and to steer the ship. 
As long as a bird w-as content to climb a tree w^ith its 
hands and feet, and then scale, like a flying squirrel, to 
the base of the next, a lizard-like tail would be all-suflicient. 
So conspicuous and so unbirdlike w'as the long appendage 
of the Archseopter3'x that Saururcc — 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 man}^ 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 b}' a large upturned bone, which, from 
its shape, is know^n 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 var}^ 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 




Fig. 315. — 1 ail of Archavpkru.c in British Museum. 



401 



402 



The 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 



^^^^^^^st^^UMn^ 



Fig. 316.— Tail hones 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. 3 16). 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 



404 



The Bird 





■ 






^^^1 


M0 -O^^^^^^^^^^^l 


Hi. 


J 


£ ^^^^^^^^^1 



Fig. 318. — Fan-tailed Pigeon, showing extreme development of taiL 







Fio. 319. — Emeu, a tailless bird. (Courtesy of N. Y. Zoological Society.) 



Tails 



405 



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 





^G. 320. Fig. 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- 
mg organ of a whale than the tail-fin of a fish, since it is 
expanded horizontally instead of vertically. 



4o6 



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 it can turn around, as if on a 
pivot, without being carried down-stream, even when 
in the centre of a rapid, swirling current. 




Pig. 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 mdented 
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 damty 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 upw^ard, 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 
graduated fork. The quartet of forked-tailed birds men- 
tioned above are splendid fliers, but we shall see that skill 



4o8 



The Bird 



in flight depends but Uttle 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 




P^iG. 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 momentaril}^ 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 





Fig. 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 



The Bird 



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 




Fig. 326. — Chimney Swift clinging To wall, resting upon tail. 

family, — the creepers, woodpeckers, and swifts. These 
birds really sit upon their tails, the feathers of which are 
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 41 1 

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 w^as, 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 woodpecker 
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 w^ork to hammer a hole into 
the w^ood, 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 



41 2 



The Bird 



low, l^eneath the wing-tips, while active, nervous species 

carry it more or less raised. 

In certain of the fl3^catchers 
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 
'The-becM" 

The ierking motion of the 

Fig. 327.— Tail of Chimney Swift. ., ^ , 

tail seems to have become 
a regular habit with many birds, and, curiously enough. 





Fig. 328.— Tail of Flicker. 

especially with those which spend their lives chiefly along 



Tails 



413 



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 w^e 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 3'et 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 
manoeuvred 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, w^hich 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 iustant 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 415 

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 is 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 Emeu-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 w^ith several tail-feathers over five 



41 6 The Bird 

times as long as their tiny bodies. \Vhen 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 



4i8 



The Bird 



and of his wild ancestors the Jungle-fowl, with the graceful 
overarching feathers, is a type of tail found elsewhere 




Fig. 333.— Roof-like tail of Jungle-fowl. 

onl}^ in certain pheasants. In the Boat-tailed Grackle 
the arrangement is reversed, the apex of the slope being 




Fig. 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.d. 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- 
hind their foster-mother, for 
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 




Fig. 335.— Useful tail of Peacock 
Pheasant. 



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 




Fig. 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 



421 



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. 
Naturall}' 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 displa}" ; 
although the analogy ceases when 
we find that such a case among 
birds is no less interesting than 
where the phenomenon is reall}" 
what it appears to be. Upon 
seeing a specimen of the beau- 
tiful trogon commonly called 
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 dove, 
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 




Fig. 337. ^Tail-coverts of Quezal. 



422 



The Bird 



hidden by the overhanging train of gorgeous plumes, 
which are in reaUty 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 




Fig. 338. — Train of Peacork 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 423 

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 roos1> 



Fig. 339. — Rear view of train of Peacock, sliuwing 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: (a) 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 birds 
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 h 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 brilhantly 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 case of the inheritance of acquired characters, a much- 
mooted question not many 3^ears 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 




ERHAPS the most fascinating phase of Nature 
is the way in which she cares for her chil- 
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 awa}-, 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 
tin}^ 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 spawming-grounds in the uppermost reaches 
of rivers, or the cod boldly playing for her offspring the 



42: 



428 The Bird 

chance in the letter}' of hfe in the open ocean. Of her 
nine milhons 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 w^orld — 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 entirel}^ out of the 




Fig. 342. — Comparison of eggs of reptiles and birds, 
(a) Egg of Hen. (b) Egg of Skate, (c) Egg of Snake, (d) Egg of Turtle. 
(e) Egg of Alligator. 



43° 



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 solutions 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 4 t^ 1 

— 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 




Fig. 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 



432 



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 bod}^ 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 laj^s 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 necessar}- 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 b}' the curioii& 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 
plainh' 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 j^oung, 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 



43^ 



The Bird 



body between the thighs. Both sexes are provided with 
this contrivance during the breeding season, and reheve 
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 




Fig. 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 j^oung, 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, 




Fig. 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 man}^ misfortunes and mishaps as the water- 



438 



The Bird 



fowl, except perhaps the big and pugnacious swans, who 
can take better care of themselves, and lay onl}^ 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, (Fig. 356,) and consequently we here find only two 




Fig. 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 



440 The Bird 

large complement of eggs (eight to twenty) in order to 
bring to maturity enough }'Oung 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 m^ethod of nidifi- 
c at ion. 

'' 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 



The Eggs of Birds 



441 



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. 3.50. — 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 som.e 
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-^ 

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 emmently 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. 

" I 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 ^^^ ^^^^ 

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 hungr}/ 




Fig. 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 

eggs 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 is 
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 wTens 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- 
bill'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 w^hen 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 is 
rare indeed to find the nest of a grouse unguarded, and 
the mother bird will all but wait until 3'our 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 exacth^ 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, 



45° 



The Bird 



swooping down one after another upon the nests and 
each impahng an egg upon its beak and flying off with it. 
They would never dare such open villainy were the herons 
undisturbed. 




Fig. 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 shallow 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 w^ere 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 oology, or the science of egg-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 (6) egg of Black-necked Stilt 

w^hich 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 




Fig. 8.58. — Eggs of Cassowary. 




Fig. 359. — Eggs of Ostrich. 



453 



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 w^ere 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-patrolHng 
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 hundi'ed instances might prove 




Fig. 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 
eggs of sea-birds, — of certain of those species which nest 
on inaccessible cliffs. If pigment was developed in the 



45^ 



The Bird 



eggs 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' eggs side by side and find no two 
alike, while the extremes would never be recognized as 
belonging to the same species of bird. 




Fig. .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 



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 
egg 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 egg 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 
of the eggs in a single nest, heightening their resemblance to pebbles or sea- 
shells. 

Occasionally, in the eggs of birds which number only 
two in a nest, one egg 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 eggs 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 46 1 

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 3X5 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 ^jjyornis 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 

ipHE 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 \ery 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 
egg 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 
egg, 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. 




Fig. 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 Uttle 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 embr3^o 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 chalazce. 
These act as pads to protect the yolk from sudden jars, 
but the}^ do not act as suspensories. A hen never turns 
her eggs, 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 Egg 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 egg 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 half 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 slowl}^ in that portion. This 
is because much of the w^hite 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 thickty covering its 
entire surface, like the rounded protulierances of the berry. 
Now a curious thing happens. A tiny nick appears in one 
side, which graduall}^ 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. A^Tien 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 ogg, from first division into two 
cells up to well-formed larval t-adpole. (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 
laid, 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 laj-er 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 
egg. 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 
egg ? Just this. ^\Tien 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 

^ --^^^ ^■V^s*.:^ '!t'-^'4^ ^ 



(7;//^ 



"■ .v<:v'- ,>^-i^?^?i>f:•,r^^,v.-•■ 









.•'/ 



.'1 






Fig. 366. — Third-day stage of embryo chick. (See Fig. 364.) Greatly enlarged- 
M, Muscle-plates (false vertebrse). 

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 



47° The Bird 

(these layers being known as the ectoderm and endoderm, 
or outer skin and inner skin). The name gastrula, or httle 
stomach, is certainly most applicable, for an animal of 
this kind consists of hardly more than stomach and mouth. 

But the embr3^o 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 
growth, during a short three weeks, the embryonic states 
of all its unnumbered generations of ancestors. The record, 
like that of palaeontology, 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 Archa^opteryx, 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, ^^'ere 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 w^hen we know 
that while, in the case of the hen's egg, three weeks are 
required before the chick is read}^ 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 onh^ 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 n.eatly joined together, 
and are so mutuall}^ 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 
sternum — 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 



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 wdll show a low, round- 
ed ridge, extending the whole 
length from the neck to the 
tail. While w^e can never be 
absolutely certain that perfect 
homology exists between the 
two, 3'et it is very significant 
that soon after its develop- 
ment it dwindles away, leav- 
ing four conical, isolated 
}3i^iJs — 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 




Fig. 367. — Early embryo of Canada 
Goose, showing fin-like limbs. 



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, is 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 earh^ 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. 



47^ The Bird 

have been observed, instantly bringing to mind that some- 
what gull-hke, toothed bird of old — Icthyornis. 

The origin and subsequent changes, in the embrj'O 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 is 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 




Fin. 368. — Pineal eye in Lizard 



477 



478 



The Bird 



P.E 



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 ej-es 
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 
Pohphemus, 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 
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- 




FiG. 369.— Pineal eye in Chick (P. E.). 



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 Hke tiny cones 
than an3'thing else (Fig. 11). The muscles and the cartilage 
skeleton are well defined on the fourteenth day, and about 
this time the tiny beak wdth 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 is 
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 ps3^chological life commences, with 
intermingled perceptions, instincts, and gleams of intelli- 
gence. Here belong the making of nests and journeys, 



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. Macmillan Co., New York. 
Org.^nic Evolution. 

M. M. Metcalf. Macmillan Co., New York. 
Variation in AnIxVials and Plants. 

H. M. Vernon. Henry Holt & Co., New York. 
BOOKS FOR THE IDENTIFICATION OF NORTH AMERICAN BIRDS 
Guide to the Birds of New England and Eastern New York. 

Ralph Hoffmann. Houghton, Mifflin & Co., Boston. 
Handbook of Birds op Eastern North America. 

F. M. Chapman. Appleton & Co., New York. 
Handbook of Birds of the Western United States. 

Florence M. Bailey. Houghton, Mifflin & Co., Boston. 
Key to North American Birds (2 vols.). 

Elliot Coues. Dana Estes & Co., Boston. 
Birds of North and Middle America (3 parts; others to follow). 

Robert Ridgway. Bulletin of the United States National Museum, 
No. 50, Washington, D. C. 
History op North American Land Birds (3 vols.). 

Baird, Brewer, and Ridgway. Little, Brown & Co., Boston. 

483 



484 Appendix 

BIRDS IX GENERAL 

Dictionary of Birds. 

Alfred Newton. A. <t C. Black. London, 
Riverside Natural History, Vol. IV. Birds. 

L. Stejneger. Houghton, Mifflin & Co., New York. 

MISCELLANEOUS 

Birds of Essex County, M.\ssachusetts. 

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. 



Abdominal ribs, 79 

Adaptation of feet, 361, 362 

Adaptative Radiation, 15-18; in war- 
blers, 361-367 

Adjutant, head of, 273, 276; hair 
from neck of, 276 

iEpyornis, 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, 

Air-sacs, of. with respiratory system 
of insects, 173: extent of, 173; 
function of, 174, 177; in Prairie Hen, 
177 

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 

Archaeopteryx, as parallel branch, 10; 
as ancestral type, 10; foot of, 353; 
general description of, 7; in Berlin 
Museum, 11; in British Muse<mi, 8; 
probable habits of, 12-13; restora- 
tion of, 14; tail of, 398, 399, 400, 401 

Aristotle, cf. with Darwin, 12 



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; evolu- 
tion of-, 64-70; ot 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 

Bill, 
function of, 223. 224, 250, 251 
of Avocet, 237, 239; Archaeopteryx, 
226; Cormorant, 227, 228; Cross- 
bill 24, 249, 245; Crow, 226; 
Shoveller Duck, 233, 235; Purple 
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, 
242; Pelican, 228, 229, 230; 
Crook-billed Plover, 240, 241; 
American Raven, 225; Black Skim- 
mer, 231, 232, 236; Snakebird, 
228, 229; Dowitcher Snipe, 241; 
Spoonbill, 220, 236, 239; Stilt, 237; 
Chimney Swift, 244, 246, 245; 
Tailor-bird, 245; Tern, 231, 232; 
Toucans, 243, 244; Triceratops, 

485 



486 



Index 



226; Woodcock, 219, 221, 222; 
Woodpeckers, 245 
Blackbird, down on nestling, 26 
Blood, circulation of, 182, 183, 184; 
compared with amcfiba, 185; red 
corpuscles of, 184, 185; white cor- 
puscles of, 185 
Bobolink, cause of colour change in 

spring, 297 
Bob-white, effect of climate on, 293 

295; moult of, 43 
Body, of Herons, 286; Petrels, 286 
Bod}--feathers, of Apterj-x, 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 embrj'o 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 
embrj'o, 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, chin-feathers of Great, 267; 

weight of, 285 
Butterfly, eggs of, 428; torn by birds, 147 
Buzzard, Black-breasted, feeding on 
Emeu eggs, 159 



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 » 

Chewink, foot of, 367 
Chicken, stomach glands of, I35 



m^w 



Chuck-will's-widow, comb on toe i_ 
Circulatorj' system of pigeon, 183 
Classification, based on toes, 354, ■ 
Clavicle, function of. So; of Hoatz: 

in mammals, 86 
Claws of foot, 368 

three on wing of, Osprey, 322; O- 
338, 339; Swan, 322 
Climate, effect on plumage of, Bol,>- 

white, 292, 295; Song Sparrow, 2()?, 

295; South American Pipit, 295, J'- 

Turkey Vulture. 322; White-thrr:, •; 

Sparrow, 291, 294; Wood ThrusI 
Cockatoo, feet of, 371; LeadU 

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, 430 

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 
ColumeUa. of Owl, no, 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 
Conrlan, 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 



487 



Ciane, 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; xNight 
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, 254 

Down, development of, 23; from head 
of young Bobolink, 26; magnified 
from young Song Sparrow, 27; 
models of developmsnt of, 24, 25; 



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 

E 
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 
Ear, canals of, 218; in owls, 216, 217; 

structure of, 217, 218 
Eclipse plumage, 48, 49 
Edible birds' nest, see Swiftlet. 
Eggs, 

abnormal number laid by African 
Waxbill, 444; domestic Hen, 444; 
Flicker, 444 

of iEpyornis, 461; alligator, 429; 
Anna Hummingbird, 443; Archae- 
opterj\x, 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, 430; 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, 459; 
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 embr\'onic study, 462 

of Grebe, 432; Hairy Woodpecker, 445; 



488 



Index 



Eggs, 

of Hen, development of, 466; for 
embrj'onic study, 462; structure of, 
464 

of Hummingbird, 436; Jellj'fish, 427; 
Junco, 434; Killdeer 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, 436; 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 embrj'o chick, 480; 

reptiles, 480 
Egret, crest of Sno^^y, 315, 322; neck 

curves of, 73; use of wing of, 350 
Embrj^o, 

aorta, 476, 478 

development of limbs, 474, 475; of 
girdles, 475; of three toes, 475 

drawing of third-day embrj'o, 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 vertebrae, 472; 
heart, 472 

twelfth-day, 473 
Emeu, body-feathers of, 239; feather 

of, 36; lack of tail in, 402, 404 
Emeu-wren, tail of, 415 



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; embrj'o 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 
Eye, 

Apterj'x, 254, 255, 256; compared 

with camera, 207, 208; iris of, 210 
lashes of Hornbill, 257; Ostrich, 257; 

Seriema, 257 
lids of, 214, 215; Brown Thrasher, 

212, 213; Woodcock, 221, 256 
mammals, 209, 254; nocturnal birds, 

254 
pineal eye in, embrv'o 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; thirty-six- 
hour embryo, 472 
Expression of face of birds, 252 



Falcon, 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, 363, 
364; Yellow Pahn 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, ss', pattern on, 58-61; 
structure of, 31-38 
Feathers, arrangement of, 38-40; in 
tail of Archa^opterj^x, 398, 399 
400, 401; in modern bird, 399, 400 
of Cassowarj', 338; colour of, 53-61; 
of Condor, 36, 336; development 
of, 17-38; down}- condition of. 35; 
of embryo bird, 479, 480; of 



Ind 



ex 



489 



Feathers (continued), 

Emeu, 36; of embryo of twelfth- 
day, 22; moult of, 40-53 
number of, in tail, of Archaeopteryx, 
400; of Cormorant, 400; of Duck, 
400; of Ostrich, 402; of Peafowl, 
402; of Fantail Pigeon, 402 
of Ostrich, 35, 336; papilla? 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 Put?-back 
Shrike, 287; of wing, 320-352; 
worn-out Hummingbird's breast, 44 

Feather-ears, of owl, 267, 268 

Feather-tips, in Bobolink, 297; 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; classifi- 
cation based on, 354, 355; evolu- 
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; heart of, 181; 
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, cf. with swimming, 327; Condor, 
324, 326; Steamer Duck, 337; cer- 
tain Flycatchers, 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, 
331, 332 

Flipper, of Penguin, 341, 342, 343 

Flycatcher, feet of, 360; flight of, 324, 
326; tail of Least, 412 



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, 1.58; 
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 Tvrant, 161; whales, 148 

Food-pellets of Owl, 132, 133 

Foot, claws of, 368; tendons of, 191, 
192; of alligator, 354; Archseop- 
terJ^x, 353; bear, 102; of bird cf. with 
man, 99, 100; Caracara, 378; Casso- 
warj', 394, 396; Chewink, 367; Chuck- 
will's-widow, 369; Cockatoo, 371; 
Coot, 387; Crow, 3.56; Cuckoo, 372; 
Donkey, 394, 395; Duck, 382, 389, 
390; Golden Eagle, 374, 376; Harpy 
Eagle, 375; Flami go, 388; Fly- 
catchers, 360; Gallinule 385, 386, 
387; Grebe, .391; RufTed 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 



Index 



gastrula of egg of, 466; segmentation 
of egg ot, 467; used as food, 167 



G 



Gallinule, foot of, 385, 386, 387 
Game-birds number of eggs laid by, 438 
Gannet, bill of, 227, 228 
Gastrula, 466, 468; compared with 

sponge, 469, 470 
Gill-arclies, 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; embryo 

chick, 476; fishes, 473 
■Giraffe, neck-vertebr« 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 nestlmg Robin, 166; Peli- 
can, 166 
Goat-sucker, West African, wing orna- 
ments of, 349 
Goldfinch, flight of, 329; tongue of, 125 
Goose, Canada, embrj'o 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; foot 

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, 

Laughing, nest of, 437; protective 
coloration of, 309, 312; number of 
eggs laid by, 436 
Gyrfalcon, aggressive coloration in, 309 

312 



H 

Hatching of embryo Chick, 480; Os- 
trich, 481 

Hawk Duck, food of, 158; head of, 211; 
feet 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 Vulture, 272, 
273; Seriema, 257; Sloth, 210; 
Wild Turkey, 273, 275 

Heart, beats of that of bird, 182; 
chambers of, 182, 184; of croco- 
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, loi; 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, 
294; W'ood Thrush, 294 

Hummingbird, Anna, nest of, 443; eggs 
of, 443; bills of, 244, 245, 246, 247. 



Index 



491 



248; crests of, 267; eggs of, 436, 461; 
feet of, 368; Hight 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 palaeontology, 2; 
Thomas, quoted, 2 

Hyoid, 111; of eagle, 114 



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 
IngersoU, 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 



Jabiru, atlas and axis of, 72 
Jaguar, standing on toes, loi 
Jelly-fish, eggs of, 427 
Junco, 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 



Lacrymal glands, 211 

Lamprey, gill-l^asket of, 112 

Lark, foot of horned, 367; tail of 

meadow, 414; cause of colour change 

in Siberian black, 295, 297 



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, S78, 
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, evolution of, 178, 179, 180; 
character of, 174, 175; cf. 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, cf. with Ostrich, 13; number of 
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, 49; 
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 embrj^o chick, 69, 70 

Muscles, of body, 189, 190; cells of, 



492 



Index 



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 Perguin, 
188; structure of, 193; of wing and 
breast of Pigeon, 190; of wing in 
Owl Parrot, 333 

N 

Neck, of Flamingo, 281; Heron, 281; 
Loon, 277; Snake-bird, 282, 283; 
Swan, 282 

Neck vertebrae, cf. with Giraffe, 73, 75; 
cf. 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- 
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, 
456, 459; Tern, 453, 456, 457; Hairy 
Woodpecker, 444, 445 

Nictitating mem bane, 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), 



479; eyelashes of, 257; leg of, 100; 
length of intestines, 140; neck and 
vertebrae of, 69, 71; nest of, 453, 454; 
number of eggs laid by, 433; 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 Llf, 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 
of, 153 



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 Kea, 161; 

foot of, 372; number of eggs laid by, 

441 ; use of wing in, 322 
Partridge, California, crest of, 259; nest 

and eggs of, 438; Plumed, crest of, 

259; Scaled, feathers of, 289, 290 
Passe res, 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 



493 



Pelvic girdle, see Thigh-girdle. 

Pelvis, compared with that of reptiles, 

74; vertebrte in, 74 
Penguin, aggressive coloration in. 309, 
3io; 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, effect 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-sacs 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 

Protectiv^e coloration, in Brown Creeper, 

303, 304; FHckers, 302, 303, .304; 
Ivory Gull, 309, 311; Laughing Gull, 

304, 306; Motmot, 303; Nighthawk, 
296, 301; Ostrich, 306, 307; Ptar- 



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 
Putiin, 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 

Ratitae, 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 Archseop- 

teryx and of reptiles, 79; embryo, 

473, 474; function of, 77 79; 

Hatteria Lizard, 77; Screamer, 77; 

significance of numerous, 78 
Road-runner, food of, 157; foot of, 

373; tail of, 413 
Robin, glottis of nestling, 166; moult 

of, 43; spots in young, 316, 317 
Rock-jumper, body-feathers of, 288; 

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 

S 

Salivary glands, original function of, 
117, 118; in Swiftlets, 119; Swifts, 
119; Woodpeckers, 118 

Salmon, eggs of, 427 

Sandgrouse, feet of, 383 

Sandpipers, protective coloration in, 
299; semipalmated; feet of, 384 



494 



Index 



Sapsucker, tongue of, 124 

Scales, of carp, 289, 290; on legs of 
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, l)irds 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 



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 ofj 81; value in 
classification of, 80; of Flamingo, 80; 
Ostrich, 81 

Stilt, 237 

Stomach, 134-140; of Chicken (young), 
135; Enghsh 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, 
120 

Swim-bladder of fishes, 178, 179 

Swimming compared with flight, 327 

Syrinx, drum of Mallard, 168, 170; 
structure of, 172 



Tail, of Archa^opteryx, 398, 399, 400, 
401; evolution of, 398-403; feathers 
of, 402, 403; lack of, in Emeu, 402, 
404; in Cassowary, 402 



Index 



495 



Tail, 

number of feathers in Archseopteryx, 
400; Cormorant, 400; Duck, 400; 
Ostrich, 402; Peatowl, 402; Fan- 
tail Pigeon, 402 
ornaments ot, 414-421; ploughshare- 
bone of, 400; sham, of Quezal, 421, 
422; sh m, of Peacock, 422, 423 
vertebraj of Bald Eagle, 403; embryo 

bird, 403; Ostrich, 402 
use of, 405; voluntary decoration of, 
424, 425, 426; of creeper, 410, 411; 
deer, 413; Pin-tail Duck, 415; 
Blue Duck, 406; Emeu-wren, 415; 
Least Flycatcher, 412; Japanese 
long-tailed fowl, 417, 419; Jungle 
Fowl, 418; Boat-tailed Grackle, 
418; Green Heron, 413; Junco, 
414; Meadow Lark, 414; Lyre- 
bird, 420, 421; Mexican Motraot, 
424, 425, 426; Murre, 406, 407; 
Grass Parrakeet, 408; Peacock, 422, 
423; Pehcan, 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, cf. with Dino- 
saur, 90 

Thrasher, eyelids of Brown, 212, 213; 
nictitating membrane of, 213 



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, 
«^9-l> 395; embryo, 474; Ballinule, 
385,386; Grebe, 391; Ruffed Grouse, 
380, 381; Heron, loi; comb on 
Heron, 387; 388; perching function 
of hind, 359; horse, 358; Wood Ibis, 
385; jaguar, loi; young kangaroo, 
394, 395; European House Martin, 
381; monkey, 358; number of, 353; 
Usprey, 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, 
371,372 

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, 129; Humming- 
bird, 127; Loiy, 125; Owls, Larks, and 
Swifts, 122; Pelican, 120, 121; Sap- 
sucker, 124; Toucan, 126; AVood- 
peckers, 122 

Toucan, bill of, 243, 244; tongue of, 126 

Towhee, iris of, 256 

Trachea, of amphibian, 169; of cranes, 
170, 171; cf. with oesophagus. 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 Cassowarv, 396; of Dino aur, 
396, 397 

Triceratops, beak of, 226; brain of, 200 

Turbinal bones, 205 

Turkey, breast-ornament of Wild, 280 

Turtle, beak of Snapping, 224; egg of, 
428, 429 

" Two Bird-Lovsrs in Mexico," quota- 
tion from, 301 

r 

Ulna, 2 

Umbrella-bird, crest of, 264, 266 

Uncinate processes, 77 



Vegetable feeders, 143. 144 
Vertebrae, of Bald Eagle, 403; bird, 
cervical of, 71-74; embrv'o, 403; 



496 



Index 



Vertebrae (continued) 

function of, 196; Jabiru, neck 
vertebrte 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 Turkev, 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- 
noha, 366; Myrtle, 364; Pine, 366; 
Worm-eating, 163; Yellow Palm, 363 

Warbler-bush, wings of, 347 

W'arblers, evolution of, 361-367 

Water-birds, number of eggs laid by, 
436, 437, 438 

Wattles, of Bell-bird, 273; Condor, 271; 
Wild Turkev, 273, 275; King Vulture, 
272, 273 

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; of Ptero- 
dactyls, 285 

Whale, food of, 148; tail of, compared 
with that of bird, 405 

Whydah-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 



Wing of, Albatross, 320, 321, 325, 332; 
Great Auk, 339, 340; Racor-billed 
Auk, 339,340; Cassowarj^ 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; Riffed 
Grouse, 347; Herring Gull, 328; Young 
Green Heron, 320, 323; Great ^\hite 
Heron, 321; Sleeping Eeron, 344; 
Hummingbird, 320, 321, 325; Mallard, 
47; Murrelets, 339; Yourg Osprey, 

322, 351; Ostrich, 321,337,338,339; 
Twelve-wired Bird of Paradise, 348; 
Parrot, 322; Parrot Cwl, 333; Pen- 
guin, 321, 341, 342, 343; Pheasant, 

323, 324, 327; Screamer, 346; Black 
Skimmers, 324; Erglish Sparrow, 46; 
Spoonbill, 350; Trumpeter S\Aan, 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 m, 208; sense of touch 
in, 219, 221, 222; ■ning-song of, 248 

Woodhewer, tail of, 410 

Woodpecker, tail of 410, 411, 412; 
nest and eggs of Hairy, 445; char- 
acter of fgg-shell of, 4eO: colon- of 
eggs of, 444; function of sahva 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 

X 

X-ray photograph of Pigeon, 63 

Y 

Yellow-throat, life-habits of Maryland, 
362 

Z 

Zygodactyl toes, 369, 370, 371, 372 



THE AMERICAN NATURE SERIES 

The fortunate increase in the attention paid by the American ])eople 
to Nature study, has led to the pubUcation of many popular books on the 
subject, some of which are good, and some not. In the hope of doing 
something toward furnishing a series where the seeker will surely find a 
readable book of high authority, the iniblishers of the American Science 
Series have begun the publication of the American Nature Series. It is 
the intention that in its own way, the new series shall stand on a par with 
its famous predecessor. 

The primary object of the new series is to answer questions — those 

(outside of the domain of i)hilosophy) which the contemplation of Nature 

is constantly arousing in the mind of the unscientific intelHgent person. 

But a collateral object will be to give some intelligent notion of the 

causes of things. 

The books will be under the guarantee of American experts, and 
from the American point of view ; and where material crowds space, pref- 
erence will be given to American facts over others of not more than equal 
interest. 

The series will be in five divisions: 

GROUP I. CLASSIFICATION OF NATURE 

This division will consist of three sections. 

Section A. A large popular Natural History in several volumes, 
with the topics treated in due i)roportion, by authors ofunquestioned 
authority. There is no existing Natural History which does not fall short 
in some one of these particulars. Possibly the Natural History in the 
American Nature Series may not be kept ideal regarding all of them, but 
if it is not, the fault will not be due to carelessness or apathy on the part 
of the publishers. 

The books so far arranged for in this section are : 
FISHES, by David Starr Jordan, President of the Leland Stanford Uni- 
versity. 2 Volumes. 
INSECTS, by V^ERNON L. Kellogg, Professor in the Leland Stanford Junior 

University. 
TREES, by N. L. Britton, Director of the New York Botanical Garden. 
WILD MAMMALS OF NORTH AMERICA, l)y C. Hart Merriam, 
Chief of the United States Biological Survey. 
Section B. A shorter Natural History by the authors of Section A, 
preserving its i)opular character, its proportional treatment and its author- 
ity so far as that can be preserved without its fullness. 

Section C. Identification books— " How to Know," brief and in 
portable shape. By the authors of the larger treatises. 



AMERICAN NATURE SERIES {Continued) 

GROUP II. FUNCTIONS OF NATURE 

These books will treat of the relation of facts to causes and effects — 
»f heredity in organic Nature, and of the environnaent in all Nature. In 
treating of Inorganic Nature, the physical and chemical relations will be 
specially expounded; and in treating of organized creatures, the relations 
fo food and climate, with the peculiarities of their functions — intei'nal and 
external. 

THE BIRD : ITS FORM AND FUNCTION, by C. W. Beebe Curator 
of Birds in the New York Zoological Park. 

GROUP III. REALMS OF NATURE 

Detailed treatment of various departments in a literary and popular 
"nay. 

Already published : 
FERNS, l)y Campbell E. Waters, of Johns Hopkins University. Svo, 

pp. xi + 362. Price 83.00 net. 

GROUP IV. WORKING WITH NATURE 

How to propagate, develoj) and care for the i)lants and animals. 
Published in this division is : 
NATURE AND HEALTH, by Edward Curtis, Professor Emeritus in the 
College of Physicians and Surgeons. l:^mo, $1.25 net. 

Arranged for are : 
CHEMISTRY OF DAILY LIFE, by Henry P. Talbot, Professor of 
Chemistry in the Massachusetts Institute of Technology. 

DOMESTIC ANIMALS, by Willla.m H. Brewer, Professor Emeritus in 

Yale University. 
THE CARE OF TREES IN LAWN, STREET AND PARK, by B. E. 

Ferxow, Late Head of the Cornell School of Forestry. 

GROUP V. DIVERSIONS FROM NATURE 

This division will include a wide range of writings not rigidly system- 
atic or formal, but written only by authorities of standing. 

FISH STORIES, by David Starr Jordan, President of the Leland Stan- 
ford Junior University. 

HORSE TALK, by William H. Brewer, Professor Emeritus in Yale 
University'. 

BIRD NOTES, by C. W. Beebe, Curator of Birds in the New York 
Zoological Park. 

HENRY HOLT AXl) COMPANY, Publisheus 

29 WEST TWENTY-THIRD STREET, NEW YORK 




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