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ART. VIII.-1. Biologia Centrali-Americana. Aves, Vol. I., by

Osbert Salvin, M.A., F.R.S., and Frederick Ducane Godman, F.R.S. London, 1875–1887. 2. The Geographical Distribution of the Family Charadriidæ ;

the Plovers, Sandpipers, Snipes, and their Allies. By Henry Seebohm, F.L.S. London, 1888. 3. A History of British Birds. Three Vols. By Henry

Seebohm, F.L.S. London, 1883. 4. Classification of Birds. By Henry Seebohm, F.L.S.

London, 1890. 5. The Fauna of British India, including Ceylon and Burma.

Birds, Vol. I., by Eugene W. Oates. London, 1889. 6. A Monograph of the Alcedinidæ, or Family of Kingfishers. By R. B. Sharpe, F.L.S. 1868-1871. 7. Catalogue of the Birds in the British Museum. Vols. I., II., III., IV., VI., VII., X., XII., and XIII. By R. B. Sharpe, F.L.S. 1874-1890.


O other branch of Natural History approaches, in popu-

larity, that one which is devoted to the study of birds. Many reasons concur to give this well-recognized pre-eminence to Ornithology. Every natural object doubtless possesses a certain beauty in the eyes of those who have made a special and prolonged object of study. But the beauty of a bird is readily to be perceived by most persons, even though they may be devoid of any scientific training. Birds appeal in various ways to our senses and emotions as well as to our intellect, and lend attraction to what is quite external to and independent of them. Who does not feel the charm bestowed upon a landscape by the distant view of birds in graceful flight, and by the rapid movements of others in the foreground ? How often, whilst strolling through our English woods, when the year has just began to wane, do we not miss, and regret, the tuneful and cheering melodies of spring! Few indeed are those persons who do not enjoy the song of the thrush and the mellifluous note of the wood wren, as well as the exceptionally full sweetness of the nightingale !

The Zoologist who cares for beasts and reptiles, has generally but rare and brief intervals wherein he may observe the subjects of his predilection as they live and move in freedom; but with birds it is quite otherwise.

We have spoken of the beauty of birds making itself manifest to all who have eyes to see, and such is indeed the case even with our English birds. Besides the rarer species, no one will dispute the attractiveness to the eye of our common blue titmouse, our golden-crested wren, our chaffinch and our yellowhammer ; but when we extend our view over the whole class of birds, including the forms which inhabit tropical lands, we see that no other animals can compete with them successfully as to beauty and brilliancy of coloration.

titmouse,

There are indeed many most handsome butterflies, many splendid beetles, and the glory of the golden moth of Madagascar when once seen is not readily to be forgotten. Nevertheless the beauty of each and all of these is exceeded by those lovely living gems of the new world, the hummingbirds—in which the combined beauty and brilliancy of coloration has reached the acme, amongst living things. Second only to them are the beautiful sun-birds of the old world ; and the gorgeousness of various pheasants, peacocks, and parrots, will doubtless at once occur to the reader's imagination. But 'grace

of form, no less than charm of hue, is characteristic of almost all birds, and the more the details of bird-structure are understood, the more the beauty of harmony that form expresses

will become manifest. A bird is one of the most wonderfully organized of all animals, and almost the whole of its organization is arranged to facilitate flight. The flights some birds will take, moreover, are extraordinary phenomena in themselves. A falcon belonging to Henry IV. of France is known to have flown from Fontainebleau to Malta- distance of 1350 miles—in one day. The celebrated racehorse Eclipse ran one mile in one minute ; but a hawk may fly 150 miles in an hour! Our swifts and swallows fly every year from England to Southern Africa and to the Moluccas, and the restless wandering flight of various oceanic birds is still more surprising. That such action should be possible in a hot-blooded animal with an internal bony skeleton, needs a most careful and peculiar arrangement of its organs. These are so packed as to place the centre of gravity where it can best be sustained, and all the organs are so constructed as to produce in combination the greatest strength and warmth, with the least possible weight. Nothing is more marvellous than the structure of a feather. No

space

can here be given, however, to its description. It must suffice to affirm it to be an organ at once so light and so strong, and one which at the same time seems so thoroughly to shut in and retain the body's heat, that it is impossible to imagine anything more perfect.

Bones are necessarily more or less heavy structures, but the bones of most birds, while their solid substance is exceedingly strong, are wonderfully lightened by the details of its arrange

—а

ment

ment and still more by the fact, that most of them contain not marrow, but warm (and therefore light) air. In some birds even every bone of each toe is thus permeated, and air passes into the skeleton freely by means of large air-sacs, into which cavities in the lungs directly open. But for flight, great power is no less necessary than lightness of structure ; and voluminous muscles are needed to bring the parts of the skeleton, above all the wings, into vigorous play. Hence the great mass of flesh upon the breast, where is accumulated all the muscles needed to depress the wings and so raise the body in the air. But not only are these muscles so placed, but by a truly admirable contrivance the antagonizing muscles, which raise the wing, are also situated on the breast, and are thus conveniently disposed with reference to the centre of gravity. In other animals the muscles which raise the arm are situated on the back, but a very ingenious and simple contrivance enables them to be placed on the bird's breast. This contrivance is the winding of the tendon in which the elevating muscles end) round a sort of bony pulley, which permits its insertion into that upper surface of the arm bone, whereon it must be inserted if the wing is to be raised at all. But muscles, however voluminous, are useless unless their action is stimulated by a copious supply of wellpurified blood. This necessary stimulation is well provided for in birds by a double modification. In the first place a valve of the heart, which in ourselves and in beasts consists but of membrane, in birds is formed of contractile muscle itself. Secondly the stream of the blood tends to be not only thus more vigorously propelled, but also to be more purified by the general permeation of the body with air from the lungs.

Obviously the further an organ: is removed from the centre of gravity, the more inconvenient would it be to have its weight and bulk augmented. Thus the arm of a bird is reduced to what is barely necessary to sustain the great feathers of the wing and to extend or fold the arm itself. The hand is diminished to an extreme degree, and its few rudimentary fingers are closely bound together. Yet birds have many very handy acts to perform, and have often to weave wonderfully dexterous structures in their nest-building. For this the bill has to serve as a hand, and is, indeed, a most skilful and delicate organ of prehension. Yet such an organ it could not be were it not for the great mobility of the neck which, even when the neck is short, is such as to enable the bird to turn its head. round and look directly over its back. The exclusive devotion of the arms to flight, necessitates the constant employment of the hind limbs for other locomotion. For this they need vigorous

muscles, muscles, although by a special mechanism birds are enabled to grasp securely the twigs and branches on which they perch, almost without effort. Yet it would be very awkward were the muscles disposed about their feet and toes as ours are. Accord ingly here again the heavy muscular mass is gathered together in the thighs and upper parts of the legs—near the centre of gravity—their action being conveyed to the parts they are destined to move, by long and slender tendons. So careful is this packing process in birds, that the parts which grind the food and act as teeth, are placed not in the jaws, but in the centre of the body-in the gizzard. They consist of the small stones which most birds swallow for this purpose—all those, that is, which seed on grain and other substances that require grinding

In man and beasts, the organ of voice—the larynx—is situated high up close beneath the root of the tongue; but in birds, even the vocal organ-know in them as the 'syrinx'-is brought near the centre of gravity. Instead of being, as in us, at the summit of the windpipe, it is situated at the lower end of that tube, just where it divides into the two bronchi. A very wonderful

organ
is the

eye

of the bird. To say that a man has the 'eye of a hawk,' is a familiar expression to denote great keenness of vision; but when we reflect that such a bird has often to observe its prey on the ground from a great height, and to descend rapidly and seize it, keeping it all the time well in view during its descent, it becomes plain to us how delicate and extensive its powers of adjustment must be. Birds have a special mechanism for sweeping the eye rapidly and often by means of a third eyelid. This may be seen any day at our Zoological Gardens by observing for a short time the eye of some eagle and noting the film which seems at frequent intervals to shroud it for a moment. A rudiment of this delicate membrane exists at the inner angle of our own eye. however, it performs no known useful function.

But besides the interest and attractiveness of birds themselves, there is much beauty in their eggs and in the wonderful contrivances they construct to shelter them. It has been observed that the eggs of most birds which lie in exposed places are marked and spotted in various ways, but that otherwise they are generally white. Some birds, however, though they form covered nests, have their eggs spotted. The guillemots are remarkable for the extreme degree of variation in colour and markings which their eggs exhibit, and the eggs of the grebe are no less singular as to form, being pointed at each end. The largest known egg is that of an extinct bird, the Æpiornis,

In us,

which formerly inhabited Madagascar. It is very much larger than that of the ostrich. The notion that the size of a bird is in proportion with that of the egg it lays, is a natural but mistaken one. If the egg of the æpiornis was—as it possibly was-once an object of cominerce in the East, it

may

be that we owe to it the fable of the roc's

egs
with which

every

reader of the Arabian Nights is familiar.

Many aquatic birds make no nest at all, laying their eggs simply on some ledge of rock by the sea-side. It is useful for eggs so placed to have each end pointed, a form which makes them less liable to fall from an insecure position. The opposite extreme (as regards habits) to such nestless species is found in the weaver birds, which construct immense nests in common, or rather form vast aggregates of nests placed sociably side by side. They appear to form their breeding-places under one cover-each nest having its own separate entrance on the under side of the whole structure, and not communicating with the nest next to it. The whole mass may be ten feet in diameter, and ultimately break down from its own increasing weight.

One of the most perfect nests of our own country's birds is that of the wren. It is completely domed and lined with many feathers, some hair and fine moss. The female alone builds it, and sometimes, as is not wonderful, spends a fortnight in the process of constructing an abode more than thirty times her own size. As a rule, the external appearance of the nest so harmonizes with its surroundings, that it may almost defy detection. This is not, however, constantly the case, and Professor Newton has known an instance, in which built year after year

in a hole in a wall in such a way, that the bright green moss entering into its construction made it very conspicuous in consequence of the white chalk which was adjacent to it.

In great contrast to the neat and attractive nest of the little wren, is that of the gay-plumaged kingfisher. It is found, commonly, on the bank of some stream opening amongst roots, and overshadowed by bushes. From the entrance a passage leads gently upwards, it may be three feet, to a chamber about eight inches in diameter. There we find no soft bed of moss, grass, or feathers, but a mere accumulation of fish-bones and rotten pieces of fish, often with maggots and the droppings of the birds themselves—a most filthy and offensive hole for so brilliantly dressed a bird to make its exit from.

Every one knows the curious habit of the cuckoo, which comes to us in the middle of April and departs in August, leaving its young to follow it the month after. This habit is

a wren

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