Page images
PDF
EPUB
[ocr errors]

touch. But the sight is remarkably keen, and the eye possesses great powers of accom modation to different distances. B. perceive even small objects distinctly, at distances at which they would be quite indistinguishable to the human eye, and thus are enabled to seek their food. B. of prey also appear to possess in great perfection the sense of smell. The nostrils of all B. open on the upper surface of the bill. Hearing is acute in B., and particularly in nocturnal B., although the organs of this sense are less compli cated than in mammalia, and there is seldom any vestige of an external ear. Singing B. are extremely sensitive to differences of pitch. The voice and musical powers depend upon the conformation of the windpipe and larynx, which differs very much in different birds.

Reproduction takes place by eggs (see REPRODUCTION and EGG), which are hatched after they have passed from the body of the mother. B. generally sit upon their eggs, their bodies supplying the warmth necessary to hatch them (see INCUBATION); and this office is usually undertaken by the female alone, but sometimes is shared by the male. In very warm climates, the ostrich leaves her eggs to be hatched by the heat of the sun, but in colder climates sits upon them. A very few B., as the cuckoo, deposit their eggs in the nests of other B., to be hatched by them. Some 5. construct no nest, but lay their eggs on the bare rock, as many sea-fowl do, or in holes rudely scratched in the earth or sand; many, however, show in the construction of their nests the most admirable instincts. See NESTS. The number of eggs varies, in a state of nature, from 1 to about 20, being generally smallest in the larger B., and particularly in B. of prey. B. generally breed only once a year, but some B. twice. The care which B. take of their young is as admirable as the ingenuity which they display in nest-building, and more universal. Some B. are able to run about, and pick up food as soon as they leave the shell; others remain in the nest for days, or even weeks, and must be supplied with food by their parents. Many species are social, particularly at the breedingseason, and form large settlements, which they guard in common; and some even unite in the construction of large nests, which belong to a whole community. The rapacious B., and particularly the larger ones, are very solitary in their manner of life.

B. change their feathers (molt), in general, once a year, and the colors of the plumage in many cases vary much in summer and winter. The change of color, how ever, often takes place without change of feathers, and in B. which molt both in spring and autumn, the autumn molting is much more complete than that of spring. The gayest plumage of many B. is assumed at the breeding-season, with which, also, the song of B is connected. See SONG OF BIRDS. The plumage of the male is, in general, more gay than that of the female, all the young at first resembling the female in plumage. The plumage usually characteristic of the male is occasionally assumed by the female, and most frequently by females which have become unfit for the ordinary functions of their sex.

The brain in B. differs in some important respects from that of mammalia (see BRAIN), presenting resemblances to the brain of reptiles and fishes; but it is of large size, often larger than even in quadrupeds. The manifestation of intelligence is not, however, usually so great in B. as in quadrupeds. Their nest-building, their migrations (see BIRDS OF PASSAGE), and many other things of greatest interest, must be ascribed to instinct.

In the geographical distribution of B., the limits of species are not so exactly circumscribed by mountains, seas, and rivers as in other classes of animals, their powers of flight enabling them to pass over these obstacles. Yet some species, and even groups, are found exclusively in certain regions: thus humming-birds are all American, penguins are found only in the southern seas, and B. of paradise are confined to New Guinea and the neighboring islands. See SPECIES.

The free movements of B. through seemingly boundless space, the joyous song of many, and the characteristic tones of all-their brilliant colors, their lively manners, and their wonderful instincts-have from the earliest ages made a strong impression on men's minds, and in the infancy of intellect gave rise to many peculiar and mysterious associations with this class of creatures. Hence the flight of B. was made the foundation of a particular art of divination. See AUGURIES and AUSPICES. Religion borrowed many of its symbols from them, and poetry many of its ornaments.

In an economical point of view, B. are very important. The flesh and eggs of almost all B. may be eaten, although those of B. of prey and of fish-eating B. are generally reckoned unpleasant. Their feathers are employed for various purposes of use and ornament; their dung is valuable for manure, and guano (q.v.) is nothing else than the accumulated dung of sea-fowls. Many B. are extremely useful in preventing the multiplication of insects and worms, and compensate in this way for the mischief which they occasionally do in fields and gardens. Domestic poultry are a source of considerable profit, upon account of their eggs, flesh, and feathers. See POULTRY. Some kinds of B. of prey have been tamed, and trained to the use of the sportsman. Ece FALCONRY.

About 5000 existing species of B. are known. As to their systematic arrangement, see ORNITHOLOGY.

The order of B. presents in the dodo (q. v.) a remarkable and well-ascertained instance of the recent extinction of a species, and even of a genus. It is also a remarkable and

[graphic][subsumed][subsumed][ocr errors][subsumed][subsumed][subsumed]

BIRDS.-1. Wren (Troglodytes parvulus). 2. Oriole (Oriolus galbula). 3. Yellow cockatoo. 4. 8. Agami (Psophia crepitans). 9. Bullfinch (Pyrrhula vulgaris). 10. Bird of Para of avocet.

bittern.

15. Tawny owl (Syrnium aluco). 16. Head of whip-poor-will. 17. Nightingale pecker (Picus martius). 21. Stork.

[graphic][subsumed][subsumed][merged small][subsumed]

12. Great auk. 13. Head of flamingo.

Frigate-bird. 5. Head of blue-bird (Silvia sialis). 6. Memura (Memura superba).
adise (Paradisea apoda). 11. Head of cuckoo.
(Luscinia philomela). 18. Sea-eagle or osprey.

7. Head of

14. Head 19. Head of pelican. 20. Head of black wood

« EelmineJätka »