BIRD 



731 



BIRD 



birds have a very keen sense of sight. Indeed, 

 in some species this is little less than marvel- 

 ous. A kite which has soared so high that 

 the human eye cannot see it, can often spy 

 far below on the ground a tiny mouse, upon 

 which it will drop with unerring aim. Some- 

 times, as in the owl, the sensitiveness to light 

 is so great that the bird is practically blind in 

 the daytime, but at night he is truly "lord of 

 the dark green wood." The eye of a bird is 

 much like that of a human being, but it 

 possesses certain advantages all its own. For 

 it has an extra eyelid, called by naturalists the 

 nictitating or winking membrane, which it may 

 draw at will. 



The sense of hearing, too, is very well devel- 

 oped in birds not better than in human beings, 

 as is the sense of sight, but probably as well. 

 They have no external ears, but the opening 

 to the internal ears is fairly large. No better 

 proof of this acute sense of hearing is necessary 

 than the ease with which certain birds mimic 

 sounds, as does the mocking bird, or learn to 

 repeat words, as does the parrot. 



The senses of touch and taste are not highly 

 developed in birds, nor, it is believed, is that 

 of smell, though some birds seem to make use 

 of this last-named sense in seeking out their 

 food. The condor and the common buzzard, 

 however, find their food by sight and not by 

 smell. 



Special Senses. In addition to these senses 

 possessed by man, birds, according to some 

 authorities, have also a so-called "sixth sense" 

 the sense of direction. Whatever this sense 

 be called, it is exhibited in a marked degree 

 by the carrier pigeon, which will fly swiftly back 

 to its home, even when it has been sent away 

 by train in a wicker case. Even more remark- 

 able is the ability of a flock of migrating birds 

 to fly straight to the spot where they had their 

 homes the year before, even when to reach 

 it they must cross tracts of water which afford 

 no landmarks whatever. A person who has 

 interested himself in providing homes for cer- 

 tain kinds of birds, as the bluebird or martin, 

 may feel certain that each spring they will 

 return to him. One observer writes: 



My neighbor was very busy one Saturday 

 morning putting up his ornamental bird house 

 "For my martins," he explained, "will arrive 

 about the twelfth." The completed house was 

 promptly taken over by the sparrows, but the 

 bird-lover did not worry. On the morning of the 

 twelfth we heard a commotion, and sure enough, 

 the martins had arrived and were driving the 

 sparrows from their premises. 



It is not only in this special sense or instinct 

 that birds show their adaptation to the necessi- 

 ties of their life; there are peculiarities of 

 structure, too. Thus there is no danger of a 

 perching bird falling from its twig while sleep- 

 ing, for the muscles in its legs are so arranged 

 that, when the bird perches, its toes are bent 

 and cannot open until the bird rises again. 

 Some birds' feet are specially made for scratch- 

 ing in the ground, some for holding prey, some 

 for swimming, and the bills are equally well 

 adapted to just the services they must perform. 



Song. Without their power of song, birds 

 would not be so greatly loved, however beauti- 

 ful many of them are. Yet only a compara- 

 tively small number can really sing, and these 

 are often the ones which have the plainest 

 plumage. Almost all birds make some sound 

 many seem to have a well-developed language 

 by which they make themselves understood; 

 but no one welcomes especially the harsh caw 

 of the crow, the scream of the jay or the hoot 

 of the owl. However, the nightingale, the 

 mocking bird, the thrush, the linnet, the warb- 

 lers, the skylark and certain others these are 

 welcome everywhere; for the song of the male 

 in the mating or nesting season affords one of 

 the greatest pleasures which all out-of-doors 

 has to offer. The lark, of whom Shelley sings 



Sound of vernal showers 



On the twinkling grass. 

 Rain-awakened flowers, 

 All that ever was 

 Toyous, and clear, and fresh, thy music 



doth surpass, 



and the nightingale with its "eternal passion, 

 eternal pain" have been most celebrated in 

 poetry, but there are other birds which give 

 equal pleasure to innumerable listeners. 



The organ which produces the voice of birds, 

 whether it be melodious song or discordant 

 cry, is not the larynx, as in man, but a special 

 organ which only birds have, called the syrinx. 

 'Man uses his tongue in his speech; a bird 

 does not. 



"Home Life" of Birds. Birds usually live in 

 pairs and in some species, as the eagles and 

 hawks, a union lasts for life. With the major- 

 ity of birds, however, a new mating takes place 

 each spring, and the first act of the pair is 

 to seek out a suitable place for a home. Most 

 birds build nests, all those of one species 

 making just the same kind, but there are some 

 curious exceptions to the nest-building mle 

 (see NEST). In the nest the eggs are laid, for 

 all birds without exception are hatched from 



