SONG or BIRDS. All birds have some voice or cry which they litter, and most of them various noes appropriate to various occasions. The power of producing clear and sweet musical Rotes is chiefly found in certain families of the order some of which, as the lark, pour forth their song in the air; butt the greater number, like the thrush and nightingale, sit while they sing. The compass and variety of notes, the power of trilling and shaking, the loudness, clearness, and sweetness of the song, differ very much in different species, each of which may be as perfectly recognized by its song as by its form or plumage. There are also, as is well known, great differences among individuals of the same species, and Mr. Jesse asserts his confidence that there nte nota ble differences between the song of the birds of the same species generally in one district and in another, just as there are provincial dialects and modes of pronunciation in human speech. " The song, for example, of a thrush near London, or in any of the home counties, has little resemblance, except in specific character, to that of the same bird in Devonshire or near Exeter. The same notes. I suppose, will all of them be detected, but they art arranged for the most part into a different tune, and are not sung in the same way. They are given with different values, and the singing is pitched in a different key. One great distinction between the two cases is the number of guttural notes of which the song of a Devonshire thrush is often made up, but which near London are heard only at the end of a bar, or even much less frequently; while those chief notes, which mainly constitute the song of the other bird, and make it so impressive, are rarely pronounced by the Devonshire Scenes and Occupations of Country Life, p.
112.
, The singing of birds is chiefly connected with the love-season; although some birds sing at other seasons also, during fine weather, and when food is abundant, as if merely to utter their happiness, and by uttering, to increase it. It is during the pair ing-time that they are most vocal; the singing of many is continued with frequency also during the period of incubation, but with some change of character, exhibited in a marked degree by the chaffinch. The male alone sings. Female birds have voice also, but do not, possess the power of warbling like their mates. There are generally con• siderable anatomical differences in the larynx of the two sexes.
There. can be no doubt that the singing of the male bird is intendedto attract and please the female, and that he delights in this display of his own powers. In this respect., there is no difference between the birds of most melodious song and those of harsh discordant voice. The crowing of the cock and the gobbling of the turkey have the same purpose as the song of the nightingale. In them may be also seen an emula tion which is ready further to display itself in combats, and probably these take place among the males of all birds. But questions of rivalry seem in part to be decided among some of the songsters of the groves by mere musical displays. Caged birds evidently often sing from emulation. It is said that canaries may be taught to sing a complete tune from a musical box, adjusted to play one tune only, A mirror should be placed before the bird and over the box.
The imitative powers so remarkably possessed by the mocking-bird and a few other species, are to some extent possessed by many birds.