Birds also have an instinct to make vocal calls; but if kept from birth out of hearing of the peculiar notes of their species, they come to make cries of a different sort, or learn to make the notes of some other species with which they are thrown.
4.

The principal agency for the learning of the animals, and for the supplementing of their instincts, is Imitation.

The sight of certain movements on the part of the adult animals, or the hearing of their cries, calls, notes, etc., leads the young to fall into an imitation of these movements or vocal performances.

The endowment which such a young animal has in the direction of making movements and cries similar to those of his species aids him, of course, in imitating these in preference to others.

So the endowment and the tendency to imitate directly aid each other in all such functions, and hurry the little creature on in his acquisition of the habits of his species.