According to the school to which Mr. Long belongs, young birds learn their song from their parents, just as young children learn how to talk. In the words of Barrington, “Notes in birds are no more innate than language is in man, but depend entirely upon the master under which they are bred, as far as their organs will enable them to imitate the sounds which they have frequent opportunities of hearing.”
Similarly Michelet writes: “Nothing is more complex than the education of certain singing birds. The perseverance of the father, the docility of the young, are worthy of all admiration.” There can be no doubt that young birds are very imitative. The young of the koel—an Indian parasitic cuckoo—make ludicrous attempts to caw in imitation of the notes of their corvine foster-parents; but later, when the spring comes, they pour forth the very different notes of their species. In the same way the young of the common cuckoo, no matter by what species they are reared, all cry “cuckoo” when they come of age. Ducklings, pheasants, and partridges, hatched under the domestic hen, and fowls reared by turkeys, have the calls peculiar to their species. It may, of course, be urged that these learn their cries from others of their own kind. Here again, then, actual experiment is necessary to determine which view is correct. Such experiments were performed by Mr. John Blackwall as long ago as 1823. He writes:—
“I placed the eggs of a redbreast in the nest of a chaffinch, and removed the eggs of the chaffinch to that of the redbreast, conceiving that, if I was fortunate in rearing the young, I should, by this exchange, ensure an unexceptional experiment, the result of which must be deemed perfectly conclusive by all parties. In process of time these eggs were hatched, and I had the satisfaction to find that the young birds had their appropriate chirps.
“When ten days old they were taken from their nests, and were brought up by hand, immediately under my own inspection, especial care being taken to remove them to a distance from whatever was likely to influence their notes. At this period an unfortunate circumstance, which it is needless to relate, destroyed all these birds except two (a fine cock redbreast and a hen chaffinch), which, at the expiration of twenty-one days from the time they were hatched, commenced the calls peculiar to their species. This was an important point gained, as it evidently proved that the calls of birds, at least, are instinctive, and that, at this early age, ten days are not sufficient to enable nestlings to acquire even the calls of those under which they are bred. . . . Shortly after, the redbreast began to record (i.e. to attempt to sing), but in so low a tone that it was scarcely possible to trace the rudiments of its future song in those early attempts. As it gained strength and confidence, however, its native notes became very apparent, and they continued to improve in tone till the termination of July, when it commenced moulting. . . . By the beginning of October . . . it began to execute its song in a manner calculated to remove every doubt as to its being that of the redbreast, had any such previously existed.” Mr. Long lays great stress on the manner in which parents inculcate into their young fear of enemies. Fear, he asserts, is not instinctive; young creatures, if found before they have been taught to fear, are not alarmed at the sight of man. I admit that very young creatures are not afraid of foes, and that, later, they do display fear, but I assert that this change is not the result of teaching, that it is the mere development of an inborn instinct which does not show itself until the young are some days old, because there is no necessity for it in the earliest stages of the existence of a young bird.