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Furnarias, and it is very curious that the young birds, when only partially fledged, are constantly heard in the nest or oven apparently practising these duets in the intervals when the parents are absent; single measured notes, triplets, and long concluding trills are all repeated with wonderful fidelity, although these notes are in character utterly unlike the hunger cry, which is like that of other fledglings. I cannot help thinking that this fact of the young birds beginning to sing like the adults, while still confined in their dark cradle, is one of very considerable significance, especially when we consider the singular character of the performance; and that it might even be found to throw some light on the obscure question of the comparative antiquity of the different and widely separated Dendrocolaptine groups. It is a doctrine in evolutionary science that the early maturing of instincts in the young indicates a high antiquity for the species or group; and there is no reason why this principle should not be extended, in the case of birds at any rate, to language. It is true that Daines Barrington's notion that young song-birds learn to sing only by imitating the adults still holds its ground; and Darwin gives it his approval in his Descent of Man. It is perhaps one of those doctrines which are partially true, or which do not contain the whole truth; and it is possible to believe that, while many singing birds do so learn their songs, or acquire a greater proficiency in them from hearing the adults, in other species the song comes instinctively, and is, like other instincts and habits, purely an "inherited memory."
258 The Naturalist in La Plata.
The case of a species in another order of birds--Crypturi--strikes me as being similar to this of the oven-bird, and seems to lend some force to the suggestion I have made concerning the early development of voice in the young.
Birds peculiar to South America are said by anatomists to be less specialized, lower, more ancient, than the birds of the northern continents, and among those which are considered lowest and most ancient are the Tinamous (rail and partridge like in their habits), birds that lead a solitary, retiring life, and in most cases have sweet melancholy voices. Rhynchotus rufescens, a bird the size of a fowl, inhabiting the pampas, is perhaps the sweetest-voiced, and sings with great frequency. Its song or call is heard oftenest towards the evening, and is composed of five modulated notes, flute-like in character, very expressive, and uttered by many individuals answering each other as they sit far apart concealed in the grass. As we might have expected, the faculties and instincts of the young of this species mature at a very early period; when extremely small, they abandon their parents to shift for themselves in solitude; and when not more than one-fourth the size they eventually attain, they acquire the adult plumage and are able to fly as well as an old bird. I observed a young bird of this species, less than a quail in size, at a house on the pampas, and was told that it had been taken from the nest when just breaking the shell; it had, therefore, never seen or heard the parent birds. Yet this small chick, every day at the approach of evening, would retire to the darkest corner of the
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dining room, and, concealed under a piece of furniture, would continue uttering its evening song for an hour or longer at short intervals, and rendering it so perfectly that I was greatly surprised to hear it; for a thrush or other songster at the same period of life, when attempting to sing, only produces a chirping sound.