BRITISH WARBLERS
neither, I think, does any other interpretation. It simply starts with the assumption of "one voice, one value," and shows how the sounds produced, whether harsh, monotonous or beautiful, may each in their own particular fashion possess a similar meaning. So much for its use.
We must now refer briefly to the question often asked as to whether a young bird learns to sing or whether it sings instinctively through racial preparation, as a duckling swims instinctively when placed in water. Is song, that is to say, a matter of tradition—handed down from parent to offspring—or is it a matter of congenital endowment? There are facts placed on record—and I believe perfectly authentic facts—which seem to show that tradition may play a larger part than it is sometimes given credit for. Young birds reared in confinement away from their own species, but in company with other songsters, are said to reproduce only those notes which they have been accustomed to hear. I have all along combated the view that the young bird sings true to type just because it has predominant opportunities, of hearing its parents' notes, and despite the facts here alluded to, I still think that each species has a definite congenital song. When is the young bird supposed to learn its song—whilst in the nest or during the winter months? The former, one would suppose, would be the more susceptible period, yet that is precisely the time when the voices of many songsters are heard the less frequently, if indeed they have not ceased altogether. The Grasshopper Warbler, after a period of comparative silence, only recommences to sing when its young have left the nest; the Nightingale becomes well-nigh silent when the time comes for the exercise of parental care; the Marsh Warbler's song grows more and more feeble at a corresponding time, and so on. If therefore song is an individual acquirement, a matter of imitation, what is there to prevent the young from assimilating the notes of the more vociferous individuals of other species in the vicinity of their nest? Nothing, I imagine, so long as we exclude the
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