The auditory template model describes how male birds learn to sing and was developed by Peter Marler through his experiments on chaffinches. First, he observed that males were only sensitive to songs during two periods: following hatching and during their first spring after hatching. Additionally, he discovered that the chaffinches weren’t sensitive to any song, only the songs of their conspecifics. Through further experimentation, he also determined that males who were deafened produced more abnormal songs than males who were deprived of a tutoring song. From these data, Marler hypothesized that male chaffinches possess a crude template that they match to conspecific songs during their sensitive period, and that they later refine these songs by listening to themselves sing. This process of song learning is known as the auditory template model. Though this model explains the way some birds learn how to sing, recent experiments have produced data that do not fit this model. Experiments with white-crowned sparrows showed that even though male hatchlings do not learn heterospecific song when tutored by a speaker, they do learn heterospecific song when tutored by a heterospecific male. This seems to counter the idea of a pre-encoded crude template that serves to filter out heterospecific song. Other song learning modalities, such as in the marsh wren and European robin seem to counter the auditory template model. Marsh wrens are sensitive to songs from ten days after they hatch to their first spring, and like chaffinches, have a descending ability to learn songs the older they get. However, unlike chaffinches, if marsh wrens learn a lot of songs before winter they will be less ready to learn songs in the following spring, and vice versa. Indigo bunting prove to be another kind of exception to the auditory template model. The indigo bunting has no species-specific song and forms groups that share a repertoire that changes from year to year. It has also been shown that indigo bunting males can switch groups and will learn new songs to better fit in with their new neighbours. Though the auditory template model has proven accurate for some species, the many variations in song learning have shown that it is hardly ubiquitous among all bird species.
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