Birdsong learning as a social process

This paper describes a 30-year investigation into the role of social and ecological factors affecting song learning in song sparrows, Melospiza melodia. It addresses the question of why song sparrows learn the songs they do, given that they are exposed to many more songs than they will keep for their final repertoire of 7-11 song types. A young song sparrow moves from his natal area at about 1 month of age, eventually settling in an area where he learns the songs of the resident males and attempts to establish his own territory. Birds that share many songs with their neighbours in their first breeding season (the spring following their hatch summer) survive for more years on territory than birds that do not. Many features of the song-learning process lead to a high level of sharing with first-year neighbours, including preferentially learning the songs of their tutor-neighbours who survive the winter, and learning songs that are shared by several tutors. Social interaction appears to be critical in song learning, but indirect effects (eavesdropping on adults countersinging) seem to be at least as important as direct interaction between the young bird and his tutor-neighbours. Although our evidence suggests that the song-learning strategy of young song sparrows is beneficial to them, a preliminary analysis suggests it may not benefit their tutors.