Song sparrows do not learn more songs from aggressive tutors

• Social interactions are an important factor in birdsong learning.
• A major hypothesis is that young birds will learn from more aggressive tutors.
• We quantified aggressiveness of tutor males in a population of song sparrows.
• We then correlated the aggression of tutors with their tutoring success.
• There was no effect of aggression on tutoring success.

Birdsong has long been a prominent model system for studying learning of vocal signals. However, despite widespread acknowledgment of the importance of social factors in shaping birdsong learning, few studies have attempted to parse out and analyse specific social variables in a naturalistic context. Here we report a field study of song learning in song sparrows, Melospiza melodia, which tests the role of a specific social factor, the aggressiveness of potential song tutors. The hypothesis that young birds may learn more from more aggressive tutors was proposed over three decades ago, but has only been tested in laboratory studies, and with mixed results. We assayed aggression and signalling of potential tutors through repeated playback experiments in the field during the song-learning period of a cohort of young sparrows. We also recorded these young birds and traced their repertoires back to potential tutors. We asked whether consistent individual differences in aggressive and signalling behaviours of tutors would predict the degree to which their songs were learned by young birds in the cohort of the year. We sampled more than half of the adult male (potential tutor) population and almost all of the young males (tutees), and replicated the results of a previous study on this same population concerning which songs were learned from which tutors. However, we found no effect of the aggressiveness of potential tutors, their levels of their aggressive signalling or their level of normal singing on their tutoring success. In short, young song sparrows do not learn more from aggressive tutors. We argue for further research on other social factors under natural conditions.