Abstract:
Between-year repeatabilities for several song characteristics were measured in a population of willow warblers. The results show that repertoire size has a significant repeatability (0.497), and that the song characteristic with the highest repeatability was song versatility (0.770). However, an analysis of the evolvability of these traits suggests that, given a minimum heritability, repertoire size would have higher residual and additive genetic variance than song versatility. Father-son regressions for all song characteristics were not significant due to the small sample size and the low heritability that is expected from the repeatability results.