Sexual Response of Female Great Tits to Variation in Size of Males' Song Repertoires

Abstract

We investigated the effects of the size of the males' song repertoire on the sexual display behavior of female great tits, in an attempt to determine the relative "attractiveness" of different sizes of repertoire. Previous work had discovered a correlation between the repertoire size of males and their lifetime reproductive success. In our experiment, females were brought into reproductive behavior by photoperiod and hormone manipulations and tested in the laboratory. Tests involved repertoire sizes ranging from one to five song types, spanning most of the variation found in natural populations of singing males. The number of copulationsolicitation displays given by the females increased with repertoire size. Our results are consistent with the "truth in advertising" model of sexual selection for the evolution of large repertoire size in songbirds. Females obtain a direct reproductive advantage from mating with males with large repertoires.