The response of male and female song sparrows to geographic variation in song

We tested female and male Song Sparrows (Melospiza melodia) from a Pennsylvania site for discrimination between local songs and foreign songs recorded in New York. In Experiments 1 and 2 we measured the copulatory response of female Song Sparrows to playback of local and foreign songs. In Experiment 3 we measured the aggressive response of territorial males to playback. We used mean responses per subject as sample points in the statistical analysis in Experiment 1, but to avoid pseudoreplication we designed Experiments 2 and 3 with sufficient numbers of exemplars of local and foreign songs to use mean responses per exemplar as sample points. Responses in all three experiments were significantly stronger for local than for foreign songs. Song Sparrow songs show a great deal of variation within locales, and a pattern of gradual and subtle geographic change, so it is not obvious how or why our subjects performed the discrimination.