Vireo song repertoires and migratory distance: three sexual selection hypotheses fail to explain the correlation

Previous studies have found a relationship between migration and the degree of elaboration of sexually selected traits, but investigators have differed in the mechanisms they proposed to account for this association. We examined the relationship between song repertoire size and distance migrated among birds in the genus Vireo. There is a strong positive relationship between migratory distance and repertoire size in this genus, but our data do not support the specific predictions of any of the three proposed mechanisms (the "rapid pairing," "good migrations," and "territory lottery" hypotheses). Migration distance is presumably correlated with other life-history characteristics that influence the development of sexually selected traits.