Song repertoires and sexual selection in the Red-winged Blackbird

The female choice and male-male competition hypotheses for the evolution of song repertoires were tested by studying repertoire size, pairing success, reproductive experience, and territory size in the Red-winged Blackbird. Analysis of these variables produced the following results: These results are consistent with the hypothesis that song repertoires in the Red-winged Blackbird evolved in response to male-male competition.