Experimental alteration of male song quality and output affects female mate choice and pair bond formation in zebra finches

Although bird song is thought to be important in mate attraction, little is known about how females perceive differences in song and which specific elements of song females prefer. Most studies, to date, have examined female choice during preference tests for song stimuli, and most have treated females with oestrogen prior to testing. At present, it is unclear whether song preferences during such tests reflect actual mate preferences. This study tested the hypothesis that experimentally altering male courtship vocalizations (song) would affect female mate choice and the formation of long-term socially monogamous relationships. Male zebra finches, Taeniopygia guttata, were vocally distorted using two minor and reversible techniques. Females in a two-choice paradigm preferred control males over vocally distorted or muted males. In a pair bond formation experiment, all control males had paired 5 days into the study, whereas only one vocally distorted male had paired. By the end of 2 weeks, however, four nerve-transected males and one air-sac-punctured male had paired. These results suggest that females do use song quality as a basis for choosing males. However, other male qualities may eventually override vocal quality as the basis for female choice.