IT'S NOT JUST THE SONG: Male Visual Displays Enhance Female Sexual Responses to Song in Brown-Headed Cowbirds

Abstract

Even though it is widely acknowledged that mate choice in female songbirds is likely to be based on multimodal cues such as those encoded in audiovisual song displays, procedural difficulties have limited studies of mate choice in songbirds mainly to acoustic signals. In the current study, we used audiovisual recordings of male Brown-headed Cowbirds (Molothrus ater) to test the sexual responses of females to males' song displays. Using the copulation-solicitation displays of estradiol-treated females (n = 9), we found that audiovisual playbacks of males performing wing-spread song displays were significantly more sexually stimulating for females than presentations of song accompanied by video of nondisplaying males, or song alone. Results from this study clearly showed that the visual stimulus of the wing-spread display in particular, not just the visual stimulus of a conspecific male in general, elicits the maximum observed response from females. In the Brown-headed Cowbird, females' sexual preferences for song as revealed by studies of copulation-solicitation displays have been shown to parallel males' mating success, so our results likely reflect an effect of visual displays on the mating success of wild males.