Song Type Switching in a Highly Social Songbird Species

Abstract

Songbirds are an established comparative model for the development and evolution of language in humans due to their vocal learning abilities that are rare among non-human animals. In this study, we tested the Repertoire Size Hypothesis, which argues that the number of learned vocalizations (i.e., songs) a songbird learns is the target of sexual selection. We tested this in the Brown-headed Cowbird (Molothrus ater obscurus) – a species where males acquire an average of 5 different song types in their repertoires (range: 2-7 song types). The focus of the study was to determine whether males switched song types more in the beginning of a song bout directed at unfamiliar females versus the ending of a song bout. A total of 31 male Brown-headed Cowbirds in the wild were observed in Santa Barbara, Fresno, Kern, Sacramento, Merced, Stanislaus, Riverside, Kings, San Luis Obispo, and Imperial Counties – all located in California. Our analysis revealed that there was a significant difference between the first songs in a bout and the last songs with significantly more switching in the beginning of a song bout. This provides evidence that sexual selection can place pressure on the cognitive skills of vocal learning non-human animals to learn larger repertoires and be able to present their learned vocalizations efficiently during social interactions.

Details

Session 1

9:30am – 11:00am

Grand Salon