Dissertation Research: Vocal Behavior at Subspecies and Dialect Boundaries in the Bronzed Cowbird

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Non Technical Abstract Proposal #: 98001041 PI: M. Ryan / P. Warren The last three years of research on the bronzed cowbird (Molothrusaeneus)have uncovered a social system that differs in many important ways from other birds. This project will attempt to determine what effects these differences have on their evolution. Songs of male bronzed cowbirds will be recorded and compared among different populations. Songs will also be played back to male cowbirds to determine what variation in song means to the birds. As brood parasites, cowbirds possess an unusual form of reproduction; the female cowbird lays her eggs in the nests of other bird species who then raise her offspring as if it were their own. The effects of brood parasitism on the cowbirds' host species have been much publicized and much debated. But what are the evolutionary consequences for the cowbirds themselves? One consequence is that male cowbirds do not have the opportunity to learn their songs until they leave their foster parents and join their own species. Thus, their opportunities for learning are constrained in a way unlike that in other species. What role does song learning play in evolutionary processes like speciation? To address this problem, this study asks whether groups of cowbirds which have been separate from one other are likely to split into different species. It is hoped that information gathered on this little-studied species of cowbird will contribute to a general understanding of its behavior, its use of habitat, and therefore its potential to impacts on other species.