DISSERTATION RESEARCH: Understanding effects of social behavior on extinction risk in avian cooperative breeders

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It is well known that some social behaviors can lead to increased extinction risk when populations are small. For example, there can be a breakdown of group defense against predators when there are few individuals. However, less is known about the flipside -- how some social behaviors might protect small populations against extinction. Research supported by this grant is focused on an unusual social behavior called cooperative breeding, whereby offspring from one year forgo breeding to assist their parents in raising offspring the next year. It is proposed that this behavior can help populations survive after their habitat has been degraded. This is being studied in the White-breasted Thrasher, a cooperatively breeding bird that lives on two small islands in the Caribbean. This species is endangered, with only 1000 individuals remaining in the largest population. It is of particular interest because several years ago part of its habitat was impacted to create a resort. It is predicted that that groups with cooperative breeders will increase in size. The proposed research combines field work with modeling to determine the role cooperative breeding as a possible buffer to extinction and the extinction risk for this species. In addition to helping understand extinction risk, this work will contribute directly to conservation of an endangered species. It is listed on the U.S. Endangered Species Act and is the second-most endangered cooperatively breeding bird in the world. Results from this research will inform management actions to reduce extinction risk of the species, including animal translocations, forest restoration, and nature reserve design. In addition, through organization of after-school workshops and mentoring of undergraduates, this work will use birds to educate young people from both the Caribbean and the US about biological diversity and scientific research.