DISSERTATION RESEARCH: Reproductive Cooperation and Conflict in the White-Throated Magpie-Jay

University Of California-Davis, Davis CA

Investigators

Abstract

eproductive cooperation and conflict in the white-throated magpie-jay John McAllister Eadie, PI Elena Catherine Berg, co-PI This study will analyze the relationship between kinship, parentage, and behavioral variation within a Costa Rican population of white-throated magpie-jays (Calocitta formosa), a highly gregarious bird inhabiting the tropical dry forests of Central America. In this cooperative breeding bird, territorial groups typically consist of a breeding pair, their immature offspring, and one or more helpers (adult offspring that forego their own breeding attempts and assist the breeders with nest-building, defense against predators, and feeding of the incubating female and her nestlings). In most cooperative breeders, males act as helpers, but the magpie-jay is particularly interesting in that these sex roles are reversed: only females stay behind. This provides a rare opportunity to study interactions between related females and assess the factors affecting female reproductive decisions. Specifically, we will test a recent model of reproductive behavior that predicts the precise conditions under which females should 1) lay eggs "parasitically" in the nests of other females, 2) breed alone, or 3) act as non-breeding helpers in their natal territory. By testing the specific predictions of this model in a field setting, it will be possible to evaluate the factors affecting reproductive decisions among females, creating a springboard for future research on the relationship between cooperation and conflict in birds. To test this model, behavioral and molecular data will be collected on multiple groups of magpie-jays during three breeding seasons. Observational data will be collected on patterns of nesting and helping behavior, and molecular analyses of blood samples collected from adults and nestlings will be used to establish the reproductive output of individual females as well as patterns of kinship within and among groups. This is an exciting new approach because it offers a fresh outlook on female alternative reproductive tactics, provides a theoretical framework for linking cooperating breeding and parasitism, and outlines specific predictions that can be tested in the field.