The objectives of this project are to 1) allow the principal investigator to learn and become proficient in avian endocrine research techniques, and 2) apply these techniques to address new questions about the hormonal basis of sexually-selected behaviors in dabbling ducks. The study will include four experiments with captive northern pintails (Anas acuta) and white-cheeked pintails (A. bahamensis) that are designed to 1) test the hypothesis that the stimuli associated with pair formation induce hormonal changes that alter male behavior and dominance relationships, 2) test the effect of experimental manipulations of sexually-selected morphological traits on male behavior, hormonal dynamics and pairing success, 3) examine the hormonal correlates and energetic costs of aggressiveness in polygynous, monogamous, and unpaired males, and 4) compare hormonal responses to a social challenge in northern pintails, a monogamous and non-territorial species , and white-cheeked pintails, which are occasionally polygynous and highly territorial. Blood samples taken during these experiments will be analyzed for 5 hormones using celite chromatography and radioimmunoassay. This cross-disciplinary project will address not only the effect of hormones on behavior but also the feedback of behavior and social interactions on hormones. Few studies of mate choice have considered the implications of endocrine mechanisms in the evolution of sexually-selected behavior.
