My research program focuses on the evolutionary and behavioral ecology of birds. The model system that my students and I have used since 1980 is the house wren (Troglodytes aedon), a migratory, cavity-nesting songbird. Because house wrens cannot excavate their own nest cavities, they readily use the 816 nestboxes that we provide on a forested study area 20 km north of the university.

Many of our descriptive and experimental studies have focused on two major topics:

• The first is what selective forces shape reproductive effort, and, particularly, how reproductive costs shape life history trade-offs. Currently we are carrying out experiments to determine at which stage(s) of the reproductive cycle (egg-laying, incubation, nestling/fledgling provisioning) costs are exacted.



• A second research emphasis is on sexual selection. We are investigating the basis of mate-choice decisions by female house wrens, focusing on why females engage in extra-pair matings. This project is testing the hypothesis that females engage in extra-pair matings in order to enhance the immunocompetence of some of their offspring. With a ready supply of birds and nests, we can address these and many other questions, including at the present time studies of incubation behavior and the relationship between parental condition and offspring cell-mediated and humoral immune response.