My research is in animal behavioral ecology and physiology. Throughout much of my career, I have conducted field studies of birds to address questions related to sex-ratio manipulation, brood parasitism, extra-pair paternity, nestling competition, and the effects of hormones on parental investment. I am currently involved in a study of incubation behavior by birds nesting in Amherst College's own bird sanctuary. My collaborators, students, and I are examining how female tree swallows make reproductive decisions in the face of certain physiological constraints (for example, increases or decreases in ambient temperature), based on their current physical condition as well as their prospects for future survival.

In recent years, I have spent much of my time studying fish in the laboratory. One of my primary research interests is studying the effects of environmental contaminants, particularly compounds that interfere with the neuroendocrine system, on fish behavior and neurophysiology. My students and I have found that exposure to environmentally-relevant levels of contaminants can suppress male-typical behavior and alter neurotransmitter activity in the brain. These studies have implications not only for wild fish populations, but for other vertebrates as well. We are also engaged in studies of the role of aggression in the evolution of cerebral lateralization, the partitioning of cognitive functions between the two hemispheres of the vertebrate brain.