My interests center in two areas of behavioral ecology: animal communication and mating systems. In my work on animal communication, I have for many years investigated functional aspects of bird song in collaboration with Steve Nowicki and Susan Peters of Duke University . One focus of this work has been on exploring the implications of proximate mechanisms of song development and song neurobiology for ultimate questions concerning the function of song in male-female communication. This focus has led to investigations of the effects of early nutritional stress on the development of the brain nuclei that control song and on the quality of song learning, using song and swamp sparrows as study organisms. We have also examined, using song sparrows, the preferences of females for well-learned over poorly-learned songs and for local over foreign songs. Another focus of our song work has been on how singing behaviors are used in aggressive signaling between male birds. We have examined a variety of possible aggressive signals in song sparrows, including song type matching, partial matching, song type and variant switching frequencies, and the use of low amplitude “soft song.” We are especially interested in determining which behaviors are reliable indicators of attack and in elucidating the mechanisms that maintain reliability.

In my research on mating systems, I have focused on the evolution of social polygyny, a mating system in which one male simultaneously forms long term associations with more than one female. In this work I have studied red-winged blackbirds, pied flycatchers, and house wrens. Females of these species that mate with an already-mated male typically experience a cost due to receiving reduced male help with parental care. The key question then is why females choose to pay this cost of polygyny. In addressing this question I have emphasized testing between alternative hypotheses using field experiments. I have also investigated the effects of polygynous mating on other aspects of behavior and on morphology.