Dissertation Research: The Endocrine Basis of Species Differences in Avian Paternal Care

Indiana University, Bloomington IN

Investigators

Abstract

Surprisingly little is known about the hormonal basis of species differences in avian parental care. Of particular interest is how parental males integrate song and territorial behavior with parental behavior, since time spent on one activity usually precludes time spent on the other. The objective of the proposed research is to determine whether circulating levels of the hormones testosterone and prolactin are responsible for the difference in paternal behaviors of two related species of songbird, the blue-headed vireo (BHV) and the red-eyed vireo (REV). Male BHVs incubate eggs, while male REVs are far more typical among songbirds in that they do not. Thus the species differ greatly in the degree to which males contribute to parental care. Using hormone manipulations in free-living males of both species, this research will test whether alterations in an individual's circulating hormone levels will lead to corresponding alterations in its song and parental behaviors. The mechanisms of parental care in Passeriformes, the largest order of birds, have not been examined as closely as those in other avian orders. The proposed research provides a strong test of the predicted functions of testosterone and prolactin in parental males.