The proposed research will examine California Towhee (Pipilo crissalis) duet song as a tool for addressing the evolution of vocal communication between pairs of socially monogamous birds. Previous studies of duetting have been few, especially among temperate species, and have failed to arrive at a general consensus regarding the functional significance of this complex trait. Discrete reproductive costs and benefits of duet song will be specified to allow for experimental tests of predictions and relevant hypotheses. Previous research suggests that duetting in California Towhees occurs in a variety of contexts such as territory defense, mate guarding, ensuring partner commitment, and individual recognition. This study will provide an integrated, complete analysis of vocal duet function by considering multiple potential benefits accrued to individuals in pairs that duet and will be one of the first studies to experimentally test multiple adaptive hypotheses for the function of duet song in birds.
