How Song Experience Affects Female Mate-Choice, Male Song, and Monoaminergic Activity in the Auditory Telencephalon in Lincoln's Sparrows.

A sexual signal can indicate not only the signaler's attractiveness as a potential mate but also the signaler's competitiveness relative to rivals. As the attractiveness or competitiveness of the prevailing signaling environment increases, individuals prospecting for mates should change their choice threshold, whereas competing individuals should shift resources toward elevating their own competitiveness. Previous studies show that experimental elevations of song competition increase male competitive behavior in Lincoln's sparrows (Melospiza lincolnii) and European starlings (Sturnus vulgaris). Through a series of experimental manipulations using laboratory-housed Lincoln's sparrows, we have also discovered that females change the strength of their song preferences depending on the attractiveness of the song environment to which they have recently been exposed; compared to a less-attractive environment, a highly-attractive environment elevates the threshold for releasing phonotaxis behavior toward male song. These behavioral adjustments are associated with changes in forebrain monoaminergic activity that are triggered by experimental manipulations of the quality of the song environment. Findings from these studies suggest possible neural mechanisms for the regulation of adaptive behavioral plasticity associated with dynamic sexual signaling environments.