The image on the left depicts three female cowbirds. Females use subtle visual signals to communicate with one another and with males.  Thus, what may appear to be three females doing little may well be three females reacting to each others visual signals, as well as the behavior of other birds in the area.  It is quite possible that one way females learn preferences for specific males is by watching other females reactions to males vocal and social behavior. Recent studies in our lab indicate that females are very competitive among themselves for the attention of males and there may be many parallels between the development of female preferences and the development of male song production.

The image on the right depicts four male cowbirds singing to one another. This communicative interaction is of great significance to the establishment of male social order but also appears to be a very important way for males to stimulate and attract female cowbirds. These two photographs are instructive of gender differences in the nature of communication in this and many species.  The male communicative behavior is obvious, competitive, and can be overtly aggressive. The female behavior is subtle, and difficult to observe. This is one reason why much more is known about development and function of male communication. In the end, much of the male behavior is designed to impress the female. 

This is a spectrogram of the actual song used to elicit a female copulation solicitation posture followed by a series of whistles that are sometimes produced when the male mounts the female.  In the far left of this spectrogram the song is labeled as well as the introductory notes, which trigger the solicitation posture in the female. The whistle sequence is also labeled. High-ranking males use the whistle sequence much more than low ranking males who may frequently use no whistle advertisement at all.

These baby cowbirds were hand reared from the egg. The eggs were collected from nests, which we placed in aviaries during the breeding season. We place fake eggs in the nests, which encourages the females to lay their eggs in these nests. These baby birds will be raised in our aviaries where they will choose mates and breed in the following spring. After microsatellite parentage analysis is performed to determine their parents, we will be able to investigate group and individual level effects on reproductive success and the quality of the young produced. Recent work indicates that the reproductive success of the individual cannot be predicted without an understanding of group level social effects.