We examined the relationship between singing and reproductive success in cowbirds. We amassed data from 17 captive flocks (164 males, 167 females) that we have studied over 4 years. For each flock, we conducted extensive observations on social interactions as the birds competed, courted, and...

Extrapair fertilizations complicate our understanding of cooperative breeding in a number of ways. For example, auxiliaries may reduce the costs of seeking extrapair fertilizations for breeding males or females, and auxiliary males may themselves seek copulations with the breeding female in...