Why are Birds Bright and Colorful?

wp051bd43d_05_06We study the ecology and evolution of reproductive behavior in birds. We are particularly interested in extra-pair mating, which occurs when individuals mate with individuals ‘outside’ their supposedly monogamous relationships. In most birds extra-pair males only provide sperm – they do not help with parental care. Thus, if females are choosing to mate with these males, then the potential genetic benefits of sperm from another male are likely to be small. So why is extra-pair mating so common in birds? One explanation is that females gain better (‘good’) genes for their offspring that enhance their immunity or attractiveness, but finding these genes has been difficult.