Why do Females Engage in Extra-pair Copulation? A Review of Hypotheses and their Predictions.

Behavioural ecologists have become aware that extra-pair copulations form a major element of avian mating behaviour. Previously, attention was focused primarily on the benefits of this behaviour to males. However now that it is realized that females are not just passive participants, but instead may be largely in control of which male fathers their young, the major goal is to understand what females gain from extra-pair copulations. In this paper we summarize some of the existing hypotheses and we advance and discuss some new predictions that may open perspectives for future research.