ANTIPREDATOR EFFECT OF CONSPICUOUS PLUMAGE IN A MALE BIRD

Sexual selection theory suggests that conspicuous plumage in male birds evolves through contest competition between males and choice of bright males by females. A basic assumption is that brightness is limited by increased predation or other mortality agents. Alternatively, the unprofitable prey hypothesis suggests that conspicuous birds signal to predators that they are difficult to catch. In this study, stuffed pied flycatchers, Ficedula hypoleuca, were exposed to sparrowhawks, Accipiter nisus. Contrary to the assumption of sexual selection theory, the hawks attacked dull-coloured females more often than conspicuous males. These results provide the first experimental evidence for the unprofitable prey hypothesis, and suggest that predation may sometimes reinforce sexual selection processes. © 1992 The Association for the Study of Animal Behaviour.