Does beak colour affect female preference in zebra finches?

Mate choice in the zebra finch, Taenopygia guttata, has been extensively studied and the results have been thought to provide support for the hypothesis that females prefer brightly coloured males even in a monogamous species. A bright, red beak colour was seen as the important feature upon which females based their preference. However, many recent studies have failed to find any effect of beak colour on female preference, and some suggest that females use display rate to choose a mate. The evidence provided by various zebra finch studies is critically examined and two possible explanations for why the results differ are suggested. First, there may be a hierarchy of choice criteria with display rate being more important than beak colour. Second, it is possible that female preference for male beak colour depends on female experience of males during maturation. Finally studies on the role of beak colour in zebra finches should consider the possibility that it is males rather than females who are responding strongly to beak colour differences between the sexes. (C) 1996 The Association for the Study of Animal Behaviour.