The role of sexual imprinting for sex recognition in zebra finches: A difference between males and females

In sexually dimorphic birds, morphological characteristics are assumed to play an important role in conspecific sex recognition. In spite of the limited evidence, most studies done so far support this assumption. Less attention has been given to the question of how adult birds may have acquired the ability to discriminate between the sexes. This study investigates the relationship between the early experience of young birds and their later competence in differentiating between male and female conspecifics. Young white zebra finches, Taeniopygia guttata, were reared by white parents. The white morph of this species lacks all sexually dimorphic markings, except for a difference in the intensity of the red coloration of the bill. Bill colour of the parents was manipulated by applying nail polish. As adults, males and females were tested for their preference in a series of two-choice tests. Males showed a clear preference for birds with the same bill colour as their mother, irrespective of the sex of the stimulus birds. Females, on the other hand, preferred males to females, but did not differentiate on bill colour. It can be concluded that in zebra finch males sex recognition is guided by morphological characteristics that have acquired their signal value during rearing. For females, other factors, such as behavioural cues, appear to be most important for sex recognition. (C) 1995 The Association for the Study of Animal Behaviou