Effects of testosterone on the behaviour of the domestic chick. I. Effects present in males but not in females.

In male chicks, specific facilitation of male copulatory movements occurs at a lower dosage of testosterone oenanthate than does facilitation of approach to the test object, or of attack. The latter effects can be dissociated in other ways from the first; they may depend upon a single central change in visual responsiveness or persistence. Females show none of these changes, although they are capable of the behaviour patterns involved, and do show other behavioural effects of testosterone. On day 3 normal males copulate and attack more, and flee less than do females.