Early exposure to females affects interactions between male White Leghorn chickens

Abstract

To examine the effect of rearing condition on White Leghorn chickens we observed interactions between pairs comprising one male reared in an all-male group (single-sex) and one male reared with females (mixed-sex). Two males, one from each treatment, were placed in a neutral arena with either a stuffed female chicken (model) or a white jug which served as a control stimulus (control). Trials were conducted both before (20 weeks of age) and after (47 weeks of age) single-sex males were exposed to females. At 20 weeks, mixed-sex males displayed significantly more sexual behaviour in the presence of a female model than did single-sex males. In contrast, single-sex males were significantly more aggressive than mixed-sex males during the control presentation. At 47 weeks mixed-sex and single-sex males did not differ in the frequency of either sexual or aggressive behaviours. This result was due to a decrease in the frequency of sexual behaviours by mixed-sex males and of aggressive behaviours by single-sex males. Our results suggest that rearing males in all-male groups may decrease sexual behaviour and increase aggressive behaviour, but that the difference disappears with age and/or adult exposure to females.