Abstract
In order to study the effects of social interactions on the diurnal variation of copulatory behavior, the feeding time was changed (9:00 or 15:30), and variations of social behaviors with the same or other sexes were observed. (1) Sexual approach in cocks was very frequent in the late afternoon and the peak became higher when fed at 15:30. (2) The number of acceptance in hens was more in the late afternoon, though the rate of acceptance for approach in cocks was higher after feeding. So the peak of acceptance in the late afternoon became higher when fed at 15:30, and coitus was concentrated in this time. (3) A peak of aggression among cocks appeared just after feeding, and the peak was shifted by changing the feeding time. (4) Then, feeding at 15:30 increased copulatory behavior as well as aggressive behavior in the late afternoon and these accelerations were occupied by the most superior cock in a group. The possibility was discussed that notable expression of the dominance by the most superior cock during the eating time might affect hens in the group to increase acceptance.
