Grouping in Japanese quail. 1. Agonistic behavior during feeding

Agonistic behavior in male Japanese quail, shown by aggressive pecking after feed restriction, was potentiated in unstable groups (a visitor bird moved to a new cage containing an unfamiliar resident each 24-hr period) but not in stable (a pair that was never changed once the birds were placed in cages) groups. The resident quail were more aggressive than either visitors or individuals of the stable groups. Ambivalent behavior (behavior characterized by an aggressive action followed immediately by a submissive posture) during feeding competition was observed in both the unstable and stable groupings. The ambivalent behavior appeared to be a conditioned response and was probably a result of the motivation to feed after a period of feed deprivation. During the experimental period the stable pairs of quail gained 28% of their initial body weight, but the resident and visitor quail, which were in the unstable grouping, gained only 15 and 13%, respectively. The differences in percentage weight gain were significant. Paired testes weights of the resident and visitor quail were significantly less than those of the stable birds.