Behavioral correlates of post-breeding weight change in a captive flock of American flamingos (Phoenicopterus ruber ruber).

In a captive flock of American flamingos (Phoenicopterus ruber ruber), a pattern of weight loss after the breeding season was observed in the majority of individuals of both sexes, but weights eventually stabilized after several months. Social dominance (as determined by a 6-month behavioral study) was a highly significant predictor of early post-breeding weight loss, with dominant individuals undergoing less severe weight loss over this period; and behavioral observations supported the hypothesis that social dominance enhanced access to food in both males and females. Later in the study period, social dominance was no longer a significant predictor of weight changes, but rather individuals that had undergone previous large weight losses seemed to spend a greater amount of time feeding in an apparent effort to offset weight loss. Over the course of the study, there was a marked decline in both the proportion of agonistic encounters that were resolved and in the proportion of agonistic encounters that occurred at the feeder. These trends occurred even though there was no evidence of a decrease in overall use of the feeder. Thus, dominance-related differences with respect to food access and post-breeding weight loss appeared to be transitory phenomena, which corrected themselves as levels of aggression eventually declined. Intervention to increase the equality of food access in the post-breeding period may not be necessary in captive flamingo flocks, since low social rank in most cases appears not to have harmful long-term consequences.