Social rank behaviour in a captive colony of polynesian rats (Rattus exulans)

Abstract

The behaviour of a colony of Polynesian rats was observed through one-way glass. Social interactions between 11 female and 8 male rats were studied. The postures of Rattus exulans (Peale) are similar to those described for R. norvegicus and R. rattus, except that there is no submissive posture and the eyes are partially closed in aggressive postures that may involve or may lead to contact with another rat. The social organisation is based on hierarchical relationships. Dominance is reinforced by overt aggression, rather than by avoidance or submissive behaviour. This causes a marked stress response in individuals of low social rank, which is manifested in low body weight, high adrenal weight, and poor body condition. The reproductive potential is restrained by responses to the high aggressive levels, which are probably intensified by high population density. Thus, the social behaviour and organisation of R. exulans may provide an intrinsic mechanism of population control that favours dispersal and a curbing of reproduction at high densities. © 1979 Taylor & Francis Group, LLC.