The role of previous social encounters and body mass in determining social rank:: an experiment with white-tailed deer

The social organization of many vertebrates is based on dominance behaviours occurring between pairs of individuals. Initial encounters between any two individuals can be crucial in determining the dominance relationship that will prevail between them throughout their lifetime. Achieving a high dominance status can be critical when competition for limited resources such as foraging sites is intense. The mechanisms that prevail for the establishment and stability of dominance relationships between individuals are, however, poorly understood. Our study aims to identify factors influencing the establishment of dominance relationships between young individuals, using white-tailed deer, Odocoileus virginianus, fawns as a model species, and to evaluate the possibility of long-term individual recognition after temporal separation. We used an experimental approach to test the alternative hypotheses that dominance relationships after temporal separation are explained by (1) the outcome of the previous encounters between opponents or (2) the body mass difference between individuals independently of the outcome of initial encounters. Social rank was established during the first encounters between individuals based on differences in body mass and was maintained afterwards even when the differences in mass between individuals were reversed. Our results suggest that individual long-term recognition may influence the outcome and the stability of dominance relationships after temporal separation of individuals. Dyadic dominance relationships seem to be established early in life and may then endure into adulthood. (c) 2006 The Association for the Study of Animal Behaviour Published by Elsevier Ltd. All rights reserved.