A study of the biology of the wild rabbit, Oryctolagus cuniculus (L.), in confined populations. II. The effects of season and population increase on behaviour

Abstract

The major activities of wild rabbits in confined populations are classified and aefined. Seasonal changes of behaviour are described. The social organization of rabbits in three confined populations during the 1958 breeding season is presented in detail. With increase in density, the number of breeding groups in each population increased, and mean size of group territory and home range decreased. Male home ranges remained larger than female home ranges, and the home ranges of dominant males larger than those of their subordinates except under the most crowded conditions, when all animals in the group moved over the same area irrespective of dominance or sex. Mean size of home range was greatest during the summer months, when social pressures were absent, and smallest during the breeding season, when social activities were at a maximum. During the breeding season the dominant and older animals moved over larger areas than their younger subordinates, and males moved over larger areas than females. During the summer most of these differences disappeared. Aggression between males was always high. With increase in population, aggression against foreign males increased. Aggression between females was low at low densities. As the population grew, aggression between the females belonging to the same group increased. Most shifts of home range occurred during the period of group formation, when young adults of both sexes were forced to move to join breeding groups, and towards the end of the breeding season when the older young began competing sexually with their parents. Shifts of young rabbits during the breeding season were also common, but many of these were probably due to experimental scattering of kittens. The formation of breeding groups was initiated by the behaviour of old females with previous breeding histories.