Group territoriality and the benefits of sociality in the African lion, Panthera leo

We analysed 38 years of data on 46 lion prides in the Serengeti National Park, Tanzania, and found that territorial competition directly affected critical components of female fitness and that larger prides gained and maintained access to the highest-quality habitat. Neighbours had a significant negative effect on female reproductive success and survival, and larger prides were significantly more likely to maintain control of disputed areas and to improve the quality of their territories. Adult females were significantly less likely to be alone when a pride had more neighbours, suggesting sensitivity to risk of encounter. In most cases, the effects of intergroup territorial competition were associated only with prides that had not recently split (i.e. that were not closely related). Overall, males were more important in group-territorial competition than expected, and female mortality and wounding rates were significantly associated with male neighbours, suggesting that males may use lethal aggression to tip the balance of power in favour of their prides. Within the Felidae, only lions are consistently gregarious, and our research illustrates that numerical advantage in territorial competition is a primary benefit of group living in lions and may have been important in the evolution of lion sociality. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.