Effects of provisioning on the social behaviour of Japanese and rhesus macaques: Implications for socioecology

Long-term studies have shown remarkable similarity in the social behaviour and relationships of Japanese and rhesus macaques living in free-ranging groups. The vast majority of these studies have been of provisioned groups and many key principles have been derived from them. Provisioning is known to influence various aspects of life history and demography, as well as quantitative aspects of social behaviour, such as the frequencies of grooming and aggression. It has been widely assumed, however, that the fundamental characteristics of social behaviour and relationships observed in provisioned populations are representative of those that would occur under natural conditions. This paper reviews findings from fieldwork on Japanese macaques living under natural conditions, and compares them with patterns of social behaviour reported by multiple studies of provisioned groups of both species. Differences are apparent in the nature of social relationships between adult females, between adult males, and between adult males and females. Some of these differences can be attributed to the increased levels of aggression associated with provisioning. Others appear to be related to demographic peculiarities of provisioned groups, such as large size and skewed sex ratio. These differences can be used to generate predictions concerning the influence of ecological variables on the dynamics of social relationships and social structure. Ways in which these predictions could be tested by further fieldwork on provisioned and natural populations are discussed.