Some Variables Affecting the Behaviour of Irus Macaques in Dyadic Encounters
Abstract
1. The behaviour of the 61 pairings fit the general outline of wild macaque behaviour established in many field studies over the last decade. Thus the relatively high frequencies of fighting among males, of grooming among females, of mounting, grooming and inspecting among heterosexual pairs, and the predominance of non-aggressive behaviours overall—these patterns are all familiar from field studies. Such similarities between the present data and field data on this and related species suggest that many of the factors which determine sex roles in the wild are also present in dyads of the species isolated from their normal social and ecological conditions.
2. Throughout the history of field and zoo studies of primate social behaviour, distance between animals has been recognized as an important variable (Chance, 1954). Even in the confined situation of the present experiment, distance between two animals proved to be highly reliable and sensitive to a variety of influences. Thus the tendency for macaques spatially to display their social relationships is a robust phenomenon extending even to close confinements.
3. Successive encounters between animals resulted in a decrease in their total social contact, in their grooming, and an increase in their average distance. This effect was apparently dependent upon physical contact between the animals. Irus macaques have a variety of visual signals which potentially could be employed across a transparent barrier. But this experiment produced no evidence of such independent operation of the macaque's visual communication system.
