PROXIMITY STRUCTURE IN A CAPTIVE COLONY OF JAPANESE MONKEYS (MACACA-FUSCATA-FUSCATA) - AN APPLICATION OF MULTIDIMENSIONAL-SCALING

Spatial proximity was used to investigate the social structure of a group of 14 Japanese macaques (Macaca fuscata fuscata) living in Cavriglia Park (Arezzo, Italy). Instantaneous sampling was used to collect data. From April 1984 to March 1985, 273 hr of observation were accumulated. Time spent in proximity by any two monkeys was transformed into a similarity index. Two triangular matrices were created with these indices (one for the non-breeding and the other for the breeding season) and submitted to nonmetric multidimensional scaling (MDS). During the non-breeding season proximity proved closely related to hierarchical relationships and the existence of two real social classes was suggested. Tendency to loneliness was associated in this period with old age in females and low rank in both females and males. Moreover, socially stable versus socially unstable animals had different spacing patterns. Almost the same central-peripheral structure was outlined in both seasons, consistently with a stable oikia hypothesis for this group under these conditions. During the breeding season social organization was influenced by individual sexual interest. A male spacing pattern emerged, probably in correlation with female homosexuality, which played a preeminent role in the sexual context. The relative loneliness of sexually immature individuals was evident in this season. © 1990 Japan Monkey Centre.