Social and Individual Behaviors in Captive Slow Lorises

Abstract

Two groups of wild-born slow lorises were housed together in a semi-natural laboratory environment for 20 weeks. The animals are nocturnal and were observed under dim red illumination by means of a low-light TV camera. The behavior of each animal was videotaped for 5 consecutive minutes 3 times a week. Then, written records were obtained of everything that the animal did or had done to it, moment by moment, as well as the time spent on each activity. Analyses were carried out to determine: which behaviors accounted for the majority of time and frequency scores, how behavior changed over time, and what were the dynamics of within-group interaction. The most striking finding was the degree of sociability found to exist among adult slow lorises. Once they had become familiar with one another, they approached each other often but seldom left during an ongoing interaction, spent much time sitting in proximity to one or more others or in passive contact, social groomed and play-fought. Agonistic behavior was infrequent and did not have serious consequences. The tendency to interact in predominantly friendly ways with others was true of all individuals in a group. These findings were surprising because nocturnal prosimians once were believed to be relatively solitary. However, the present results are in keeping with those of recent field reports on other, related species. It is apparent that the old view of nocturnal prosimians is in need of some revision.