A simple ethological monitoring system to assess social stress in group-housed laboratory rhesus macaques

The increasing awareness of the importance of social housing of laboratory primates results in the establishment of group housing in many facilities. Our aim was to develop a set of manageable tools to allow continuous monitoring of social relations within groups and to establish an objective, scientific ground on which changes in group composition could be based. We studied 38 adult rhesus monkeys (Macaca mulatta) grouped as five one-male/multi-female groups using focal sampling. We recorded the occurrence and direction of aggressive and non-aggressive social interactions as well as time spent inactive in proportion to social contacts, feeding and other activities. The present analysis clearly identified low-ranking animals with none or few affiliative contacts and who also spent much time inactive and separated from other low-ranking animals. This suggests that the present approach results in useful information concerning compatibility bt tween group members and enables identification of animals experiencing high social stress.