Social behavior of a captive group of golden snub-nosed langur Rhinopithecus roxellana

Detailed accounts of social relationships in the golden snub-nosed langur Rhinopithecus roxellana are rare, and little is know about its social structure. The aim of this study was to contribute to the understanding of social relationships by analyzing patterns of affiliative and aggressive interactions in a captive group of this poorly known species. The 11 focal individuals were organized into a one-male unit, or OMU (i.e., a single adult male that associates with multiple adult females and their offspring), and an all-male unit, or AMU (i.e., a social unit formed only by males). One-minute instantaneous scans and ad libitum sampling techniques were used to record affiliative and agonistic behaviors, respectively. In general, OMU and AMU individuals displayed similar amounts of affiliative behaviors. However, affiliative interactions were more frequent within than between subunits. On the other hand, AMU members displayed more aggression towards members of their own subunit, and more often counterattacked any group member than did individuals of the OMU. Although OMU and AMU individuals did not interchange more agonistic behaviors with members of their own subunit than with members of the other subunit, they intervened more often on behalf of members of their own subunit, and against individuals of the other subunit. We discuss our results in the context of what is known regarding social behavior in captive and wild populations of this species and other primates with a multilevel social system.