A newly-found pattern of social relationships among adults within one-male units of golden snub-nosed monkeys (Rhinopithecus roxenalla) in the Qinling Mountains, China

Group living provides various advantages to individuals in regards to protection avoidance, intergroup competition, productive success and social information. Stable one-male units (OMUs) consist of relationships between the adult females and the resident male as well as the relationships among adult females. Based on continuous observation of a reproductive group of golden snub-nosed monkeys (Rhinopithecus roxellana) in the Qinling Mountains, we analyzed the relationships among adult individual dyads within 4 OMUs. The results indicated that in golden snub-nosed monkey societies, females not only had no strong tendency to build a relationship with the resident male in the OMU but also had no strong tendency to build relationships with other females in the OMU. In comparison with hamadryas (Papio hamadryas) and gelada baboons (Theropithecus gelada), the relationships within golden snub-nosed monkeys OMUs showed neither the star-shaped pattern observed in hamadryas baboons nor the net-shaped pattern observed in gelada baboons. We concluded that the relationships within golden snub-nosed monkey OMUs indicated a third pattern in nonhuman primate societies. Future research is required to determine the potential mechanisms for such a pattern.