Figure 5: The multilevel society of the Golden snub-nosed monkey.

The fundamental level of social organization is the one-male, multifemale social unit (OMU), which contains a single breeding male, several breeding females (harem) and their offspring. There also exist all-male units (AMU), in which several bachelor males reside together. Many of these are juvenile and sub-adult males who transferred directly into the AMU from their natal OMU. In some cases adult AMU members are previous residential males of an OMU. AMU members are characterized by an age-graded dominance hierarchy and kin relationships. Solitary males are principally adults who have been replaced as breeding males in their OMU. However they may transfer into an all-male band or follow the breeding band and try to take over an OMU from the residential male. The breeding band is an aggregation of OMUs that coordinate their daily activity. Although they feed, forage, rest and travel together in a coordinated manner, members of different OMUs within the breeding band rarely engage in social interactions. The all-male band is composed of 1–3 AMUs that are socially distinct from each other but coordinate their activities in close spatial proximity. The herd is composed of an associated breeding band, all-male band and solitary males. Although the social components within a herd are often separated, they are characterized by considerable home range overlap and coordinate travel. The troop is composed of two or more herds in a large home range that engage in seasonal fission–fusion dynamics. Individuals and OMUs have been observed to transfer between herds of this multilevel society. The snub-nosed monkey illustrations are copyrighted 2014 by Stephen D. Nash/IUCN/SSC Primate Specialist Group. Used with permission.