ugandan red colobus groups are multi-male. habitat quality and predation can affect group size which range in size from as few as 3 to as large as 85 individuals, although an average group size is around 40 individuals. the size of a group is often determined by how many males are present. within a social group males are the stable component and rarely successfully move to another group. females can disperse to other groups easily and are attracted to groups which contain a higher number of males. in all social groups of ugandan red colobus females out-number males. this natural imbalance is further exaggerated by the predatory action of common chimpanzees which single out females and juveniles as prey. within groups there is a dominance hierarchy with adult males being dominant over adult females, most likely because of their larger size.