The mantled guereza lives in stable social groups usually containing three to fifteen members. The groups usually contain one male, several females and juveniles. In some populations, groups containing several males are common. In multi-male groups, males tend to be aggressive with one another with one being dominant. Some males may be expelled from these groups. Multi-male groups may contain father-son pairs or unrelated males. Males that are not part of groups either live solitarily or with other outside males in bachelor groups. The females keep the groups cohesive and they are matrilineally related. They rarely disperse from their natal groups, except possibly when they break apart. Males on the other hand, usually leave when they become subadults or adults. They may start out being solitary and or in bachelor groups. They gain entry into a social group either by being on the periphery or displacing a group male.
