They are predominantly arboreal, and while they utilise all levels of the forests they have been observed to keep mostly to the lower canopies for the purposes of travel and foraging It has been proposed that matrilineal troops of Saimiri boliviensis are formed due to an abundance of fruit and insects present in their habitat, which is not present in the habitats of other species of the Saimiri genus. Biology Saimiri boliviensis are mostly arboreal but will occasionally also be found on the forest floor. They are diurnal and have been observed to be most active during the early to mid-morning, before resting for one or two hours in the afternoon, followed by another period of activity from the early afternoon to evening. Social systems The black-capped squirrel monkey is found in female dominated troops of around 45 to 75 monkeys, unlike its relative the Common squirrel monkey which habitually lives in male dominated troops of around 15 to 50. Similar to most other species of monkeys, female Saimiri boliviensis will remain in the troop into which they are born, while males are more likely to be excluded by more dominant females. When they reach sexual maturity, male Black-capped squirrel monkeys will disperse from their natal troop into smaller all-male groups, and will eventually join a larger mixed-sex troop, often together with other males from the all-male group. Black-capped squirrel monkey troops display high levels of aggression between females. Female monkeys will often compete with other female members of the troop to determine access to resources, however it has been observed that despite heavy competition for food they still prefer to live in large groups in order to reduce the likelihood of predation. Reproduction A Black-capped squirrel monkey will typically reach sexual maturation at around 3 years of age for females and 5 years of age for males. The yearly reproductive cycle of mature Saimiri has been observed by several researchers to be affected by a number of environmental factors, including the cycles of rainfall and levels of illumination in their habitat. The mating season coincides with the dry season, and will typically result in a single infant being born to each mother. It has been suggested that adult female monkeys are more receptive to environmental cues for the mating season to begin, and the response in males is in part attributed to behavioural and scent cues from the females.