Group Formation of Squirrel Monkeys
The Squirrel Monkey is probably one of the most studied Monkeys on the planet. They are small and not aggressive and stay in groups, which makes it easy to keep track of them.
The social behaviour of squirrel monkeys Although squirrel monkeys are among the most popular laboratory and zoo animals, relatively little is known about their social behaviour in the wild. There have been some field studies (Baldwin, 1985; Baldwin and Baldwin, 1971; Boinski, 1987a, 1987b; Boinski and Mitchell, 1994), which have shown that the social behaviour of Saimiri oerstedi of Central America differs significantly from that of S. boliviensis and S. sciureus of South America. As only the latter two species are currently kept in captivity, I will focus on their social behaviour. In addition to the information available from field studies, a considerable amount of data on the squirrel monkey’s social behaviour has been collected in the semi- natural environment of Monkey Jungle in Miami (Baldwin and Baldwin, 1981; DuMond, 1969; DuMond and Hutchinson, 1967).
Group size in the wild varies significantly in different geographic areas. The most common size is from 20 to 40 animals; however, groups exceeding 200 animals have been reported, though it is not clear whether such large groups consist of a single unit, or are in fact composed of several smaller groups traveling together during periods when food is abundant. Group composition has only been determined from a few feral groups of about 20 animals. These groups included about three adult males and at least twice as many adult females. The adult females function as the core of a Saimiri group, and all other group members are attracted to them. There are clear sub-groups of adult females, juvenile females, adult males and juvenile males. Within the group, the males are sexually segregated (although this is less pronounced in S. sciureus than in S. boliviensis), tending to live at the periphery of the group, except during the mating season, when they are spermatogenic and more socially active. Outside the breeding season, the females can react very aggres- sively towards approaching males. Saimiri groups are matrilinear.
Young males leave their natal group in small troops of three to five animals at the age of three years. Adult males stay in a breeding group for two or three seasons (Mitchell et at., 1991), until other males take over the group.