sometimes occur, but these are believed to be temporary mergers of two groups. On average, groups contain about 60% more females than males. The squirrel monkey groups have a home range of between . Group ranges can overlap, especially in large, protected areas such as Manuel Antonio National Park. Less overlap occurs in more fragmented areas. Groups can travel between per day. Unlike some other monkey species, the group does not split into separate foraging groups during the day. Individual monkeys may separate for the main group to engage in different activities for periods of time, and thus the group may be dispersed over an area of up to at any given time. The group tends to sleep in the same trees every night for months at a time, unlike other squirrel monkeys. There are no dominance hierarchies among the females, and the females do not form coalitions. Males in the group are generally related to each other and thus tend to form strong affiliations, and only form dominance hierarchies during the breeding season. This is especially the case among males of the same age. Neither males nor females are dominant over each other, an egalitarian social system that is unique to Central American squirrel monkeys. In South American species, either the females (S. boliviensis) or males (S. sciureus) are dominant over the other sex, and both sexes form stable dominance hierarchies. Groups of Central American squirrel monkeys generally do not compete or fight with each other. Male Costa Rican squirrel monkeys are known to have very close bonds with each other. Although South American species of squirrel monkeys often travel with and feed together with capuchin monkeys, the Central American squirrel monkey only rarely associates with the white-headed capuchin. This appears to be related to the fact that the food the Central American squirrel monkey eats is distributed in smaller, more dispersed patches than that of South American squirrel monkeys. As a result of the different food distribution, associating with capuchin monkeys would impose higher foraging costs for the Central American squirrel monkey than for their South American counterparts. In addition, while male white-headed capuchins are alert to predators, they devote more attention to detecting rival males than to detecting predators, and relatively less time to detecting predators than their South American counterparts. Therefore, associating with capuchins would provide less predator detection benefits and impose higher foraging costs on