Animal Behavior: These animals are social and tend to form groups of approximately thirty individuals. Groups of up to 100 have been reported. For the most part, these large groups split into smaller subgroups to forage. The whole group is only together for a few weeks out of the year. Group size varies with habitat type and seems to depend largely on the productivity of the area. These spider monkeys live mainly in the top of the tree canopy where they forage diurnally. They tend to feed heavily in the early morning and rest for the remainder of the day. These monkeys are among the most agile of the primates. They are often seen hanging by one limb or by the tail, which essentially functions as a fifth limb. They walk nimbly along the upper surfaces of branches and are able to pick things up with their tails.

Eating Habits: These monkeys eat mainly ripe fruit and less frequently leaves and flowers. They may also eat some nuts, seeds, insects, arachnids, and eggs.

Range: Ateles geoffroyi inhabit mature rainforests and montane forests.

Conservation Efforts: This monkey is listed as endangered. Apparently, it is tolerant of some logging but depends upon large areas of tall forest. It is hunted for food and is locally extinct from most accessible areas. It's large group numbers and noisy habits make this species easy to find.

Animal Facts: Head and body length ranges from 305 to 630mm, and tail length from 635 to 840mm. With respect to body length, Ateles geoffroyi have extremely long limbs and tails. The head is small and the muzzle substantial. The upper fur is black, brown, or reddish and the face is often marked with a pale mask of unpigmented skin around the eyes and muzzle. The arms and feet are dark and the underparts paler (white, pale brown, reddish, or buff).