The Squirrel Monkey has a white mask of fur around their eyes, with dark brown or black around the mouth. They are very curious and intelligent primates and have the largest brain relative to size of all primate species. In the wild they live in large groups up to 100. They are exceptionally good climbers, and only occasionally come down from the trees. Their tail is not prehensile so they are unable to use it to hang from trees. However, they do use their long tail for balancing when jumping form tree to tree. Squirrel monkey's will spend about 10% of their day resting while the remainder is spent being active, with up to 80% of their time foraging for food. Squirrel monkeys have approximately 30 different calls which can be divided into multiple groups including: noisy, twitters, peeps, chucks, cackels, and pulsed calls.
Squirrel monkeys have a polygamous (having more than one mate) mating system. Typically only one or two males copulate the most frequently of any in the group. Females are responsible for almost all of the parental care of their offspring.
Predators includes raptors, snakes and felids.