Squirrel monkeys primarily eat insects and fruit, but they occasionally supplement their diet with small vertebrates, nectar, flowers, buds and seeds. Squirrel monkeys prefer to go after stationary insects; grasshoppers and caterpillars are their favorite foods. Some of the small vertebrates they consume are birds and bats.
Squirrel monkeys are New World monkeys found throughout Central and South America, primarily in tropical rainforests. However, unlike many other tropical species of monkeys, squirrel monkeys can inhabit a much wider variety of habitats, including edge forests, which are regions of forest that have begun to regenerate after a major ecological disturbance, such as natural disasters or human expansion. Only two of the five species of squirrel monkeys are classified as threatened by the International Union for Conservation of Nature, and the common squirrel monkey is frequently captured for the pet-trade industry and medical research.
Squirrel monkeys face predation from raptors, snakes and large cats, but the most common predators of the monkeys are raptors. To avoid these predators, squirrel monkeys in Peru have been known to frequently travel with another primate species called the Capuchin monkey. The Capuchin monkeys use an alarm system to alert the other monkeys of nearby predators, warning the squirrel monkeys at the same time.