Peruvian Spider Monkey, Ateles chamek

The Peruvian Spider Monkey (Ateles chamek), known also as the Black-Faced Black Spider Monkey, is a species of spider monkey that resides not only in Peru, but also in Bolivia and Brazil. At 2 feet long, they are rather large among the species of monkey, and their strong, prehensile tails can be up to 3 feet long. Unlike many other species of monkey, they have only a vestigial thumb, an adaptation which enables them to travel utilizing brachiation. The Peruvian Spider Monkeys live in groups of 20 to 30, but these groups are rarely all together at one time. The size and the dynamics of the resulting subgroups fluctuate with the availability of food and sociobehavioral activity. They show a preference for eating fleshy fruit, but will alter their diet in response to scarcity of ripe fruit. Individuals of this species also eat small animals, insects, and leaves based on their availability. The females separate from the band to give birth, usually in the fall. These females inhabit a group of core areas where the resources are plentiful in certain seasons. Usually, the males exhibit ranging over longer distances than the females, with movement of individuals enhancing the fluidity of subgroup size. The Peruvian Spider Monkeys are independent at about 10 months, with a lifespan of about 20 years.

The monkey weighs up to 20 pounds. The body can be 24 inches long and tail 36 inches long. It has four elongated fingers and virtually no thumb, which is normal for spider monkeys but unusual for other monkeys. It can move with ease through the trees and it utilizes its tail like an extra limb in a type of locomotion as brachiation. It has an agility that can only be compared to the gibbon of Asia.

The range of this monkey is not limited to Peru but includes Bolivia and Brazil. They live mostly in lowland forests, occupying the canopy and the sub-canopy levels, but they have been observed utilizing a variety of habitat types. They live in territorial bands of 6 to 12 individuals whose territory covers about 20 square kilometers. The band size is rather seasonal, most likely because the females separate themselves from the band for a few months to give birth, mostly in the fall. It has to contest with other spider monkeys, wooly monkeys, and howler monkeys for territory and food.

These monkeys feed on leaves, berries, small animals such as birds and frogs, flowers, termites, grubs, fruits, and honey. It is mostly frugivorous with a tendency to display folivory in times when fruit is scarce. It will also eat insects, bird eggs, baby birds, and frogs. In the Amazon, groups of these monkeys show strong seasonal variations in habitat based on if fleshy fruits are available. The foraging habits of this species cause the monkeys to be an important component of seed dispersal patterns for many tree species within Amazonia.

The spider monkey has a reproductive period that can span throughout the entire year, though most offspring are born at the start of the Autumn season. It has a gestation period of roughly 140 days. The pregnant female monkey leaves the group to have her baby and returns 2 to 4 months later. The newborn spider monkey is independent at about 10 months.

This species of spider monkey, along with other species within the genus Ateles, is threatened because of exploitation by humans and loss of habitat. It is currently listed on the IUCN Red List of Threatened Species as endangered and is classified in Appendix II of CITES in spite of having been listed as a species of “Least Concern” in 2003.

Image Caption: Spider monkey (Ateles chamek) in São Paulo Zoo. Credit: Miguelrangeljr/Wikipedia (CC BY-SA 3.0)