The Peruvian spider monkey (Ateles chamek) is a spider monkey that inhabits the tropical rainforests of Bolivia, Brazil, and Peru. It has an entirely black coat, long arms and legs, and a prehensile tail it uses freely; it grips branches securely with the bare patch on the underside of the tail. It chiefly feeds on fruit, and also consumes flowers, insects, and bark, contributing to seed dispersal. While forming large troops of 20–50 individuals, it typically moves in smaller parties of around three individuals, and in this patrilocal society females leave the group after reaching maturity. Populations have declined due to hunting and deforestation, and it is classified as Endangered (IUCN Category I B).