The black-capped squirrel monkey (Saimiri boliviensis) is named from its squirrel-like behaviour – it lives in trees and spend most of its time hopping between branches. It is distinguishable from similar species by the dark black cap and the white ‘Roman type’ arch pattern over the monkey's eyes, which is more narrow and rounded than the ‘Gothic type’ arch pattern over the eyes of the other species. Also known as Bolivian squirrel monkeys, Peruvian squirrel monkeys, and black-headed squirrel monkeys, it is endemic to Brazil, Bolivia, and Peru and is found in lowland tropical rainforests near water in densely forested and swampy regions. The extremely long squirrel monkey tail is not prehensile, which means it cannot use it to grab onto things – it is primarily for balance.
