The black squirrel monkey (Saimiri vanzolinii), also known as the blackish squirrel monkey or black-headed squirrel monkey, is a small New World primate, endemic to the central Amazon in Brazil. It largely resembles the female of the far more common Bolivian squirrel monkey, though the latter lacks the black central back. This squirrel monkey has one of the most restricted geographical distributions for a primate, living in várzea forest in the confluence of the Japura and Solimões rivers. Its entire range is within the Mamirauá Sustainable Development Reserve. It resides in the reserve with two other Saimiri species. It is a social primate that travels with other black squirrel monkeys in large troops within its habitat. Its small size makes it an easy target for its predators; however, it may resist predators when it travels in large troops. Its species overall has positive effects on the economy. Description Black squirrel monkeys are small primates. They have blackish-gray fur over most of their body except for their legs and stomach. Their legs can be yellow or have a reddish tint. Their stomachs will have a yellow tint. They have short and dense fur everywhere except for certain areas on the face. They lack hair in the areas of the nostrils and lips, and the skin is black in these areas. Black squirrel monkeys tend to be 27 to 32 centimeters in length not including the length of their tails. Their full length, including their tails, can be about 40 centimeters longer than their length without their tails. Male black squirrel monkeys range in weight anywhere from . Female black squirrel monkeys have a weight range of . Distinctive characteristics They get their name from the strip of black that extends from their head to the end of their tail. The black fur above their eyes forms a shallow arch and is lower on their foreheads than other species. Their tails are specifically distinct from the Saimiri sciureus species because black squirrel monkeys have much thinner tails. Lifespan On average, black squirrel monkeys live up to 15 years in their natural habitat, the várzea forest. They can live about 5 to 10 years longer than that when they are kept in captivity. Taxonomy The black squirrel monkey falls under the genus, Saimiri. There are four other species that fall under this same genus with the black squirrel monkey. Saimiri boliviensis Saimiri oerstedi