Measuring just 25 to 40 centimeters in length (10-15 inches), the squirrel monkey is often the first primate species seen by visitors to Tambopata National Reserve. They are extremely curious monkeys, roaming through the forest canopy in large troops, seemingly undisturbed by the presence of humans far below, often following a leader in single file along frequently used routes.
Weighing between 1.7 and 2.4 pounds (770 to 1090 grams), squirrel monkeys can be seen throughout the Amazon basin. Their natural range extends from Central America to South America.
Research conducted by naturalists since the mid-1980s has established the existence of five subspecies of squirrel monkey, dispersed across the specie’s extensive range. The black-capped squirrel monkey (Saimiri sciureus boliviensis), also found in Bolivia and Brazil, can be seen in Tambopata National Reserve.
As its name suggests, the black-capped squirrel monkey is easily identified by its black crown, below which its expressive white face contrasts with the short yellow-orange fur of its upper parts and is complemented by the white of its underparts.
In common with most New World monkeys, the squirrel monkey is active during the day. They spend practically their entire lives in the rainforest canopy, where they move through the branches with considerable agility. The litheness exhibited by squirrel monkeys is particularly impressive given the fact that their tails –which are as long as their bodies- are not prehensile and therefore cannot be used to aid them when climbing. Instead, squirrel monkeys use their tails in the same way that human tightrope walkers steady themselves with a balancing pole.
Their small size makes squirrel monkeys vulnerable to predators, and they gather into large groups as a defensive measure. Squirrel monkeys live in large mixed male and female troops. While troops of up to five hundred individuals have been recorded, smaller groups of around twenty-five members are often observed.
Within troops, individuals will employ a range of vocalizations, including warning calls when the presence of predators is detected. Squirrel monkeys have the largest brain size to body mass ratio of any primate and they are described by scientists as among the most vocal of all New World monkeys, employing at least twenty-six different calls, ranging from purring to barking, screaming and squawking. Squirrel monkeys’ natural predators include birds of prey, snakes and felines.
The diet of the omnivorous squirrel monkey includes insects, fruits, seeds, flowers, tree gum and small vertebrates. They can sometimes be seen foraging in mixed groups with capuchin monkeys. Females give birth to their young in the rainy season, when rainforest fruits are abundant.
Because they are gentle and affectionate, squirrel monkeys have for many years been victims of the international pet trade; however, their numbers are not considered threatened.
Other species of monkey sighted regularly in the trees surrounding Tambopata Ecolodge, and in the branches above the nearby trails maintained by the lodge, include the saddleback tamarin monkey (Saguinus fuscicollis), dusky titi monkey (Callicebus moluch), and brown capuchin monkey (Cebus apella). Further from the Ecolodge, in the forests explored during the different excursions guests are offered, in addition to these species the red howler monkey is also commonly sighted (See itineraries).