White-Faced Sakis belong to the group of New World monkeys. Their small bodies contrast with long and heavily furred tails. Otherwise called the 'Guianan Sakis', these primates have powerful bodies and strong muscles on their legs, making them excellent jumpers. These animals display sexual dimorphism: males are distinguished by black overall coloration and buff-furred faces, whereas females have considerably lighter coats with bright patches, stretching from each eye to the chin. As opposed to Howler monkeys, these animals don't have prehensile tails and cannot grip objects with their tails.
The natural range of this species includes parts of Brazil, some remote areas of the neighboring Venezuela as well as the major parts of French Guiana, Guyana and Suriname. Within this territory, White-faced sakis are distributed throughout upland and lowland rainforests, occurring along the Cuyuni river basin, between the Caroni and the Orinoco Rivers. In both wet and dry habitats, these animals require sufficient amount of fruit-bearing trees and watering holes.
White-faced sakis gather into very small units of only 2 - 4 individuals. Group members take daily trips of 1 - 2 kilometers. They are most active in the early morning and early afternoon. As much as 9 hours of their active time are spent travelling. Mutual grooming is very important activity for these primates, performed by males and females and particularly, between mothers and infants. Experienced individuals teach young ones skills of infant care. Populations in captivity exhibit communal care with all members of the group helping rear offspring of each other. When moving, they use all of their four limbs. These monkeys actively use vocalizations in the daily life. The most common calls are chirps and high-pitched whistles. Meanwhile, loud calls act as territorial display. When facing a threat, these animals give out growling noises, puff themselves up to look bigger than they are as well as shake branches of trees at full strength.
Captive individuals of this species (such as those in zoos) generally exhibit monogamous mating system with very rare exceptions. Meanwhile, those in the wild tend to be either polygynous (where a single male mates with numerous females) or polyandrous (where a single female mates with numerous males), especially groups of more than 2 - 3 individuals. The reproductive system is also determined by the proportions of males and females in a given group. Reproduction occurs during the spring months. A single infant is born after 146 - 170 days of gestation. The baby grows up very quickly. Older siblings of the last 1 - 2 years usually contribute to rearing the newborn monkey. It's independent at 6 months old, although remains with its natal group before leaving at 1 year old. White-faced sakis are able to produce offspring of their own at 4 years old.
White-faced sakis are primarily threatened by loss of their natural habitat as a result of deforestation. These monkeys attract hunters for their meat as well as their highly-valued tails. In addition, some individuals of this species are captured and sold as pets.
According to IUCN, the White-faced saki is relatively common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List.
Due to their diet, White-faced sakis act as important seed dispersers of the plants they consume, thus benefiting the local ecosystem.