White-whiskered spider monkey is endemic to the Amazon basin and is among the least known spider monkeys of the region. It's a quite large and slender primate with a long, prehensile tail, often acting as a 'fifth limb'. The spider-like legs of this monkey are very long. The animal has a furless area on the underside of its tail tip. The wrinkles and ridges of the primate help to grip objects. White-whiskered spider monkeys lack thumbs, due to which their hands act as hooks. Additionally, their shoulder joint is very flexible, allowing them to move by swinging from branch to branch.
White-cheeked spider monkeys occur in the Amazon basin of Brazil, where they inhabit area the Rio Tapajós and the Rio Tocantins. Usual habitat for this species is upper levels of the primary rainforest canopy. However, these primates may be found in other habitats within their range.
White-cheeked spider monkey is an insufficiently explored animal, which is endemic exclusively to Brazil. This species is thought to have ‘fission-fusion’ social system, gathering into groups of 20 - 30 individuals. Each group contains multiple males and females as well as individuals of different ages. These groups usually split into smaller sub-groups to forage and rest. Individuals occasionally travel solitarily. Females of the group generally remain in so-called 'core area' of the community's territory. These primates are diurnal creatures, being active by day and sleeping by night in the trees. When travelling among trees, they display amazing agility, arm swinging, climbing, running along tree branches quadrupedally and walking on two legs.
White-cheeked spider monkeys generally maintain frugivorous diet, which consists of 80% fruits and 20% leaves, flowers, buds, bark, decaying wood, seeds, honey and small insects.
Little is known about the mating system and reproductive behavior of the White-cheeked spider monkeys. However, it is suggested that they exhibit polygynous mating system, as they live in mixed-sex groups of up to 30 individuals. This species exhibits very slow reproductive rate. Although they may breed at any time of year, females produce only one infant every 2 - 4 years, after 200 - 232 days of gestation. The newborn baby clings to the belly of its mother. After a while, the female carries the infant on her back. Females disperse and join another group as soon as becoming mature at 4 years old. On the other hand, males are ready to breed by 5 years old and usually continue living with their natal group.
This endangered species currently has a very small, restricted natural range, which is fragmented by major highways, including the Transamazon and the Cuiabá-Santarém. Through their range, White-cheeked spider monkeys face continuous, large-scale deforestation and land alteration into soy bean plantations. These primates are commonly hunted. And finally, all the above-mentioned factors are compounded by the extremely slow reproductive rate, which doesn't allow the scattered populations to recover.
The IUCN Red List and other sources don’t provide the number of the White-cheeked spider monkeys’ total population. Today, this species’ numbers are decreasing and it is classified as Endangered (EN) on the IUCN Red List.
Maintaining frugivorous diet, these primates act as important seed dispersers of the plants they consume, thus benefiting the local ecosystem.