White-whiskered spider monkey (Ateles marginatus)

Also known as: Marimanda spider monkey, White-cheeked spider monkey
GenusAteles (1)
SizeMale head-body length: 50 cm (2)
Female head-body length: 34 - 51 cm (2)
Tail length: 61 - 75 cm (2)
Female weight: 5.8 kg (2)

Classified as Endangered (EN) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

One of the least known of the Amazonian spider monkeys, the white-whiskered spider monkey is a relatively large, slender monkey with long, spider-like limbs and a long, prehensile tail, which can act like a fifth limb. As in other spider monkeys, the underside of the tail tip is hairless and has wrinkles and ridges which aid in gripping. Hook-like hands with reduced thumbs and an extra mobile shoulder joint also aid the spider monkey in swinging easily beneath branches (2) (4) (5) (6). Spider monkeys usually have rather coarse, short fur (2) (4), which in the white-whiskered spider monkey is black, with a white patch on the forehead and a white line between the ears and chin (2) (7). The head is fairly small, with a prominent muzzle (4). Male and female spider monkeys are similar in size and colouration, but, interestingly, the female can often be mistaken for a male as a result of an unusually elongated clitoris (4) (5).

The white-whiskered spider monkey is endemic to the Brazilian Amazon, south of the Amazon River between the Rio Tapajós and the Rio Tocantins (1) (2) (4) (7).

This species mainly occurs in primary rainforest, where it is generally found in the upper levels of the forest (1) (2) (5), although other habitat types are also used to a lesser degree (8).

Spider monkeys are agile primates, capable of moving swiftly through the trees by swinging, climbing, running along branches on all fours, or even walking bipedally (1) (2) (4) (5). Fruit makes up over 80 percent of the diet, although young leaves, flowers, buds, bark, decaying wood, seeds, honey and occasionally small insects are also taken (1) (2) (4). Spider monkeys are thought to be important seed dispersers (1).

Although little information is available on the social and reproductive behaviour of the white-whiskered spider monkey, it is likely that, like other spider monkeys, it lives in a ‘fission-fusion’ society, in which groups of up to 20 to 30 individuals, of both sexes and all ages, regularly divide into small groups, with the only persistent relationship being between the female and offspring (1) (2) (4) (5). Breeding appears to occur year-round (2) (4), with the female spider monkey giving birth to a single offspring after a gestation period of between 200 and 232 days (4). The young spider monkey clings to the female’s belly at first, later riding on her back (6). Female spider monkeys reach sexual maturity at around four years, and males at five years, with young males generally remaining in the group, while females move out to join a new group on reaching maturity (2) (5). Spider monkeys reproduce relatively slowly, with the female giving birth only once every two to four years (2) (4). Lifespan may be more than 20 years in the wild (6).

The already restricted range of the white-whiskered spider monkey is cut by major highways such as the Transamazon and the Cuiabá-Santarém, and its habitat is subject to widespread deforestation and land conversion (1) (9). As with all spider monkeys, this species is also particularly susceptible to hunting (1) (4), with a slow reproductive rate making it difficult for populations to recover from losses (1). The decline of the white-whiskered spider monkey is predicted to continue into the future, particularly as vast areas of forest are cleared to make way for soy bean plantations (1).

The white-whiskered spider monkey occurs in a number of national forests in Brazil, including the Tapajós National Forest and Xingu National Forest, although more strictly protected areas will be needed for its conservation (1). Surveys are being carried out throughout the range of the white-whiskered spider monkey (1), and it has been chosen as a ‘flagship’ species for the preservation of Cristalino State Park, where it is still relatively abundant (9) (10). Fauna and Flora International and the Fundação Ecológica Cristalino, together with their community education programme, Escola da Amazônia, are working together to help protect the Cristalino State Park, one of the most diverse areas in the region. It is hoped that promoting environmental awareness amongst local communities will go some way towards helping to conserve this charismatic monkey and its Amazon forest home (9) (10).

To find out more about the conservation of the white-whiskered spider monkey see:

Authenticated (02/07/09) by Matthew Richardson, primatologist and author.

  1. IUCN Red List (July, 2014)