Capuchin Monkey

Capuchin monkeys are New World monkeys of the subfamily Cebinae, found in tropical forests of Central and South America as far south as northern Argentina, with the highest numbers in Brazil. They measure 30 to 56 cm with tails as long as the body, weigh 1.4 to 4 kg and are usually dark brown with cream colouring around the neck. Groups of 10 to 35 have hierarchies based on age and sex. They are omnivores, eating leaves, fruit, seeds, arthropods, molluscs and vertebrates. They are the only neotropical primates that frequently use tools in the wild, using rocks as hammers and anvils to open fruits and nuts, and they have the largest brain-to-body ratio of any nonhuman primate.

About the capuchin monkey

Capuchin monkeys are small, intelligent New World monkeys of the subfamily Cebinae, found in the forests of Central and South America from Honduras to northern Argentina. They belong to the family Cebidae with the squirrel monkeys and are famous for using stone tools to crack open nuts.

There are two groups, now split into separate genera. The gracile capuchins, genus Cebus, include the white-faced and white-fronted capuchins. The robust or tufted capuchins, genus Sapajus, include the tufted capuchin, Sapajus apella. The two lineages split about 6.2 million years ago, possibly when the forming Amazon River separated monkeys to its north from those in the Atlantic Forest to the south. The number of species is still debated.

The name comes from the Capuchin friars, whose brown hooded robes reminded Portuguese explorers of the monkeys' coloring. In Brazil they are called macaco-prego, and in Central America carablanca, or white-faced monkey.

Capuchins measure 30–56 cm (12–22 in) in body length, with a tail just as long, and weigh 1.4–4 kg (3–9 lb). Colors range from black and brown to buff and whitish depending on the species, and many are dark brown with a cream or off-white area around the neck. Robust capuchins all have a tuft of fur on the head and some form of beard, while male gracile capuchins never have tufts and no gracile capuchin has a beard.

A big brain for its size

Capuchins have the largest brain-to-body ratio of any primate other than humans, along with complex brain wiring. Scientists link this to their social lives and their sophisticated foraging. They are considered the most intelligent of the New World monkeys and are often used in cognitive research.

Behavior and diet

Like most New World monkeys, capuchins are diurnal and live in the trees. Groups of about 6 to 40 include related females, their young and several males. Usually one dominant male leads and has first rights to mate, though in white-headed capuchins an alpha male and an alpha female lead together. Groups defend the core of their territory, marking it with urine, and they keep the peace through mutual grooming. Calls warn of predators, keep members in contact and help form new groups.

At night capuchins sleep in tall trees with many horizontal branches, staying away from the trunk to avoid climbing predators, and they often switch sleeping trees from night to night.

What capuchins eat

Capuchins eat a wider range of foods than other monkeys in their family. Plant foods include fruit, flowers, leaves, seeds, pith, woody tissue, sugarcane, bulbs and sap. Animal foods include insects and other arthropods, snails and shellfish, frogs, which they are especially good at catching, and other vertebrates. Capuchins near water crack crabs and shellfish with stones.

Robust capuchins have shorter limbs, heavier jaws and, in males, a bony crest on the skull, adaptations for hard nuts and palm fruits. Gracile capuchins lack these features and find such foods hard to eat.

Tool use

Capuchins are the only New World primates that regularly use tools in the wild. Some place a nut on a flat stone anvil and strike it with a heavier rock, choosing hammer stones by weight and size for the food in question. Young monkeys learn this over years by watching experienced adults. Excavations in Brazil showed that some wild populations have kept this stone-tool tradition for at least 3,000 years.

Tufted capuchins have been seen gathering river stones from up to a mile (1.6 km) away and using stones nearly as heavy as themselves to crack palm nuts. Some robust capuchins also dig with stones and probe for prey with sticks. White-fronted capuchins have used leaves as cups to drink water. In the mosquito season, capuchins crush millipedes and rub them on their backs, which acts as a natural insect repellent.

Young

Females give birth about every two years after a gestation of 160 to 180 days. Infants cling to the mother's chest at first and later ride on her back. Adult males rarely help raise the young. Females mature at about four years and males at about eight.

Range and habitat

Capuchins range from Honduras through Central America and across much of South America to northern Argentina. They are especially common in Argentina, Brazil, Costa Rica, Honduras, Paraguay and Peru, and Brazil has the most. The Panamanian white-faced capuchin is the northernmost species. Gracile capuchins live mainly in Central America and northern and northwestern South America, while robust capuchins evolved in the Atlantic Forest and later spread north into the Cerrado and the Amazon.

They prefer places with shelter and easy food, such as lowland forest, mountain forest and rainforest. In Central America, white-faced capuchins live in wet lowland forest on the Caribbean coast and dry deciduous forest on the Pacific side. They adapt easily to areas settled by people. By scattering seeds in their droppings, capuchins help forests regrow.

Gracile vs robust capuchins

The two groups differ in build, fur and feeding.

Conservation status

Capuchin status varies by species. All gracile capuchins except one are rated Least Concern on the IUCN Red List; the Ka'apor capuchin is Critically Endangered. Among robust capuchins, the tufted capuchin is Least Concern, but the blond and crested capuchins are Endangered and the golden-bellied capuchin is Critically Endangered. According to the IUCN Red List, nearly all capuchin species are decreasing.

The main threats are deforestation, the pet trade and hunting for bushmeat. Their fast breeding and adaptability help capuchins survive forest loss better than some primates, but fragmentation is still a threat. In Brazil, capuchins are the wild animals most often traded illegally, and social media images of capuchins dressed as pets have been linked to rising public demand for them. Natural predators include jaguars, cougars, coyotes, snakes, crocodiles and birds of prey; the harpy eagle is the main predator of the tufted capuchin.