SQUIRREL MONKEYS AND CAPUCHINS: Cebidae

PHYSICAL CHARACTERISTICS

Cebids (members of the family Cebidae, including squirrel monkeys and capuchins) have round heads, forward-facing eyes, rounded snouts, and small ears. Squirrel monkeys are the smallest cebids. They have a slim body with a dense, soft fur that is gray to black on the crown of the head. The body may be yellow, golden, or reddish. The shoulders are gray to olive, and the underparts are white to yellow. The forearms, hands, and feet are yellow to golden. The furry tail has a black tip.

Capuchins have a heavy body build. The face is covered with short fur, while the rest of the body has longer fur. Color ranges from black to brown to yellowish beige. The chest and shoulders have patches of white, and the underparts are light-colored. The tail is usually coiled at the tip, earning it the nickname ringtail monkey.

GEOGRAPHIC RANGE

Squirrel monkeys are found in most of South America and in Central America (just Costa Rica and Panama). Capuchins are found in most of South America and Central America and the Caribbean islands of Trinidad and Tobago.

HABITAT

Cebids are found in the spreading forest canopy and in smaller understory trees. Squirrel monkeys also inhabit swamps, while capuchins thrive in dry forests.

DIET

Squirrel monkeys eat predominantly fruits and insects, but also feed on flowers, shoots, buds, leaves, spiders, frogs, bats, and crabs. Capuchins consume mainly fruits, but also eat insects, snails, lizards, small birds, baby squirrels, crabs, and oysters.

BEHAVIOR AND REPRODUCTION

Cebids are arboreal (tree-dwelling) and diurnal (active during the day). They form large groups headed by a dominant male. Capuchin groups have a dominant female that submits only to the dominant male. The dominant male defends his group but does not try to control the members. Squirrel monkey groups, on the other hand, may or may not have dominant females, depending on the species. However, only the dominant male mates with the receptive females. Nevertheless, all cebids, males and females, have several partners. Females have a single infant, which keeps a close relationship to its mother. Fathers do not share in childrearing. Cebids use vocalizations to communicate. They urinate on their hands, then rub them on their fur and feet to scent mark territory. This behavior is called urine washing.

CEBIDS AND PEOPLE

Cebids are popular as pets and zoo exhibit animals. They are used in medical research. They have been used in the space program to test the effects of space travel. Capuchins are trained to help disabled persons, using their human-like hands to perform daily tasks, such as feeding people.

CONSERVATION STATUS

IUCN lists the yellow-breasted capuchin as Critically Endangered, facing an extremely high risk of extinction, because of habitat loss and degradation, and hunting for food. It classifies the red-backed squirrel monkey as Endangered, facing a very high risk of extinction, and the black squirrel monkey and the crested capuchin as Vulnerable, facing a high risk of extinction, due to habitat loss and degradation.

COMMON SQUIRREL MONKEY (Saimiri sciureus): SPECIES ACCOUNTS

Physical characteristics: Common squirrel monkeys weigh 1.5 to 2.75 pounds (0.6 to 1.2 kilograms), with the males being larger than the females. They measure about 12 inches (30 centimeters), with a tail length of about 16 inches (41 centimeters). The fur is short and dense. The round head is gray to black on top, with a white face mask and a black snout surrounded by black fur. Eyes are large and ears are small. The back is olive-gray, and the underparts are light yellow. The forearms, hands, and feet are yellow-orange. The long tail tipped with black is non-prehensile, or incapable of grasping things such as tree branches.

Geographic range: Common squirrel monkeys are found in Brazil, Colombia, French Guiana, Guyana, Suriname, and Venezuela.

Habitat: Common squirrel monkeys occupy the middle layers of the forest with abundant vines and other vegetation. They also inhabit mangroves and forests along rivers and streams.

Diet: Common squirrel monkeys feed mainly on soft fruits and insects. They also eat frogs, spiders, snails, crabs, and occasionally bats.

Behavior and reproduction: Depending on available habitat, common squirrel monkeys live in groups of twenty to 300. Subgroups of males, mothers with offspring, and juveniles are formed within the main group. They are active during the day, foraging together in small groups. They are mostly arboreal but are sometimes found on the ground. They normally walk on all fours, but can move on their hind legs.

Males and females have several partners. Before the mating season, adult males gain weight on the upper body and in the genital organs in what is known as the "fatted male" condition. They also fight with one another to determine who will mate with the females. One large offspring is born during the rainfall season when food is plentiful. The young stay with the mother for about a year. Males do not share in parenting.

Common squirrel monkeys and people: Common squirrel monkeys are sometimes hunted for food. They are sold as pets and used for medical research.

Conservation status: Common squirrel monkeys are not considered a threatened species. ∎

WHITE-THROATED CAPUCHIN (Cebus capucinus):SPECIES ACCOUNTS

Physical characteristics: White-throated capuchins weigh 5.9 to 8.6 pounds (2.7 to 3.9 kilograms), with males being larger than females. They measure about 18 inches (46 centimeters) with a tail that is just as long. The robust body is fully furred, with white to yellowish coloration on the throat, head, and shoulders. The back, arms, and legs are black. The long, black, hairy tail is semiprehensile, able to wrap around tree branches, but unable to function as a fifth limb for holding objects.

Geographic range: White-throated capuchins are found in Colombia, Costa Rica, Honduras, Nicaragua, and Panama.

Habitat: White-throated capuchins occupy evergreen forests with full canopies and those with less-developed canopies but dense understory. They also inhabit mangroves and dry deciduous forests.

Diet: White-throated capuchins feed on plants and animals. Fruits are their favorite food, but they also eat shoots, leaves, flowers, buds, berries, and nuts, as well as insects, spiders, crabs, small birds, baby squirrels, and lizards. They eat oysters, using rocks to open the shells.

Behavior and reproduction: White-throated capuchins form groups of ten to twenty individuals, typically with more adult females than males, but ruled by a large, older male. They are arboreal and active during the day. When foraging, they call out to one another, using squeaks, shrieks, and chatters. They groom each other, looking through each other's fur to remove parasites and dirt. Males defend the group's territory, rubbing urine on their fur and feet and distributing that scent among the trees. They have been known to throw branches and fruits at perceived enemies, including humans.

Adults have several partners. Females have single births. The newborn clings to its mother's undersides or across her shoulders. After six weeks, the infant rides on its mother's back. Males do not share in childcare. Young males leave their birthplace as early as age two.

White-throated capuchins and people: White-throated capuchins are the familiar creatures associated with organ-grinders who used to entertain in city streets. They are popular in zoos worldwide. Their intelligence makes them a prime candidate for medical research. Farmers consider them pests for raiding crops.

Conservation status: White-throated capuchins are not considered a threatened species. ∎

WEEPER CAPUCHIN (Cebus olivaceus):SPECIES ACCOUNTS

Physical characteristics: Weeper capuchins weigh 5.3 to 6.6 pounds (2.4 to 3 kilograms), males being larger than females. They measure about 20 inches (55 centimeters) with a tail that is just as long. They have an orange-brown body and yellowish shoulders and upper arms. A wedge-shaped, dark brown coloration extends from the forehead to the back of the head. The long, brown tail tipped with black is semiprehensile, so it can wrap around a branch.

Geographic range: Weeper capuchins are found in Brazil, French Guiana, Guyana, Suriname, and Venezuela.

Habitat: Weeper capuchins inhabit the middle and lower layers of evergreen rainforests. They also live in dry forests, mountain forests, gallery forests (woods along streams and rivers), and shrub woodlands.

Diet: Weeper capuchins eat fruits, buds, shoots, and roots of small trees. They also feed on insects, snails, and birds.

Behavior and reproduction: Weeper capuchins form groups of eight to fifty individuals, ruled by a dominant male. They are arboreal and forage during the day. They take breaks to groom each other's fur, removing parasites and dirt. Capuchins claim territory by urine washing. They soak their hands with urine, which they rub on their fur and feet, leaving the scent throughout their forest routes. They show aggression by shaking branches and bouncing up and down. They have about a dozen vocalizations, one of which is a sad sound that earned them the name "weeper."

All receptive females mate with the dominant male at a given time. Females have single births. The newborn is able to cling to its mother's fur right away. The father does not take care of the young but may find food for the mother. Females stay with the group, but males leave home as early as two years of age.

Weeper capuchins and people: Weeper capuchins are hunted for food in some areas. They are also used in medical research.

Conservation status: Weeper capuchins are not considered a threatened species. ∎

FOR MORE INFORMATION

Books:

Kavanagh, Michael. A Complete Guide to Monkeys, Apes and Other Primates. New York: The Viking Press, 1983.

Kinzey, Warren G., ed. New World Primates: Ecology, Evolution, and Behavior. New York: Aldine de Gruyter, 1997.

Napier, John R., and Prue H. Napier. The Natural History of the Primates. Cambridge, MA: The MIT Press, 1986.

Nowak, Ronald M. Walker's Primates of the World. Baltimore: The Johns Hopkins University Press, 1999.

Periodicals:

Bergman, Charles. "The Peaceful Primates." Smithsonian (June 1999): 78–86.

Web sites:

Broekema, Iris. "Natural History of the White-Throated Capuchin (Cebus capucinus)." The Primate Foundation of Panama. http://www.primatesofpanama.org/academicresources/articles/capuchin.htm (accessed on July 6, 2004).

Schober, Nathan, and Chris Yahnke. "Cebus olivaceus (Weeping Capuchin)." Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Cebus_olivaceus.html (accessed on July 6, 2004).

The Squirrel Monkey Breeding and Research Resource. "Saimiri Natural History." University of South Alabama Department of Comparative Medicine. http://www.saimiri.usouthal.edu/saimiri.htm (accessed on July 6, 2004).