New World Monkeys
New World Monkeys
Spider monkeys and woolly monkeys
The New World monkeys of Central and South America belong to the families Callitrichidae (the marmosets and tamarins), Cebidae (squirrel monkeys and capuchins), Aotidae (night monkeys), Pitheciidae (sakis, titis, and uakaris), and Atelidae (howler monkeys and spider monkeys). Marmosets and tamarins are discussed in a separate entry. The other species of New World monkeys include capuchins (Cebus ), night monkeys or douroucoulis (Aotus ), titis (Callicebus ), squirrel monkeys (Saimiri ), sakis (Pithecia ), bearded sakis (Chiropotes ), uakaris (Cacajao ), howler monkeys (Alouatta ), spider monkeys (Ateles ), the woolly spider monkey (Brachyteles arachnoides ), and woolly monkeys (Lagothrix ).
Cebid monkeys are all arboreal tree dwellers that feed on leaves, fruit, birds’ eggs, tree frogs, and bark-dwelling insects and their larvae. The night monkey (Aotus spp.), as their name suggests, are the only nocturnal New World monkeys; the rest are diurnal, or active during the day.
The cebid monkeys vary in size from the squirrel monkey (Saimiri sciureus ) with a body length of 10 in (25 cm) plus a 15 in (38 cm) tail, and a weight of about 1.5 lb (0.68 kg) to the woolly spider monkey, or muriqui, which has a body length of 18 in (46 cm), plus a 30 in (75 cm) tail, and weighs about 35 lb (17.5 kg). The males and females of most species of cebid monkeys are approximately the same size, but the two sexes often have different colorings, a phenomenon known as sexual dimorphism.
The larger species of cebid monkeys have a prehensile tail with a naked patch at the base that has fingerprint like ridges for sensitive gripping. The smaller, more agile monkeys do not have a prehensile tail, but can, nevertheless, readily leap from branch to branch.
The group territories of different species of New World monkeys often overlap, and as many as five different species have been found living in one tree, usually at different levels. Some monkey groups have been known to establish long-lasting “friendships” with the social groups of a different monkey species.
The average gestation period of New World monkeys is about 145 days, which is about three weeks shorter than the gestation period of Old World monkeys, although some New World monkeys gestate as long as 225 days. The breasts of cebid monkeys are located near the armpits so that they can be reached by the young riding on the mother’s back. Unlike humans, apes, and most Old World monkeys, female New World monkeys do not menstruate. In general, the smaller species are monogamous, living in family groups with only one male and one female, while the larger species tend to be polygamous with one male and a harem of several females.
Capuchins
The best known New World monkey (the one often known as the “organ grinder” monkey) is the capuchin (genus Cebus ). This small monkey got its name from the dark patch of hair on the top of its head that resembles the hood worn by Capuchin monks. The four species of capuchins are also sometimes called ringtail monkeys because they carry their tails with the end curved into a circle.
Capuchins occur throughout Central and South America, from Honduras to southern Brazil. They live in open or closed forests, low-lying rainforests, or forested mountainsides. Capuchins eat a lot of fruit and often raid cultivated orchards; when an animal locates a good fruit tree, it makes loud whistling calls that draw the rest of its group to the food source.
Capuchins measure about 18 in (45 cm) long, with a tail of the same length. The tail is only semi-prehensile, in that the monkey can wrap it around a branch to anchor itself, but the tail cannot support the animal’s weight. Capuchins are intelligent monkeys with a relatively large brain.
The black-capped capuchin (C. apella ) of Colombia has a mat of dark fur standing up on its crown, often forming “horns,” while the remainder of the body is grayish brown. This monkey cracks nuts against the branches on which it sits.
Other species of capuchins lack the mat of hair on the head and have more variation in their body color. The white-fronted capuchin (C. albifrons ) is found in an area from Ecuador to Colombia and even on the Pacific shores, where they eat oysters and crabs. This monkey is light tan in color with little variation in shading. The white-throated capuchin (C. capucinus ) is found from Central America to Ecuador. It is also primarily pale with a white face, but its fur grades into black down its back, on the crown on its head, and on its hands and feet. The weeper or wedge-capped capuchin (C. nigrivittatus ) has a crown patch that makes a dark point above the eyes.
The capuchins congregate in large groups of up to 30 members, including several males, who often bond together. After a 180-day gestation period, a single infant is born. Females mature sexually at age four, males at seven or eight. These friendly, intelligent monkeys have been known to live in captivity for more than 40 years.
Night monkeys
Previously thought to comprise only a single species (Aotus trivirgatus ), genetic studies have recently suggested that as many as eight species of night monkeys should be recognized. These species fall into two groups: four species of gray-necked night monkeys that inhabit an area essentially north or the Amazon River and four species of red-necked night monkeys that occur almost exclusively south of the Amazon River. Night monkeys have round, fur-fringed faces, no obvious external ears, and big eyes surmounted by white triangles of face fur. The fur is brown-gray with an orangish tone on the chest and abdomen, but the color can vary considerably.
Night monkeys measure about 14 in (36 cm) long, plus a 12 in (30 cm) tail and weigh about 2 lb (0.8 kg). They are found in forested regions from Panama to Argentina. These monkeys sleep in holes in hollow trees and eat fruits, leaves, and some insects. Unlike most monkeys, they do not use their fingers to remove foreign bodies from the fur monkeys they are grooming; instead, they sorts through the fur with fingers and then removes the offending bits with their teeth. The eyes of the night monkey lack the reflective layer behind the retina that most nocturnal mammals have.
Male night monkeys are very aggressive, and family groups of parents with one or two young avoid contact with other groups. The males scare away other night monkeys by arching their backs, spitting, leaving scent on branches, and growling with a variety of sounds that are made more resonant by an inflatable sac on the throat. After a 133-day gestation period, the female produces usually one young, which is then carried by the father. The young become sexually mature at about two years.
Titis
There are thought to be about 19 species of titis, all in the genus Callicebus, although the taxonomy of this genus is in a state of flux and the number of species may change. The name titi derives from the Aymara language, meaning “little cat.” Titis all have long hair, which makes them appear to be larger than they actually are. Titis are small monkeys, measuring about 10 in (25 cm) long, plus a tail that may be an additional 12-20 in (30-50 cm), and weigh less than 2 lb (about 0.8 kg).
The white-handed titi (C. torquatus ) and the dusky titi (C. moloch ) occupy the same forested region of the upper Amazon. The dusky titi lives along rivers and in wet forests, while the white-handed titi lives on higher ground. The white-handed titi likes heights so much that it sleeps on the branches of the tall emergent trees that stand above the high canopy of the rain forest, several hundred feet above the forest floor.
The white-handed titi is primarily dark red in color, with a white neck band and light-colored, yellowish hands. The white collar and “gloves” earn it the nickname “widow monkey” because its coloration matches the traditional apparel of a Brazilian widow. The dusky titi is gray, leaning toward reddish, with lighter areas. The masked titi (C. personatus ), inhabits a small area in the coastal forests of southern Brazil. This species has black hands and feet and dark fur on its face.
Titis are very vocal monkeys, chattering away with many different types of sounds for long periods, especially early in the morning. They live in family groups, and much of the chatter is between different groups. When resting on a branch, titis sit with all four feet tightly together, ready to leap for a new branch in a single movement if danger threatens. Often, when two titis sit side by side, they entwine their tails. The single young is born quite helpless and must be carried for the first three months of its life. That task falls to the father, except for the first two days of the infant”s life. After it begins to get around the trees on its own, the young one is still guarded, protected, taught, and played with by the father.
Squirrel monkeys
There are five species of squirrel monkeys, the smallest of the New World monkeys. The common squirrel monkey (Saimiri sciureus ) is found in the rainforests, riverine forests, and mangrove swamps of Brazil, Colombia, French Guiana, Guyana, Suriname, and Venezuela. The red-backed squirrel monkey (S. oerstedii ) occurs only in Panama and Costa Rica in the middle levels of the forest, where they eat primarily fruit, though they also use their narrow, sharply pointed teeth to devour small insects. The Bolivian squirrel monkey (S. boliviensis ) inhabits primary and secondary tropical rainforests in Brazil, Bolivia, Colombia, Peru, and Venezuela, while the blackish squirrel monkey is found only in a small tract of moist, swamp forest in northeastern Brazil. The fifth species, S. vanzolinii, inhabits a small forest pocket in northwestern Brazil.
The common squirrel monkey is the species often kept as a pet. Its thick, short fur is gray, the chest is white, its legs are yellow, and it has white circles around its eyes, giving it a widow”s peak above the nose. A large dark oval of bare skin encircles the nose and mouth on the muzzle.
Squirrel monkeys do not have a prehensile tail, and all swinging on branches is done with their arms, while their tails tend to rest curled over their shoulder. The tail is considerably longer than their 12 in (30 cm) body.
Squirrel monkey groups vary from 20 animals up to 200 individuals. When such a large group takes over a tree, the other cebid species, even the larger ones, are overwhelmed and forced to leave. The large squirrel monkey social group has very complex social relationships among individuals and subgroups. Some subgroups consist only of males, who remain by themselves except during mating season. This precludes a male from taking care of its single offspring, unlike most of the species of New World monkeys. The mother monkey”s female friends may help raise and care for an infant. A single infant squirrel monkey is born after a gestation period that varies from 152-172 days. It becomes independent at about a year and sexually matures at three years for females and five for males. Squirrel monkeys have been known to live almost 15 years.
In the 1960s, the red-backed squirrel monkey was imported into the United States by the thousands for use as pets. Capture for the pet trade together with the destruction of their rainforest habitat has endangered the wild populations of this monkey. Today, the United States government has outlawed the importation of primates except for legitimate scientific purposes.
Sakis and uakaris
The sakis, bearded sakis, and uakaris belong to the subfamily Pitheciinae and all have long shaggy hair. These monkeys of the Amazon basin and farther north eat primarily fruit and seeds. They bear one offspring, probably taken care of by the mother. The five species of sakis (Pithecia ) have nostrils that are set farther apart than those of any other New World monkey. They differ from the two species of bearded sakis in several ways. The tail of the saki is as long as its 16 in (40 cm) body length and is thick, bushy, somewhat baseball-bat shaped, and tapers to a pointed tip. The tail of the bearded saki is blunt at the tip. Sakis live in small family groups of only three or four individuals and prefer the lower reaches of the rainforest trees and may even venture onto the ground. Bearded sakis stay wholly in the trees and prefer the upper layers, where a group of up to about 30 members stays in close touch. Sakis are known to eat birds and small mammals, something that the bearded sakis never do.
The male white-faced saki (P. pithecia ) of the Guianas and northeastern Brazil has a stark white face set in a circular hood of long black hair, and a triangle of black fur from between the eyes to the nose and mouth. The female and young of the white-faced monkey do not have white faces, rather, they are dark brown or black with some whitish fur around the face.
The adult female has a line of white fur running from the eyes and around the mouth and has a reddish tone to the chest and abdomen.
The monk, or hairy saki (P. monachus )of the upper Amazon is colored very much like the female white-faced saki. The fur on its head curves forward as if forming a monk”s hood that partially conceals the face.
Bearded sakis tend to look as if they have just come from a beauty salon. Their short, soft fur is very smooth, their full beards appear to be carefully trimmed, and poufs of longer fur above the eyes are smoothly bouffant. They have longer canine teeth than many monkeys, which they use to break up tough fruit to reach the seeds inside.
The endangered black-bearded, or red-backed, bearded saki (Chiropotes satanas ) lives between the Orinoco and Amazon rivers. The white-nosed bearded saki (C. albinasus ) lives primarily south of the Amazon.
Uakaris are slightly larger than sakis but, unlike all other New World monkeys, have a very small tail. These monkeys live strictly along river banks. The red uakari (Cacajao rubicundus ) is particularly ugly, with a vivid, naked, red face, and a bald head which is naked back to behind its ears, where a rust-colored coat of very long, shaggy fur begins. The bald uakari, also called the white uakari (C. calvus ), has a similar appearance but has yellowish or silvery fur. Some authorities regard C. rubicundus as a subspecies of C. calvus. The black-headed uakari (C. melanocephalus ) has black fur on its head, and its arms, hands, and feet are also black, while its legs and tail are red. The yellow-brown body is not as raggedly shaggy as in the other uakaris. This species appears to be thriving in western Brazil but may be endangered in the rest of its range.
The name uakari (also spelled ouakari ) was given to these animals by the Tupi people of the Amazon basin. These monkeys live at all levels in the rainforest and rarely descend to the ground. They are better at leaping between branches than many other monkeys. The social groups may number up to 30 individuals. Female uakaris give birth to a single offspring every other year after a gestation of about 180 days.
Howler monkeys
The six to eight species of howler monkeys in the subfamily Alouattinae possess a throat swelling with a special form of hyoid bone (the bone supporting the tongue muscles) that allows them to produce a deep, thundering roar, which can be heard more than 2 mi (3 km) away. Because of this throat swelling, their lower jaw juts forward more than in most other species of monkey. This jutting is not as noticeable as it might be, however, because the howlers are bearded. The throat is larger in the males than the females, and it is largest in the dominant male in a group of monkeys containing several males.
Howler monkeys are quite large, weighing up to 20 lb (9 kg) and measuring 33 in (91 cm) long, with an equally long and very strong prehensile tail, which is naked on the end third. Howler monkeys use their prehensile tail to attach themselves firmly to branches, and they may hang from their tail to keep their hands free while feeding on leaves. The mantled howler monkey (A. palliata ) has to eat so many leaves to get the nourishment it needs that its intestines make up one-third of the volume of its body. The mantled howler monkey is found from southern Mexico south to western Colombia and Ecuador and it has a black body with a gold mantle, or fringe, down the sides.
Howler monkey species vary primarily in their coloring. The Guatemalan or Mexican black howler monkey (A. pigra ) is completely black, from the bare base to the tip of its tail. All the howlers have naked black faces, but the black-and-red howler (A. belzebul ) has red hands and feet as well as tail tip. The Venezuelan red howler (A. seniculus ) is bright copper. Only the black howler (A. caraya ) has different forms of the males and females. The young of black howler monkeys are born golden-brown, and the males turn black as they mature. A howler group contains up to 20 monkeys, with two to four males and five to ten females in the group. A single young howler is born after a gestation of about 180 days. It clings to the mother”s abdomen for the first several weeks until it matures enough for it to be able to cling to its mother”s tail. It then moves around and rides her back, where it remains for a year or more. Howler females reach maturity at about five years, and males at six to eight years.
The Guatemalan black howler monkey is an endangered species. Although some howlers live higher in the mountains, this lowland species is losing its habitat to logging and agricultural conversion. They are also hunted, and individual animals are easily caught because their loud voices betray their location.
Spider monkeys and woolly monkeys
The subfamily Atelinae includes the spider monkeys, the woolly spider monkeys, and the woolly monkeys. These monkeys are as large as howler monkeys but thinner.
Spider monkeys (Ateles spp. ) are found in approximately the same range as the howler monkeys, though spider monkeys occur farther north in Mexico and extend south to Brazil. Howler monkeys may eat slightly immature fruit, while spider monkeys wait until it is truly ripe. The arms of spider monkeys are longer than their legs, giving them an ungainly spider-like appearance. Spider monkeys are extremely agile and can walk along branches, hang upside down, leap sideways, and even leap long distances downward. Spider monkeys are very adroit at swinging from branches by arm to arm movements, also called brachiation, an ability that requires special flexibility in the shoulders. Their tails are quite thick toward the base but slender and with a naked patch with ridges toward the tip, which makes it quite sensitive.
The long tail is especially useful because, unlike many other monkeys, spider monkeys do not have an opposable thumb, meaning they are not very adept with their hands. Their skeletons show the remains of the thumb, and some individual animals have a slight protrusion where a thumb would be. Spider monkeys live in large groups, though they often tend to break up into smaller family subgroups.
All spider monkeys have fairly long, shaggy fur, which is mostly dark brown or black. The fur on the head is brushed forward. The Central American spider monkey (A. geoffroyi ) has golden, reddish, or bronze fur on its body and usually black hands and feet. The white-bellied spider monkey (A. belzebuth ) of the upper Amazon has chest and abdomen of a lighter color than the rest of its body. The brown-headed spider monkey (A. fusciceps ) lives from Panama to Ecuador, between the ranges of the other two species.
In coastal parts of Brazil, the spider monkey”s territory is taken over by the woolly spider monkey or muriqui (Brachyteles arachnoides ). The woolly spider monkey is the heaviest monkey in Brazil, weighing 35 lb (16 kg); it has the chunky body and thick fur of the woolly monkey but lacks a thumb. It is lighter brown in color than most of its relatives.
The woolly spider monkey”s social groups, which used to number about 30-40, are now down to typically 6-20. Within a group”s territory, the individuals separate by gender and can frequently be seen hugging each other. There may be fewer than 1,000 woolly spider monkeys left, reduced from half a million individuals when Europeans first arrived in South America. The large size and gentle nature of the woolly spider monkey makes them easy targets for hunting, and this species is now on the endangered species list.
The two species of woolly monkeys (Lagothrix ) live in western South America, mostly at fairly high altitudes. Their thick fur makes the woolly monkeys
KEY TERMS
Brachiating —Swinging from tree limb to tree limb hand over hand.
Diurnal —Refers to animals that are mainly active in the daylight hours.
Gestation —The period of carrying developing offspring in the uterus after conception; pregnancy.
Monogamous —Of males and females, mating for life.
Nocturnal —Active in or relating to nighttime.
Opposable —Of the thumb or first toe on a primate, set far enough from the remainder of the fingers to be useful in grasping objects.
Polygamous —Of males and females, taking more than one mate at a time.
Prehensile —Grasping, as the specialized tail in many monkeys.
Sexual dimorphism —The occurrence of marked differences in coloration, size, or shape between males and females of the same species.
look larger and stouter than they really are. The common woolly monkey (L. lagothricha ), also known as Humboldt”s monkey, is colored gray, black, or brown. The yellow-tailed or Hendee”s woolly monkey (L. flavicauda ) is deep red-brown with yellow fur along its tail and around its genitals. This monkey lives in a small mountainous area in northern Peru. The yellow-tailed woolly monkey was thought to be extinct from hunting for food and the pet trade, but a small wild population was rediscovered in the 1970s, and this critically endangered species is now being bred in captivity.
Endangered New World monkeys
The Atlantic rainforest in Brazil has been called one of “the most devastated primate habitats in the world.” Sixteen of the 21 primate species and subspecies that live in that ravaged Brazilian ecosystem are found nowhere else, and will disappear along with their habitat. The human population of the region continues to put pressure on the forests, which are cut down for agricultural use, living space, and firewood. The endangered woolly spider monkey has become a symbol of the conservation crisis in Brazil.
Other endangered species include the southern bearded saki (Chiropotes satanas, the yellow-tailed woolly monkey (Lagothrix flavicauda ), and the Central American squirrel monkey (Saimiri oerstedii ). As more and more of the rainforest is cleared, other New World monkeys will be added to the endangered species list. The only ways to save these endangered primates are to preserve their natural forest habitat, and to control the hunting of the rarer species.
Resources
BOOKS
Kerrod, Robin. Mammals: Primates, Insect-Eaters and Baleen Whales. Encyclopedia of the Animal World series. New York: Facts on File, 1988.
Kinzey, W.G., ed. New World Primates: Ecology, Evolution and Behavior. New York: Aldine de Gruyter, 1997.
Napier, J.R., and P.H. Napier. The Natural History of the Primates. Cambridge, MA: The MIT Press, 1985.
Nowak, Ronald M. Walker”s Mammals of the World. 6th ed. Baltimore: The Johns Hopkins University Press, 1999.
Peterson, Dale. The Deluge and the Ark: A Journey into Primate Worlds. Boston: Houghton Mifflin, 1989.
Preston-Mafham, Rod and Ken Preston-Mafham. Primates of the World. New York: Fact of File, 1992.
Strier, K.B. Faces in the Forest: The Endangered Muriqui Monkeys of Brazil. Cambridge, MA: Harvard University Press, 1999.
Sussman, R.W. Primate Ecology and Social Structure. Vol. 2, New World Monkeys. Needham Heights, MA: Pearson Custom Publishing, 1999.
Jean F. Blashfield
New World Monkeys
New World monkeys
The New World monkeys of Central and South America belong to the family Cebidae and to the family Callitrichidae (the marmosets and tamarins ). The Cebidae, or capuchin-like monkeys, are distinguished from the marmosets and tamarins by their possession of nails instead of claws on most fingers and toes, and three molars instead of two on either side of each jaw. Finally, cebids tend to give birth to one offspring at a time , while the marmosets and tamarins tend to have twins.
Cebid monkeys include capuchins (Cebus), night monkeys or douroucoulis (Aotus), titis (Callicebus), squirrel monkeys (Saimiri), sakis (Pithecia), bearded sakis (Chiropotes), uakaris (Cacajao), howler monkeys (Alouatta), spider monkeys (Ateles), the woolly spider monkey (Brachyteles arachnoides), and woolly monkeys (Lagothrix).
Cebid monkeys are all arboreal tree dwellers that feed on leaves, fruit, birds' eggs, tree frogs , and bark-dwelling insects and their larvae. The night monkey or douroucouli (Aotus trivirgatus), is the only nocturnal New World monkey; the rest are diurnal, or active during the day.
The cebid monkeys vary in size from the squirrel monkey (S. sciureus) with a body length of 10 in (25 cm) plus a 15 in (38 cm) tail, and a weight of about 1.5 lbs (0.68 kg), to the woolly spider monkey, or muriqui, which has a body length of 18 in (46 cm), plus a 30 in (75 cm) tail, and weighs about 35 lb (17.5 kg). The males and females of most species of cebid monkeys are approximately the same size, but the two sexes often have different colorings, a phenomenon known as sexual dimorphism.
The larger species of cebid monkeys have a prehensile tail with a naked patch at the base that has fingerprint-like ridges for sensitive gripping. The smaller, more agile monkeys do not have a prehensile tail, but can nevertheless readily leap from branch to branch.
The group territories of different species of New World monkeys often overlap, and as many as five different species have been found living in one tree, usually at different levels. Some monkey groups have been known to establish long-lasting "friendships" with the social groups of a different monkey species.
The average gestation period of New World monkeys is about 145 days, which is about three weeks shorter than the gestation period of Old World monkeys, although some New World monkeys gestate as long as 225 days. The breasts of cebid monkeys are located near the armpits so that they can be reached by the young riding on the mother's back. Unlike humans, apes , and most Old World monkeys, female New World monkeys do not menstruate. In general, the smaller species are monogamous, living in family groups with only one male and one female, while the larger species tend to be polygamous with one male and a harem of several females.
Capuchins
The best known New World monkey (the one often known as the "organ grinder" monkey) is the capuchin (genus Cebus). This small monkey got its name from the dark patch of hair on the top of its head that resembles the hood worn by Capuchin monks. The four species of capuchins are also sometimes called ringtail monkeys because they carry their tails with the end curved into a circle.
Capuchins occur throughout Central and South America, from Honduras to southern Brazil. Capuchins live in open or closed forests , low-lying rain forests, or forested mountainsides. Capuchins eat a lot of fruit and often maraud through cultivated orchards; when an animal locates a good fruit tree, it makes loud whistling calls that draw the rest of its group to the food source.
Capuchins measure about 18 in (45 cm) long, with a tail of the same length. The tail is only semi-prehensile, in that the monkey can wrap it around a branch to anchor itself, but the tail cannot support the animal's weight. Capuchins are intelligent monkeys with a relatively large brain .
The black-capped capuchin (C. apella) of Columbia has a mat of dark fur standing up on its crown, often forming "horns," while the remainder of the body is grayish-brown. This monkey cracks nuts against the branches on which it sits.
Other species of capuchins lack the mat of hair on the head and have more variation in their body color . The white-fronted capuchin (C. albifrons) is found in an area from Ecuador to Columbia and even on the Pacific shores, where they eat oysters and crabs . This monkey is light tan in color with little variation in shading. The white-throated capuchin (C. capucinus) is found from Central America to Ecuador. It is also primarily pale with a white face, but its fur grades into black down its back, on the crown on its head, and on its hands and feet. The weeper or wedge-capped capuchin (C. nigrivittatus) has a crown patch that makes a dark point above the eyes.
The capuchins congregate in large groups of up to 30 members, including several males, who often bond together. After a 180-day gestation period, a single infant is born. Females mature sexually at age four, males at seven or eight. These friendly, intelligent monkeys have been known to live in captivity for more than 40 years.
The night monkey
The douroucouli (Aotus trivirgatus), or night monkey, is the only nocturnal monkey. It has a round, furfringed face, no obvious external ears, and big eyes surmounted by white triangles of face fur. The fur is brown-gray with an orangish tone on the chest and abdomen, but the color can vary considerably.
The night monkey measures about 14 in (36 cm) long, plus a 12 in (30 cm) tail and weighs slightly more than 2 lb (1 kg). Night monkeys are found in forested regions from Panama to Argentina. These monkeys sleep in holes in hollow trees and eat fruits , leaves, and some insects. Unlike most monkeys, it does not use its fingers to remove foreign bodies from the fur of a monkey it is grooming; instead, it sorts through the fur with fingers and then removes the offending bits with its teeth. The eyes of the night monkey lack the reflective layer behind the retina that most nocturnal mammals have.
Male night monkeys are very aggressive, and family groups of parents with one or two young avoid contact with other groups. The males scare away other night monkeys by arching their backs, spitting, leaving scent on branches, and growling with a variety of sounds that are made more resonant by an inflatable sac on the throat. After a 133-day gestation period, the female produces usually one young, which is then carried by the father. The young become sexually mature at about two years.
Titis
There are three species of titis, all in the genus Callicebus. The name titi derives from the Aymara language, meaning "little cat." Titis all have long hair, which makes them appear to be larger than they actually are. The three species of titi are small, measuring about 10 in (25 cm) long, plus a tail that may be an additional 12-20 in (30-50 cm), and weigh less than 2 lb (about 0.8 kg).
The white-handed titi (C. torquatus) and the dusky titi (C. moloch) occupy the same forested region of the upper Amazon. The dusky titi lives along rivers and in wet forests, while the white-handed titi lives on higher ground. The white-handed titi likes heights so much that it sleeps on the branches of the tall emergent trees that stand above the high canopy of the rain forest, several hundred feet above the forest floor.
The white-handed titi is primarily dark red in color, with a white neck band and light-colored hands. The white collar and "gloves" earn it the nickname "widow monkey" because its coloration matches the traditional apparel of a Brazilian widow. The dusky titi is gray, leaning toward reddish, with lighter areas. The third species, the masked titi (C. personatus), inhabits a small area in the coastal forests of southern Brazil. This species has black hands and feet and dark fur on its face.
Titis are very vocal monkeys, chattering away with many different types of sounds for long periods, especially early in the morning. They live in family groups, and much of the chatter is between different groups. When resting on a branch, titis sit with all four feet tightly together, ready to leap for a new branch in a single movement if danger threatens. Often, when two titis sit side by side, they entwine their tails. The single young is born quite helpless and must be carried for the first three months of its life. That task falls to the father, except for the first two days of the infant's life. After it begins to get around the trees on its own, the young one is still guarded, protected, taught, and played with by the father.
Squirrel monkeys
There are two species of squirrel monkeys, the smallest of the New World monkeys. The common squirrel monkey (Saimiri sciureus) lives throughout most of South America's rain forest region. The red-backed squirrel monkey (S. oerstedii) occurs only in Panama and Costa Rica in the middle levels of the forest, where they eat primarily fruit, though they also use their narrow, sharply pointed teeth to devour small insects. Some authorities regard the red-backed squirrel monkey as a subspecies of the common squirrel monkey.
The common squirrel monkey is the species often kept as a pet. Its thick, short fur is gray, the chest is white, its legs are yellow, and it has white circles around its eyes, giving it a widow's peak above the nose. A large dark oval of bare skin encircles the nose and mouth on the muzzle.
Squirrel monkeys do not have a prehensile tail, and all swinging on branches is done with their arms, while their tails tend to rest curled over their shoulder. The tail is considerably longer than their 12 in (30 cm) body.
Squirrel monkey groups vary from 20 animals up to 200 individuals. When such a large group takes over a tree, the other cebid species, even the larger ones, are overwhelmed and forced to leave. The large squirrel monkey social group has very complex social relationships among individuals and subgroups. Some subgroups consist only of males, who remain by themselves except during mating season. This precludes a male from taking care of its single offspring, unlike most of the species of New World monkeys. The mother monkey's female friends may help raise and care for an infant. A single infant squirrel monkey is born after a gestation period that varies from 152-172 days. It becomes independent at about a year and sexually matures at three years for females and five for males. Squirrel monkeys have been known to live almost 15 years.
In the 1960s, the red-backed squirrel monkey was imported into the United States by the thousands for use as pets. Capture for the pet trade together with the destruction of their habitat of rain forest has severely endangered the wild populations of this monkey. Today, the United States government has outlawed the importation of primates except for legitimate scientific purposes.
The saki family
The sakis, bearded sakis, and uakaris belong to the subfamily Pitheciinae and all have long shaggy hair. These monkeys of the Amazon basin and farther north eat primarily fruit and seeds . They bear one offspring, probably taken care of by the mother. The two species of sakis (Pithecia) have nostrils that are set farther apart than those of any other New World monkey. They differ from the two species of bearded sakis in several ways. The tail of the saki is as long as its 16 in (40 cm) body length and is thick, bushy, somewhat baseball-bat shaped, and tapers to a pointed tip. The tail of the bearded saki is blunt at the tip. Sakis live in small family groups of only three or four individuals and prefer the lower reaches of the rain forest trees and may even venture onto the ground. The bearded saki stays wholly in the tree and prefers the upper layers, where a group of up to about 30 members stays in close touch . Sakis are known to eat birds and small mammals, something that the bearded sakis never do.
The male white-faced saki (P. pithecia) of the Guianas and northeastern Brazil has a stark white face set in a circular hood of long black hair, and a triangle of black fur from between the eyes to the nose and mouth. The female and young of the white-faced monkey do not have white faces, rather, they are dark brown or black with some whitish fur around the face. The adult female has a line of white fur running from the eyes and around the mouth and has a reddish tone to the chest and abdomen.
The monk, or hairy saki (P. monachus) of the upper Amazon is colored very much like the female whitefaced saki. The fur on its head curves forward as if forming a monk's hood that partially conceals the face.
Bearded sakis tend to look as if they have just come from a beauty salon. Their short, soft fur is very smooth, their full beards appear to be carefully trimmed, and poufs of longer fur above the eyes are smoothly bouffant. They have longer canine teeth than many monkeys, which they use to break up tough fruit to reach the seeds inside.
The endangered black-bearded, or red-backed, bearded saki (Chiropotes satanas) lives between the Orinoco and Amazon rivers and has bare red skin patches on its face. The white-nosed bearded saki (C. albinasus) lives primarily south of the Amazon.
Uakaris are slightly larger than sakis but, unlike all other New World monkeys, have a very small tail. These monkeys live strictly along river banks. The red uakari (Cacajao rubicundus) is particularly ugly, with a vivid, naked, red face, and a bald head which is naked back to behind its ears, where a rust-colored coat of very long, shaggy fur begins. The bald uakari, also called the white uakari (C. calvus), has a similar appearance but has yellowish or silvery fur. Some authorities regard C. rubicundus as a subspecies of C. Calvus. The black-headed uakari (C. melanocephalus) has black fur on its head, and its arms, hands, and feet are also black, while its legs and tail are red. The yellow-brown body is not as raggedly shaggy as in the other uakaris. This species appears to be thriving in western Brazil but may be endangered in the rest of its range.
The name uakari (also spelled ouakari) was given to these animals by the Tupi people of the Amazon basin. These monkeys live at all levels in the rain forest and rarely descend to the ground. They are better at leaping between branches than many other monkeys. The social groups may number up to 30 individuals. Female uakaris give birth to a single offspring every other year after a gestation of about 180 days.
Howler monkeys
The six species of howler monkeys in the subfamily Alouattinae possess a throat swelling with a special form of hyoid bone (the bone supporting the tongue muscles) that allows them to produce a deep, thundering roar, which can be heard more than 2 mi (3 km) away. Because of this throat swelling, their lower jaw juts forward more than in most other species of monkey. This jutting is not as noticeable as it might be, however, because the howlers are bearded. The throat is larger in the males than the females, and it is largest in the dominant male in a group of monkeys containing several males.
Howler monkeys are quite large, weighing up to 20 lbs (9 kg) and measuring 33 in (91 cm) long, with an equally long and very strong prehensile tail, which is naked on the end third. Howler monkeys use their prehensile tail to attach themselves firmly to branches, and they may hang from their tail to keep their hands free while feeding on leaves. The mantled howler monkey (A.palliata) has to eat so many leaves to get the nourishment it needs that its intestines make up one-third of the volume of its body. The mantled monkey is found from southern Mexico south to Ecuador and has a black body with a gold mantle, or fringe, down the sides.
Howler monkey species vary primarily in their coloring. The Guatemalan or Mexican black howler monkey (A. villosa) is completely black, from the bare base to the tip of its tail. All the howlers have naked black faces, but the black-and-red howler (A. belzebul) has red hands and feet as well as tail tip. The red howler (A. seniculus) is bright copper . Only the black howler (A. caraya) has different forms of the males and females. The young of black howler monkeys are born golden-brown, and the males turn black as they mature. A howler group contains up to 20 monkeys, with two to four males and five to ten females in the group. A single young howler is born after a gestation of about 180 days. It clings to the mother's abdomen for the first several weeks until its tail matures enough for it to be able to cling to its mother's tail. It then moves around and rides her back, where it remains for a year or more. Howler females reach maturity at about five years, and males at six to eight years.
The mantled, Guatemalan, or brown howler monkey (A. fusca) is an endangered species . Although some howlers live higher in the mountains , this lowland species is losing its habitat to logging and agricultural conversion. They are also hunted, and individual animals are easily caught because their loud voices betray their location.
Spider monkeys and woolly monkeys
The subfamily Atelinae includes the spider monkeys, the woolly spider monkeys, and the woolly monkeys. These monkeys are as large as howler monkeys but thinner.
Spider monkeys (Ateles) are found in approximately the same range as the howler monkeys, though spider monkeys occur farther north in Mexico and extend south to Brazil. Howler monkeys may eat slightly immature fruit, while spider monkeys wait until it is truly ripe. The arms of spider monkeys are longer than their legs, giving them an ungainly spider-like appearance. Spider monkeys are extremely agile and can walk along branches, hang upside down, leap sideways, and even leap long distances downward. Spider monkeys are very adroit at swinging from branches by arm to arm movements, also called brachiation, an ability that requires special flexibility in the shoulders. Their tails are quite thick toward the base but slender and with a naked patch with ridges toward the tip, which makes it quite sensitive.
The long tail is especially useful because, unlike many other monkeys, spider monkeys do not have an opposable thumb, meaning they are not very adept with their hands. Their skeletons show the remains of the thumb, and some individual animals have a slight protrusion where a thumb would be. Spiders live in large groups, though they often tend to break up into smaller family subgroups.
All spider monkeys have fairly long, shaggy fur, which is mostly dark brown or black. The fur on the head is brushed forward. The black-handed, or Geoffroy's spider monkey (A. geoffroyi) of Central America has golden, reddish, or bronze fur on its body and usually black hands and feet. The long-haired spider monkey (A. belzebuth) of the upper Amazon has chest and abdomen of a lighter color than the rest of its body. The brown-headed spider monkey (A. fusciceps) lives from Panama to Ecuador, between the ranges of the other two species.
In coastal parts of Brazil, the spider monkey's territory is taken over by the woolly spider monkey or muriqui (Brachyteles arachnoides). The woolly spider monkey is the heaviest monkey in Brazil, weighing 35 lb (16 kg); it has the chunky body and thick fur of the woolly monkey but lacks a thumb. It is lighter brown in color than most of its relatives.
The woolly spider monkey's social groups, which used to number about 30-40, are now down to typically 6-20. Within a group's territory, the individuals separate by gender and can frequently be seen hugging each other. There may be only a few hundred woolly spider monkeys left, reduced from half a million individuals when Europeans first arrived in South America. The large size and gentle nature of the woolly spider monkey makes them easy targets for hunting, and this species is now on the endangered species list.
The two species of woolly monkeys (Lagothrix) live in western South America, mostly at fairly high altitudes. Their thick fur makes the woolly monkeys look larger and stouter than they really are. The common woolly monkey (L. lagothricha), also known as Humboldt's monkey, is colored gray, black, or brown. The yellow-tailed or Hendee's woolly monkey (L. flavicauda) is deep red-brown with yellow fur along its tail and around its genitals. This monkey lives in a small mountainous area in northern Peru. The yellow-tailed woolly monkey was thought to be extinct from hunting for food and the pet trade, but a small wild population was rediscovered in the 1970s, and this endangered species is now being bred in captivity.
Endangered New World monkeys
The Atlantic rainforest in Brazil has been called one of "the most devastated primate habitats in the world." Sixteen of the 21 primate species and subspecies that live in that ravaged Brazilian ecosystem are found nowhere else, and will disappear along with their habitat. The human population of the region continues to put pressure on the forests, which are cut down for agricultural use, living space, and firewood. The endangered woolly spider monkey has become a symbol of the conservation crisis in Brazil.
Other endangered species include the southern bearded saki (Chiropotes satanas, the yellow-tailed woolly monkey (Lagothrix flavicauda), and the Central American squirrel monkey (Saimiri oerstedii). As more and more of the rain forest is cleared, other New World monkeys will be added to the endangered species list. The only ways to save these endangered primates are to preserve their natural forest habitat, and to control the hunting of the rarer species.
Resources
books
Kerrod, Robin. Mammals: Primates, Insect-Eaters and BaleenWhales. Encyclopedia of the Animal World series. New York: Facts on File, 1988.
Knight, Linsay. The Sierra Club Book of Small Mammals. San Francisco: Sierra Club Books for Children, 1993.
Napier, J.R., and P.H. Napier. The Natural History of the Primates. Cambridge, MA: The MIT Press, 1985.
Napier, Prue. Monkeys and Apes: A Grosset All-Color Guide. New York: Grosset & Dunlap, 1972.
Peterson, Dale. The Deluge and the Ark: A Journey into Primate Worlds. Boston: Houghton Mifflin, 1989.
Preston-Mafham, Rod, and Ken Preston-Mafham. Primates of the World. New York: Fact of File, 1992.
Jean F. Blashfield
KEY TERMS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .- Brachiating
—Swinging from tree limb to tree limb hand over hand.
- Diurnal
—Refers to animals that are mainly active in the daylight hours.
- Gestation
—The period of carrying developing offspring in the uterus after conception; pregnancy.
- Monogamous
—Of males and females, mating for life.
- Nocturnal
—Active in or relating to nighttime.
- Opposable
—Of the thumb or first toe on a primate, set far enough from the remainder of the fingers to be useful in grasping objects.
- Polygamous
—Of males and females, taking more than one mate at a time.
- Prehensile
—Grasping, as the specialized tail in many monkeys.
- Sexual dimorphism
—The occurrence of marked differences in coloration, size, or shape between males and females of the same species.