New World monkeys I: Squirrel monkeys and capuchins

(Cebidae)

Class Mammalia

Order Primates

Family Cebidae

Subfamily Cebinae

Thumbnail description
Squirrel monkeys have slender bodies while capuchins are more robust and have prehensile tails; both genera have rounded heads with flat faces and short muzzles; some capuchins have tufts of fur on their heads; all are arboreal and move quadrupedally

Size
Squirrel monkey body weight, 1.2–2.75 lb (0.55–1.25 kg); Capuchin body weight, 2.4–7.3 lb (1.1–3.3 kg)

Number of genera, species
2 genera; 12 species

Habitat
Forest-living, occurring in a range of forest types from dry forest to dense evergreen tropical rainforest

Conservation status
Critically Endangered: 1 species, 2 subspecies; Endangered: 2 subspecies; Vulnerable: 1 species

Distribution
Both genera are widely distributed over parts of Central and South America, with some species being isolated in very small populations in certain countries

Evolution and systematics

Monkeys in the New World are classified into the infraorder Platyrrhini, which are distinguished from the Old World monkeys by nostrils that are widely separated and open to the side. Within this infraorder are three families, one of which is the Cebidae. Dentition is 36 teeth with a dental formula of (I2/2 C1/1 P3/3 M3/3) × 2 = 36. Within the Cebidae are five subfamilies including the Cebinae. The Cebinae includes the squirrel monkeys (genus Saimiri) and the capuchins (genus Cebus).

Initially all squirrel monkeys were grouped in one species, Saimiri sciureus (Linnaeus, 1758). Hershkovitz (1984) then split the genus Saimiri into four distinct species: Saimiri boliviensis (with two subspecies), Saimiri oerstedii (with two subspecies), Saimiri sciureus (with four subspecies), and Saimiri ustus. In 1985 a fifth species (Saimiri vanzolinii Ayers, 1985) was delineated in a small pocket of forest in northwestern Brazil based on chromosomal differentiation. This taxonomy is now generally accepted and validated based on chromosomal evidence.

Capuchin systematics is more cloudy and disputed, as it has been from early times. This is due to a high degree of individual variation, changes in coloration associated with age, sexual differentiation, and occasional hybridization. The current taxonomy follows the divisions established by Hershkovitz (1955) of one "tufted" species: Cebus apella (10 subspecies); and three "untufted" species: Cebus albifrons (11 subspecies), Cebus capucinus (4 subspecies), and Cebus olivaceus (5 subspecies). A fifth species (Cebus xanthosternos Weid-Neuwied, 1826) was formally recognized (formerly a subspecies of Cebus apella) in 1997. A controversial recent revision by Groves (2001) has clouded the systematics by further elevating former subspecies of Cebus apella to two additional species: Cebus libidinosus (4 subspecies) and Cebus nigritus (3 subspecies).

Physical characteristics

All Cebinae are characterized by round heads with large forward facing eyes and relatively rounded muzzles that do

not protrude much from the face. The bodies of the squirrel monkeys are small and rather slender, with adult males being larger than adult females, especially prior to and during the breeding season. Squirrel monkey bodies are covered with dense short fur. Color varies from gray to black on the crown of the head, the muzzle is black, the back is yellow to golden to reddish, the shoulders are gray to olive, the undersides are white to yellow, and the forearms, hands, and feet are yellow to golden. The tail is fully furred, nonprehensile, and typically longer than the body length. Head and body length is 10.8–14.6 in (27.5–37 cm); tail length is 14.2–17.8 in (36–45.2 cm). Body mass is 1.2–2.75 lb (0.55–1.25 kg).

Scientists have grouped the squirrel monkeys into two groups based on the shape of the white arch of supraorbital fur above their eyes: Gothic (pointed) and Roman (rounded). Saimiri boliviensis and Saimiri vanzolinii have Roman arches, while Saimiri oerstedii, Saimiri sciureus, and Saimiri ustus have Gothic arches.

Capuchins have robust, medium-size bodies. Adult males are slightly larger than adult females, and head shape and body proportions differentiate the sexes. Capuchin bodies are fully furred, with short fur around their faces, and short to longer dense fur on the rest of their bodies. Fur coloration varies from black to brown to buff, with patches of white on chests and shoulders. Undersides are generally lighter from yellow to brown, and the crown of the head is usually darker, with some species having delineated black caps. Capuchins all have opposable thumbs and opposable big toes. Tails are fully furred and prehensile. Head and body length is 12.6–22 in (32–56 cm); tail length is 15–22 in (38–56 cm). Body mass is 2.4–7.3 lb (1.1–3.3 kg).

Capuchins have been grouped according to the presence (Cebus apella and Cebus xanthosternos) or absence of tufts (Cebus albifrons, Cebus capucinus, and Cebus olivaceus) on their heads.

Distribution

Squirrel monkeys are found throughout the Amazon basin from central Colombia to Bolivia and northeastern Brazil (including Ecuador, French Guiana, Guyana, Peru, Suriname,

and Venezuela). The Saimiri oerstedii species range in Costa Rica and Panama.

Capuchins are found in Central and South America from Belize, throughout the Amazon basin and Brazilian coastal forests and south to Argentina. Countries include Argentina, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guyana, Honduras, Nicaragua, Panama, Paraguay, Peru, Suriname, Trinidad and Tobago, and Venezuela.

Habitat

Squirrel monkeys have a wide distribution in primary and secondary forest types from gallery to low canopy hillside and riverine forests, palm forests, high and lowland rainforest, swamp, mangrove, and marsh forests. Squirrel monkey habitat ranges in altitude from sea level to 6,500 ft (2,000 m).

Capuchins inhabit virtually every type of forest in the Neotropics including dry forests, deciduous forests, and rain-forests. Capuchin habitat ranges from sea level to 8,500 ft (2,700 m) in altitude in the Colombian Andes.

Behavior

Both genera of the subfamily Cebinae are diurnal and arboreal in habit. In the wild, squirrel monkeys are found in multimale-multifemale groups of 10–55 animals, with some groups as large as 300 individuals observed. Larger groups tend to break into smaller groups for foraging during the day, aggregating together at night. Sex ratio is close to 1:1, with some species having fewer adult males than adult females. Society generally revolves around the adult females, as studies show that all age/sex classes including adult males are most attracted to the adult females. Females are responsible for determining spatial relations between adult animals through affiliative and agonistic interactions. In Saimiri boliviensis and to some extent in Saimiri oerstedii, males are peripheral to the group in the nonbreeding season and are actively chased away when they approach non-estrus adult females. Adult females of these species are dominant to adult males except during the breeding season. Adult males are more integrated into the groups in Saimiri sciureus, and all adult males are dominant to all females. Juvenile and adult animals will huddle together during times of rest, with adult animals huddling almost exclusively in same-sex groupings. The huddling behavior is distinct, with animals in lateral contact and each animal's head tucked against its chest and its tail curled over its head and body.

Capuchins live in multimale-multifemale groups of 8–30 animals, with some larger groups of up to 50 animals noted for Cebus oliveceus. Sex ratio is 1:1 in some species, with other species having more females than males. Troops generally have one male who is dominant to all other individuals, and who aggressively defends the group against other groups. Males typically emigrate from their natal groups at between 2 and 4 years of age. Cebus capucinus groups have been reported to have frequent turnover of adult male group membership. Some species are reported to have males that are occasionally solitary or nomadic. All capuchin species are territorial. Capuchin individuals are active throughout most of the day traveling and foraging within their range.

Communication is both vocal and visual. Both genera are vulnerable to predation and give alarm calls in response to large carnivorous mammals, boas, and birds of prey. It has been reported that Cebus apella males have an alarm call directed towards harpy eagles. This call is a distinctive barking that varies in frequency and loudness to indicate to other group members the relative proximity of the eagle. Squirrel monkeys are known to emit more than 24 different vocalizations including predator alarm calls and distancing calls that allow individuals to locate each other when out of sight while foraging. Unique visual signals include the so-called "genital displays" of the squirrel monkey. One leg is extended outward, presenting a view of the genitals to another animal. Both male and female individuals use this signal as a greeting when one animal flashes another its genitals from a distance (open genital display). The genital display is also used to establish and exert dominance when a dominant animal approaches another at very close proximity and exposes its genitals to the other while averting its gaze (closed genital display). The submissive animal will huddle quietly facing the display. Erections and occasionally the squirting of urine often accompany closed genital displays by males.

Both squirrel monkeys and capuchins practice urine washing of the fur with their hands; this may help an animal scent mark its surroundings and other olfactory communication. Capuchins are known to throw things towards potential predators in their aggressive displays. Boinski reports Cebus capucinus in Costa Rica throwing branches, fruit, and other objects at coatimundis, tayras, opossums, and humans. She describes one incident in which a capuchin threw a squirrel monkey at her when it had depleted its supply of readily detachable branches.

Capuchins are also noted for their manual dexterity and ability to manipulate objects. They have comparatively large and developed brains for their body size. Their high level of intelligence has made them one of the primates of choice for animal behavior and cognitive research. Young capuchins in captivity are easily trained, leading to their popularity in the pet market. Older animals become problematic as pets once reaching sexual maturity, and male capuchin pets are sometimes castrated or have their teeth pulled to try and control their aggressive tendencies. This trainability of young capuchins in the past led to their being used as organ grinder monkeys in many parts of the world. Now some capuchin females are being trained as helper animals for paraplegics and other wheelchair-bound humans. With a capuchin's ability to move in three-dimensional space and retrieve items desired by their human hosts, they have proven themselves much more helpful than canine companions. In captivity they are avid tool users, and in the wild have been observed using rocks to open oysters and one was seen using a branch as a club to kill a snake that had been caught under a fallen branch. In captivity they have been observed to use their prehensile tails to manipulate and play with objects.

Social and self-grooming is a common behavior in capuchin monkeys and social grooming helps to reinforce the group dynamics. Dominant animals are groomed more than less dominant animals. Squirrel monkeys have rarely been observed to engage in social grooming, with the exception of some mothers grooming their infants. They do engage in high frequencies of self-grooming using both fingers and toes to groom their fur. Capuchins also engage in self-anointing behavior, often rubbing fragrant items on their chests and other body parts. This behavior is also seen in captivity, with onions being of particular interest.

Feeding ecology and diet

Both genera are omnivorous. Squirrel monkeys are primarily frugivorous and insectivorous. They require a high level of protein in their diets, most of which is acquired by the consumption of animal prey. Diet includes fruits, nuts, flowers, buds, seeds, leaves, gum, insects, spiders, crabs, and some smaller vertebrates including frogs and bats. Capuchins are primarily frugivorous, but also include animal prey in their diet. This animal prey includes insects and smaller vertebrates (bird eggs, small birds, nestling squirrels, and lizards). Cebus capucinus have been observed eating oysters and using rocks to crack open the shells. Capuchins also beat fruit or nuts against hard surfaces to tenderize them or crack them open to get the seeds inside. Squirrel monkeys and capuchins overlap in much of their range and tolerate each other, even sharing food sources, eating side by side in the same fruiting trees. The squirrel monkeys are able to exploit more of the resources since their smaller size and lighter weight allows them to forage on smaller branches and to reach the tips of larger branches. Squirrel monkeys in Panama have been reported to spend 95% of the day traveling or foraging during the dry season. When fruit is not plentiful in the dry season, capuchins substitute pith and seeds for fruit and increase their daily ranging to try and locate the few fruiting trees available. When one troop member discovers a fruiting tree, it vocalizes to alert the rest of the troop to its location. Dominant Cebusapella males control access to preferred food items during times of scarcity, restricting other animals' access until they have eaten their fill.

Reproductive biology

Both genera have a polygamous mating system with promiscuous mating. Single births are the rule for both genera. Squirrel monkeys have a yearly reproductive cycle with a 2–3 month breeding season and a corresponding 2–3 month birthing season. The birth season (approximately 5.5–6 months after the breeding season) is correlated with the wet season and food abundance in their specific range. Unique among primates is an annual change in the males' physiology that occurs just prior to the breeding season. Adult males increase in body weight 10–30% (primarily in the upper body), and the testes double or triple in size, accompanied by the onset of spermatogenesis. These males are referred to as "fatted males." During the breeding season females have an estrus cycle of 12–14 days. The gestation period varies from 155–180 days. Females generally reach sexual maturity at three years with males not reaching full sexual maturity (evidenced by attaining the fatted stage) until 5–6 years. The ratio of infant size to mother size is the largest for any mammal, approaching 1:6. Infant birth weight is 3.2–3.9 oz (90–110 g).

Some species of capuchins are reported to be seasonal breeders, while others breed year round with a peak of births in a certain season. For many capuchin species paternity is often unknown as females have been seen to mate with more than one male. Estrus females follow and solicit mating from males, and males rarely fight over access to females. Female Cebus apella tend to groom and breed only with the dominant male, which is thought to create a bond so that he will protect the infants that he has sired. Females reach sexual maturity at 4–5 years; males do not reach full maturity until 8–10 years of age. Female estrus cycles are 18 days for Cebus apella, and the gestation period for Cebus varies from 149 to 168 days. Infants at birth are about 8.5% of the mother's weight, about 8 oz (220 g).

Both infant squirrel monkeys and capuchins are dependent on their mothers for parental care. An infant squirrel monkey clings to its mother's back from day one. It rides in the middle of her back with its head turned to one side, clutching her fur tightly with hands and feet and wrapping its tail tightly around her body. When nursing, the infant crawls forward and positions its head under her arm, rooting around under her armpit until it finds the nipple. Infants ride this way for several months. At 3–4 weeks other animals attempt to carry the infant and the mother may allow older females without young to carry the infant, but the mother always maintains visual contact. Juvenile females are occasionally allowed to carry infants, but the mother always remains nearby, ready to retrieve the infant at the first sound of trouble. It is thought that this is the way in which young females learn mothering skills. Infants begin to be weaned at five months and are independent from the mother by 11–12 months, just prior to their mother giving birth during the next birthing season. The youngster still maintains a close relationship with its mother and often travels nearby her and the new infant. Capuchin infants initially

cling to the mother's underside or across her shoulders, and at about six weeks align their bodies along the mother's back. As infants and juveniles, both genera return to the mother for protection and security when stressed. At 2–3 months they begin to explore their environment and develop social relationships with other group members and begin to play with similar aged infants. Social play helps animals learn the subtleties of proper social behavior and the control of aggressive responses. It also helps to develop sexual behavior and to integrate the young into the group.

Conservation status

Both genera are widespread in parts of their range and extremely restricted in other areas. All are at least listed in Appendix 2 of CITES. The IUCN lists one subspecies of Saimiri oerstedii (S. o. oerstedii) as Endangered and the other (S. o. citrinellus) as Critically Endangered due to a severely fragmented population, low population numbers, and continued habitat loss and degradation. The IUCN lists Saimiri vanzolinii as Vulnerable due to a limited range, fragmented populations, low population numbers, and continued habitat loss and degradation. During the 1960s and 1970s over 25,000 squirrel monkeys per year were exported from Peru alone for the research and pet markets. Annual export quotas limit the number of squirrel monkeys to a sustainable harvest, although the quality of monitoring has come under question. The IUCN lists one subspecies of Cebus apella (C. a. robustus) as Endangered due to continued habitat loss and degradation. Cebus xanthosternos is listed as Critically Endangered by IUCN since only one small population is known, and this population suffers from continued habitat loss and degradation as well as hunting for food. International captive breeding programs are underway for both of these Endangered Cebus populations. Annual export quotas for Cebus apella from Guyana are imposed by CITES.

Significance to humans

Both genera are used as a model for human research in many forms: biomedical, pharmacological, physiological, behavioral/social, etc. Members of both genera are commonly found as pets and zoo animals throughout the world. Capuchins and squirrel monkeys are hunted for food (bushmeat) in major portions of their range. In the United States captive breeding programs have been established to help supply the scientific, biomedical, and zoological communities. Squirrel monkeys were used in the space program prior to the use of human astronauts.

Species accounts

List of Species

Bolivian squirrel monkey

Saimiri boliviensis

subfamily

Cebinae

taxonomy

Saimiri boliviensis (I. Geoffroy and Blainville, 1834), Guarayos Mission, Rio San Miguel, Santa Cruz, Bolivia. Four subspecies. Elevated from subspecies of Saimiri sciureus in 1984.

other common names

English: Black-headed squirrel monkey.

physical characteristics

Fur is sexually dichromatic—males gray and females black. Yellow at base of crown, on forearms, hands, and feet. Roman (rounded) arch over eyes. Head and body length is 12.2 in (31 cm). Tail length is 14.2 in (36 cm). Weight is 24.7–38.4 oz (700–1,088 g).

distribution

Brazil, Bolivia, Colombia, Peru, and Venezuela.

habitat

Primary and secondary tropical rainforest.

behavior

Diurnal and arboreal. Multimale-multifemale groups of 20–50 animals. During breeding season males form hierarchy, and are

dominant over females. For the rest of the year males are peripheral and subordinate to the females. Both males and females use genital display towards conspecifics. Female social aggression is common.

feeding ecology and diet

Predominately eat fruits, seeds, and animal prey including frogs, snails, insects, and spiders. Fruit is eaten earlier in the day, with animal protein eaten later.

reproductive biology

Promiscuous mating. Males become "fatted" with upper body weight gain, an increase in testes size, and active spermatogenesis just prior to the breeding season. Males compete with each other for dominance during the breeding season. Breeding season is followed six months later by a birth season (coinciding with the wet season) when food is most abundant. Females reach sexual maturity at 36 months and gestation is 155–170 days. Births are single.

conservation status

Widespread and uncommon to locally common. Main pressures on populations include habitat degradation, deforestation, hunting for food, and collection for laboratories. Listed in Appendix 2 of CITES.

significance to humans

Hunted for food in those areas of range where larger mammals have been depleted. Collected for pet, zoo, and research market.

Red-backed squirrel monkey

Saimiri oerstedii

subfamily

Cebinae

taxonomy

Saimiri oerstedii (Reinhardt, 1872), David, Chiriquí, Panama. Two subspecies. Elevated from subspecies of Saimiri sciureus in 1984.

other common names

English: Panamanian squirrel monkey; French: Saïmiri à dos roux, Singe-écureuil à dos rouge; Spanish: Barizo dorsirrojo, mono tití.

physical characteristics

Black crown; rust-orange back, hands, and feet; olive-gray hips, shoulders, and tail base. Tail tip is black. Gothic (pointed) arch over eyes. Head and body length is 10.6 in (27 cm). Tail length is 14.3 in (36 cm). Weight is 21.2–33.5 oz (600–950 g).

distribution

Costa Rica and Panama.

habitat

Subtropical and tropical lowland rainforest.

behavior

Diurnal and arboreal. Multimale-multifemale groups of 20–55 animals. Males integrated into group structure year-round, yet are peripheral in behavior during the non-breeding season. Males are vigilant and aggressive to outside threats and other groups. Males remain in natal group, females emigrate. Mothers groom infants, unseen in other squirrel monkey species.

feeding ecology and diet

Predominately eat fruits, seeds, leaves, and insects.

reproductive biology

Promiscuous mating. Males become "fatted" with upper body weight gain, an increase in testes size, and active spermatogenesis just prior to the breeding season. Breeding season in January and February, birth season in July. Births are single.

conservation status

Scattered small populations throughout range. Main pressures on populations include habitat loss, degradation, and deforestation. Listed as Endangered by the IUCN.

significance to humans

None known.

Common squirrel monkey

Saimiri sciureus

subfamily

Cebinae

taxonomy

Saimiri sciureus (Linnaeus, 1758), Cayenne, French Guyana. Taxonomy is disputed, has four subspecies.

other common names

French: Saimiri écureuil; German: Totenkopfaffchen; Spanish: Mono ardilla.

physical characteristics

Fur is gray to black crown; olive-gray back; light yellow under-side; yellow-orange forearms, hands, and feet; white ears and around eyes. Head and body length is 10.8–14.6 in (27.5–37 cm). Tail length is 15–17.8 in (26.5–45 cm). Weight is 19.5–44.1 oz (559–1,250 g).

distribution

Brazil, Colombia, French Guiana, Guyana, Suriname, and Venezuela.

habitat

Primary and secondary rainforest, riverine forest, and man-grove swamps from sea level to 6,600 ft (2,000 m).

behavior

Diurnal and arboreal. Multimale-multifemale groups of 20–300 animals. Strict male dominance hierarchy with males dominant over females and integrated within the group year-round. Male emigration upon sexual maturity.

feeding ecology and diet

Squirrel monkeys have a high need for protein. Predominately eat fruit and animal prey including frogs, snails, crabs, insects, spiders, and occasionally bats.

reproductive biology

Promiscuous mating often with multiple mountings. Males become "fatted", with upper body weight gain, an increase in testes size, and active spermatogenesis just prior to the breeding

season. This is followed six months later by a birth season (coinciding with the wet season) when food is most abundant. Females reach sexual maturity at 30–36 months and gestation is 168–180 days. Births are single.

conservation status

Widespread and uncommon to locally common. Main pressures on populations include habitat degradation, deforestation, hunting for food, and collection for laboratories. Listed in Appendix 2 of CITES.

significance to humans

Collected for the pet and research markets. Annual export quotas from Guyana to U. S. laboratories. Hunted for food in some areas of its range.

Blackish squirrel monkey

Saimiri vanzolinii

subfamily

Cebinae

taxonomy

Saimiri vanzolinii Ayers, 1985, left bank of Lago Mamirauá, mouth of Rio Japura, Amazonas, Brazil.

other common names

English: Black squirrel monkey.

physical characteristics

Fur is gray or black back with a black stripe; gray shoulders; yellow hands and forearms; Roman (rounded) arch over eyes. Head and body length is 10.8–12.6 in (27.5–32 cm). Tail length is 16.3–17.5 in (41.5–44.5 cm). Weight is 22.9–33.5 oz (650–950 g).

distribution

A small tract of 367 sq mi (950 sq km) in northeastern Brazil.

habitat

Swamp and white-water flooded tropical moist forest.

behavior

Diurnal and arboreal. Multimale-multifemale groups of up to 50 animals.

feeding ecology and diet

Predominately eat fruit and animal prey including insects and spiders.

reproductive biology

Promiscuous mating. Males become "fatted" with upper body weight gain, an increase in testes size, and active spermatogenesis just prior to the breeding season. Breeding season is followed six months later by a birth season (coinciding with the wet season) when food is most abundant. Births are single.

conservation status

Smallest distribution of any squirrel monkey. Main pressures on populations include habitat degradation and deforestation. Listed as Vulnerable by the IUCN.

significance to humans

None known.

White-fronted capuchin

Cebus albifrons

subfamily

Cebinae

taxonomy

Cebus albifrons (Humboldt, 1812), Orinoco River, Venezuela. Eleven subspecies.

other common names

None known.

physical characteristics

Fur color varies from light to dark brown with a dark wedge-shaped cap and white-yellow underside. Head and body length is 14.1–18.1 in (35.8–46 cm). Tail length is 15.8–18.7 in (40.1–47.5 cm). Weight is 3.1–7.2 lb (1.4–3.3 kg).

distribution

Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Trinidad and Tobago, and Venezuela.

habitat

Primary deciduous, gallery, mangrove, and flooded forest up to 6,500 ft (2,000 m).

behavior

Diurnal and arboreal. Multimale-multifemale groups of 10–30 individuals with more adult females than males. Group is led by one dominant male, and all animals are in a dominance hierarchy. Males emigrate from natal group.

feeding ecology and diet

Predominantly eat fruit and animal prey. Diet includes fruit, seeds, nectar, pith, insects, and small vertebrates.

reproductive biology

Polygamous, both sexes mate promiscuously. Females reach sexual maturity at 3.5–4 years. Gestation is 5.5 months. Births are single. Birth peak February–July.

conservation status

Widespread and uncommon to locally common. Main pressures on populations include habitat degradation, deforestation, and hunting for food. Listed in Appendix 2 of CITES.

significance to humans

Hunted for food (bushmeat) and kept as pets in Brazil. Considered crop pests in parts of their range and killed.

Black-capped capuchin

Cebus apella

subfamily

Cebinae

taxonomy

Cebus apella (Linnaeus, 1758), French Guiana. Ten subspecies.

other common names

English: Brown or tufted capuchin; French: Sapajou apelle; Spanish: Capuchino de copete.

physical characteristics

Fur is dark to light brown on body with underside and shoulders sometimes lighter; hands and feet always black. Adults have two tufts of erect fur on crown of head. Head and body length is 13.8–19.2 in (35–48.8 cm). Tail length is 14.8–19.2 in (37.5–49 cm). Weight is 3–10.6 lb (1.4–4.8 kg).

distribution

Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname, and Venezuela.

habitat

Primary and secondary rainforest to semi-deciduous and montane forest up to 8,800 ft (2,700 m).

behavior

Diurnal and arboreal. Multimale-multifemale groups of 8–16 individuals with sex ratio of 1:1. One male is dominant to all group members. Dominant males fight when two groups meet at food trees. Males emigrate from natal group.

feeding ecology and diet

Predominantly eat fruit, seeds, nectar pith, and animal prey including insects, frogs, reptiles, birds, bats, and other small mammals.

reproductive biology

Polygamous, both sexes mate promiscuously, although dominant male guards estrus females during part of their cycle. Females reach sexual maturity at 4–5 years. Gestation is 149–158 days. Estrus cycle is 18 days. Birth season is October–January. Births are single.

conservation status

Widespread and uncommon to locally common. Main pressures on populations include habitat degradation, deforestation, and hunting for food. Listed in Appendix 2 of CITES. One subspecies, Cebus apella robustus, is listed as Endangered by IUCN.

significance to humans

Hunted for food and as crop pests, collected and exported for pet and scientific research markets.

White-throated capuchin

Cebus capucinus

subfamily

Cebinae

taxonomy

Cebus capucinus (Linnaeus, 1758), northern Colombia. Four subspecies.

other common names

English: White-shouldered capuchin; French: Sajou à gorge blanche; Spanish: Mono capuchino.

physical characteristics

Fur: white to yellowish throat, head, and shoulders; black back, tail, arms, and legs. Head and body length is 13.2–17.8 in (33.5–45.3 cm). Tail length is 13.8–21.7 in (35–55 cm). Weight is 5.9–8.6 lb (2.7–3.9 kg).

distribution

Colombia, Costa Rica, Honduras, Nicaragua, and Panama.

habitat

Primary and secondary evergreen forest, rainforest, mangroves, and deciduous dry forest from sea level to 6,900 ft (2,100 m).

behavior

Diurnal and arboreal. Multimale-multifemale groups of 10–20 individuals with more adult females than males. Males defend the groups' territory. Communicate vocally when out of sight while foraging. Threat displays towards humans and other animals. Males emigrate from natal group.

feeding ecology and diet

Fruits, leaves, berries, nuts, seeds, shoots, buds, flowers, and animal prey including insects, spiders, crabs, and small vertebrates (birds, baby squirrels, lizards). Males will forage on forest floor.

reproductive biology

Polygamous, both sexes mate promiscuously. Females reach sexual maturity at 3–4 years, although females have been documented to give birth as young as 28 months. Gestation is 157–167 days. Birth season is December–April. Births are single.

conservation status

Widespread and uncommon to locally common. Main pressures on populations include habitat degradation, deforestation, and hunting for food. Listed in Appendix 2 of CITES.

significance to humans

Hunted for food and as crop pests in parts of their range. Collected for zoo and pet trade in past.

Weeper capuchin

Cebus olivaceus

subfamily

Cebinae

taxonomy

Cebus olivaceus Schomburgk, 1848, southern base of Mt. Roraima, 3,050 ft (930 m), Bolivar, Venezuela. Five subspecies.

other common names

English: Wedge-capped capuchin.

physical characteristics

Fur is tawny brown on body, with lighter shoulders and upper arms; brownish yellow head with black wedge on cap. Head and body length is 14.7–18.1 in (37.4–46 cm). Tail length is 15.7–21.8 in (40–55.4 cm). Weight is 5.3–6.6 lb (2.4–3 kg).

distribution

Brazil, French Guiana, Guyana, Suriname, and Venezuela.

habitat

Evergreen rainforest, lowland forest, cloud forest, dry forest, and submontane forest up to 6,500 ft (2,000 m).

behavior

Diurnal and arboreal. Multimale-multifemale groups of 8–50. One male is dominant to all group members and is the breeding male. Dominant display by branch shaking, jumping up and down and bouncing. Males emigrate from natal group as young as two years of age.

feeding ecology and diet

Fruits, seeds, and animal prey including snails and social insects. Feed on the ground and in the canopy.

reproductive biology

Polygamous, but only one breeding male at any time. Females reach sexual maturity at 5–6 years. Gestation is 5–6 months. Birth season is May–August. Births are single.

conserzvation status

Widespread and uncommon to locally common. Main pressures on populations include habitat degradation, deforestation, hunting for food, and collection for research. Listed in Appendix 2 of CITES.

significance to humans

Hunted for meat in parts of their range. Some exported annually from Guyana for research market.

Yellow-breasted capuchin

Cebus xanthosternos

subfamily

Cebinae

taxonomy

Cebus xanthosternos Wied-Neuwied, 1826. Monotypic; elevated from subspecies of Cebus apella in 1997.

other common names

English: Yellow-bellied capuchin.

physical characteristics

Fur is dark to light brown on body with underside and shoulders yellowish gold. Adults have two tufts of erect fur on crown of head. Head and body length is 13.8–19.2 in (35–48.8 cm). Tail length is 14.8–19.2 in (37.5–49 cm). Weight is 3–10.6 lb (1.4–4.8 kg).

distribution

Atlantic forest of Southern Bahia, Brazil.

habitat

Coastal forest.

behavior

Not known in the wild, but assumed to be similar to Cebus apella.

feeding ecology and diet

Not known in the wild, but assumed to be similar to Cebus apella.

reproductive biology

Not known in the wild, but assumed to be similar to Cebus apella.

conservation status

Listed as Critically Endangered by the IUCN. Main pressures on populations include habitat loss and degradation, hunting for food, and collection for pet and scientific research markets in the past.

significance to humans

Hunted to near extinction. An international captive breeding program has been in place since 1992.

Resources

Books

Coimbra-Filho, Adelmar F., and Russell A. Mittermeier, eds. Ecology and Behavior of Neotropical Primates. Vol. 1. Rio de Janiero: Academia Brasileira de Ciencias, 1981.

Moynihan, Martin. New World Primates. Princeton, NJ: Princeton University Press, 1976.

North American Regional Studbook for Saimiri sciureus. 1st ed. Santa Ana: New World Primate TAG, American Zoo and Aquarium Association, 2002.

Olney, P. J. S., ed. 1982 International Zoo Yearbook. Volume 22. London: Zoological Society of London, 1982.

Rosenblum, Leonard A., and Robert W. Cooper, eds. The Squirrel Monkey. New York: Academic Press, 1968.

Rowe, Noel. The Pictorial Guide to Living Primates. East Hampton, NY: Pogonias Press, 1996.

Smuts, Barbara B., et al. Primate Societies. Chicago: The University of Chicago Press, 1986.

Wolfheim, Jaclyn H. Primates of the World: Distribution, Abundance, and Conservation. Seattle: University of Washington Press, 1983.

Periodicals

Boinski, S. "Use of a Club by a Wild White-faced Capuchin (Cebus capucinus) to Attack a Venomous Snake (Bathrops asper)." American Journal of Primatology 4, no. 2 (1998): 177–179.

Hershkovitz, Philip. "Taxonomy of Squirrel Monkeys genus Saimiri (Cebidae, Platyrrhini): A Preliminary Report with Description of a Hitherto Unnamed Form." American Journal of Primatology 6, no. 4 (1984): 257–312.

Jack, K., and L. Fedigan. "Life History of Male White-faced Capuchins (Cebus capucinus), Santa Rosa National Park, Costa Rica." American Journal of Primatology 54, Supplement 1 (2001): 50.

Rylands, Anthony B., Ernesto Rodriguez-Luna, and Liliana Cortes-Ortiz. "Neotropical Primate Conservation—The Species and the IUCN/SSC Primate Specialist Group Network." Primate Conservation 17 (1996/1997): 46–69.

Rylands, Anthony B., et al. "An Assessment of the Diversity of New World Primates." Neotropical Primates 8, no. 2 (2002): 61–93.

Santos, Ilmar B., and Jean-Marc Lernould. "A Conservation Program for the Yellow-breasted Capuchin, Cebus apella xanthosternos." Neotropical Primates 1 (1993): 4–5.

Other

Vermeer, Jan. The Nutrition of Squirrel Monkeys (Saimiri): Report of an EEP-Survey. Romagne: La Vallee des Singes, 2000.

Kenneth C. Gold, PhD