There are 56 species of cebids in 5 genera and 3 subfamilies. The most diverse group of cebids are the marmosets and tamarins (Callitrichinae), with 43 species. Callitrichinae includes Goeld's marmosets (Callimico), 21 species of marmosets (Callithrix), 4 species of lion tamarins (Leontopithecus), and 17 species of tamarins (Saguinus). There are 8 species of capuchins (Cebus) in the subfamily Cebinae and 5 species of squirrel monkeys (Saimiri) in the subfamily Saimiriinae. (Gold, 2004; Nowak, 1991)
Cebids are found in a variety of forested habitats in tropical and sub-tropical areas. They are found in dense, evergreen tropical forests to dry forests. Altitudinal range varies from sea level to 2000 meters in squirrel monkeys and sea level to 2700 meters in capuchins. Marmosets and tamarins are mainly found in primary, lowland wet forests. (Gold, 2004; Heymann, 2004; Nowak, 1991)
Cebids include some of the smallest primates and the smallest true monkeys, with pygmy marmosets averaging masses of 110 grams in males. Marmosets and tamarins (Callitrichinae) are generally smaller, with average mass ranging from 110 grams to 620 grams. Squirrel monkeys (Saimiriinae) are also small primates, with average mass ranging from 550 to 1250 grams. Capuchins (Cebinae) are more robust, with average masses ranging from 1.1 to 3.3 kg. In marmosets and tamarins, females are generally larger. In squirrel monkeys and capuchins, males are generally larger than females and males may have different head and body proportions than females. (Gold, 2004; Heymann, 2004; Nowak, 1991)
Cebids are characterized by round heads with large, forward facing eyes and relatively short muzzles. All species are covered with fur, including the tail, ranging from short and dense in squirrel monkeys and capuchins to long and silky in tamarins and marmosets. Only capuchins have prehensile tails, although their tails are used mainly to steady themselves, rarely to grasp objects. All other cebid species have non-prehensile tails. (Gold, 2004; Heymann, 2004; Nowak, 1991)
Cebids have long tails, generally longer than their body length. Squirrel monkeys range from 27.5 to 37 cm in body length and 14.2 to 17.8 cm in tail length. Capuchins are from 32 to 56 cm in body length and 38 to 56 cm in tail length. Marmosets and tamarins are from 14 to 29 cm head and body length and 20 to 40 cm in tail length. Fur color varies from white or buff through grays and browns to black. Some species of capuchins and marmosets and tamarins have tufts of fur on their heads, or longer hair on the head and shoulders, forming a mane or cape, as in golden lion tamarins. (Gold, 2004; Groves, 2001; Nowak, 1991)
Cebid hands have long, thin digits with flattened or curved nails. The thumbs are opposable in squirrel monkeys and capuchins and the first toe is large, well-developed and largely opposable in all species. Cebids possess bacula. The dental formula is i 2/2; c 1/1; pm 3/3; m 3/3, except in Leontopithecus, Saguinus, and Callithrix, in which third molars are lacking. (Gold, 2004; Heymann, 2004; Nowak, 1991)
Squirrel monkeys and capuchins generally have a promiscuous mating system, with both males and females mating with multiple individuals. Capuchin females solicit mating from multiple males, including the group's dominant male, making paternity difficult to determine. Males do not compete for access to females. (Gold, 2004)
Marmosets and tamarins are characterized by monogamy or polyandry, with each social group having a single, dominant, breeding female. These dominant females either breed with a single male or with multiple males. Gould's marmosets are the exception, with multiple breeding females present in social groups. Other marmoset and tamarin species have been reported to have multiple breeding females, but these are generally the daughters of the dominant female, and they have much lower reproductive success. (Heymann, 2004)
Squirrel monkeys and capuchins give birth to a single offspring each year and species may be seasonal breeders, often with breeding during the wet season when food is abundant, or species may breed throughout the year. Gestation is 155 to 180 days in squirrels monkeys and 149 to 168 days in capuchins. Females have estrus cycles during the breeding season that vary from 12 to 18 days in length. Male squirrel monkeys change their morphology during the breeding season, gaining a substantial amount of weight in their upper body. Males in this breeding condition are called "fatted" males. (Gold, 2004; Heymann, 2004; Nowak, 1991)
Marmosets and tamarins give birth mainly to dizygotic twins, although single births and triplets are also reported. They give birth once yearly during a breeding season that corresponds with the local wet season. Births occur at night. In captivity births occur twice a year, but this is rarely observed in the wild. The exception to this pattern are Goeld's marmosets, which give birth to a single young during the wet season, although births may occur year-round in captivity. Gestation length is from 129 to 183 days. (Heymann, 2004)
Squirrel monkey females reach sexual maturity at 3 years old, males at 5 to 6 years. Capuchin females become sexually mature at 4 to 5 years, males at 8 to 10 years. Marmosets and tamarins reach sexual maturity at 12 to 24 months old. (Gold, 2004; Heymann, 2004; Nowak, 1991)
In squirrel monkeys, females care for their young almost constantly for several months after birth. At 3 to 4 weeks old she may allow other mature females with young to carry her young, but she will maintain visual contact at all times. Juvenile females may also be allowed to briefly carry the young. Young are weaned at 5 months and become independent at 11 to 12 months, just before the mother gives birth to her next infant. Even after independence, young squirrel monkeys stay close to their mother and travel with her. (Gold, 2004)
Capuchin young also rely almost entirely on their mother for care. They are carried on the mother's underside for the first 6 weeks of life, after which they switch to riding on her back. Capuchin young nurse for several months and other members of the group will come to assist young capuchins if they become distressed. Both capuchins and squirrel monkeys remain close to their mother, but begin to explore their environment at about 2 to 3 months old, including playing with similarly aged individuals. (Gold, 2004; Nowak, 1991)
Marmoset and tamarin females give birth to young with one of the largest body masses, relative to female body mass, of all mammals. The combined birth weight of twins is 20% of maternal body mass, only tarsiers have higher ratios of infant to maternal body mass. This large investment by females in young before their birth is offset by extensive parental investment by males after the young are born. Male tamarins care for young from birth, carrying and protecting them. They return the young to their mother for nursing occasionally. Marmosets and lion tamarins share infant care among all group members and Goeld's marmoset females carry their young until about the second week of life, when all group members begin to help. Carrying such large offspring is a significant energy burden. Even captive tamarin males lose up to 10% of their body mass in the first few weeks of caring for newborn young. Wild tamarins that have to travel to search for food are likely to experience much larger stresses. Young marmosets and tamarins are weaned at about 3 months old. Group care extends to communal feeding of young as well, young emit a chattering or squawking vocalization that prompts group members to give up food items. (Heymann, 2004; Nowak, 1991)
Data on lifespan are generally from captive conditions. Squirrel monkeys have been known to live more than 15 years in captivity, capuchins have been reported living up to 47 years in captivity, and marmosets and tamarins have been reported living up to 12 years in smaller species or up to 18 years in larger species. (Nowak, 1991)
All cebid species are highly social, living in groups that cooperate in finding food and raising young. All species are active during the day and arboreal. Groups are highly variable in organization, they are usually multimale-multifemale groups and most often are not restricted to family groups. Capuchin group sizes are from 8 to 30 animals, squirrel monkeys are found in groups of 10 to 55, although groups of up to 300 animals have been reported. Marmosets and tamarins are generally found in smaller groups, from 3 to 15 but usually 4 to 9. Squirrel monkey groups are generally organized around dominant, adult females. Capuchin groups are typically led by a dominant male that defends the group against others and all capuchin groups are territorial. Marmoset and tamarin groups are typically organized around a single, dominant, breeding female. Marmosets and tamarins also sometimes participate in larger, mixed-species groups during the day. There may be some partitioning of space and foraging resources during the day, and the species separate at night, but contact is re-established during the day through vocalizations. (Gold, 2004; Heymann, 2004; Nowak, 1991)
Capuchins, marmosets, and tamarins use social grooming extensively, while squirrel monkeys have rarely been observed to engage in social grooming. Social interactions are complex. Capuchins in particular are noted for their intelligence and manual dexterity, including reports of tool use in the wild (using a rock to open oysters and using a branch to kill a snake). (Gold, 2004; Heymann, 2004)
Home range sizes vary substantially, both among and within all cebid species. Home range sizes reported in the literature vary from 0.1 hectares in pygmy marmosets to 120 hectares in brown capuchins and up to 276 hectares in golden-rumped lion tamarins. Home ranges of neighboring groups generally overlap considerably. (Gold, 2004; Heymann, 2004; Nowak, 1991)
Cebid species are very vocal, with a wide variety of social and alarm calls. Capuchin species are reported to have alarm calls that vary in frequency and duration to indicate the relative distance of harpy eagles. Cebid species have calls that indicate distance to maintain social cohesion, alert other group members of the presence of predators, and vocalizations to elicit specific responses in other group members, such as food soliciting in young. Vocalizations seem to be learned, as young cebids "babble" and don't show proper contextual use of vocalizations. (Gold, 2004; Heymann, 2004; Nowak, 1991)
Cebid species also extensively use chemical cues in communication. Squirrel monkeys and capuchins practice urine washing of their fur, possibly in order to scent mark the environment. Marmosets and tamarins apply scent gland secretions to objects in their environment as well as other members of their social group, urine washing has been observed rarely. Scent marking "parties" have been reported in mustached tamarins, where multiple individuals get together to scent mark each other and objects for several minutes. Scent marking may be more frequent in males or females, depending on social organization. Capuchins also practice self-anointment, where they rub their bodies with an odiferous substance. (Gold, 2004; Heymann, 2004)
Visual displays are also used, such as the genital displays of squirrel monkeys. Genital displays are used as a greeting and as a way to exert dominance. Posturing, facial expressions, and the fluffing of fur and hairy tufts are other forms of visual communication. (Gold, 2004; Heymann, 2004; Nowak, 1991)
Cebids are omnivorous, eating mainly fruits and insects, but also including nuts, flowers, buds, seeds, leaves, plant gums and exudates, other invertebrates, and some vertebrate prey in their diet. Squirrel monkeys require higher levels of protein in the diet, which they get by eating plenty of animal prey. Capuchins have been observed manipulating food, such as using rocks to open oysters or smashing nuts and fruits to soften them or open them to get the seeds. Marmosets and tamarin species include lots of plant gums and exudates in their diet and may also take nectar. Dietary flexibility allows cebid species to use other sources of food during seasons with few ripe fruits. Some marmoset and tamarin species also eat fungi and capture insects as they try to escape from army ant hordes. (Gold, 2004; Heymann, 2004; Nowak, 1991)
Because of their arboreal nature, most cebids are preyed on by raptors, arboreal snakes, and arboreal felids. Small cebids are especially vulnerable to predation by a wide variety of predators. Cebid species will aggressively defend themselves against predators. Even small species will attack snakes and throw objects at predators. Group members collaborate in defense, mobbing potential threats. Groups are also constantly vigilant in order to warn each other of potential threats and seek refuge. Marmoset and tamarins species that participate in mixed-species groups may experience increased protection from predation through increased vigilance. (Gold, 2004; Heymann, 2004; Nowak, 1991)
Cebid species are widespread and ubiquitous members of tropical forest ecosystems, where they play important ecosystem roles. They are a rich source of understanding of the evolution of social systems, mating strategies, and many other natural history features. Cebids have long been used as pets, in zoos, hunted for food, and many species have been important in biomedical research. Capuchins are highly intelligent and trainable and are now used extensively as helper animals for disabled people. Squirrel monkeys were used in the NASA space program before human astronauts. (Gold, 2004; Heymann, 2004; Nowak, 1991)
Although all primate species may carry diseases that can be transmitted to humans, this is typically only a concern in captive animals and their handlers. Common marmosets may be a rabies reservoir in Brazil.
Cebids include widespread and common species, as well as species that are rare or have restricted ranges. Cebid species populations are probably most profoundly affected by habitat destruction, although many species are also affected by research and pet trade markets and by hunting. A subspecies of Cebus apella (C. apella robustus) is listed as endangered by the IUCN. Cebus xanthosternos and Cebus kaapori are listed as critically endangered. Captive breeding programs are underway for these species. Two subspecies of Saimiri oerstedii are at risk: S. o. oerstedii is considered endangered and S. o. citrinellus is considered critically endangered. Saimiri vanzolinii is listed as vulnerable. Leontopithecus caissara is considered one of the 25 most endangered primate species worldwide, it is listed as critically endangered. All other Leontopithecus species are endangered. Other endangered marmosets and tamarins are: Callithrix flaviceps, Saguinus bicolor, and Saguinus leucopus. Saguinus oedipus is critically endangered. (Gold, 2004; Heymann, 2004; International Union for the Conservation of Nature, 2007)
Cebid fossils are known from the upper Oligocene. (Nowak, 1991)
Tanya Dewey (author), Animal Diversity Web.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
helpers provide assistance in raising young that are not their own
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
A substance that provides both nutrients and energy to a living thing.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
the business of buying and selling animals for people to keep in their homes as pets.
chemicals released into air or water that are detected by and responded to by other animals of the same species
Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
breeding takes place throughout the year
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