Overview

Distribution

Range Description

Cebus olivaceus is found in lower Brazilian Amazonia, north of the mainstream of the Amazon and east of the Rio Negro, extending north through the Guianas and into northern Venezuela (Hill I960; Napier 1976). In the northern parts of its range, C. olivaceus extends north to the Río Orinoco and west to the Río Caroni. It has been recorded on the Island of Caviana in the Marajó Archipelago (Fernandes et al. 1995)

C. o. olivaceus extends south from there throughout the Guianas it would seem (excepting a possible hiatus in French Guiana where the form castaneus might occur), but the limits to its range in Brazil are unclear. C. o. olivaceus, type locality São Joaquim, upper Rio Branco, Roraima, Brazil, is the form occurring in the Venezuelan Amazon (Bodini and Pérez-Hernández 1987) and to the south and east it perhaps extends across the Rio Branco into Brazil, limited in the north by the Serra Parima and Serra Pacaraima, meeting with C. o. olivaceus somewhere in northern Pará or Amapá, but this is conjecture. Hill (1960) extends the range of C. o. olivaceus as far as the Rio Parú, a north bank tributary of the Amazon just above the Rio Jari. In Suriname, C. o. olivaceus is almost entirely restricted to the interior. Like Chiropotes and Ateles, it just enters the old coastal plain in a small part of western Surinam (Mittermeier 1977). Sussman and Phillips-Conroy (1995) indicated that it occurs throughout Guyana, and there is no evidence to suggest otherwise for French Guiana.

Cebus o. brunneus probably occurs throughout the Cordillera de la Costa and it would seem the Cordillera de Merida of extreme north-western Venezuela (Bodini and Pérez-Hernández 1987).

Cebus o. apiculatus is distributed throughout central Venezuela, south of the Orinoco between the ríos Caroni and Ventuari (Bodini and Pérez-Hernández 1987).

Cebus o. nigrivittatus occurs in the Venezuelan Amazon, north of the Rio Orinoco, east into Roraima, and across upper the Rio Branco, restricted to the south of the Serra Pacaraima and the highlands along the southern boundaries of the Guyana to the Rio Paru do Oeste. It is not known which subspecies of Cebus olivaceus occurs in northern Pará and Amapá in Brazil, but possibly the Rio Jari marks the boundary between C. o. olivaceus (to the east) and C. o. nigrivittatus (to the west).

Bodini and Pérez-Hernández (1987) indicate an as yet undescribed form north of the Rio Orinoco, and C. o. apiculatus west of the Rio Caroni, extending west to the Río Orinoco.
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Geographic Range

Weeping capuchins are found in South America. Their range extends from the northern neotropics to northwestern Venezuela to the southern reaches of the Amazon Basin (Eisenberg and Redford, 1989). They exist in dry deciduous forests on the llanos of Venezuela and mature tropical forests of Guyana (Nowak, 1999).

Biogeographic Regions: neotropical (Native )

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Physical Description

Morphology

Physical Description

Weeping capuchins are similar in body size to small dogs, about 500 mm in length. The tail in this species is semiprehensile and is roughly the same length as the body, making an overall length of approximately 840 mm (Eisenberg and Redford, 1989).

Males and females generally weigh around 2.5 to 2.8 kg, but the males may weigh about 800 g more. The body is a mostly off-white to pale buff in color. The head is the same color as the body, but has a black to dark gray wedge-shaped patch extending from the forehead backwards over the cranium. The forearms also exhibit this dark black to gray color. The tail is black-tipped and is often carried coiled at the tip. This "ring-tail" is strong enough to support the entire body weight for long periods and is often used while feeding to free up the hands (Nowak, 1999).

Range mass: 1100 to 4300 g.

Average mass: 2500-2810 g.

Range length: 605 to 1120 mm.

Average length: 840 mm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
In Suriname, Cebus olivaceus is for the most part restricted to undisturbed high forest, although it is occasionally seen in liana forest and mountain savanna forest as well. Although Mittermeier and van Roosmalen (1981) never observed C. olivaceus along rivers in Surinam, Muckenhirn et al. (1975) sighted four groups in river edge forest in Guyana. However, it is not clear from their description if the sightings were in marsh forest or riverbank high forest. In Venezuela, C. olivaceus occurs in habitats quite different from those occupied in Suriname. In Suriname, they were found to use mainly the lower canopy and understory, a pattern very similar to the tufted capuchins (Mittermeier and van Roosmalen 1981). Superficially, the locomotor repertoire of Cebus olivaceus is similar to that of C. apella, with quadrupedal walking and running, bounding and galloping, climbing and leaping being the major patterns.

The best information available on the ecology and behaviour of C. olivaceus comes from studies of a population on a cattle ranch, Hato Masaguaral, in low, seasonally dry gallery forest (14–23 m in height) in the Venezuelan llanos, pioneered by Oppenheimer and Oppenheimer (1973) and continued by Robinson (1981, 1984a,b, 1986, 1988a,b; De Ruiter (1986), Srikosomatara (1987), Fragaszy (1986, 1990), O’Brien (1990), and others. Miller (1996a,b, 1998) has carried out a study over three years of the feeding ecology and social behaviour of the species in another ranch in the Venezuelan llanos, Hato Piñero.

The species lives in multimale-multifemale groups of 8-40 individuals; generally larger than C. apella. Miller (1996b) made a special study of the effects of group size on seasonal foraging costs, intergoup and intragroup competition and aggression. Her two study groups ranged in size from 15-18 (1-2 adult males and 0-4 adult females) and 35-39 (5-6 adult males and 17-19 adult females) over two years of her study. Muckenhirn et al. (1975) counted 11 groups in Guyana which ranged in size from 6-15 and averaged 9.0 per group. Two groups accurately counted by Oppenheimer and Oppenheimer (1973) in Venezuela contained 19 (one adult male, one subadult male, eight females, six juveniles, three infants) and 33 animals (four adult males, three subadult males, eight females, 12 juveniles, six infants). Eleven groups observed at Hato Masaguaral ranged from eight to more than 40 animals (De Ruiter 1986; Robinson 1986) and the group of 22 animals studied by Fragaszy (1986) contained three adult males. The groups studied by Robinson (1988a) all had more females than males. This resulted from a bias in the birth sex ratio, higher female than male survivorship (irrespective of group size) between the ages of 3 and 7 when the males disperse, and differences in maturation rates between the sexes. Males and especially females form quite stable dominance hierarchies in the group. The highest-ranking female is dominant to all except for the highest-ranking male (Robinson 1981). Females may sometimes emigrate, and males emigrate from their natal groups usually between the age of two and eight, but do not appear to reach adult size until they are about 15, and even then may remain reproductively inactive if they have not assumed a dominant position in a new group (Robinson and Janson 1987).

A group in the Voltzberg study area of Mittermeier and van Roosmalen (1981) covered roughly 100 ha, although this was only a small portion of the group's range. Robinson (1986) recorded a range size of 275 ha (over 14 months) for his group of about 20 animals at Hato Masaguaral.

Less information on diet is available for C. olivaceus than for any other Guianan primate. They eat fruits, seeds, insects and other arthropods, supplemented by some leaves and flowers. At Hato Masaguaral, Robinson (1986) recorded that fruits, mostly ripe and fleshy, constituted the largest category of food items (56%), and included 50 species from 30 families, especially Moraceae and Rubiaceae. Fig trees (Ficus) which fruit throughout the year, were a staple almost every month. Buds, leaves and shoots were infrequent items in the diet, and were generally chewed and the fibrous remains spat out. They spend a large amount of time foraging for insects and small animal prey. Robinson (1986) recorded that they spent almost 70% of their day searching for and processing food. Foraging behaviour, including age and sex differences, is described by Fragaszy (1986). The range of animal prey is enormous, and includes snails, arthropods including spiders, millipedes, and insects (cockroaches, mantids, stick insects, termites, grasshoppers, cicadas and scale insects, caterpillars, beetles and their grubs, ants, bees and wasps), frogs and their eggs, iguanas, bird’s eggs and nestlings and even an adult ground dove (Columbina talpacoti), and squirrels (Sciureus granatensis). The relative proportions of different items in the diet changed throughout the year. Invertebrates replaced ripe fruit as the chief item in the diet as the number of fruiting species declined (November and December). The beginning of the rainy season (April, May) was marked by a flush of new leaves and an increase in phytophagous insects taken by the monkeys. The amount of fruit in the diet peaked in the late wet season, declining towards the beginning of the dry season.

Unlike the tufted capuchins which are often seen with squirrel monkeys, C. olivaceus groups rarely associate with other species although,

The data currently available are insufficient to determine if C. olivaceus has a distinct breeding season. Newborn infants have been seen in the Raleighvallen-Voltzberg Nature Reserve in December and early January, in the middle of the wet season (Mittermeier 1977). In northern Venezuela, the birth season is from May to August, during the wet season (Robinson and Janson 1987). Males reach maturity in about eight years but reach fully adult size at about 12, whereas females become reproductively active at about six years of age (Oppenheimer and Oppenheimer 1973; Robinson 1988a). Adulthood lasts about 30 years in females and 24 in males (Robinson 1988a). They give birth to single young, which maintain close contact with their mothers for the first nine months (Levy and Bodini 1986). Vocalizations and a number of behaviour patterns, including such as urine rubbing, “bouncing”, tooth grinding, and head-shaking are described in the pioneer study by Oppenheimer and Oppenheimer (1973; see also Freese and Oppenheimer 1981) and a detailed analysis of their vocalizations was carried out Robinson (1984b).

Systems
  • Terrestrial
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Weeping capuchins are found in typical llanos habitat of semi deciduous, dry tropical forests.They usually use the lower to middle layers of the forest in order to hunt for food as well as flee from predators. Capuchins use the forest floor and turn over leaf litter in search of small vertebrates and invertebrates. They show a broad tolrerance for habitat types (Eisenberg and Redford, 1989).

Range elevation: 500 to 2700 m.

Average elevation: 1000-1800 m.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: forest ; rainforest ; mountains

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Trophic Strategy

Food Habits

Foraging and dietary patters of C. olivaceus are related to the group size and also to the season in which the animals are observed. It is believed that perceived predation risk plays a significant role in the pattern of food intake. Predation may also influence individual fitness, not only directly, but by its impact on foraging success (Miller and Teaford, 2000).

Weeping capuchins consume fruits, palm nuts, seeds, berries, and many varieties of small vertebrates and invertebrates. A strict hierarchy determines the priority of access to food of the younger capuchins (Eisenberg and Redford, 1989). Other foods may include flowering buds, shoots, barks, gums, arachnids, eggs, and even other small mammals. Some coastal species may also include oysters, crabs, and other marine life (Nowak, 1999).

Animal Foods: mammals; insects; terrestrial non-insect arthropods; mollusks; aquatic crustaceans

Plant Foods: leaves; wood, bark, or stems; seeds, grains, and nuts; fruit

Primary Diet: omnivore

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Associations

Ecosystem Roles

Weeping capuchins probably help to control insect populations. They are also important in dispersing the seeds of fruits they eat. As a prey species, these monkeys probably affect predator populations.

Ecosystem Impact: disperses seeds

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Predation

Weeping capuchins have only a few predators in the wild. They are arboreal and can easily escape from ground predators. The major predator of these monkeys are humans. Live capuchins are in demand because of their mild temperments. They are used as pets, in zoo exhibits and may also be used as a food source for many natives.

Weeping capuchins are a favorite food for some snakes as well as some of the larger tropical rodents (Eisenberg and Redford, 1989).

Known Predators:

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Known predators

Cebus olivaceus is prey of:
Rodentia
Serpentes
Homo sapiens

This list may not be complete but is based on published studies.
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Known prey organisms

Cebus olivaceus preys on:
Mollusca
Arthropoda
Crustacea
Insecta
Mammalia

This list may not be complete but is based on published studies.
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Life History and Behavior

Life Expectancy

Lifespan/Longevity

In captivity a capuchin may live as long as 55 years. Capuchins in the wild live an average of 34 to 36 years (Nowak, 1999).

Range lifespan

Status: captivity:
45 to 55 years.

Average lifespan

Status: captivity:
50-52 years.

Typical lifespan

Status: wild:
30 to 47 years.

Average lifespan

Status: wild:
40-44 years.

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Lifespan, longevity, and ageing

Maximum longevity: 47 years (captivity) Observations: One wild-born animal was about 47 years of age when it died in captivity (Richard Weigl 2005).
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Reproduction

These animals mate polygynously, with the dominant male in the troop copulating with all of the receptive females.

Mating System: polygynous

Weeping capuchins are polygamous. There is one dominant male who is responsible for mating with all receptive females in the troop.

Males reach reproductive maturity at 7 years and females are able to bare young in their fourth year (Eisenberg and Redford, 1989). Mature females produce offspring every 19 months on average, although it is not uncommon for females to give birth in successive years. (DiBitella and Janson, 2001). Females give birth to 1 young after a gestation period of 160 days. The infant weighs approximately 200 to 500 g and is able to cling to its mother's hair only moments after being born (Nowak, 1999).

Breeding season: Breeding season: Oct. -Feb. during peak food availability

Range gestation period: 145 to 170 days.

Average gestation period: 160 days.

Range weaning age: 1.5 to 4 months.

Average weaning age: 2.35 months.

Average age at sexual or reproductive maturity (female): 4-6 months.

Average age at sexual or reproductive maturity (male): 7-9 months.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average number of offspring: 1.

Average age at sexual or reproductive maturity (female)

Sex: female:
2190 days.

Female capuchins are the primary care givers. The male may invest some time in foraging for the female but invests little or nothing in parental care (Nowak, 1999).

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Rylands, A.B., Boubli, J.-P. & Mittermeier, R.A.

Reviewer/s
Mittermeier, R.A., Rylands, A.B. (Primate Red List Authority) & Hoffmann, M. (Global Mammal Assessment Team)

Contributor/s

Justification
Listed as Least Concern as the species is widespread, common, and there are no major threats resulting in a significant population decline.

History
  • 2003
    Least Concern
    (IUCN 2003)
  • 2003
    Least Concern
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This species is not threatened.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

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Population

Population
This species is common. The density of C. olivaceus in the Voltzberg Study area in Surinam was estimated by Mittermeier (1977) to be about 4 individuals/km². At the Nourague Field Station in French Guiana, C. olivaceus is much rarer than Cebus apella. Guillotin et al. (1993) estimated densities of 2/km² and a biomass of 6.3 kg/km², compared with 29.1/km² and a biomass of 86.9 kg/km² for the tufted capuchins. The only other density data for this species comes from Guyana, where Muckenhirn et al. (1975) found a range of 1.8-22.2 animals/km² in five different localities.

Population Trend
Unknown
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Threats

Major Threats
There are no major threats, but they are certainly impacted by hunting in some regions.
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Management

Conservation Actions

Conservation Actions
This species is listed on CITES Appendix II. It occurs in many protected areas across its range:

Cebus olivaceus olivaceus

Brazil
Tumucumaque National Park (3,882,376 ha)
Cabo Orange National Park (630,017 ha)
Lago Piratuba Biological Reserve (394,223 ha)
Rio Trombetas Biological Reserve (409,578 ha)
Uatumã Biological Reserve (942,786 ha)
Jari Ecological Station (207,370 ha)
Niquia Ecological Station (282,803 ha)

French Guiana
Parc amazonien de Guyane (3,300,000 ha)

Suriname
Brownsberg Nature Park (8,400 ha) (Mittermeier and van Roosmalen 1982; Norconk et al. 2003)
Raleighvallen-Voltzberg Nature Reserve (56,000 ha) (Mittermeier and van Roosmalen 1982)
Tafelberg Nature Reserve (140,000 ha) (Mittermeier and van Roosmalen 1982)
Eilerts de Haan Gebergte Nature Reserve (220,000 ha) (Mittermeier and van Roosmalen 1982)
Sipaliwini Savanna Nature Reserve (100,000 ha) (Mittermeier and van Roosmalen 1982)
Brinckheuvel Nature Reserve (6,000 ha) (within range)

Guyana
Kaieteur Falls National Park (11,655 ha)
Iwokrama Forest Reserve (364,000 ha) (Sussman and Phillips-Conroy 1995)

Venezuela
Canaima National Park (3,000,000 ha)
Jaua-Sarisariñama National Park (330,000 ha)

Cebus o. brunneus

Venezuela
Sierra Nevada National Park
Henri Pittier National Park
El Tama National Park?
Yurubi National Park?
Yacambu National Park?
Guatopo National Park?

C. o. nigrivittatus

Venezuela
Yapacana National Park
Duida-Marahuaca National Park

Undescribed subspecies
Aguaro-Guariquito National Park?
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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Negative

Weeping capuchins may carry many forms of human pathagens. They may also be able to transmit them to other animals or pet species (Nowak, 1999).

Negative Impacts: causes or carries domestic animal disease

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Economic Importance for Humans: Positive

Weeping capuchins have been sought by many people as pets. They are highly intelligent and can be trained to do tricks and perform tasks (Nowak, 1999). Many capuchins are kept in zoos or are trained to be part of TV programs. A particular weeping capuchin, "Marcelle" had a role in the television series "Friends." The character who owned this monkey was eventually forced to give him to the San Diego Zoo, because, as primatologists will tell you, MONKEYS DO NOT MAKE GOOD PETS.

Positive Impacts: pet trade

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Wikipedia

Wedge-capped capuchin

The wedge-capped capuchin or weeper capuchin (Cebus olivaceus) is a capuchin monkey from South America. It is found in northern Brazil, Guyana, French Guiana, Suriname, Venezuela and possibly northern Colombia.[1] The Cebus genus is divided into several different species. However, taxonomists argue over the specific divisions within the genus, which are uncertain and controversial. Cebus olivaceus is known to dwell in tall, primary forest and travel over long distances during the day.[3]

These primates are medium-sized monkeys with distinctive "wedge cap" markings on their head and slightly longer limbs than other capuchins for jumping through the forest canopy.[4] Similar to other capuchin monkeys, the diet of wedge-capped capuchin primarily consists of fruits, invertebrates, other plant parts, and on rare occasions small vertebrates. They have also been known to rub millipedes against their fur, especially in the rainy seasons, as a potential means of mosquito repellent.[5] Although this species is classified as an animal of least concern by IUCN Red List of Threatened species, it falls prey to many predators in South America ranging from vultures to jaguars.

Cebus olivaceus is a polygamous species that lives in groups anywhere from 5-30 individuals, with a female biased sex ratios. The group is organized according to a pre-determinded hierarchal system of dominance for both males and females. Although biological lineage is less of a factor of dominance for males than it is for females, due to male migration between groups. Wedge-capped capuchin partake in several behavioral mechanisms to assert and maintain dominance within the group including: infanticide, when an infant is deliberately killed; grooming, used to facilitate social rapport; and alloparenting, which is when members of the group care for offspring that are not their own.

Description[edit]

Size and Physical Description[edit]

Adult wedge-capped capuchins weight approximately 3 kg, but weight varies moderately with sex.[6] They receive their name from a black triangle of dark fur centered on their foreheads. Generally this species is light brown to brown with yellow and gray tinges on varying parts of their bodies.[3] Their “wedge cap” starts between the eyes and extends backwards to cover the top of the head. Their faces are hairless and surrounded by light brown or blonde fur.

Wedge-capped capuchins show similar levels of sexual dimorphism as other capuchin monkeys. On average, males weigh about 30% more than females.[7] Additionally, males have relatively longer canines than females (even after overall body size is accounted for). Male maxillary and mandibular (upper and lower) canines of males are on average 70% and 40% larger than female canines respectively. This may be indicative of male competition for females.[8]

Locomotion and morphology[edit]

Wedge-capped capuchins have been compared to tufted capuchins to discern the relationship between locomotion and skeletal proportions. Wedge-capped capuchins spent relatively more time running and jumping through the forest canopy while tufted capuchins spent more time walking and moving slowly. As such, wedge-capped capuchins have relatively longer limbs (particularly the hind limbs) than tufted capuchins.[4]

Phylogeny[edit]

Due to large physical variations in Cebus, taxonomists have frequently debated the exact classifications and details of the genus. However, most agree that the wedge-capped capuchin shares the genus with four others: C. apella, C. albifrons, C. capucinus, and C. kaapori. The wedge-capped capuchin has a diploid chromosome number of 52, though some others in the genus have 54 chromosomes. Nine human chromosomes correspond to those of the C. olivaceus. Phylogenetic analysis and constructions of cladograms have demonstrated that the wedge-capped capuchin is closely related to C. apella.[9][10]

Habitat and range[edit]

Wedge-capped capuchins prefer undisturbed primary forests in which they can move through the canopy (locomotion and limb morphology). They occupy the rainforests of northern Brazil and Venezuela, as well as the drier forests along riverbeds in Guyana, Suriname, and French Guiana.[2] These habitats vary in terms of forest height, composition, and continuity. When wedge-capped capuchins have the option between dense high-canopy primary forests and more fragmented, lower forests, they generally inhabit the primary forests.[11]

Diet[edit]

Wedge-capped capuchins are omnivorous and eat both animal and plant foods. Foraging behavior varies seasonally, as well as with age and sex. In general, these monkeys spend approximately equal amounts of time exploiting animal and plant resources.[12] The exception to this are infants that spend far more time foraging for plants foods than animals. Most of the plant food consumed is ripe fruit, the majority of which are figs. Their animal prey is almost exclusively invertebrates. Their prey consists of snails, wasps, caterpillars, grasshoppers, ants, birds eggs and many insects that inhabit palm crowns.[13]

While males and females spend about the same amount of time foraging for insects, they exploit different types of resources. Males spend more time searching for insects on the surface of branches, while females search for most of their insects atop palm trees. There is little variation in plant material consumed between males and females.[12] Also, adults and sub-adults eat more animal material than juveniles and infants.[12]

Food washing[edit]

Food washing has been observed in non-human primates including macaques and capuchins. The primates will sometimes wash their sandy fruits and foods prior to eating them. This act has been described as an example of protoculture.[14] Wedge-capped capuchins were shown to wash sandy food in four spontaneous occasions in both captive and wild populations. Urbani found that food washing was a response to certain circumstantial problems and not through imitation or learning, as argued in studies of other species.[15]

Behavior[edit]

Wedge-capped capuchins live in groups ranging from as few as 5 individuals to more than 30 individuals. The groups generally consist of one reproductively active adult male, several adult females and their offspring, and, in some cases, non-reproductive adult males. Juveniles generally make up about 50% of a groups population. The population structure is heavily skewed toward females. There are approximately 2 females to every male at birth.[16] This ratio increases to more than 4 adult females for every adult male. This is the result of both female-biased birth ratios and male migration behavior.[6]

A wedge-capped capuchin in São Paulo Zoo.

Birthrate in wedge-capped capuchins varies with age. Younger and middle-aged females (6 to 26 years old) give birth as often as once every two years. Older females (older than 26 years) may only give birth once every three or four years. It is important to note that both male and female wedge-capped capuchins live as long as 36 years.[6]

In wedge-capped capuchins, males emigrate from their natal groups while females generally remain in the same group for the majority of their lives. Males generally leave their natal group between 3 and 6 years of age. Young males spend little time alone after leaving their natal groups and quickly integrate into a new group. Males prefer to join groups with a high ratio of females to adult males, as this maximizes their probability for future mating success.[17] Immigrating males generally meet little opposition when joining a new group. Older females may migrate to new groups on rare occasions.[6]

Infanticide[edit]

Infanticide, or the deliberate killing of an infant, in any non-human primate is of considerable interest to ecologists because it can affect the particular primate's reproductive success and ultimately lead to great demographic changes within the primate's troop. Infanticide has been observed in C. olivaceus.

Genetically, it may pay for a male Wedge-capped capuchin to kill an unrelated newborn, so that he can then mate with the mother sooner than if the baby was still alive. This allows the male to propagate his genes faster through the troop. However, we see in Valderrama's research,[18] that in only one of the three cases studied, did the infanticidal male gain reproductive success from the killing. High-ranking females' infants were targeted in all three cases. The variability surrounding the infanticide among the three cases studied is characteristic surrounding infanticide among any other non-human primates.

Dominance hierarchy[edit]

Both male and female wedge-capped capuchins have a dominance hierarchy. Female status is often established based on matrilines, with dominant mothers tending to have dominant daughters. Male dominance is not as easily passed from one generation to the next due to male migration.

This dominance hierarchy is particularly helpful in explaining female-initiated agonistic behavior. Females higher in the hierarchy tend to be more aggressive toward both females and males that are lower on their respective dominance hierarchies. Aggressive behavior includes lunging, vocalization, and chasing. Sometimes many females chase males together. Male aggression, interestingly, was not correlated with position in the dominance hierarchy. Male aggression toward females is generally limited to vocalizations, lunging, and chasing.[19] On one occasion, however, an adult male was observed to attack and kill a young adult female from the same group. This level of aggression is not the norm, usually being practiced in the animal kingdom as a method of takeover.[20]

Grooming[edit]

Grooming behavior plays an important role in the group dynamics of wedge-capped capuchins. Grooming may be a way for both sub-adult males and females to integrate themselves into the adult social structure. This has been particularly well-documented in female-female interactions. Sub-adult females rarely groom each other, but rather focus their attention on grooming older females. These young females, who stay in their natal groups, must develop relationships with adult females to assimilate into the adult female social structure. In these instances, young females often seek out grooming opportunities with adult females. The adult females who are the recipients of this behavior are generally less enthusiastic about the interaction than their younger counterparts. This may indicate that adult females gain little benefit from these grooming interactions compared with sub-adult females. Sub-adult females may support their older companions in aggressive interactions. Young females that fail to establish relationships with older females become peripheral to the group and lose access to resources.[21]

Grooming behavior among adult females has a different pattern. Contrary to the normal pattern in primates, females often groom individuals who are lower in rank than they are. This may be largely due to the presence of two different grooming strategies among adult female wedge-capped capuchins. One of these strategies is referred to as appeasement. Subordinate females, when approached by dominant females, will lie down and solicit grooming. This has been interpreted as a way to avoid aggressive behavior from the dominant female. Interactions where a dominant female approaches a subordinate one often end in aggressive behavior, and soliciting grooming is a way to diffuse that aggression. This form of grooming is usually not reciprocated by the subordinate female.[22]

The other form of grooming behavior among adult females is affiliative. In contrast to grooming as appeasement, affiliative grooming is dependent on reciprocation. These interactions usually occur between individuals that hold high or intermediate positions in the dominance hierarchy. This form of grooming helps establish alliances between females that may provide both social and material advantages.[22]

Alloparenting[edit]

Allomaternal care is when an individual other than an infant’s mother helps care for it, is common in wedge-capped capuchins. There are several behaviors associated with allomaternal care in these monkeys, including nursing and carrying the infant. For the first three months after birth, infants are cared for exclusively by their mothers. However, allomaternal care dramatically increases during the next three months of development to the point where infants generally receive less care from their mothers than from other females. Siblings provide far more care for infants than non-related individuals. Additionally, high-ranking females interact more often with the infants of low-ranking females than vice versa. Allomaternal care is provided most often by juveniles and young adults. Adult females participate far less in alloparental care. This is common among many primate groups and indicates that young females may gain valuable experience in raising infants that will help them in the future.[23]

It is important to note that allomaternal nursing (wet nursing) is common in wedge-capped capuchins but very rare among other primates. Even more interesting is that this nursing behavior in wedge-capped capuchins is not correlated with relatedness. This behavior may be an example of reciprocity, where the favor of one female nursing another’s infant is eventually returned.[23]

Parasitic nursing has also been observed in wedge-capped capuchins. In these instances, juvenile and young adult females, who are usually higher in the dominance hierarchy, nurse from older females of lower rank. In contrast to allomaternal behavior, parasitic nursing does not appear to give any benefits to the monkey providing the milk.[24]

C. olivaceus in French Guiana

Interaction with other species[edit]

Wedge-capped capuchins sometimes rub themselves with millipedes they find while foraging. The monkeys rub the millipede against their fur, sometimes for as long as two minutes at a time. They also occasionally put the millipede in their mouths, remove them, and continue to rub them over their bodies. These capuchins often share these millipedes. The purpose of this strange behavior is difficult to determine. One theory is that the millipede, when threatened, releases noxious chemicals as a defense mechanism. These chemicals may act as insect repellants against mosquitos. This behavior is most common during the rainy season, when mosquitos are most prevalent.[5]

Predation[edit]

Wedge-capped capuchins have been observed to give alarm calls if they observe a potential predator. Such predators include jaguars, ocelots, tayras, boa constrictors, caimans, and collared peccaries. In addition, alarm calls have been observed when the capuchin sees one of several birds, such as hook-billed kites, black vultures, green ibises, rufous-vented chachalacas, Harpy Eagles, or Ornate Hawk-Eagles. Due to these predators, the wedge-capped capuchin has taken to living in groups; as group size increases, vigilance per animal decreases, though it has not yet been demonstrated that capuchins in larger groups are any less vulnerable than those in smaller groups.[25]

Threats and Conservation Status[edit]

Wedge-capped capuchins are ranked as an animal as least concern on the IUCN Red List of Threatened Species. The wedge-capped capuchin is ranked as least concern because the animal is common and has a widespread range. Human hunting is one of the major threats to capuchin survival in some regions.[26]

References[edit]

  1. ^ a b Groves, C. P. (2005). Wilson, D. E.; Reeder, D. M, eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. p. 138. OCLC 62265494. ISBN 0-801-88221-4. 
  2. ^ a b Rylands, A. B., Boubli, J.-P. & Mittermeier R. A. (2008). "Cebus olivaceus". IUCN Red List of Threatened Species. Version 2011.2. International Union for Conservation of Nature. Retrieved 2012-01-19. 
  3. ^ a b Fragaszy, Dorothy M., Elisabetta Visalberghi, and Linda Marie. Fedigan. The Complete Capuchin: The Biology of the Genus Cebus. Cambridge: Cambridge UP, 2004. Print
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  5. ^ a b Valderrama, Ximena, John G. Robinson, Athula B. Attygalle, and Thomas (2000). "Seasonal Anointment with Millipedes in a Wild Primate: A Chemical Defense Against Insects". Journal of Chemical Ecology 26: 2781–2790. doi:10.1023/A:1026489826714. 
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  17. ^ Robinson, John G. (1988). "Group Size in Wedge-Capped Capuchin Monkeys Cebus olivaceus and the Reproductive Success of Males and Females". Behavioral Ecology and Sociobiology 23: 187–197. doi:10.1007/bf00300353. 
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  26. ^ http://www.iucnredlist.org/details/full/40021/0
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