Vervet monkey

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TAXONOMY

Suborder: Haplorrhini
Infraorder: Simiiformes
Superfamily: Cercopithecoidea
Family: Cercopithecidae
Subfamily: Cercopithecinae
Genus: Chlorocebus
Species: Ch. aethiops, Ch. cynosuros, Ch. djamdjamensis, Ch. pygerythrus, Ch. sabaeus, Ch. tantalus
Subspecies: Ch. p. excubitor, Ch. p. hilgerti, Ch. p. nesiotes, Ch. p. pygerythrus, Ch. p. rufoviridis, Ch. t. budgetti, Ch. t. marrensis, Ch. t. tantalus

Other names: Ch. aethiops: Cercopithecus aethiops, Cercopithecus aethiops aethiops, or Chlorocebus aethiops aethiops; grivet or savanna monkey; singe vert (French); grünmeerkatze (German); mono verde (Spanish); grön markatta or vervett (Swedish); Ch. cynosuros: malbrouck; Ch. djamdjamensis: Bale Mountains vervet or djam-djam; Ch. pygerythrus: Cercopithecus aethiops pygerythrus or Chlorocebus aethiops pygerythrus; vervet monkey; Ch. sabaeus: Cercopithecus aethiops sabaeus or Chlorocebus aethiops sabaeus; green monkey; Ch. tantalus: Cercopithecus aethiops tantalus or Chlorocebus aethiops tantalus; tantalus monkey

Conservation status: multiple

Life span: 11 to 13 years (captive)
Total population: Unknown
Regions: Sub-Saharan Africa
Gestation: 5.5 months (165 days)
Height: 490 mm (M), 426 mm (F)
Weight: 5.5 kg (M), 4.1 kg (F)

The classification of vervet monkeys was recently updated, moving all of the species from the genus Cercopithecus to a new genus, Chlorocebus (Rowe 1996; Groves 2001). There are now at least six species of vervets recognized, but often in the literature, they are ubiquitously referred to as Chlorocebus aethiops (Ch. aethiops) by their former genus, Cercopithecus aethiops (C. aethiops) (e.g. Grubb et al. 2003). They are sometimes lumped together with a group of primates called guenons, medium-sized arboreal African monkeys of the genus Cercopithecus (Lernould 1988; Oates 1996). Groves (2001) recommends further revision of this genus and in the future, there will likely be more species and subspecies identified (Grubb et al. 2003).

MORPHOLOGY

Typically, Ch. aethiops, Ch. pygerythrus, Ch. tantalus and Ch. cynosuros have a yellow to greenish-brown coat with white undersides and white fur on their brows and cheeks. They have bluish skin on their abdomens while their faces, hands and feet are all black-skinned (Rowe 1996; Groves 2001). Males of all species of vervets have bright blue scrotal areas contrasting with red penises. This striking coloration, when combined with the white fur of their undersides is highlighted in what is referred to as the “red, white, and blue display” (Fedigan & Fedigan 1988; Rowe 1996). There is some variation in fur length and coloration among the species. Chlorocebus sabaeus has golden-green fur with pale hands and feet. The tip of the tail is golden yellow as are the backs of the thighs and cheek whiskers. They do not have a distinguishing band of fur on the brow, like other species, and males have a pale blue scrotum (Groves 2001). Bale Mountains vervets, Ch. djamdjamensis, have much longer, thicker fur than other species and their fur is darker brown. They have dark gray hands and feet and white beards and there is only a faint white brow band in this species (Groves 2001). Infant vervets are born with black natal coats and pink faces that gradually change to the adult coloration by 12 weeks of age (Lee 1984).

Vervet monkey sitting
Chlorocebus

All vervet males and females are sexually dimorphic and wild adult males weigh between 3.9 and 8.0 kg (8.60 and 17.6 lb), averaging 5.5 kg (12.1 lb), and measure between 420 and 600 mm (1.37 and 1.97 ft), averaging 490 mm (1.61 ft) from the top of the head to the base of the tail. Wild adult females weigh between 3.4 and 5.3 kg (7.50 and 11.7 lb) and average 4.1 kg (9.04 lb), and measure between 300 and 495 mm (11.8 in and 1.62 ft), averaging 426 mm (1.40 ft) (Napier 1981; Skinner & Smithers 1990).

Vervets move quadrupedally and they are equally as comfortable on the ground as they are in the trees. They are semi-terrestrial and semi-arboreal, spending time feeding and traveling on the ground during the day and retreating to the trees to sleep at night (Fedigan & Fedigan 1988). They have the characteristic cheek-pouches like other members of the superfamily Cercopithecoidea which allow them to forage and store food to be eaten later (Rowe 1996).

Lifespan in wild vervets is difficult to characterize because of high rates of predation in the long-term study areas. One female was at least 13 years old when she died and females in captivity have lived this long. Between 11 and 12 years, serious health problems are seen in captive vervets and this is probably the upper limit of their lifespan (Fairbanks & McGuire 1986).

RANGE

CURRENT RANGE MAPS (IUCN REDLIST):
Chlorocebus aethiops | Chlorocebus cynosuros | Chlorocebus djamdjamensis | Chlorocebus pygerythrus | Chlorocebus sabaeus | Chlorocebus tantalus

Vervets are the most widespread of the African monkeys and inhabit large parts of sub-Saharan Africa (Wolfheim 1983; Lernould 1988). They are found broadly across the continent from Senegal to Ethiopia and north into Egypt and Eritrea as well as southward to South Africa. Vervets are largely absent from the forests of the Congo Basin in west-central Africa, though some species inhabit the edges of these forests (Wolfheim 1983). The species are separated geographically but some areas of hybridization occur (Groves 2001). Political instability in some regions in eastern and western Africa has made censusing vervets difficult, but the range is reasonably defined (Zinner et al. 2002). Chlorocebus pygerythrus ranges from the Ethiopian Rift Valley in central Ethiopia eastward into Somalia, and southward into Kenya, northern Tanzania and eastern Uganda. To the north, Ch. aethiops is found in Sudan, east of the White Nile River, Ethiopia, Eritrea, and probably into southeastern Egypt. In the southeastern part of its range, Ch. aethiops hybridizes with Ch. pygerythrus as well as with Ch. p. hilgerti at the Omo River in Ethiopia (Isbell & Enstam under review). Another species of vervet found in Ethiopia is Ch. djamdjamensis, restricted to the Bale Mountains region and surrounding highland areas east of the central Rift Valley. Chlorocebus tantalus is found in Sudan, Uganda, and northwestern Kenya around Lake Turkana, one of Africa’s Great Lakes, and its range stretches west into Togo, Benin, Nigeria, Niger, Chad, Cameroon, Equatorial Guinea, Central African Republic, Congo, and into Ghana where it is restricted by the Volta River. It hybridizes with Ch. p. rufoviridis in Uganda along the northern and western shores of Lake Victoria (Isbell & Enstam under review). The westernmost species of vervet is Ch. sabaeus, found from Senegal to the west bank of the Volta River in Ghana and ranging in Mauritania, Mali, Gambia, Guinea-Bissau, Guinea, Sierra Leone, Liberia, Côte d’Ivoire, and Burkina Faso. Chlorocebus cynosuros is found in northern Namibia, Angola, southern Democratic Republic of Congo, Botswana, and in Zambia (Groves 2001). Chlorocebus is also found in Rwanda, Burundi, South Africa, Lesotho, Zimbabwe, Swaziland, Malawi, and Mozambique (Seier 2003).

In addition to being found in 39 African nations, one species of vervet is also found on the Cape Verde islands off the west coast of Africa in the Atlantic Ocean and on several Caribbean islands in the West Indies. Chlorocebus sabaeus was introduced in the late 1600s to the islands of St. Kitts, Nevis, and Barbados when ships involved in the slave trade traveled from to the Caribbean from West Africa (van der Kuyl et al. 1996). Green monkeys traveled as pets or as items to be traded and sold and have since adapted well to life on these islands where they are sometimes considered a pest species (Fedigan & Fedigan 1988; Boulton et al. 1996).

Dorothy Cheney and Robert Seyfarth have conducted long-term research on vervets at Amboseli National Park in southern Kenya since 1977. Lynne Isbell has also been conducting long-term research on vervets at Amboseli and with Karin Enstam at a private conservation area, Segera Ranch, in north-central Kenya since 1992. Vervets have also been studied in the Caribbean for several decades. Most of the current published information about vervets is from studies done at these sites.

HABITAT

Vervets are habitat generalists, as is obvious from their widespread range in Africa and the success of introduced populations. They are tolerant of a wide variety of habitats and can live in humid rainforests, semi-desert environments, or swamps from sea level to elevations up to 4500 m (14,764 ft); their only limitation seems to be water availability and the presence of sleeping trees (Wolfheim 1983; Chapman & Fedigan 1984; Fedigan & Fedigan 1988). Because of this limitation, they are especially prevalent in riverine forests bordering savannas. They are also able to exploit areas near cultivated fields because they are adept at raiding crops (Struhsaker 1967; Oates 1996; Isbell et al. 1998). Additionally, vervets can survive quite well in urban areas (Wolfheim 1983; Shimada & Shotake 1997). Vervets are rarely found in the depths of dense forests, but rather utilize the edges of tropical rain forests, lowland evergreen forests and montane forests. They seem to prefer wooded rather than heavily forested areas, such as dry deciduous forest, scrub forests and gallery forests, which are composed of both trees and shrubs (Nakagawa 1999). They are not found in open grassland with no trees, but they spend some time in open savannas moving between wooded areas (Wolfheim 1983).

Data on climate have been provided for study sites within their range. In Senegal, there are two seasons; the dry season lasts from November to May and the rainy season lasts from June to October. The mean annual rainfall is 954 mm (3.14 ft), and almost all of it falls in the months from June to October. The dry season has maximum temperatures between 33° and 40° C (91.4° and 104° F) while the rainy season is slightly cooler, with average maximum temperatures ranging from 30° to 33° C (86° to 91.4° F) (Harrison 1984). In Cameroon, the wet season lasts from May to September while the rest of the year is dry. The average annual rainfall is 497 mm (1.63 ft) and average monthly temperatures range from 22.7° to 33.7° C (72.9° to 92.7° F) (Nakagawa 1999). The climatological conditions in which vervets live in Kenya include a drier season lasting from September to January or March with average annual rainfall reaching 700 mm (2.30 ft) (Isbell et al. 1999).

Two vervet adults with infant vervet
Chlorocebus

In the West Indies, vervets inhabit both densely populated areas in urban habitats as well as highly cultivated agricultural habitats with lower human population density (Hoorocks 1986). Because agriculture and fuelwood extraction have significantly decreased in the last 30 years, vervets also inhabit thickly wooded ravines of secondary forest (Boulton et al. 1996). They can be found in mangrove swamps, in stands of sea grape, a tropical evergreen, and in pasturelands bordering wooded areas (Chapman & Fedigan 1984). The rainy season lasts from July to September and the dry season stretches from December to May. The average temperature on St. Kitts is 23.9° C (79° F) (Poirier 1972; Hoorocks 1986).

ECOLOGY

In much of their range, seasonal availability of food and water necessitates the ability of vervets to forage for and consume a wide variety of foods. In fact, vervets, along with chimpanzees (Pan troglodytes and P. paniscus) and baboons (Papio species), have the most omnivorous diet of all primates. Vervets eat all of the types of food that any primate is known to eat including leaves, gum, seeds, nuts, grasses, fungi, fruit, berries, flowers, buds, shoots, invertebrates, bird eggs, birds, lizards, rodents, and other vertebrate prey. They have a strong preference for fruit and flowers, which are seasonal resources, and from month to month vervets vary their diet tremendously to cope with fluctuations in food availability (Harrison 1984; Fedigan & Fedigan 1988). Brushfires during the dry season often temporarily reduce vegetative cover so that little is available during the beginning and middle of the rainy season (Adeyemo 1997). Subsequently, vervets can suffer severe nutritional stress accompanied by hair loss and changes in skin color (Isbell 1995). In more developed and agricultural areas, vervets are less subject to nutritional stress and seasonal availability of food because they depend on sources of food provided by humans including cultivated fruits, vegetables, and cereal crops (Saj et al. 2001). On Barbados, vervets consume fruits and vegetables grown in subsistence gardens and on larger plantations. Some of the most damaged crops include corn, sweet potato, bananas, mangos, papayas, guavas, cherries, cucumbers, peanuts and yams (Saj et al. 2001; Boulton et al. 1996). They have become an increasing nuisance to farmers that grow these crops and one management option has been to trap crop-raiding vervets and sell them research facilities for use in biomedical research (Horrocks & Baulu 1994).

In addition to varying their diet according to environmental conditions, vervets change their daily activity patterns depending on the season. Generally, they travel, feed, and sleep as a group (Harrison 1983). In the rainy season, vervets spend their mornings, from about 7:00 a.m. to 11:00 a.m., traveling, feeding and drinking water and the afternoons, from 11:00 a.m. to 3:00 p.m., are spent feeding, drinking water, resting, grooming and doing some traveling (Adeyemo 1997). The proportion of time spent doing each activity changes during the dry season so that less time is spent traveling and feeding and more time is spent drinking, resting, and grooming in the mornings. During afternoons in the dry season, more time is spent drinking water, feeding and grooming than during the rainy season. The evenings, from 3:00 p.m. until 7:00 p.m., are spent feeding and traveling to the sleeping tree (Adeyemo 1997). Sleeping trees utilized by vervets average 7.7 m (25.3 ft) in height and are usually found in wooded areas rather than standing alone or in small clusters of trees amidst open grassland. One reason vervets use sleeping trees is to decrease the risk of predation (Nakagawa 1999). In their natural habitat, potential predators include lions, leopards, cheetahs, other felid predators such as African wild cats, servals and caracals, hyenas, black-backed jackals, raptors and baboons (Papio species). In the West Indies, dogs are serious predators and in most areas throughout their range, humans hunt vervets either for meat or as a means to control the population (Isbell & Enstam 2002; Zinner et al. 2002).

vervet monkeys on nest
Chlorocebus

Like changes in their diet and activity pattern, the day range length and home range size of vervet groups changes seasonally as well. In Senegal, vervets travel between 665 and 2670 m (.413 and 1.66 mi) during a single day (Harrison 1983). Home range size and population density varies based on the spread of resources available in each habitat. The smallest home ranges are seen among vervets on St. Kitts and average .06 km² (.023 mi²) and the largest are seen among vervets living in Senegal, where home ranges are as large as 1.78 km² (.687 mi²) (Harrison 1983). Where there are few resources, like in Senegal, vervets need to range farther to survive and fewer animals are supported by the ecosystem. On St. Kitts, where agricultural foods are readily available and in condensed areas such as on plantations, large numbers of animals can be supported in a much smaller space (Harrison 1983). Population densities range from 9 individuals per square kilometer (5.6 per square mile) at the Segera Ranch in Kenya to 255 individuals per square kilometer (158 per square mile) on St. Kitts (Harrison 1983; Isbell & Enstam under review). When groups encounter one another at the border or overlapping areas of their home ranges, interactions can be described as friendly, where the two groups temporarily merge, or as agonistic, with serious fighting between members of both groups (Cheney 1981; Chapman & Fedigan 1984). The expression and degree of territoriality among vervets is facultative and conditions such as habitat type, season, intensity of predation, distribution, abundance, and defendability of resources, and the history of relationships between the groups are all factors contributing to the nature of the interaction of two groups (Kavanaugh 1981; Chapman & Fedigan 1984). In environments with clustered, easily defendable resources, territoriality is economically sound, especially in highly seasonal environments; vervets have much to lose by allowing neighboring groups into their range to exploit their food resources, especially at certain times of year. In other types of environments, such as savanna woodlands, resources are widely distributed and would be difficult for one group to defend without serious energetic costs, therefore, territorial behavior is not expected under these conditions (Kavanaugh 1981).

SPECIAL NOTES

Vervets are among the most used primates in biomedical research in the United States and abroad (Carlsson et al. 2004). Because they are small, easily handled, nonendangered, evolutionarily closely related to humans, and easily bred in captivity, vervets are a popular species for use in biomedical primate research (Ervin & Palmour 2003). Specifically, vervets are important in studying high blood pressure and AIDS. They are one of the few species of nonhuman primates that naturally develops high blood pressure and simian immunodeficiency virus (SIV), the ancestor of human immunodeficiency virus (HIV), is widespread throughout wild populations (Chakrabarti 2002; Ervin & Palmour 2003). There is compelling evidence that SIV was transferred from monkeys or apes in Africa to humans and led to the emergence of HIV/AIDS in humans. Studying naturally occurring SIV and the origins of HIV/AIDS in vervets and other African primates may help scientists discover a cure or vaccine for the disease (Chakrabarti 2002).

Content last modified: January 3, 2006

Written by Kristina Cawthon Lang. Reviewed by Karin Enstam.

Cite this page as:
Cawthon Lang KA. 2006 January 3. Primate Factsheets: Vervet (Chlorocebus) Taxonomy, Morphology, & Ecology . <http://pin.primate.wisc.edu/factsheets/entry/vervet/taxon>. Accessed 2020 July 7.

SOCIAL ORGANIZATION AND BEHAVIOR

Like other Old World monkeys such as macaques (Macaca species), vervets live in multi-male/multi-female groups and exhibit female philopatry (Struhsaker 1967). They live in groups of seven to 76, but the minimum number of adults necessary to maintain a stable group is two. If only one adult remains in a group with juveniles, the group merges with a neighboring troop (Fedigan & Fedigan 1988; Isbell et al. 1991). The average group size at Amboseli National Park is 24, and the average group size across all study sites is 25 individuals (Struhsaker 1967; Fedigan & Fedigan 1988). The composition usually includes a ratio of 1.5 adult females to one male. There are generally between one and seven adult males and two and ten adult females plus their offspring (Cheney & Seyfarth 1990). On Barbados, the average group size is slightly smaller, with only 15.3 individuals per group (Horrocks 1986).

Mother and infant vervet
Chlorocebus

Females remain in their natal groups throughout their entire life; therefore the core of the social group is closely related adult females and their dependent offspring. A linear dominance hierarchy according to matriline exists within the group and high-ranking females and their close relatives (mothers, sisters, and daughters) are the most sought-after grooming partners and have preferential access to food resources (Isbell et al. 1999). High-ranking females enjoy priority access to food during foraging bouts and have access to higher quality food, which greatly increases their yearly food intake compared to lower- and mid-ranking females (Whitten 1983). Consuming more and higher quality food confers an advantage to females both in overall health and in higher reproductive success. With higher stores of body fat, females are less likely to experience amenorrhea induced by malnutrition and they are likely to have higher milk quality that contributes to faster infant growth and therefore decreased mortality in their larger infants, and decreased interbirth intervals (Whitten 1983). Furthermore, obvious signs of nutritional stress are less evident in high-ranking females. At Amboseli, 31.4% of the adult vervets showed hair loss and changes in skin color associated with limited food availability, but low-ranking vervets were more likely to exhibit these external signs of stress than their comparably well-fed high-ranking conspecifics (Isbell 1995).

Rank relationships between females can be seen when one adult female supplants another; when the higher-ranking female approaches the lower-ranking female, the one lower in rank moves away from the approaching female and is displaced (Isbell et al. 1999). In addition to approach-avoidance interactions, vervets can be placed within the dominance hierarchy based on fighting between individuals (Isbell 1995). Females are supported by their relatives in agonistic interactions and form coalitions that last a lifetime. Daughters inherit the rank of their mothers because of social support given to their daughters even after they reach adulthood (Fairbanks & McGuire 1986).

Males emigrate from their natal groups around the time they reach sexual maturity and change social groups several times throughout their lifetimes (Struhsaker 1967; Cheney & Seyfarth 1990). The age at which males first transfer is around five years. Transfer coincides with sexual maturity and one explanation for male transfer is to avoid breeding with their mother or sisters (Cheney & Seyfarth 1983). Emigration is risky for young males, not only because they increase their risk of predation when they are not part of a group, but also because adult female vervets often attack transferring males (Cheney & Seyfarth 1983; Isbell et al. 2002). Because of the geographic distribution of vervet territories, highly overlapping and with multiple neighboring groups, males are able to transfer into neighboring groups without crossing large expanses of land, but decreasing the risk of predation is not the only reason young vervets immigrate into neighboring groups; they chose their new groups non-randomly and based on the presence of closely related male relatives (Cheney & Seyfarth 1983). Furthermore, they do not transfer alone but rather with older brothers or peers. By transferring into a group with relatives (half-brothers or half-sisters) and by emigrating with a partner, young vervet males decrease their risk of predation during the transfer process as well as decrease potential conflict as they move into a group with a few relatives (Cheney & Seyfarth 1983). These factors are important enough to outweigh the risks of breeding with their nieces in their new groups, but statistical analysis has shown that vervets transferring with close relatives into a group with close relatives actually decreases the possibility of mating with closely related kin (Cheney & Seyfarth 1983). Males transfer multiple times over their lives in order to avoid breeding with their sexually mature daughters; the rate coincides with maturation rates among females, therefore males transfer groups every two years. At the time of secondary transfer, adult males do not transfer with a partner nor do they join groups with close relatives (Cheney & Seyfarth 1983). Most transfers occur during the breeding season, from April to June. During this time, females are most likely to tolerate a new male in the group because they are sexually receptive (Cheney et al. 1988).

Mother and infant vervet
Chlorocebus

Once integrated into their new group, male vervets occupy the lowest rank. Like females, males also have a linear dominance hierarchy . This hierarchy is separate from the females’ and includes all adult males within the group. Rank among males can be assigned based on displacement interactions as well as physical fighting (Isbell 1995). When males attain alpha status within the group, they hold this position between three and five years (Fairbanks & McGuire 1986). The alpha male in a vervet group inhibits the social behaviors and interactions with females of the lower-ranking males in the group (Keddy Hector & Raleigh 1992). He restricts their access to high-ranking females through aggression and prevents them from maintaining spatial proximity to, grooming of, or other affiliative behaviors with females. By doing so, he decreases the chances of subordinate males forming alliances with high-ranking females and he protects his position as a primary breeder within the group (Keddy Hector & Raleigh 1992). It is important to the alpha male to minimize the chance of relationships forming between dominant females and subordinate males because while males are dominant over females in one-on-one interactions, females form coalitions and several related females are dominant over any male. Females in these coalitions will support a male during a dominance interaction and can help determine the outcome of the male dominance hierarchy (Cheney 1983).

REPRODUCTION

Vervets are seasonal breeders. Among captive vervets in Kenya, the mating season lasts from July to September and births are grouped between November and January (Eley et al. 1986). In wild African populations, the breeding season lasts from April to June and the majority of births are concentrated from October to December (Cheney et al. 1988; Baldellou & Adan 1997). In the West Indies, births occur throughout the year but most are concentrated from April to July (Horrocks 1986). One of the reasons seasonal breeding is thought to have evolved in vervets is the advantage of giving birth during times of food abundance. After the rainy season, food resources are much more plentiful compared to other times of the year. Lactating females and new infants are not as likely to be nutritionally stressed during this time of year, increasing the chances of survival of both the mother and her infant (Baldellou & Adan 1997).

Females reach sexual maturity around four years of age, in the wild, and usually give birth for the first time around age five (Cheney et al. 1988). In captivity, females mature more quickly and can give birth as young as two years of age (Fairbanks & McGuire 1985). On Barbados, female vervets reach sexual maturity at 2.8 years of age (Horrocks 1986). Female vervets have no external signs of ovulation (Eley et al. 1989; Cheney & Seyfarth 1990). Data from captive vervets provide information about reproduction. The ovarian cycle lasts 32.5 days, on average, and is characterized by menstruation. Peak sexual receptivity occurs around day 13 of the cycle (Else et al. 1986; Eley et al. 1989). Female vervets have cycles throughout the year, but ovarian cycles are irregular during the non-breeding seasons (Else et al. 1986). Males reach sexual maturity around five years of age, but do not achieve full adult weight until six years of age, limiting the opportunity for mating before then. Gestation lasts 163 to 165 days (Eley et al. 1986; Andelman 1987). The interbirth interval varies between one and two years, depending on if the mother had a surviving offspring the previous breeding season. If she has successfully raised an infant, she is more likely to skip a breeding season whereas a female that has lost an infant is more likely to reproduce the following year (Lee 1984; Cheney et al. 1988). In the West Indies, the interbirth interval is slightly less than one year (Horrocks 1986).

PARENTAL CARE

Mother and infant vervet
Chlorocebus

Infant mortality among wild vervets is exceptionally high during the first year of life. At Amboseli, 57% of all infants die in their first year because of predation or malnutrition and subsequent illness (Cheney et al. 1988). With such high levels of mortality among young vervets, it is essential that parental care is provided. Mother vervets are the primary caregivers to their infants. During the first three months of life, 90% of the infant’s time is spent within two meters (6.56 ft) of its mother (Lee 1984; 1987). For the first two weeks, they are in almost constant contact with each other, with the infant nursing frequently throughout the day. During the first week of life, infant vervets wrestle gently with older female relatives in the group and begin to play socially by the third week of life. After six weeks, the percent of time spent at distances greater than two meters (6.56 ft) increases quickly, especially during weeks seven through nine (Lee 1984). At this stage, the mother begins to resist nursing attempts by the infant so that by 12 weeks, the mother is almost constantly rejecting the nursing attempts of her infant. Weaning is not complete at this time, however, as some young vervets are seen nursing into their second year of life if their mother has not reproduced again (Lee 1984). The percentage of time spent in close proximity to the mother decreases over time so that between four months and one year of age, young vervets only spend about 30% of their time within two meters of their mothers. After one year of age, this percentage drops to about 10% (Lee 1987).

Because female vervets remain in their natal groups for life and males do not transfer until the age of five, infants often have several siblings within the group. Between 17 and 20% of a young vervet’s time is spent near its siblings (Lee 1987). Older sisters play an important role in providing care for their younger siblings, allowing them to practice mothering skills and adding to the protection of the infant from predators and other group members. Additionally, the mother is able to more efficiently forage when her infant is with an allomother, so this break in caretaking may provide and important boost to both the infant and the mother (Lee 1987). Other females in the group are attracted to infants and can act as allomothers as well. All group members are attracted to high-ranking infants more often than low-ranking infants and attempt to gain access to high-ranking females through their infants. Males use this tactic in order to form social relationships that might lead to future mating opportunities while subordinate females attempt to decrease aggression from dominant females within the group (Lee 1987; Keddy Hector & Raleigh 1992). The close association between siblings can also lead to alliances and support during agonistic interactions. Older siblings of both sexes are active in defending and protecting their younger brothers and sisters from the aggression of unrelated individuals (Lee 1987). These alliances are maintained as the animals age. Males that remain near their brothers often transfer as pairs when they leave their natal group (Cheney & Seyfarth 1983; Lee 1987).

The dominance hierarchy is established even for the youngest members of a vervet group. Among related and unrelated males, the dominance hierarchy is strictly age-graded, with older brothers dominant over their younger male siblings and younger unrelated males in the group. Older brothers are also dominant over their younger sisters (Lee 1987). Between young females, younger sisters are dominant over older sisters. Rank among unrelated juvenile females is determined according to maternal rank; daughters of high-ranking females are dominant over daughters of low-ranking females (Fairbanks & McGuire 1985; Lee 1987).

COMMUNICATION

Mother and infant vervet
Chlorocebus

Vocal communication in vervets has been well studied because of their intricate system of predator-sensitive alarm calls. Vervets give separate, distinct vocalizations for certain predators that elicit predator-appropriate responses from their conspecifics (Seyfarth et al. 1980a; Enstam & Isbell 2002). In the wild, leopards, martial eagles, and pythons pose serious predatory risks to vervets (Cheney & Seyfarth 1990; Isbell & Enstam 2002). Leopards crouch and pounce from the tall grass, eagles swoop down while flying and can use their talons to grab an infant off of a mother’s back, and pythons move through the grass and attack from the ground (Seyfarth et al. 1980a). Alarm calls serve the purpose of alerting other group members to the presence of danger. When an adult vervet sees one of these predators and gives an alarm call, the rest of the group respond appropriately. When the leopard call is given, the monkeys run up into the trees, where they are safer from the ambush style of attack typical of big cats. When the eagle alarm call is sounded, vervets look to the sky and run into dense brush or low-lying bushes in order to hide from the swooping raptor . Finally, when the snake call is given, vervets respond by looking down around them; this response is appropriate because vervets often work as a group to mob dangerous snakes (Seyfarth et al. 1980a). Adult vervets properly alert group members to the potential predator while infant and juvenile vervets often misidentify predators and give inappropriate alarm calls (Seyfarth et al. 1980b). Though the infants are able to assign the suitable class of predator, for example giving an eagle alarm call when any bird flies over, they need to learn the appropriate context in which to give alarm calls (Seyfarth et al. 1980b). The vervet sounding the alarm call conveys information about the perceived threat and the other members of the group can interpret the call and respond appropriately. This form of semantic communication was long thought to be unique to humans and the other great apes, but researchers Dorothy Cheney, Robert Seyfarth, and Peter Marler effectively proved that vervets are capable of referential communication.

LISTEN TO VOCALIZATIONS

Visual communication is also used between vervets to signal the presence of a predator. In the West Indies, where the only threat to vervets are dogs and humans, visual signals are used by an adult male to communicate to the rest of the group of a threat in the area (Horrocks & Hunte 1986). On Barbados , crop-raiding behavior is prevalent among vervets and involves all but one adult male venturing into a cultivated field and feeding. The adult male positions himself conspicuously while the rest of the group forages and instead of alarm calling in the presence of a potential predator, he simply moves from his place of prominence, signaling to the other members of the group, that are watching him as they forage, to move into cover (Horrocks & Hunte 1986). By silently signaling, the sentinel does not draw attention to himself or to the fact that his group is nearby and the predator will not be alerted to their presence. In the event that the predator has already detected the sentinel, he will vocalize loudly to warn other group members (Horrocks & Hunte 1986). Because the vervets of the West Indies have spent over 300 years in close proximity to human predators, these behaviors have evolved separately from the alarm call system seen in African vervets but are still an impressive system of communication (Fedigan & Fedigan 1988).

Another form of visual communication seen among male vervets are the “splaylegged” and “red, white, and blue” displays. Both of these capitalize on the brightly colored genitalia of male vervets and serve in communicating information about status between males (Henzi 1985; Gerald 2001). The “splaylegged display” is a sign of aggression seen when a vigilant male detects males of another group nearing the territory boundary. Either sitting on a branch or on the ground, the displaying male sits with his knees apart, exposing his genitalia. This display serves as a warning to nearby males and may act as a deterrent for males attempting to enter the group (Henzi 1985). The “red, white, and blue display” is seen when a dominant male approaches a subordinate, encircles him, and lifts his tail, exposing his brightly colored anogenital area to the lower-ranking male (Gerald 2001). This display reinforces the dominance hierarchy among males in a less energetically expensive manner than physical fighting.

Content last modified: January 3, 2006

Written by Kristina Cawthon Lang. Reviewed by Karin Enstam.

Cite this page as:
Cawthon Lang KA. 2006 January 3. Primate Factsheets: Vervet (Chlorocebus) Behavior . <http://pin.primate.wisc.edu/factsheets/entry/vervet/behav>. Accessed 2020 July 7.

 

INTERNATIONAL STATUS

CITES: Appendix II (What is CITES?)
IUCN Red List: C. djamdjamensis: VU; C. aethiops, C. cynosuros, C. pygerythrus, C. sabaeus, C. tantalus: LC (What is Red List?)
Key: VU = Vulnerable, LC = Least concern, LC = Least concern, LC = Least concern, LC = Least concern, LC = Least

Mother and infant vervet
Chlorocebus

Most of the African primates living in the dry forests of savanna woodlands, including vervets, have wide geographical distributions and are not threatened at this point (Oates 1996). All species of vervets except for Ch. djamdjamensis are of least concern for going extinct in the near future, but despite this classification, wherever vervets have been studied for long periods of time, data reveals that populations are declining (Cheney et al. 1988; Isbell & Enstam under review).

CONSERVATION THREATS & POTENTIAL SOLUTIONS

Threat: Harvesting (hunting/gathering)

Being geographically widespread and having abundant populations, vervets are subject to hunting in areas where bushmeat is locally important (Starin 1999). They are also kept as pets because they are easily acquired; when hunters kill adult vervets, they keep the dependent infants and sell them as pets (Peeters et al. 2002). While the vervet population has not suffered up to this point, there is concern that the rates of hunting of all primate species are not sustainable. Compared to other monkeys their size, vervets are not commonly exploited for hunting, but they are still under some pressure across their range (Bowen-Jones & Pendry 1999).

While the export of vervets from African countries should be closely monitored by CITES, there is evidence that illegal export and trade of vervets and other monkeys occurs and could be seriously affecting populations, especially in countries like Gambia and Senegal (Starin 1999).

Threat: Persecution

Vervets are among the few primate species that actually thrive when agriculture replaces their natural habitat (Boulton et al. 1996). Because they have become a nuisance species in many places where they interface with human agricultural development, vervets have been treated as vermin and poisoned, shot, trapped, and otherwise killed (Boulton 1996; Jones 1998). They have also been driven out of some areas by being rounded up and killed. In these drives, thousands of vervets are herded and killed for money and though they are not as widespread as they once were, so-called “monkey drives” probably still occur in parts of West Africa (Jones 1998; Starin 1999).

Threat: Changes in Native Species Dynamics

While vervets are not threatened with extinction, some populations are being locally extirpated. At Amboseli National Park, the vervet population has been declining rapidly because of indirect human-induced habitat loss. As the human population surrounding the park has grown, an attempt to separate the park from human areas through fencing has caused the elephant population within the park to be confined. Some 700 elephants are now restricted to the boundaries of the park and rather than moving over huge distances, foraging as they go, the elephants move continuously through the park, destroying saplings and adult trees on which vervets depend for food and shelter (Cheney & Seyfarth 1990). The elephants have effectively destroyed the habitat of the vervets by eliminating sleeping and foraging trees by rivers and watering holes that are necessary for vervets to survive, and the population has continued to dwindle. More than half of the vervet population at Amboseli has died and unless their habitat is restored, they are likely to be completely eliminated from the park (Cheney & Seyfarth 1990).

LINKS TO MORE ABOUT CONSERVATION

CONSERVATION INFORMATION

CONSERVATION NEWS

ORGANIZATIONS INVOLVED IN Chlorocebus CONSERVATION

Content last modified: January 3, 2006

Written by Kristina Cawthon Lang. Reviewed by Karin Enstam.

Cite this page as:
Cawthon Lang KA. 2006 January 3. Primate Factsheets: Vervet (Chlorocebus) Conservation . <http://pin.primate.wisc.edu/factsheets/entry/vervet/cons>. Accessed 2020 July 7.

 

 

 

 

 

 

 

 

 

 

 

 

 

REFERENCES

The following references were used in the writing of this factsheet. To find current references for Chlorocebus sp., search PrimateLit. Note that much of the literature uses the taxonomy Cercopithecus.

REFERENCES

Adeyemo AI. 1997. Diurnal activities of green monkeys Cercopithecus aethiops in Old Oyo National Park, Nigeria. S Afr J Wildl Res 27(1): 24-6.

Andelman SJ. 1987. Evolution of concealed ovulation in vervet monkeys (Cercopithecus aethiops). Am Natural 129: 785-99.

Baldellou M, Adan A. 1997. Time, gender, and seasonality in vervet activity: a chronobiological approach. Primates 38(1): 31-43.

Vervet monkey artwork, plate XXVII
Chlorocebus

Boulton AM, Horrocks JA, Baulu J. 1996. The Barbados vervet (Cercopithecus aethiops sabaeus): changes in population size and crop damage, 1980-1994. Int J Primatol 17(5): 831-44.

Bowen-Jones E, Pendry S. 1999. The threat to primates and other mammals from the bushmeat trade in Africa, and how this threat could be diminished. Oryx 33(3): 233-46.

Carlsson HE, Schapiro SJ, Farah I, Hau J. 2004. Use of primates in research: a global overview. Am J Primatol 63(4): 225-37.

Chakrabarti L. 2002. Natural history of simian immunodeficiency viruses: clues to the emergence and virulence of AIDS viruses. In: Burroughs T, Knobler S, Lederberg J, editors. The emergence of zoonotic diseases: understanding the impact on animal and human health. Washington DC : National Acad Pr. p 61-3.

Chapman C, Fedigan LM. 1984. Territoriality in the St. Kitts vervet, Cercopithecus aethiops. J Hum Evol 13(8): 677-86.

Cheney DL. 1981. Intergroup encounters among free-ranging vervet monkeys. Folia Primatol 35(2-3): 124-46.

Cheney DL. 1983. Extra-familial alliances among vervet monkeys. In: Hinde RA, editor. Primate social relationships: an integrated approach. Oxford ( UK ): Blackwell. p 278-86.

Cheney DL, Seyfarth RM. 1983. Nonrandom dispersal in free-ranging vervet monkeys: social and genetic consequences. Am Natural 122(3): 392-412.

Cheney DL, Seyfarth RM. 1990. How monkeys see the world: inside the mind of another species. Chicago (IL): Univ Chicago Pr. 377 p.

Cheney DL, Seyfarth RM, Andelman SJ, Lee PC. 1988. Reproductive success in vervet monkeys. In: Clutton-Brock TH, editor. Reproductive success: studies of individual variation in contrasting breeding systems. Chicago (IL): Univ Chicago Pr. p 384-402.

Eley RM, Gulamhusein N, Lequin RM. 1986. Reproduction in the vervet monkey (Cercopithecus aethiops): I. Testicular volume, testosterone, and seasonality. Am J Primatol 10(3): 229-35.

Eley RM, Tarara RP, Worthman CM, Else JG. 1989. Reproduction in the vervet monkey (Cercopithecus aethiops): III. The menstrual cycle. Am J Primatol 17(1): 1-10.

Else JG, Eley RM, Wangula C, Worthman C, Lequin RM. 1986. Reproduction in the vervet monkey (Cercopithecus aethiops): II. Annual menstrual patterns and seasonality. Am J Primatol 11(4): 333-42.

Ervin F, Palmour R. 2003. Primates for the 21 st century biomedicine: the St. Kitts vervet (Chlorocebus aethiops, SK). In: [Anonymous]. International perspectives: the future nonhuman primate resources; 2002 Apr 17-19; Bogor, Indonesia. Washington DC : Natl Acad Pr. p 49-53.

Fairbanks LA, McGuire MT. 1985. Relationships of vervet mothers with sons and daughters from one through three years of age. Anim Behav 33(1): 40-50.

Fairbanks LA, McGuire MT. 1986. Age, reproductive value, and dominance-related behaviour in vervet monkey females: cross-generational influences on social relationships and reproduction. Anim Beh 34(6): 1710-21.

Fedigan L, Fedigan LM. 1988. Cercopithecus aethiops: a review of field studies. In: Gautier-Hion A, Bourlière F, Gautier JP, Kingdon J, editors. A primate radiation: evolutionary biology of the African guenons. Cambridge ( UK ): Cambridge Univ Pr. p 389-411.

Gerald MS. 2001. Primate colour predicts social status and aggressive outcome. Anim Behav 61(3): 559-66.

Groves C. 2001. Primate taxonomy. Washington DC : Smithsonian Inst Pr. 350 p.

Grubb P, Butynski TM, Oates JF, Bearder SK, Disotell TR, Groves CP, Struhsaker TT. 2003. Assessment of the diversity of African primates. Int J Primatol 24(6): 1301-57.

Harrison MJS. 1983. Patterns of range use by the green monkey, Cercopithecus sabaeus, at Mt. Assirik, Senegal. Folia Primatol 41(3-4): 157-79.

Harrison MJS. 1984. Optimal foraging strategies in the diet of the green monkey, Cercopithecus sabaeus, at Mt. Assirik, Senegal. Int J Primatol 5(5): 435-71.

Henzi SP. 1985. Genital signaling and the coexistence of male vervet monkeys (Cercopithecus aethiops pygerythrus). Folia Primatol 45(3-4): 129-47.

Hoorocks JA. 1986. Life-history characteristics of a wild population of vervets (Cercopithecus aethiops sabaeus) in Barbados, West Indies. Int J Primatol 7(1): 31-47.

Horrocks J, Baulu J. 1994. Food competition between vervets (Cercopithecus aethiops sabaeus) and farmers in Barbados : implications for management. Rev Ecol (Terre Vie) 49(3): 281-94.

Horrocks JA, Hunte W. 1986. Sentinel behaviour in vervet monkeys: who sees whom first? Anim Behav 34(5): 1566-7.

Isbell LA. 1995. Seasonal and social correlates of changes in hair, skin, and scrotal condition in vervet monkeys (Cercopithecus aethiops) of Amboseli National Park, Kenya. Am J Primatol 36(1): 61-70.

Isbell LA, Cheney DL, Seyfarth RM. 1991. Group fusions and minimum group sizes in vervet monkeys (Cercopithecus aethiops). Am J Primatol 25(2): 57-65.

Isbell LA, Cheney DL, Seyfarth RM. 2002. Why vervet monkeys (Cercopithecus aethiops) live in multimale groups. In: Glenn ME, Cords M, editors. The guenons: diversity and adaptation in African monkeys. New York : Kluwer Acad/Plenum. p 173-87.

Isbell LA, Enstam KL. 2002. Predator (in)sensitive foraging in sympatric female vervets (Cercopithecus aethiops) and patas monkeys (Erythrocebus patas): a test of ecological models of group dispersion. In: Miller LE, editor. Eat or be eaten: predator sensitive foraging among primates. Cambridge ( UK ): Cambridge Univ Pr. p 154-68.

Isbell LA, Enstam KL. Under review. Vervet monkey: Cercopitheus (a.) pygerthus. In: Happold DCD, Kingdon, J, Butynski, editors. Mammals of Africa. London: Academic Pr.

Isbell LA, Pruetz JD, Lewis M, Young TP. 1998. Locomotor activity differences between sympatric patas monkeys (Erythrocebus patas) and vervet monkeys (Cercopithecus aethiops): implications for the evolution of long hindlimb length in Homo. Am J Phys Anthro 105(2): 199-207.

Isbell LA, Pruetz JD, Lewis M, Young TP. 1999. Rank differences in ecological behavior: a comparative study of patas monkeys (Erythrocebus patas) and vervets (Cercopithecus aethiops). Int J Primatol 20(2): 257-72.

Jones TS. 1998. The Sierra Leone monkey drives. In: Grubb P, Jones TS, Davies AG, Edberg E, Starin ED, Hill JE, editors. Mammals of Ghana, Sierra Leone, and the Gambia. Zennor ( UK ): Trendrine Pr. p 214-19.

Kavanaugh M. 1981. Variable territoriality among tantalus monkeys in Cameroon. Folia Primatol 36(1-2): 76-98.

Keddy Hector A, Raleigh MJ. 1992. The effects of temporary removal of the alpha male on the behavior of subordinate male vervet monkeys. Am J Primatol 26(2): 77-87.

Lee PC. 1984. Early infant development and maternal care in free-ranging vervet monkeys. Primates 25(1): 36-47.

Lee PC. 1987. Sibships: cooperation and competition among immature vervet monkeys. Primates 28(1): 47-59.

Lernould JM. 1988. Classification and geographical distribution of guenons: a review. In: Gautier-Hion A, Bourlière F, Gautier JP, Kingdon J, editors. A primate radiation: evolutionary biology of the African guenons. Cambridge ( UK ): Cambridge Univ Pr. p 54-78.

Nakagawa N. 1999. Differential habitat utilization by patas monkeys (Erythrocebus patas) and tantalus monkeys (Cercopithecus aethiops tantalus) living sympatrically in northern Cameroon. Am J Primatol 49(3): 243-64.

Napier PH, editor. 1981. Catalogue of primates in the British Museum (Natural History) and elsewhere in the British Isles : Part II: Family Cercopithecidae, Subfamily Cercopithecinae. London : British Museum (Natural History). 203 p.

Oates JF, compiler. 1996. Status survey and conservation action plan: African primates (Revised edition). Gland ( Switzerland ): IUCN/SSC Primate Specialist Group. 80 p.

Peeters M, Courgnaud V, Abela B, Auzel P, Pourrut X, Bibollet-Ruche F, Loul S, Liegeois F, Butel C, Koulagna D, et al. 2002. Risk to human health from a plethora of simian immunodeficiency viruses in primate bushmeat. Emerg Infect Diseas 8(5): 451-7.

Poirier FE. 1972. The St. Kitts green monkey (Cercopithecus aethiops sabaeus): ecology, population dynamics, and selected behavioral traits. Folia Primatol 17: 20-55.

Rowe N. 1996. The pictorial guide to the living primates. East Hampton (NY): Pogonias Pr. 263 p.

Saj TL, Sicotte P, Paterson JD. 2001. The conflict between vervet monkeys and farmers at the forest edge in Entebbe, Uganda. Afr J Ecol 39: 195-9.

Seier J. 2003. Supply and use of nonhuman primates in biomedical research: A South African perspective. In: [Anonymous]. International perspectives: the future nonhuman primate resources; 2002 Apr 17-19; Bogor, Indonesia. Washington DC : Natl Acad Pr. p 16-19.

Seyfarth RM, Cheney DL, Marler P. 1980b. Monkey responses to three different alarm calls: evidence of predator classification and semantic communication. Science 210(4471): 801-3.

Seyfarth RM, Cheney DL, Marler P. 1980a. Vervet monkey alarm calls: semantic communication in a free-ranging primate. Anim Behav 28(4): 1070-94.

Shimada MK, Shotake T. 1997. Genetic variation of blood proteins within and between local populations of grivet monkey (Cercopithecus aethiops aethiops) in central Ethiopia. Primates 38(4): 399-414.

Skinner JD, Smithers RHN. 1990. The mammals of the southern African subregion, 2nd edition. Pretoria (South Africa): Univ Pretoria. 771 p.

Starin ED. 1999. Conservation in the Gambia ? In: Lowe J, editor. Wildlife conservation in West Africa II. The proceedings of a symposium of the Nigerian Field Society ( UK branch); 1999 Oct 9-10; Dunstable, England. Surrey ( UK ): Nigerian Field Soc. p 38-43.

Struhsaker TT. 1967. Social structure among vervet monkeys (Cercopithecus aethiops). Behaviour 29: 83-121.

van der Kuyl AC, Dekker JT, Goudsmit J. 1996. St. Kitts green monkeys originate from West Africa : genetic evidence from feces. Am J Primatol 40(4): 361-4.

Whitten PL. 1983. Diet and dominance among female vervet monkeys (Cercopithecus aethiops). Am J Primatol 5(2): 139-59.

Wolfheim JH. 1983. Primates of the world: distribution, abundance, and conservation. Seattle (WA): Univ Washington Pr. 831 p.

Zinner D, Peláez F, Torkler F. 2002. Distribution and habitat of grivet monkeys (Cercopithecus aethiops aethiops) in eastern and central Eritrea. Afr J Ecol 40: 151-8.

Content last modified: January 3, 2006

AUDIO

IMAGES

Chlorocebus aethiops
Photo: Dennis Rasmussen
Chlorocebus aethiops
Photo: Irwin S. Bernstein
Chlorocebus aethiops
Photo: Irwin S. Bernstein
Chlorocebus aethiops
Photo: Primates in Art & Illustration Collection

Chlorocebus pygerythrus
Photo: Anne Barrett Clark
Chlorocebus pygerythrus
Photo: Anne Zeller
Chlorocebus pygerythrus
Photo: Anne Zeller
Chlorocebus pygerythrus
Photo: J. H. Shoshani

Chlorocebus sabaeus
Photo: Irwin S. Bernstein
Chlorocebus sabaeus
Photo: Irwin S. Bernstein
Chlorocebus sabaeus
Photo: Irwin S. Bernstein
Chlorocebus sabaeus
Photo: Irwin S. Bernstein

Chlorocebus tantalus
Photo: J. Stephen Gartlan

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