Vervet monkey

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).

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).

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

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

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

• Adult female snake alarm call  (Dorothy Cheney & Robert Seyfarth; University of Pennsylvania)
• Male leopard alarm call  (Dorothy Cheney & Robert Seyfarth; University of Pennsylvania)
• Subadult male eagle alarm call  (Dorothy Cheney & Robert Seyfarth; University of Pennsylvania)
• Vervet Monkey Vocalizations  (click on the sound diagram to hear each alarm call; Dorothy Cheney & Robert Seyfarth; University of Pennsylvania)

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 . . Accessed 2020 July 7.

INTERNATIONAL STATUS

For individual primate species conservation status, please search the IUCN Red List.
Also search the current scientific literature for primate conservation status (overall as well as for individual species), and visit CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora).

Conservation information last updated in 2006 follows, for comparison:

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

• No current links for Chlorocebus

CONSERVATION NEWS

• Green monkey smugglers caught red-handed  (Reuters Africa; June 2, 2008)
• Gambia: on the trail of the green monkey  (Telegraph; February 9, 2008)
• When breeding season becomes killing season  (Independent Online, South Africa; November 27, 2004)

ORGANIZATIONS INVOLVED IN Chlorocebus CONSERVATION

• Chimfunshi Wildlife Orphanage
• Frisky’s Wildlife and Primate Sanctuary Inc.
• Gombe Stream Research Centre
• Israeli Primate Sanctuary
• Limbe Wildlife Centre
• Makerere University Biological Field Station
• Monkeyland Primate Sanctuary
• Primate Sanctuary of the Animal Protection Institute
• Projet Conservation de la Foret de Nyungwe (P.C.F.N.)
• Ugandan Wildlife Education Centre
• Vervet Monkey Foundation
• Colobus 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 . . 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.

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.

Cramer PE, Gentzel RC, Tanis KQ, Vardigan J, Wang Y, Connolly B, Manfre P, Lodge K, Renger JJ, Zerbinatti C, Uslaner JM. Aging African green monkeys manifest transcriptional, pathological, and cognitive hallmarks of human Alzheimer’s disease. Neurobiol Aging. 2018 Apr;64:92-106. doi: 10.1016/j.neurobiolaging.2017.12.011. Epub 2017 Dec 20. PMID: 29353102.

Latimer CS, Shively CA, Keene CD, Jorgensen MJ, Andrews RN, Register TC, Montine TJ, Wilson AM, Neth BJ, Mintz A, Maldjian JA, Whitlow CT, Kaplan JR, Craft S. A nonhuman primate model of early Alzheimer’s disease pathologic change: Implications for disease pathogenesis. Alzheimers Dement. 2019 Jan;15(1):93-105. doi: 10.1016/j.jalz.2018.06.3057. Epub 2018 Nov 19. PMID: 30467082; PMCID: PMC6383152.

Atkins HM, Willson CJ, Silverstein M, Jorgensen M, Floyd E, Kaplan JR, Appt SE. Characterization of ovarian aging and reproductive senescence in vervet monkeys (Chlorocebus aethiops sabaeus). Comp Med. 2014 Feb;64(1):55-62. PMID: 24512962; PMCID: PMC3929220.

Barrickman NL, Bastian ML, Isler K, van Schaik CP. Life history costs and benefits of encephalization: a comparative test using data from long-term studies of primates in the wild. J Hum Evol. 2008 May;54(5):568-90. doi: 10.1016/j.jhevol.2007.08.012. Epub 2007 Dec 18. PMID: 18068214.

Content last modified: Feb 2, 2021 (age ranges for captive and wild vervets)

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