VERVET
Chlorocebus Pygerythrus
Geographic Distribution and Habitat
Until fairly recently, "vervet" referred to all members of the genus Chlorocebus, including grivets, green monkeys, tantalus monkeys, malbroucks, and vervets themselves. There is still a great deal of overlap in data, and resulting confusion. The species within Chlorocebus are quite similar yet have some distinguishing characteristics, especially as relates to their geographic ranges, food sources, threats and life spans. As of this writing, five vervet subspecies are recognized.
Vervets are native to eastern and southern Africa. Their range extends from Ethiopia to South Africa, including Tanzania, Uganda, Zambia, Malawi, Mozambique, Zimbabwe, Botswana, Swaziland, Burundi, Eastern Ethiopia, and Kenya. Populations have also been observed on some islands off the coast of Africa.
Vervets thrive on the open savanna and grassland areas with sparse forest and nearby rivers. However, they are able to survive in most areas as long as water is present. They appear to avoid densely wooded areas in favor of montane forests, tropical rainforests, and lowland evergreen forests, which contain both trees and shrubs. They populate rural areas as well as urbanized areas.
The temperatures in the vervet’s habitat vary from 25 degrees F (-4 degrees C) during the winter to 138 degrees F (59 degrees C) in the summer, the change being most dramatic in South Africa, which is further from the equator.
Until fairly recently, "vervet" referred to all members of the genus Chlorocebus, including grivets, green monkeys, tantalus monkeys, malbroucks, and vervets themselves. There is still a great deal of overlap in data, and resulting confusion. The species within Chlorocebus are quite similar yet have some distinguishing characteristics, especially as relates to their geographic ranges, food sources, threats and life spans. As of this writing, five vervet subspecies are recognized.
Vervets are native to eastern and southern Africa. Their range extends from Ethiopia to South Africa, including Tanzania, Uganda, Zambia, Malawi, Mozambique, Zimbabwe, Botswana, Swaziland, Burundi, Eastern Ethiopia, and Kenya. Populations have also been observed on some islands off the coast of Africa.
Vervets thrive on the open savanna and grassland areas with sparse forest and nearby rivers. However, they are able to survive in most areas as long as water is present. They appear to avoid densely wooded areas in favor of montane forests, tropical rainforests, and lowland evergreen forests, which contain both trees and shrubs. They populate rural areas as well as urbanized areas.
The temperatures in the vervet’s habitat vary from 25 degrees F (-4 degrees C) during the winter to 138 degrees F (59 degrees C) in the summer, the change being most dramatic in South Africa, which is further from the equator.
Vervet range, IUCN 2019
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Size, Weight, and Lifespan
Male vervets weigh between 8.6 and 17.6 lbs (3.9-8.0 kg). Females are between 7.5 and 11.7 lbs (3.4-5.3 kgs). Head and body length is 14-26 in (35-66 cm) and tail length is 17-28 in (42-72 cm). Their lifespan is up to 12 years in the wild and 24 years in captivity. Appearance
One of three primate species inhabiting the African savanna, the vervet shares the savanna with patas monkeys and baboons. Long arms and legs give the vervet a human look when sitting upright. A black face framed with a white stripe around the eyes is contrasted with light brown-gray fur on the back and white fur on the belly and inside the legs. Among the five different vervet subspecies there are variations in the fur color and length. Vervets have black skin on their feet, hands, and ears. Under the white belly fur, the skin has a bluish tinge. Males have a bright blue scrotum and red penis. Babies have a black coat and a pink face at birth. By about 12 weeks of age, their face turns black and their coat begins to lighten. 
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What Does It Mean?Allomothering:
Individuals other than the biological mother of an offspring performs the functions of a mother (as by caring for an infant temporarily). Gestation Period: The time of pregnancy from conception until birth. Montane forest: A forest that grows on the slope of a mountain, regardless of altitude or latitude, within a specific climate, just below the subalpine zone. Terrestrial: Living on the ground. Quadruped: A being who walks on all fours. |
Diet
Seasonal changes affect the diet of vervet monkeys. When fruit, seeds, and flowers are available, vervets dine well on the bounty. Wildfires occur during the dry season and can disrupt the food supply so that during the rainy season—which normally provides their most favored foods—the vervets might not have enough. Also during the dry season, when food and water are scarce, vervets have been observed eating anything possible, such as lizards, rodents, insects, invertebrates, shoots, roots, bird eggs, birds, fungi, bark, and grass. However, the majority of their diet consists of flowers, leaves, gums, and seed of trees.
In more highly populated suburban areas, vervets raid the crops of local farmers. They have been known to eat papaya, corn, beans, grains, and young tobacco plants from these plantations.
Seasonal changes affect the diet of vervet monkeys. When fruit, seeds, and flowers are available, vervets dine well on the bounty. Wildfires occur during the dry season and can disrupt the food supply so that during the rainy season—which normally provides their most favored foods—the vervets might not have enough. Also during the dry season, when food and water are scarce, vervets have been observed eating anything possible, such as lizards, rodents, insects, invertebrates, shoots, roots, bird eggs, birds, fungi, bark, and grass. However, the majority of their diet consists of flowers, leaves, gums, and seed of trees.
In more highly populated suburban areas, vervets raid the crops of local farmers. They have been known to eat papaya, corn, beans, grains, and young tobacco plants from these plantations.
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Behavior and Lifestyle
Vervets spend most of their day foraging for food, climbing trees, and loping along the ground. They are quadrupeds when on the ground, which is about half of their day. The other half is spent in the trees. The mornings are active, as they travel within their home range searching for food. In the afternoons, they rest, groom, and drink water. At night, they head for their sleeping tree (usually an acacia), a tree approximately 25 ft (7.6 m) high and within a cluster of other trees. This tree gives some protection from their multitude of predators: hyenas, jackals, cheetahs, leopards, lions, raptors, baboons, and other large cats. The range of their home area varies with the habitat, seasons, and food availability. On the wide-open savanna, vervets may move further for a food source and not show as much territorial aggression to protect such a large swath of land. In more lush environments, more animals compete for the resources and the vervets stay in a localized area and protect it from other primates. A home range can be as much as .687 sq mi (1.78 sq km). Daily Life and Group Dynamics
Vervets are primarily terrestrial primates. They spend about half of the day on the ground and the other half in the trees for protection, resting, sleeping, and acquiring food. A family group may be between 10 to 38 individuals, mostly females with a few males. Females relate within a social hierarchy. Individuals who are not closely related to the high-ranking members will vie for attention and grooming from those in a higher position. Adults and older adolescents (over three years of age) may participate in aggressive displays with those outside the group when conflict arises. This usually occurs when members of another group enter their territory. Domestic spats within groups occurs occasionally as well as members fussing over more grooming time. Grooming helps the group maintain cohesion, as vervets are highly social primates. Vervets also allomother their young. Adolescent females assist with the caring and grooming of the infants. The group will maintain their social relationships for life. Males protect the group by keeping a watchful eye out for predators. When young males become adults, they join other groups. They may even move from one group to another in order to obtain a higher ranking. |
Fun FactsWith urbanization encroaching on their habitats, the vervet has adjusted to living in the city. They sneak into homes through open windows and raid trash cans for food. Imagine calling 911 to tell them a monkey is in your house! Vervet monkeys rarely wander more than 1/3 of a mile (450 m) from a tree so that they have an escape ready if a predator shows up. In addition to skillfully navigating the treetops, vervet monkeys are also adept at swimming. Fights are avoided if possible. To show dominance, a male will prance in a circle around a lower ranked male with his tail up in the air. This shows his opponent that he means business! |
Communication
Vervets use verbal and visual communication in their group interactions. Different alarm calls designate three different types of predators. These are used to warn the group about large cat, eagle, and snake predators. When a leopard, for instance, is seen, a short call is given and the monkeys scatter into the trees. If an eagle is spotted, one of the group will give a series of short grunts. Others in the group have been observed to run toward nearby bushes and to look up to gather more information on the possible predator. Upon seeing a snake, short “chutter chutter” sounds are vocalized and monkeys will look around at the ground for the predator. There is also a vocalized warning for baboons and humans that the group members know—they respond by heading for cover.
The most common noise within group communication is low “grunts” to greet others or to warn that an unknown primate is moving into their territory. Scientist have so far determined that the vervets can understand and respond to 36 different vocalizations.
Visual communication is used by males to communicate status in the male hierarchy of a group. The dominant male will sit with legs apart (splay legged) to warn aggressors with his display of his bright blue and red genitalia. This communicates dominance to the group and establishes his territory to member of other groups.
Vervets use verbal and visual communication in their group interactions. Different alarm calls designate three different types of predators. These are used to warn the group about large cat, eagle, and snake predators. When a leopard, for instance, is seen, a short call is given and the monkeys scatter into the trees. If an eagle is spotted, one of the group will give a series of short grunts. Others in the group have been observed to run toward nearby bushes and to look up to gather more information on the possible predator. Upon seeing a snake, short “chutter chutter” sounds are vocalized and monkeys will look around at the ground for the predator. There is also a vocalized warning for baboons and humans that the group members know—they respond by heading for cover.
The most common noise within group communication is low “grunts” to greet others or to warn that an unknown primate is moving into their territory. Scientist have so far determined that the vervets can understand and respond to 36 different vocalizations.
Visual communication is used by males to communicate status in the male hierarchy of a group. The dominant male will sit with legs apart (splay legged) to warn aggressors with his display of his bright blue and red genitalia. This communicates dominance to the group and establishes his territory to member of other groups.
Reproduction and Family
Vervets begin to reproduce around the age of five, though many females are ready at age 4 and some in captivity mated at age 2 and a half. Gestation is approximately 5 and a half months, with females producing one child every one to two years. Infant mortality rate is high (around 69%) due to the vervets having many predators. Disease, especially during years of food scarcity, is also another cause of the high death rate.
Babies will ride around with their mothers for the first week, but then they begin to play and be cared for by other females in the group. Weaning occurs by the age of 1, however infants begin trying other foods at 4 months of age.
Males transfer to other groups around the age of 5 in order to avoid mating with their mother or sisters. As they try to enter other groups, the dominant females of those groups will sometimes attack them. Males may transfer groups several times during their life. Most of these transfers are during mating season, when the females in the new group are open to their advances.
Breeding season is from April to June or June to September, depending on the country. Babies are born at the end of the rainy season when food is more abundant and there is a better chance of survival for mother and infant.
Vervets begin to reproduce around the age of five, though many females are ready at age 4 and some in captivity mated at age 2 and a half. Gestation is approximately 5 and a half months, with females producing one child every one to two years. Infant mortality rate is high (around 69%) due to the vervets having many predators. Disease, especially during years of food scarcity, is also another cause of the high death rate.
Babies will ride around with their mothers for the first week, but then they begin to play and be cared for by other females in the group. Weaning occurs by the age of 1, however infants begin trying other foods at 4 months of age.
Males transfer to other groups around the age of 5 in order to avoid mating with their mother or sisters. As they try to enter other groups, the dominant females of those groups will sometimes attack them. Males may transfer groups several times during their life. Most of these transfers are during mating season, when the females in the new group are open to their advances.
Breeding season is from April to June or June to September, depending on the country. Babies are born at the end of the rainy season when food is more abundant and there is a better chance of survival for mother and infant.
Ecological Role
Vervets play an extremely important role in the ecology of the African continent. Many animals rely on the availability of vervets as a food source. Vervets repopulate the trees in the environment through dropping excrement, which contains seeds from the many fruits in their diet.
Vervets play an extremely important role in the ecology of the African continent. Many animals rely on the availability of vervets as a food source. Vervets repopulate the trees in the environment through dropping excrement, which contains seeds from the many fruits in their diet.
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Conservation Status and Threats
Vervets are listed as Least Concern on the International Union for Conservation of Nature Red List of Threatened Species (IUCN, 2016). Vervets, while still abundant, are declining in population and need protection from humans in particular. The ongoing feud between landowners and monkeys usually results in vervet monkeys being killed or captured and sold for medical research. Vervets are also hunted for bushmeat in certain rural areas. Baby vervets are highly susceptible to predation from pythons, leopards, raptors, and baboons. Extreme distress and death from lack of food and water during the dry season also impact vervet mortality. |
Conservation Efforts
Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) has listed vervets on Appendix II since 1977.
Some of the conservation efforts intended to assist the vervet monkey are land and water protection, education, international legislation, research, and monitoring. South Africa and Kenya have resources allocated to protecting this species. They manage the international trade of the vervet monkey as a research animal with strict controls.
Several organizations and individuals rehabilitate monkeys who are found injured or orphaned. Educators go to villages to raise awareness of the need to conserve wildlife, and primates in particular. The Vervet Monkey Foundation in South Africa and the Pan African Sanctuary Alliance (with 22 members in 13 African states) are two of these organizations. These groups are working with governments to step up patrols of wildlife areas, educate the next generation, give medical treatment and long-term care, and assist in apprehending wildlife poachers.
Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) has listed vervets on Appendix II since 1977.
Some of the conservation efforts intended to assist the vervet monkey are land and water protection, education, international legislation, research, and monitoring. South Africa and Kenya have resources allocated to protecting this species. They manage the international trade of the vervet monkey as a research animal with strict controls.
Several organizations and individuals rehabilitate monkeys who are found injured or orphaned. Educators go to villages to raise awareness of the need to conserve wildlife, and primates in particular. The Vervet Monkey Foundation in South Africa and the Pan African Sanctuary Alliance (with 22 members in 13 African states) are two of these organizations. These groups are working with governments to step up patrols of wildlife areas, educate the next generation, give medical treatment and long-term care, and assist in apprehending wildlife poachers.
References:
- http://pin.primate.wisc.edu/factsheets/entry/vervet/taxon
- https://a-z-animals.com/animals/vervet-monkey/
- https://alltheworldsprimates.org/Members/Home.aspx
- http://www.iucnredlist.org/details/136271/0
- https://www.arkive.org/vervet/chlorocebus-pygerythrus/
- http://www.enviro.co.za/
- https://pasaprimates.org/
- http://www.awf.org/wildlife-conservation/vervet-monkey
- Go here to listen to vocalizations:
- http://pin.primate.wisc.edu/factsheets/entry/vervet/behav
Written by Carolyn North, April 2018; with taxonomy revisions, November 2019
