Vervet monkey

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Vervet monkey [1]
Vervet Monkey (Chlorocebus pygerythrus).jpg
Adult in Gorongosa National Park, Mozambique
Calls recorded at Lake Naivasha, Kenya
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Family: Cercopithecidae
Genus: Chlorocebus
Species:
C. pygerythrus
Binomial name
Chlorocebus pygerythrus
F. Cuvier, 1821
Vervet Monkey area.png
     Native Range

The vervet monkey (Chlorocebus pygerythrus), or simply vervet, is an Old World monkey of the family Cercopithecidae native to Africa. The term "vervet" is also used to refer to all the members of the genus Chlorocebus . The five distinct subspecies can be found mostly throughout Southern Africa, as well as some of the eastern countries. Vervets were introduced to Florida, St. Kitts and Nevis, and Cape Verde. [3] [4] [5] These mostly herbivorous monkeys have black faces and grey body hair color, ranging in body length from about 40 cm (16 in) for females, to about 50 cm (20 in) for males.

Contents

In addition to behavioral research on natural populations, vervet monkeys serve as a nonhuman primate model for understanding genetic and social behaviors of humans. They have been noted for having human-like characteristics, such as hypertension, anxiety, and social and dependent alcohol use. [6] Vervets live in social groups ranging from 10 to 70 individuals, with males moving to other groups at the time of sexual maturity. [7] Studies done on vervet monkeys involve their communication and alarm calls, specifically in regard to kin and group recognition, and particular predator sightings.

Taxonomy

The vervet monkey was previously classified as Cercopithecus aethiops, now renamed 'grivet' and reclassified as Chlorocebus . The vervet and malbrouck have also been considered conspecific, or as subspecies of a widespread Ch. aethiops. [8] The different taxa are distinguished by coat colour and other morphological characteristics. The characteristics of Ch. aethiops graduate into Ch. pygerythrus where their ranges meet, thus deciding if the vervets commonly known to occur in Kenya are actually Ch. aethiops is difficult; animals in the same pack may be classified as one species or the other, and Ch. pygerythrus may also interbreed with Ch. tantalus where their ranges meet. [9]

Colin Groves recognised the below five subspecies of vervet monkey in the third edition of Mammals of the World: [1]

Groves used Ch. p. hilgerti for all East African vervets except the insular subspecies Ch. p. excubitor and Ch. p. nesiotes. The name Ch. p. centralis has been suggested to have precedence, and that Ch. p. hilgerti should be restricted to the population of southern Ethiopia. [13]

Synonymy

Ch. p. pygerythrus, as Cercopithecus aethiops, was also formerly divided into four subspecies:

These subspecies are no longer recognised and are synonymous with Ch. p. pygerythrus.

Physical description

The vervet monkey very much resembles a gray langur, having a black face with a white fringe of hair, while its overall hair color is mostly grizzled-grey. [15] [16] The species exhibits sexual dimorphism; the males are larger in weight and body length and may be recognized by a turquoise-blue scrotum. Adult males weigh between 3.9 and 8.0 kg (8.6 and 17.6 lb), averaging 5.5 kg (12 lb), and have a body length between 420 and 600 mm (17 and 24 in), averaging 490 mm (19 in) from the top of the head to the base of the tail. Adult females weigh between 3.4 and 5.3 kg (7.5 and 11.7 lb) and average 4.1 kg (9.0 lb), and measure between 300 and 495 mm (11.8 and 19.5 in), averaging 426 mm (16.8 in). [12] [17]

Behaviour

Social behaviour

A vervet monkey grooms another in Gaborone, Botswana Vervet monkeys grooming.JPG
A vervet monkey grooms another in Gaborone, Botswana
Juvenile C. p. rufoviridis, Uganda Vervet monkey (Chlorocebus pygerythrus rufoviridis) juvenile.jpg
Juvenile C. p. rufoviridis, Uganda

When males reach sexual maturity, they move to a neighboring group. Often, males move with a brother or peer, presumably for protection against aggression by males and females of the resident group. Groups that had previously transferred males show significantly less aggression upon the arrival of another male. In almost every case, males migrate to adjacent groups. This obviously increases benefits in regard to distance traveled, but also reduces the amount of genetic variance, increasing the likelihood of inbreeding. [18]

Females remain in their groups throughout life. Separate dominance hierarchies are found for each sex. Male hierarchies are determined by age, tenure in the group, fighting abilities, and allies, while female hierarchies are dependent on maternal social status. A large proportion of interactions occurs between individuals that are similarly ranked and closely related. Between unrelated individuals, female competition exists for grooming members of high-ranking families, presumably to gain more access to resources. These observations suggest individual recognition is possible and enables discrimination of genetic relatedness and social status. Interactions between different groups are variable, ranging from highly aggressive to friendly. Furthermore, individuals seem to be able to recognise cross-group vocalisations, and identify from and to which monkey each call is intended, even if the call is made by a subadult male, which is likely to transfer groups. This suggests the members within a group are actively monitoring the activity of other groups, including the movement of individuals within a group. [19]

Within groups, aggression is directed primarily at individuals that are lower on the hierarchy. Once an individual is three years or older, it is considerably more likely to be involved in conflict. Conflict often arises when one group member shows aggression toward a close relative of another. Further, both males and females may redirect aggression towards individuals in which both had close relatives that were previously involved in a conflict. This suggests complex recognition not only of individuals, but also of associations between individuals. This does not suggest recognition of other's individual kinship bonds is possible, but rather that discrimination of social relationships does occur. [20]

Female and juvenile, Kruger Park, South Africa Vervet monkeys Kruger.jpg
Female and juvenile, Kruger Park, South Africa

Alarm calls and offspring recognition

A vervet monkey mother with infant Monkey & Baby.JPG
A vervet monkey mother with infant

Vervet monkeys have four confirmed predators: leopards, eagles, pythons, and baboons. The sighting of each predator elicits an acoustically distinct alarm call. [21] As infants, vervets learn to make the variety of calls from observation alone, without explicit tutelage. In experimentation with unreliable signalers, individuals became habituated to incorrect calls from a specific individual. Though the response was lessened for a specific predator, if an unreliable individual gives an alarm call for a different predator, group members respond as if the alarm caller is, in fact, reliable. This suggests vervet monkeys are able to recognize and to respond to not only the individual calling, but also to the semantics of what the individual is communicating. [22] Vervet monkeys are thought to have up to 30 different alarm calls. In the wild, they have been seen giving a different call when seeing a human being approaching, leading researchers to believe that vervet monkeys may have a way of distinguishing between different land and flight predators. [23]

Mothers can recognise their offspring by a scream alone. A juvenile scream elicits a reaction from all mothers, yet the juvenile's own mother had a shorter latency in looking in the direction of the scream, as well as an increased duration in her look. Further, mothers have been observed to help their offspring in conflict, yet rarely aided other juveniles. Other mothers evidently can determine to which mother the offspring belongs. Individuals have been observed to look towards the mother whose offspring is creating the scream. [24]

Kin relationships

Siblings likely provide the prevailing social relationships during development. Within social groups, mother-offspring and sibling interactive units are distinct groups. The sibling interactions are heavily supportive and friendly, but do have some competition. Contests primarily involve postweaning resource allocation by the common mother. For example, siblings have conflict over grooming time allocated by their mother. Offspring are usually not born in extremely close time proximity due to the interbirth period of the mother. This time can be reduced by use of an allomother. The clarity of the familial and sibships within a group may act as a form of alliance, which would come at relatively low cost in regards to grooming. Other alliances are shown through conflict with aggressive individuals that have acted against a closely related sibling. [25]

Vervet monkey female with a baby Vervet monkey and baby.jpg
Vervet monkey female with a baby

Allomothering is the process when another individual besides the mother cares for an infant. In groups of vervet monkeys, infants are the target of a tremendous amount of attention. Days after an infant is born, every member of the group inspects the infant at least once by touching or sniffing. While all group members participate in infant caretaking, juvenile females that cannot yet menstruate are responsible for the majority of allomothering. The benefit is mutual for the mother and allomother. Mothers that use allomothers are able to shorten their interbirth periods, the time between successive births. At the same time, allomothers gain experience in rearing infants, and had more success in raising their own offspring. Juvenile females discriminate in preference for the infant they choose to allomother, and usually choose siblings or infants of high-ranking individuals. When a mother allows her juvenile daughter to become an allomother for a newborn sibling, the mother decreases her own investment in the infant, while increasing the chances of successful rearing of her immature daughter. [26]

Grandmothers and grandchildren share one-quarter of their genes, so they should be more likely to form affiliative relationships than unrelated members in a group. Not only do infants approach their grandmothers more often than unrelated members, but they also prefer their grandmothers compared to other adult female kin, not including their own mothers. Additional research has shown grandmothers show no preference over the sex of their grandchild. Interest in the grandchild spurred from the rank of the grandmother within a group. Higher-ranking grandmothers showed more interest in caring for their grandchildren when compared to low-ranking grandmothers. The presence of grandmothers has been associated with a decrease in mortality of infants. [27]

Spite

Spiteful actions are extremely rare in the animal kingdom. Often, an indirect benefit is seen for the individual acting 'spiteful' or to a close relative of that individual. Vervet monkeys have been observed to destroy a competitor's food source rather than consume or steal it themselves. While energy is being lost on destroying the food, a competitive advantage is given to the individual due to an increase in competitive gain. This would be pertinent for a male that could be displaced within his group to immigrating males. [28]

Reproduction

Female vervets do not have external signs indicating estrus, thus elaborate social behaviors involving reproduction do not occur. Typically, a female gives birth once a year, between September and February, after a gestation period around 165 days. Usually, only one infant is born at a time, though twins can occur rarely. A normal infant weighs 300–400 grams (11–14 oz). [12]

Ecology

Diet

Young vervet monkey in South Africa eating fruits of Harpephyllum caffrum Vervet Monkey Amanzimtoti.JPG
Young vervet monkey in South Africa eating fruits of Harpephyllum caffrum

The vervet monkey eats a primarily herbivorous diet, living mostly on wild fruits, flowers, leaves, seeds, and seed pods. In agricultural areas, vervets become problem animals, as they raid bean, pea, young tobacco, vegetable, fruit, and grain crops. Animal foods of their diet include grasshoppers and termites. Raids of cattle egrets and weaver bird nests have been observed where the vervets eat the eggs and chicks. [12]

A list of some natural food plants and part of the plant eaten, in South Africa: [12] [29]

Distribution and habitat

The vervet monkey ranges throughout much of Southern and East Africa, being found from Ethiopia, Somalia and extreme southern South Sudan, to South Africa. It is not found west of the East African Rift or the Luangwa River, [1] where it is replaced by the closely related malbrouck (C. cynosuros). The vervet monkey inhabits savanna, riverine woodland, coastal forest, and mountains up to 4000 m (13,100 ft). They are adaptable and able to persist in secondary and/or highly fragmented vegetation, including cultivated areas, and sometimes are found living in both rural and urban environments. [2] Annual home range size has been observed to be as high as 176 ha, with an average population density of 54.68 animals/km².

Introduced vervet monkeys are naturalised in Cape Verde. Dania Beach, Florida, is home to about 40 introduced vervets. [30]

Relationship with humans

An infant vervet monkey, South Africa Chlorocebus pygerythrus00.jpg
An infant vervet monkey, South Africa

The monkeys are used for biomedical research. [31] Many people living in close proximity to vervet colonies see them as pests, as they steal their food. Heavy fines in some areas discourage the killing of vervet monkeys. [32]

Its status according to the IUCN is "least concern".

This species was known in ancient Egypt, including the Red Sea Mountains and the Nile Valley. [33] From fresco artworks found in Akrotiri on the Mediterranean island of Santorini there is evidence that the vervet monkey was known to the inhabitants of this settlement around 2000 BC; this fact is most noted for evidence of early contact between Egypt and Akrotiri. [34] Excavations dated to the end of the 1st century AD from Berenike, a Roman-Egyptian port-town on the Red Sea coast, demonstrate that vervet monkeys must have been kept as pets at that time. [35]

Related Research Articles

Black-and-white colobus Genus of Old World monkeys

Black-and-white colobuses are Old World monkeys of the genus Colobus, native to Africa. They are closely related to the red colobus monkeys of genus Piliocolobus. There are five species of this monkey, and at least eight subspecies. They are generally found in high-density forests where they forage on leaves, flowers and fruit. Social groups of colobus are diverse, varying from group to group. Resident-egalitarian and allomothering relationships have been observed among the female population. Complex behaviours have also been observed in this species, including greeting rituals and varying group sleeping patterns. Colobi play a significant role in seed dispersal.

Patas monkey Species of Old World monkey

The patas monkey, also known as the wadi monkey or hussar monkey, is a ground-dwelling monkey distributed over semi-arid areas of West Africa, and into East Africa. It is considered the only member of the genus Erythrocebus.

Old World monkey Family of mammals

Old World monkey is the common English name for a family of primates known taxonomically as the Cercopithecidae. Twenty-four genera and 138 species are recognized, making it the largest primate family. Old World monkey genera include baboons and macaques. Common names for other Old World monkeys include the talapoin, guenon, colobus, douc, vervet, gelada, mangabey, langur, mandrill, surili (Presbytis), patas, and proboscis monkey. Phylogenetically, they are more closely related to apes than to New World monkeys. They diverged from a common ancestor of New World monkeys around 45 to 55 million years ago.

Guenon Genus of Old World monkeys

The guenons are the genus Cercopithecus of Old World monkeys. Not all members of this genus have the word "guenon" in their common names; also, because of changes in scientific classification, some monkeys in other genera may have common names that include the word "guenon". Nonetheless, the use of the term guenon for monkeys of this genus is widely accepted.

Dryas monkey Species of Old World monkey

The Dryas monkey, also known as Salonga monkey, ekele, or inoko, is a little-known species of guenon found only in the Congo Basin, restricted to the left bank of the Congo River. It is now established that the animals that had been classified as Cercopithecus salongo were in fact Dryas monkeys. Some older sources treat the Dryas monkey as a subspecies of the Diana monkey and classify it as C. diana dryas, but it is geographically isolated from any known Diana monkey population.

Pygmy marmoset Species of monkey

The pygmy marmoset, genus Cebuella, is a small genus of New World monkey native to rainforests of the western Amazon Basin in South America. It is notable for being the smallest monkey and one of the smallest primates in the world, at just over 100 grams (3.5 oz). It is generally found in evergreen and river-edge forests and is a gum-feeding specialist, or a gummivore.

Chacma baboon Species of baboon from the Old World monkey family

The chacma baboon, also known as the Cape baboon, is, like all other baboons, from the Old World monkey family. It is one of the largest of all monkeys. Located primarily in southern Africa, the chacma baboon has a wide variety of social behaviors, including a dominance hierarchy, collective foraging, adoption of young by females, and friendship pairings. These behaviors form parts of a complex evolutionary ecology. In general, the species is not threatened, but human population pressure has increased contact between humans and baboons. Hunting, trapping, and accidents kill or remove many baboons from the wild, thereby reducing baboon numbers and disrupting their social structure.

<i>Chlorocebus</i> Genus of Old World monkeys

Chlorocebus is a genus of medium-sized primates from the family of Old World monkeys. Six species are currently recognized, although some people classify them all as a single species with numerous subspecies. Either way, they make up the entirety of the genus Chlorocebus.

Grivet Species of Old World monkey

The grivet is an Old World monkey with long white tufts of hair along the sides of its face. Some authorities consider this and all of the members of the genus Chlorocebus to be a single species, Cercopithecus aethiops. As here defined, the grivet is restricted to Ethiopia, Sudan, Djibouti, and Eritrea. In the southern part of its range, it comes into contact with the closely related vervet monkey and Bale Mountains vervet. Hybridization between them is possible, and may present a threat to the vulnerable Bale Mountains vervet. Unlike that species, the grivet is common and rated as least concern by the IUCN.

Alarm signal Signal made by social animals to warn others of danger

In animal communication, an alarm signal is an antipredator adaptation in the form of signals emitted by social animals in response to danger. Many primates and birds have elaborate alarm calls for warning conspecifics of approaching predators. For example, the alarm call of the blackbird is a familiar sound in many gardens. Other animals, like fish and insects, may use non-auditory signals, such as chemical messages. Visual signs such as the white tail flashes of many deer have been suggested as alarm signals; they are less likely to be received by conspecifics, so have tended to be treated as a signal to the predator instead.

De Brazzas monkey Species of Old World monkey

De Brazza's monkey is an Old World monkey endemic to the riverine and swamp forests of central Africa. The largest species in the guenon family, it is one of the most widespread arboreal African primates. Aside from size, it can be differentiated from other cercopithecus monkeys by its orange diadem and white beard. Due to its cryptic nature, the species is not well documented in all of its habitats but has shown unique traits such as pair-bonding and aggressive behavior towards other guenons.

Malbrouck Species of Old World monkey

The malbrouck is an Old World primate from Africa that belongs to the genus Chlorocebus. The species is sometimes classified as a subspecies of the vervet monkey, or of the widespread grivet.

Green monkey Species of mammal

The green monkey, also known as the sabaeus monkey, is an Old World monkey with golden-green fur and pale hands and feet. The tip of the tail is golden yellow as are the backs of the thighs and cheek whiskers. It does not have a distinguishing band of fur on the brow, like other Chlorocebus species, and males have a pale blue scrotum. Some authorities consider this and all of the members of the genus Chlorocebus to be a single widespread species, Chlorocebus aethiops.

Allomothering, allomatural infant care/handling, or non-maternal infant care/handling is alloparenting performed by any group member other than the mother or genetic father and thus is distinguished from parental care. It is a widespread phenomenon among mammals and birds.

Roloway monkey Species of Old World monkey

The roloway monkey is an endangered species of Old World monkey endemic to tropical West Africa. It was previously considered a subspecies of the Diana monkey. It is classified as Critically Endangered due to habitat loss and continued hunting for the bushmeat trade. The roloway monkeys are mainly arboreal species, for the most part inhabiting forests in Ghana and some reserves in South-Eastern Côte-D'Ivoire. More specifically studies have shown that the C. diana roloway is mostly concentrated in Tanoé forest because of their heavy threats to extinction.

Bale Mountains vervet Species of Old World monkey

The Bale Mountains vervet is a terrestrial Old World monkey endemic to Ethiopia, found in the bamboo forests of the Bale Mountains. All species in Chlorocebus were formerly in the genus Cercopithecus. The Bale Mountains vervet is one of the least-known primates in Africa. They avoid tree-dominated and bushland areas as their habitat. These monkeys mainly reside in the bamboo forest of the Bale Mountains due their dietary specialization on bamboo, but other factors, such as climate, forest history, soil quality, and disease, are likely to play a role in their choice to inhabit this area. The Bale Mountains vervet have a very quiet behavior and tend to flee when encountering a human being. It is also known as the Bale monkey.

Tantalus monkey Species of Old World monkey

The tantalus monkey is an Old World monkey from Africa that ranges from Ghana to Sudan. It was originally described as a subspecies of the grivet. All species in Chlorocebus were formerly in the genus Cercopithecus. It is a common species with a wide range, and the International Union for Conservation of Nature has rated its conservation status as being of "least concern".

Vervet Monkey Foundation

The Vervet Monkey Foundation (VMF) is a 23-hectare not-for-profit centre for rehabilitation, education and sanctuary for vervet monkeys, near the town of Tzaneen, South Africa. Registered and established in 1993, it is situated approximately 80 miles south of The Tropic of Capricorn. The Sanctuary is a member of the Pan African Sanctuary Alliance (PASA), and GFAS, The Global Federation of Animal Sanctuaries. The foundation relies heavily on volunteer workers primarily from western countries to assist in the day-to-day running and care duties of the foundation.

Multi-male groups, also known as multi-male/multi-female, are a type of social organization where the group contains more than one adult male, more than one adult female, and offspring. Within Order Primates, it is the most common social group type, with group sizes ranging from 10 to 100 individuals. Large groups of primates are called "troops". Examples of species that can be categorized under this type of social organization include many diurnal lemurs, langurs, and most members of the family Cebidae.

Infanticide in non-human primates occurs when an individual kills its own or another individual's dependent young. Five hypotheses have been proposed to explain infanticide in non-human primates: exploitation, resource competition, parental manipulation, sexual selection, and social pathology.

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