Vervet Monkey (Cercopithecus aethiops)


MORPHOLOGY:
The average body mass for an adult male vervet monkey is around 5 kilograms, and for a female it is around 3.5 kilograms. On the abdomen the skin of both sexes is blue. The scrotum and the perianus of the male are blue in color and the penis has a red color. Both sexes of this species have long, sharp canines (Estes, 1991).

RANGE:
The vervet monkey is found throughout Southern, Eastern, and Western Africa. This species prefers to live in riverine woodland, although it is highly adaptable and can live in a variety of habitats even living amongst humans.

ECOLOGY:
The vervet monkey is an omnivorous species that prefers grasses. This species also likes to consume the various parts of the acacia tree. Fruits and seeds are also a major component of their diet. For protein the vervet monkey eats arthropods and small vertebrates such as lizards and fledgling birds. The diet does differ amongst groups occupying different habitats. The group sizes range from 5 to 76 individuals. The vervet monkey does respond to the alarm calls of other animal species such as other primates, ungulates, and birds (Estes, 1991). This is a diurnal species.

LOCOMOTION:
The vervet monkey moves quadrupedally both on the ground and in the trees (Fleagle, 1988). This species only occasionally leaps from tree to tree (Fleagle, 1988). This species descends trees in a head first manner (Estes, 1991). The fastest gait, or mode of locomotion, is a bounding gallop on all of its limbs (Estes, 1991). The vervet monkey is capable of swimming (Kingdon, 1971).

spy-hopping: This locomotory pattern is employed when the vervet monkey is travelling in tall grass which restricts its vision (Estes, 1991). When the vervet monkey runs it will hop on its hindlegs to see over the tall grass (Estes, 1991).

SOCIAL BEHAVIOR:
The vervet monkey has a multimale-multifemale social system. The males disperse and the females are philopatric. Males are forced to emigrate upon the onset of puberty when their genitalia begins to turn color (Estes, 1991). Females in the group form a linear dominance hierarchy with the daughters inheriting their rank from their mothers. High-ranking individuals have a priority access to food resources (Estes, 1991). Adult females of a group mainly interact with close relatives (Cheney and Seyfarth, 1982). Both sexes are territorial (Estes, 1991). Juvenile males will hold and care for infant siblings, but adult males generally show no interest in infants (Estes, 1991). Mothers will let other females handle her infants (Estes, 1991). Females tend to favor handling of infants belonging to higher-ranking individuals (Estes, 1991). Grooming is an important social behavior that reinforces social bonds (Estes, 1991).

VOCAL COMMUNICATION:
chutter: This is a low-pitched, monotonal and staccato vocalization (Struhsaker, 1967). The mouth is closed and the teeth are covered, and this call is emitted by adult females and juveniles (Struhsaker, 1967). This call is used to express aggressive threat and also is used to solicit support from other group members (Struhsaker, 1967).

bark: This call is low-pitched and gruff in sound (Stryhsaker, 1967). This call is emitted by adult and subadult males (Struhsaker, 1967). This call is given towards other vervet monkeys who are fighting, it is emitted to stop the fighting (Struhsaker, 1967).

intergroup grunt: This call consists of nasal grunts that have a short range (Struhsaker, 1967). This call is emitted by males in response to seeing members from another group while on patrol of a territory (Struhsaker, 1967).

squeals and screams: These calls are high-pitched and tend to be piercing (Struhsaker, 1967). The mouth position varies for these calls and the teeth may be covered or not (Struhsaker, 1967). These calls are emitted by females and juveniles that are seeking help from threats by an aggressor (Struhsaker, 1967).

woof-woof: This call is non-tonal, deep, and has a guttural sound (Struhsaker, 1967). The mouth is closed or slightly opened (Struhsaker, 1967). This call is emitted by subordinate males to show submission (Struhsaker, 1967).

wa: This call is a continuous tonal exhalation that occurs with a grimace (Struhsaker, 1967). This call is emitted by subordinate males to show submission (Struhsaker, 1967).

woof-wa: This call is a combination of the woof-woof and the wa (Struhsaker, 1967). This call is emitted by subordinate males to show submission (Struhsaker, 1967).

long aar: For this vocalization the mouth is slightly open and puckered and the teeth are covered (Struhsaker, 1967). This call is emitted by females and juveniles in response to trespassing by non-members of the group (Struhsaker, 1967). This call brings other group members to the area (Struhsaker, 1967).

rraugh: For this call the mouth is closed or partially opened and the teeth are covered (Struhsaker, 1967). This call is emitted by yearlings when they approach older members of the group, and is a signal of nonaggression (Struhsaker, 1967).

teeth-chattering: For this sound the teeth chatter, and is given by adult and subadult males (Struhsaker, 1967). This is usually given when grooming and sometimes as a response to red-white-and-blue (Struhsaker, 1967).

progression calls: This call consists of nasal grunts that have a short range, and they are emitted by group members to no specific receiver when the group starts to move (Struhsaker, 1967). The calls are emitted by all group members over the age of 4.5 months, and the calls tend also to communicate who is giving the call because there some individual variation amongst callers (Struhsaker, 1967).

purring: This call is very quiet and is given by juveniles when they are play-wrestling (Struhsaker, 1967).

uh: This call functions as a response to minor predators and is emitted by all group members except infants (Struhsaker, 1967). This call is low-intensity in nature (Struhsaker, 1967).

nyow: This call is given in response to the sudden appearance of minor predators and is given by all group members except the juveniles; this call is moderate in intensity (Struhsaker, 1991).

chirp: This call is low in frequency, and is short and sharp; the mouth is wide open and the teeth are exposed (Struhsaker, 1967). This call carries for a long distance and is emitted by females and juveniles in response to a major mammalian predator (Struhsaker, 1967).

rraup: This call is short and rough and not repeated (Struhsaker, 1967). The call is given by females and juveniles in response to avian predators, and group members respond by leaving the tree tops and/or running into thickets (Struhsaker, 1967).

threat-alarm bark: This call is like the rraup, but is given repeatedly (Struhsaker, 1967). This call is emitted by adult and subadult males and serves to communicate an aggressive threat (Struhsaker, 1967).

rrr: This call is emitted by infants and juveniles to communicate distress to their mothers and/or other group members (Struhsaker, 1967).

eh, eh: This call is given by infants and juveniles upon a reunion with their mothers (Struhsaker, 1967). This call is quiet, short, and non-tonal in nature (Struhsaker, 1967).

OLFACTORY COMMUNICATION:

VISUAL COMMUNICATION:
staring: This display by the vervet monkey is used as a threat display (Estes, 1991). The eyes are fixed on the stimulus and the eyebrows are raised and the scalp is retracted, the facial skin is also stretched by moving the ears back (Estes, 1991). Underneath the eye lids the color is different which contrasts sharply with the surrounding facial color (Estes, 1991)

head-bobbing: This is used as a threat display by the vervet monkey and head bobs up and down (Estes, 1991). This often occurs with staring with open mouth (Estes, 1991).

penile display: This is when an adult male vervet monkey will present his erect penis and scrotum so that a neighboring group will see them (Estes, 1991). This display is used to demarcate territory (Estes, 1991).

red-white-and-blue display: This display is used to communicate dominance by one male over another within a group (Estes, 1991). The male walks back and forth with his penis and scrotum in full view for the receiver to see; the sender will encircle the receiver (Estes, 1991). Occasionally the sender will stand on his hind legs and present his penis and scrotum to the receiver (Estes, 1991).

rapid-glancing: This is when an individual looks toward and away from an aggressor (Estes, 1991). This display communicates subordination and will elicit assistance from other group members (Estes, 1991).

tail signals: The position of the tail when an individual is standing on all four limbs will tell the degree of confidence of the individual (Bernstein et al., 1978). If the individual is fearful the tail will extended parallel to the ground and as the tail moves up the individual is more confident, with the most confident being when the tail is arched over the body and being parallel to the body (Bernstein et al., 1978).

TACTILE COMMUNICATION:
nose-to-nose greeting: This is when two vervet monkeys will approach each other and touch the muzzles together (Estes, 1991). This behavior is a greeting behavioral pattern and usually precedes play or grooming (Estes, 1991).

REPRODUCTION:
The vervet monkey gives birth to a single offspring. Females do not show any external signs of estrus (Estes, 1991). Dominant males in the group receive most of the copulations (Cheney and Seyfarth, 1982). The vervet monkey has dorso-ventral copulatory position. During copulation the female sometimes will look over her shoulder and looks at the male, and maybe even grab the leg of the male; often the female will move forward (Estes, 1991). Juvenile males will sometimes harass a pair that is copulating, but the two will usually ignore the juvenile male (Estes, 1991).

presenting: This behavior is preformed by the female to elicit copulation from the male; this pattern tells the male that she is ready for copulation (Estes, 1991).

REFERENCES:
Bernstein, P.W., Smith, W.J., Krensky, A. , and Rosene, K. 1978. Tail Positions of Cercopithecus aethiops. Z. Tierpsychol.. Vol. 46, 268-278.

Burton, F. 1995. The Multimedia Guide to the Non-human Primates. Prentice-Hall Canada Inc.

Cheney, D.L. and Seyfarth, R.M. 1982. Recognition of Individuals within and Between Free-ranging Groups of Vervet Monkeys. American Zoologist Vol. 22, 519-529.

Estes, R.D. 1991. The Behavior Guide to African Mammals. University of California Press.

Fleagle, J. G. 1988. Primate Adaptation and Evolution. Academic Press.

Struhsaker, T.T. 1967. Auditory Communication among Vervet Monkeys (Cercopithecus aethiops). In Social Communication among Primates, ed. S.A. Altmann. University of Chicago Press.

Last Updated: June 8, 2007.
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