Geographic Distribution and Habitat
The gray-cheeked mangabey, also called the white-cheeked mangabey, is found in Central Africa, ranging from Nigeria, south to Angola, and east to Uganda, Rwanda, and Burundi. The subspecies, also called the gray-cheeked mangabey, Lophocebus albigena albigena, is found in Southern Cameroon, ranging east to the Central African Republic, as well as south to northeastern Angola. Another subspecies of the gray-cheeked mangabey, the rusty-mantled mangabey, Lophocebus albigena osmani, is found further north in Cameroon and Southeastern Nigeria. Yet another, Johnston’s mangabey, Lophocebus albigena johnstoni, is located in Burundi, the Democratic Republic of the Congo, and Rwanda.
Gray-cheeked mangabeys live in primary and secondary rainforests, riverene forests, and swamp forests. They tend to be lowland species, though they can sometimes be found in montane forests at elevations up to 5,250 ft (1,600 m). Generally considered to to favor the forest canopy, they sometimes collect food on the forest floor.
Size, Weight, and Lifespan
The gray-cheeked mangabey is a large arboreal monkey. Females are slightly smaller and more slender than males, although it is difficult to notice this difference. Male head-to-body length measures 21–29 in (54–73 cm); females measure 17–24 in (43–61 cm) long. Both males and females have tails that are typically longer than their bodies, ranging from 28.7 to 39.3 in (73–100 cm). Males are heavier than females, weighing between 13 and 24 lb (6–11 kg); females weigh between 8 and 15 lb (3.6–7 kg).
The lifespan of the gray-cheeked mangabey varies according to their diet. Troops that consume hard-shelled nuts can wear their teeth down much faster and die younger than those who have a softer diet. In the wild they live, on average, between 20-22 years. In captivity, they typically live up to 32 years. In 2005, a captive female was still living at 36 years old.
The gray-cheeked mangabey is a large arboreal monkey with gray—and sometimes whitish—cheeks. Their long, lanky bodies are black or dark gray. The nominate subspecies L. a. albigena usually has a black patch on the nape of their neck and on their withers (the area between the shoulder blades). The hair on their head is long and scruffy, resembling little horns above their brows. Their eyes, face, and skin are also dark. Their chest and front legs are more powerfully built than the rest of their body. The long gray or tan hair on their shoulders and neck forms a cape.
They have long limbs and a long tail, which provides balance for them as they scurry through the forest. Their tail is somewhat prehensile and is strong enough to hook onto branches while leaping through the trees.
Their molars are long and their incisors are large. Cheek pouches allow them to collect and store food for later consumption.
Similar to baboons, a female mangabey’s buttocks swell and turn pink when she is ready to breed.
What Does It Mean?
A type of social hierarchy that arises when members of a social group interact, often aggressively, to create a ranking system. In social living groups, members are likely to compete for access to limited resources and mating opportunities.
The time of pregnancy from conception until birth.
A system of organization in members of a group who are ranked one above the other according to status or authority.
Narrow-edged teeth at the front of the mouth, adapted for cutting.
A race or subspecies that is given the same epithet as the species to which it belongs.
The tail of an animal that has adapted to be able to grasp or hold objects.
Also termed old-growth forest, virgin forest, or primeval forest—a forest that has attained great age without significant disturbance and thereby exhibits unique ecological features and might be classified as a climax community, an ecological community in which populations of plants or animals remain stable and exist in balance with each other and their environment.
A forest that is located nearby or adjacent to a river.
A forest that has regrown after a major disturbance, such as fire or timber harvest, but has not yet reached the mature state of primary forest.
The underside of an animal or plant.
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The gray-cheeked mangabey prefers to feed high in the forest canopy. They are mainly frugivorous (fruit-eaters), but there are seasonal fluctuations in fruit abundance that cause them to fall back on leaves, seeds, flowers, and invertebrates, such as ants, worms, caterpillars, and larvae.
Seasonal differences in resource availability affect their use of habitat. Since they consume different food items during periods of high or low fruit availability, their foraging heights also differ. During times of fruit abundance, they forage at greater heights. During times of lesser fruit, they spend more time in swampy areas and occasionally spend more time traveling for food.
Their large incisors allow them to eat and process a wide range of foods. They can even crack open nuts. Eating hard nuts and other hard foods, however, wears down their teeth and can lead to early death.
Behavior and Lifestyle
Gray-cheeked mangabeys move through the forest quadrupedally. They are diurnal (active during the day) and live in single male, multi-male, and multi-female groups. Males disperse from their natal groups and females are philopatric; that is, they remain with their natal groups.
Gray-cheeked mangabeys prefer to inhabit the middle to upper layers of the canopy. This gives them proper protection from most predators including humans, hawks, leopards, and large snakes.
Daily Life and Group Dynamics
Gray-cheeked mangabeys live in groups of 5 to 30 individuals. If groups become too large, they split apart into smaller groups.
Most of the time, confrontation between groups is rare since these mangabeys tend to avoid other groups. Their territories can cover up to several square miles and may overlap with that of other troops. The territories shift over time.
Females form a linear hierarchy, with all other females ranked below the alpha female. This hierarchy affects a female’s food intake. Higher-ranking individuals forage peacefully in the center of their group with less worry about predators and competition than those lesser-ranked individuals on the periphery. Thus, those in the center of the group consume more food.
Males also form a linear hierarchy, in which all other males are ranked below the alpha male. This affords the alpha male with greater breeding opportunities. However, this does not preclude competition and sneaky copulation by other males. Males rarely form bachelor groups and prefer to stay alone until they find the right troop.
Juvenile mangabeys enjoy play, especially high in the canopy, where they can swing and jump from tree to tree. Juveniles are much more playful than adults, but adults occasionally engage in playful activities with their young.
A single infant is born with soft fur, and his or her eyes are open.
When there is plenty of food available, mangabey groups will gather together for a while and even exchange group members.
Gray-cheeked mangabeys belong to the same family (Cercopithecinae) and tribe (Papionini) as baboons, macaques, and mandrills. In fact, they are sometimes referred to as baboon-mangabeys.
Mangabeys communicate with each other in some interesting ways. It can be difficult for them to see one another in the dense canopy, so sound is very important. Mangabeys have a special throat sac that allows them to produce loud calls. In males, the sac is larger and facilitates shrieking alarm calls to warn others when there is a threat. A male mangabey emits barking calls and grunts to let other troops know where he is so they don’t intrude. In addition, mangabeys make a “whoop-gobble” call—the whoop sound gets the attention of the other mangabeys in the area and the gobble tells everyone who and where he is. Whoop-gobble calls can be heard up to over half a mile (1 km) away.
Females join in on the loud calls, but not the whoop-gobble calls. Females emit progression calls, which consist of nasal grunts. These calls have a short range and are emitted by group members to no specific receiver.
Visual communication is used when group members come in contact with one another. Staring is a threat. Staring with an open mouth but with teeth covered is also a threat, and is often accompanied by head-bobbing. Pouting is a visual display used by females to communicate sexual receptivity. This occurs when the lips are protruded forward.
Mangabeys also use tactile communication. Tail-twining communicates strong social bonds between two individuals while they sit on a tree branch.
Reproduction and Family
The mating season starts in May and can last throughout September; however, breeding can occur year round. Mothers give birth to a single infant after a gestation period of about six months. The average time between births, also known as the interbirth interval, is 13 to 16 months. A longer interbirth interval is beneficial to gray-cheeked mangabeys. More time caring for youngsters reduces infant mortality rates.
Males reach sexual maturity at 4-5 years old, and females at about 4 years of age. At birth, the infants are carried on their mother’s ventral side (belly); after a few months they are carried on her back. The mother provides intensive care until the baby is 7 months old, and provides more general attention throughout the rest of the first year. Intensive care includes feeding, grooming, and carrying the infant for protection. At 10-12 months, aunts groom the infant more than the mother does. Siblings, both male and female, also groom infants they are related to. Sometimes males carry their infants for protection.
Due to their primary consumption of fruits and seeds, gray-cheeked mangabeys act as seed dispersers throughout the forest. In addition, when they lick nectar from flowers, pollen attaches to their coats. As they travel from tree to tree, the pollen drops from their coats, making them important pollinators as well as seed dispersers.
Conservation Status and Threats
The International Union for Conservation of Nature Red List of Threatened Species lists the gray-cheeked mangabey as Vulnerable (IUCN, 2017). The species is suspected to have undergone a population decline exceeding 30% over the past 30 years (about three generations). It used to be widespread, occupying both primary and secondary forest. Now, the expansion of access infrastructure throughout its range, increasing consumerism (especially in the western part of its range), and increasing human population has led to more intense and widespread hunting pressure.
Because gray-cheeked mangabeys are large-bodied and reap greater profit than smaller species, they are preferentially selected by hunters. As a result, they tend to be eliminated, or at least greatly reduced, in abundance before other, smaller monkey species. For example, the species now appears to be extremely rare throughout Equatorial Guinea, extinct or almost extinct in eastern Nigeria since the 1990s, also extinct along the western border of Cameroon, and can be quite uncommon elsewhere except in well-protected national parks and wildlife reserves.
In addition, habitat loss is resulting in population declines in the west and extreme east of its range. The taxon is listed as Vulnerable as the decline has been ongoing for some time and will continue into the future; causes have not ceased, nor will they in the foreseeable future.
They can adapt to living in secondary forests, but they are mainly dependent on primary forests and may be less adaptable to changes in the habitat than other monkeys. Gray-cheeked mangabeys are hunted for bushmeat in equatorial Guinea and Cameroon. Furthermore, in Uganda these mangabeys are killed for raiding crops in areas where the forest has recently been cleared.
The species is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), which means that the international trade of this species is carefully monitored and controlled. They are also listed as Class B under the African Convention, which limits the capturing and killing gray-cheeked mangabeys. These mangabeys inhabit in a number of protected areas throughout their range, including Dja Faunal Reserve in Cameroon, a World Heritage Site. Locally, however, the species is still declining due to hunting pressure and habitat loss. This suggests that the conservation of gray-cheeked mangabeys needs urgent reevaluation.
- Poulsen JR, Clark CJ, and Smith TB. 2001. Seasonal Variation in the Feeding Ecology of the Gray-Cheeked Mangabey (Lophocebus albigena) in Cameroon. American Journal of Primatology. 54:91–105.
Written by Tara Covert, January 2019