Geographic Distribution and Habitat
Black crested mangabeys. also called black mangabeys, are native to Central Africa, occupying the Democratic Republic of the Congo, south of the Congo River (previously known as the Zaire River), and possibly extinct in Angola. They are found in primary and secondary rainforests, gallery forests, and swamp lands, and typically forage in the middle and upper canopy at 39 to 98 ft (12 to 30 m) from the forest floor.
Black crested mangabeys resemble baboons (genus Papio), to whom they are believed to have diverged about four million years ago.
Size, Weight, and Lifespan
Male and female black crested mangabeys are fairly similar in size, ranging from 15 to 35 in (38 to 88 cm) in head-to-toe body length, while their tails, which are not prehensile, or able to grasp objects, add another 17 to 30 in (43 to 76 cm) to their frames.
Both sexes have similar physical characteristics, with the weight of a male ranging anywhere from 13 to 24 lbs (6 to 11 kg), and females weighing between between 9 and 15 lbs (4 to 7 kg).
Lifespan for these primates is up to 30 years.
Large slender monkeys with long limbs and hair, black crested mangabeys are distinguishable from other mangabeys by the pointed black crest of hair that sits on top of their heads. They have dark skin, dark eyelids, and close-set nostrils—similar to that of a baboon, which is why they are often referred to as “baboon mangabeys.” Deep depressions can be seen under their cheekbones.
To aid with locomotive balance, the tails of black crested mangabeys are longer than their bodies and are carried in an upright position, taking on a shape similar to that of a question mark. They have long brown or grayish-brown whiskers that practically cover their ears entirely.
Large cheeks pouches allow them to stuff their faces full of food to carry around as they rummage through the forest for extended periods of time.
What Does It Mean?
Physically adapted to living primarily or exclusively in trees.
A recurring period of sexual receptivity and fertility in many female mammals.
A forest that serves as a corridor along rivers or wetlands and projects into landscapes that are otherwise sparsely treed, such as savannas, grasslands, or deserts.
Returning to one’s birthplace or remaining with one’s birth group.
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 rainforest that has regrown after a major disturbance, such as fire or timber harvest, but has not yet reached the mature state of primary forest.
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The black crested mangabey’s diet primarily includes vegetative substances, like fruit, nuts, seeds, leaves, and flowers. During some months, nectar is also an important food source, along with maize or sweet potatoes from neighboring crops.
Their large incisors and flat molars allow them to crack open hard seeds or nuts and bite into fruit that’s far too tough-skinned for other primates. They sometimes use their teeth to rip off the bark on trees, allowing them to feed on insects and spiders living beneath.
Behavior and Lifestyle
Being highly social creatures, black crested mangabeys are considered to be non-aggressive and friendly. Since they are mostly arboreal, they are excellent jumpers, and very seldom descend to the forest floor. Black crested mangabeys are diurnal, which means they are active during daylight hours. They move about quadrupedally, that is, using all four of their limbs.
Daily Life and Group Dynamics
Males leave their natal groups, while females are philopatric and remain in their natal groups as central figures. Living in a multi-male, multi-female group of 9 to 16 individuals, each groups’ home range may overlap the home range of another group, as each group can occupy a range of 118 to 173 acres (47 to 70 hectares). Smaller groups are sometimes formed that split off from the main group or troop.
The black crested mangabeys’ genus name, Lophocebus, means “crest monkey” in Greek.
Locals have referred to them as “baboon mangabeys” since they resemble the baboon species.
Communication among black crested mangabeys is broken into four different categories—visual, vocal, olfactory, and tactile.
Social presenting, pouting, head-bobbing, and staring with or without open mouths are examples of visual communication. During social presentation, a subordinate individual presents his or her bottom to a more dominant member of the group. This type of display is used to subdue visible signs of aggression. Females pout by protruding their lips as a sign of sexual receptivity. Head-bobbing and staring with or without an open mouth gape are signs of aggression and display threatening behavior. These are often accompanied by raised eyebrows and lowered ears.
Black crested mangabeys are extremely vocal and emit loud calls to maintain distance between groups. Progression calls, or nasally grunts, are emitted each time the group starts to move to another location. Grunts are also emitted upon greeting one another. In order to communicate danger or alarm the group, they sound ‘chuckles’ and ‘whoop-gobbles.’
Olfactory communication occurs when males sniff a female’s genitals when aroused or in response to her pouting at him. This is a way for him to determine whether she is sexually receptive.
Same-sex black crested mangabeys mount one another as a means of non-sexual tactile communication and to display dominance. More dominant individuals mount subordinates in group settings.
Reproduction and Family
Female black crested mangabeys signal readiness to mate when they are in estrus, at which time their buttocks region swells and takes on a pinkish hue.
The wet seasons in July and August are when they typically give birth. The gestation period lasts for a period of 5 ½ to 6 months, resulting in a birth of a single offspring. Babies, who can weigh anywhere between 1 to 1.3 lbs (.5 kg to .6 kg), cling to their mothers’ bellies and ride on their mothers’ backs when juveniles.
Dispersing seeds around the forest is one of the main ecological roles that black crested mangabeys play in helping to regrow the forests that they occupy. They tend to toss fruit to the ground after taking a single bite, which inadvertently serves as a source of food for some other species. Pollination may occur as a result of their consumption of nectar.
Conservation Status and Threats
The conservation status of the black crested mangabey increased in severity from Near Threatened to Vulnerable after a March 2018 assessment by the International Union for Conservation of Nature (IUCN, 2018). The announcement of the change was made was made in 2019.
The justification of the change was cited as follows:
Poaching of this species for the bushmeat trade is intensifying, and much of the forest in its range is now almost “empty” of large mammals. Because of its relatively large body size, the Black Mangabey is more attractive to hunters than the smaller Cercopithecus monkeys with which it shares its range. The species is also threatened by habitat loss and is suspected to have declined by at least 30% over the past three generations (30 years).
One of the greatest threats to the species is the illegal and unregulated uprooting of timber from the Congo basin. As the human population continues to expand in that area, the need for land converted for human logging becomes even greater, thus diminishing the homes of these creatures.
Listed on Convention of International Trade in Endangered Species (CITES) Appendix II, which controls trade in species, and under Class B of the African Convention on the Conservation of Nature and Natural Resources, the capturing and killing of the black crested mangabey currently requires prior permission.
The Salonga National Park in the Democratic Republic of the Congo is an area where the United Nations Educational, Scientific and Cultural Organization (UNESCO), and United Nations Foundation (UNF) work to preserve the forest and its inhabitants, including their population of black crested mangabeys.
The Yokokala Faunal Reserve, also in the Democratic Republic of the Congo, was originally created to conserve the population of bonobos, and now also works to conserve the black crested mangabey population.
Written by Nina Shangari, November 2017; updated in December 2019