Tana River mangabey

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Tana River mangabey [1]
Cercocebus galeritus.jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Family: Cercopithecidae
Genus: Cercocebus
C. galeritus
Binomial name
Cercocebus galeritus
Peters, 1879
Tana River Mangabey area.png
Tana River mangabey range

The Tana River mangabey (Cercocebus galeritus) is a highly endangered species of primate in the family Cercopithecidae. Some authorities have included the taxa agilis and sanjei as subspecies of this species, [3] while others award these full species status. [1]


It is endemic to riverine forest patches along the lower Tana River in southeastern Kenya. It is threatened by habitat loss and degradation, which has increased in recent years. [4] This species was, together with the equally endangered Tana River red colobus, the main reason for the creation of the Tana River Primate Reserve in 1978, [5] but human encroachment within this reserve continues. [6] Recently, it has been suggested that 20,000 hectares of the Tana River Delta should be transformed into sugarcane plantations, but this has, temporarily at least, been stopped by the High Court of Kenya. [7]

Physical description

The Tana River mangabey is a medium-sized primate with a long semi-prehensile tail, yellow-brown coat, and a center part on the crown of the head with long, dark fur. The species has white eyelids that contrast to its darker face like other Cercocebus species. This contrast in the eyelids is believed to be used as part of the species complex communication system. [8] The species also has specialized dental morphology for feeding on hard nuts, seeds, and fruits.

Behavior and ecology

The Tana River mangabey is diurnal and semi-terrestrial. It spends most of its time on the ground but is still considered arboreal due to its sleeping area. The species sleeps in trees which are approximately 27-37m in height which have a sparse canopy cover of 25–60%. The primate sleeps in the forks of the branches of these trees or near the main trunk. It is believed to sleep in trees to reduce the risk of predation and chooses this site according to its last feeding position in the area. [9]

Group size ranges from 13–36 individuals, and sometimes combining to form aggregations of 50 to 60 individuals. [10] These groups consist of multiple males and multiple females. The species have an average day-range length of 1.25 km. [11] During the dry season when food is limited groups maintain discrete territories with minimal overlapping. To maintain these territories males give spatial vocalizations and territorial displays at fixed boundaries. The males within the group may also engage in active combat with outside group leaders invading the territory. In the wet season when food is abundant boundaries are broken down. Foraging ranges for different groups extend and there is considerable overlap between the different groups. During this time groups are more tolerant of one another and meet and intermingle. [12] The Tana River mangabey has a few predators, such as Python sebae , crowned eagle, martial eagle, and Nile crocodile.


The Tana River mangabey is a polygynous species with two or more males within each group depending on the size of the group. The average adult male weighs approximately 10.2 kg while the average adult female weighs 5.5 kg exhibiting sexual dimorphism within the species. [11]

The primate gives birth to a single offspring after a gestation period of approximately 170–180 days. During the first two months after birth, the infant is guarded by its mother and begins to develop a close bond. In the third month the infant begins socializing with other infants and adult group members but remains in close proximity to mom. The females within the group usually have lasting bonds with their mother while the males become more independent and spend more time away from the group or on the periphery. If a group loses one of its males, another male may be recruited from peripheral solitary males to maintain the structure of the group. [12]


The species is an omnivore, feeding on leaves, seeds, fruits, insects and reptile and bird eggs. It is an opportunistic feeder and is semi-terrestrial where it may rummage through the leaf litter for food. The mangabey gets most of its food from sub-canopy and canopy trees, although they spend most of their time feeding and moving on the ground. It consumes the fruit and seed from approximately fifty different tree species. Feeding is performed 48% of the day, while sleeping accounts for 15%, and resting accounts for 14% of the day. [11] The species annual diet consists of 46.5% seeds and 25.6% consists of fruit consumption. [13] Critical food resources for the species are Ficus sycomorus which fruits year round, and Phoenix reclinata which is also a primary food species and fruits when others do not. [14]

The Tana River mangabey has dental morphology well suited for the food type it consumes. The species has large incisors for the tearing of the tough skin on the fruits it eats. Large maxillary and mandibular fourth premolars which increase surface area to crush seeds, and a shortened face which increases bite force. [15]

Geographic range and habitat

The Tana River mangabey is found on the continent of Africa in the southeastern portion of Kenya along the Tana River. It is found within 27 forest fragments along a 60 km stretch of floodplain forests. The gallery forest along the Tana River is home to several primate species: the Tana River mangabey, Tana River red colobus, blue monkey, yellow baboon, vervet monkey, and two species of bush babies. [16]

This species is restricted to riverine gallery forests in this area. [17] The forests in which it is found are naturally fragmented due to the meandering of the Tana River and its fluctuating water levels. The forest is becoming even more fragmented due to habitat loss from human disturbance reducing the chance of the species survival.


One of the greatest threats to endangered species is habitat loss. This is also the case with the Tana River mangabey. It is estimated that 50% of the original forest has been lost in the last 20 years. The Tana River area is losing its forests to agriculture. [8] Felling of canopy trees for canoe construction, wild honey collection, and palm fronds are being used for thatching and mats. Subcanopy trees are being used for housing poles and the topping of Phoenix reclinata for palm wine collection severely impacts the resources used by the species. [18] Tana River mangabeys are also hunted and trapped in response to local crop damage. This trapping may occur and appears to be occurring at low levels within the forests.

The Tana River mangabey is listed as one of The World's 25 Most Endangered Primates. A 1994 census estimated the species population to be 1,000 to 1,200 individuals. [18] It was listed under the U.S. as being endangered in 1970. The species is also listed as critically endangered under the International Union for Conservation of Nature and under CITES is listed under Appendix I. This species is listed on Class A of the African Convention on the Conservation of Nature and Natural Resources.

The Tana River Primate Reserve was established in 1976 to protect the remaining forest along the Tana River and the endemic Tana River mangabey. The reserve protects an area of approximately 171 km² with 9.5 km² and 17.5 km² of that being forested area. The reserve contains about 56% of the Tana River mangabey groups, with approximately 44% living in forests outside of the reserve. 10% of the groups living in forests outside of the reserve are under the management of the Tana Delta Irrigation Project.

The objective of the Tana River Primate Reserve was to conserve the biodiversity within the Tana River area and protect the endangered Tana River mangabey. The conservation of this species is a high priority for primate conservation in Kenya. In 2007, the High Court in Kenya ruled the reserve was not abiding by the laws. This led to the forested areas which the mangabey inhabited losing their legal protection. [19] With the poor management of the Tana Delta Irrigation Project, habitat loss outside the reserve also continues. The Tana and Athi Rivers Development Authority, who is in charge of the project, are now in the process of expanding to establish a sugar cane plantation which will in turn remove more forested areas.

A five-year project in 1996 with the Kenya Wildlife Service and Kenya Forest Department was funded by the World Bank/GEF. The projects goals were to enhance conservation and protection of these primates and forests. The project was poorly managed and was terminated after two years of implementation, leaving the wildlife service with the protection of these areas.

The Ishaqbin Conservancy is a community initiative in the Tana River Primate Reserve. Here communities are working with Kenya Wildlife Service to develop tourism side by side with conservation. Tourism development is believed to be important in that it will secure the conservation of the habitat and the species with the communities around the reserve. Tourism will benefit both the mangabey and local communities through economic development and a reduction in habitat loss. The conservancy will also help to form a buffer around the reserve which will help to reduce human impact inside the reserve. [20]

Related Research Articles

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, macaques, and mabahlls. 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 55 million years ago.

Zanzibar red colobus Species of Old World monkey

The Zanzibar red colobus is a species of red colobus monkey endemic to Unguja, the main island of the Zanzibar Archipelago, off the coast of Tanzania. It is also known as Kirk's red colobus after Sir John Kirk, the British Resident of Zanzibar who first brought it to the attention of zoological science. It is now classified as an endangered species and in the mid-1990s was adopted as the flagship species for conservation in Zanzibar. The population is still decreasing, and conservationists are attempting to work with the local government to devise a proper, effective strategy to protect the population and habitat. Challenges include the species' habitat, which is limited to the archipelago. The species has been reclassified three times; it was previously in the genus Colobus, then in the genus Procolobus, and later in the genus Piliocolobus.

Kipunji Species of Old World monkey

The kipunji, also known as the highland mangabey, is a species of Old World monkey that lives in the highland forests of Tanzania. The kipunji has a unique call, described as a 'honk-bark', which distinguishes it from its relatives, the grey-cheeked mangabey and the black crested mangabey, whose calls are described as 'whoop-gobbles'.

Sooty mangabey Species of mammal

The sooty mangabey is an Old World monkey found in forests from Senegal in a margin along the coast down to the Ivory Coast.

Mantled guereza Species of mammal

The mantled guereza, also known simply as the guereza, the eastern black-and-white colobus, or the Abyssinian black-and-white colobus, is a black-and-white colobus, a type of Old World monkey. It is native to much of west central and east Africa, including Cameroon, Equatorial Guinea, Nigeria, Ethiopia, Kenya, Tanzania, Uganda and Chad. The species consists of several subspecies that differ in appearance. It has a distinctive appearance, which is alluded to in its name; the long white fringes of hair that run along each side of its black trunk are known as a mantle. Its face is framed with white hair and it has a large white tail tuft.

Red colobus Genus of Old World monkeys

Red colobuses are Old World monkeys of the genus Piliocolobus. It was formerly considered a subgenus within the genus Procolobus, which is now restricted to the olive colobus. They are closely related to the black-and-white colobus monkeys, and some species are often found in groups with the blue monkey. The western red colobus is frequently hunted by the common chimpanzee.

White-eyelid mangabey Genus of Old World monkeys

The white-eyelid mangabeys are African Old World monkeys belonging to the genus Cercocebus. They are characterized by their bare upper eyelids, which are lighter than their facial skin colouring, and the uniformly coloured hairs of the fur. The other two genera of mangabeys, Lophocebus and Rungwecebus, were once thought to be very closely related to Cercocebus, so much so that all the species were placed in one genus. However, it is now understood that Lophocebus and Rungwecebus species are more closely related to the baboons in genus Papio, while the Cercocebus species are more closely related to the mandrill.

Black colobus Species of Old World monkey

The black colobus, or satanic black colobus, is a species of Old World monkey belonging to the genus Colobus. The species is found in a small area of western central Africa. Black colobuses are large, completely covered with black fur, and like all other Colobus monkeys, do not have a thumb. The species has faced large declines in population due to habitat destruction and hunting by humans, and was consequently listed as Vulnerable on the IUCN Red List in 1994.

Collared mangabey Species of Old World monkey

The collared mangabey, also known as the red-capped mangabey, or the white-collared mangabey, is a species of primate in the family Cercopithecidae of Old World monkeys. It formerly included the sooty mangabey as a subspecies. As presently defined, the collared mangabey is monotypic.

The Tana River red colobus, also called the eastern red colobus, is a highly endangered species of primate in the family Cercopithecidae. It is endemic to a narrow zone of gallery forest near the Tana River in southeastern Kenya.

The Tana River Primate National Reserve is a former 170 square kilometres (66 sq mi) national wildlife reserve in south-eastern Kenya. It existed from 1976 to 2007.

Ugandan red colobus Species of Old World monkey

The Ugandan red colobus or ashy red colobus is an endangered species of red colobus monkey, recognised as a distinct species since 2001. There is disagreement however over taxonomy with many considering the Ugandan red colobus to be a subspecies. The Ugandan red colobus is an Old World monkey which is found in 5 different locations across Uganda and Tanzania.

Agile mangabey Species of Old World monkey

The agile mangabey is an Old World monkey of the white-eyelid mangabey group found in swampy forests of Central Africa in Equatorial Guinea, Cameroon, Gabon, Central African Republic, Republic of Congo, and DR Congo. Until 1978, it was considered a subspecies of the Tana River mangabey. More recently, the golden-bellied mangabey has been considered a separate species instead of a subspecies of the agile mangabey.

Sanje mangabey Species of Old World monkey

The Sanje mangabey is a highly endangered Old World monkey of the white-eyelid mangabey group from the Eastern Arc Mountains in Tanzania. They are about 50–65 centimetres (20–26 in) in length, excluding the tail, and their body colour is greyish. Fruit makes up about 70% of their diet. They live in valley forests and on mountain slopes, but are mostly ground-dwelling, which makes them susceptible to hunting and poaching. Their habitat is being degraded, and the International Union for Conservation of Nature has assessed their conservation status as being "endangered".

Niger Delta red colobus Species of Old World monkey

The Niger Delta red colobus is a critically endangered species of colobus monkey endemic to the western part of the Niger Delta. It is threatened by hunting and habitat loss.

Edumanom Forest Reserve Forest reserve in Bayelsa State, Nigeria

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Tana River Delta Ramsar Site

The Tana River Delta Ramsar Site is a wetland on the Tana River protected under the Ramsar Convention located in the Coast Province of Kenya. It was gazetted as Kenya's 6th Ramsar Site.

Eastern Congolian swamp forests

The Eastern Congolian swamp forests are a fairly intact but underresearched ecoregion of the tropical and subtropical moist broadleaf forests biome. It is located within the Democratic Republic of the Congo. This is the eastern half of one of the largest areas of swamps in the world.

Crowned eagle

The crowned eagle, also known as the African crowned eagle or the crowned hawk-eagle is a large bird of prey found in sub-Saharan Africa; in Southern Africa it is restricted to eastern areas. Its preferred habitats are principally riparian woodlands and various forests. The crowned eagle is the only extant member of the genus Stephanoaetus. A second species, the Malagasy crowned eagle became extinct after humans settled on Madagascar.


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