Cercopithecus erythrogaster

Geographic Distribution and Habitat

Red-bellied monkeys, also known as red-bellied guenons, white-throated monkeys, and white-throated guenons, are endemic to southwestern Nigeria, the Nigerian Delta, southern Benin, and Togo. They live in fragmented forest patches of primary, secondary, and riverine lowland moist forests, or in semi-deciduous or swamp forests. 

These primates often share territory with mona monkeysspot-nosed monkeysred-capped mangabeys, Niger Delta red colobuses, and white-thighed colobuses.

Red-bellied monkey range, IUCN 2020

Size, Weight, and Lifespan

Male red-bellied monkeys are larger than females. They weigh 10 pounds (4.5 kg) on average while females weigh about 4.4 pounds (2 kg). Their body is approximately 18 inches (46 cm) long; their tail is longer than their body and measures between 21 and 27 inches (55–70 cm).

Longevity in the wild is not documented, but they are known to live up to 24 years in captivity.


Beautiful and slender, red-bellied monkeys’ dense gray pelage is highlighted by a rust-red patch of fur on the belly that makes them easy to identify. Thick white hair around their neck resembles the ruffled lace collars of Renaissance noblemen—hence, their common names of red-bellied or white-throated monkeys. The crown of their head appears pointed, as do their ears.

Their narrow mouth protrudes outward. Like all guenons, they have cheek pouches in which to store food as they forage. Their flat nose has slanted nostrils. Their light brown eyes are round. Their hands and feet have five digits with opposable thumbs and toes. Their thighs are very muscular.

Photo credit: © agboola-iNaturalist/Creative Commons

Red-bellied monkeys are primarily frugivores, but their diet also includes leaves and insects. In the Lama forest of Benin, these monkeys fill themselves on ripe fruit and seem to especially enjoy the taste of the velvet tamarind and guava fruit. They also feed from a large number of evergreen shrubs and trees. During the dry season, they consume unripe fruit of various species, but favor fruit from the cotton tree, which not only provides them with food but also water. Their habitat can change drastically from one season to the next—for instance in the Oueme valley of south Benin, the land is submerged by several feet of water during the rainy season, which happens twice a year: April–July and August–September. So, when food is scarce, they occasionally raid crops.

Behavior and Lifestyle

Red-bellied monkeys are diurnal, which means that they are active during daylight hours. They live in fragmented groups in the lower levels of the canopy and, because they are rather shy, it is not easy to observe them in the wild. They travel by walking or running quadrupedally on their hands and feet, or by leaping.

Daily Life and Group Dynamics 

Depending on the location, group sizes traditionally vary from 5 to 10 individuals in Benin and 10 to 20 in Nigeria. These groups are usually composed of one single male and females with their offspring. A few males live by themselves and only join females during the mating season. With recent increasing pressure on the species’ population, groups now tend to be smaller at an average of 5 or 6 individuals, no matter the location. Members of a group maintain close relationships with each other but tend to avoid interacting with members of other groups.


There are many ways primates communicate with each other. Red-bellied monkeys use physical postures to indicate their feelings. Staring with an open mouth and head bobbing, for instance, are used to convey warnings to outsiders.

Grooming is a way to maintain good relations with members of the group while, at the same time, ridding them of parasites and cleaning their fur.

Vocalizations are used to convey different messages in different circumstances. It is probable that, like most other primate species, they use alarm calls that are specific to different predators.

Reproduction and Family

Red-bellied monkeys become mature at four years of age. They are polygynous, which means that one male can mate with several females. Females give birth to a single infant after a gestation of about 6 months.

The babies cling to their mother’s belly and feed from her. However they grow quickly and at two months of age they can be introduced to solid food.

Photo credit: © ONG ODDB-iNaturalist/Creative Commons
Ecological Role

As fruit and leaf eaters, it is probable these animals play an important role as seed dispersers and possibly pollinators.

Conservation Status and Threats

The International Union for Conservation of Nature lists red-bellied monkeys as Endangered (IUCN, 2016) appearing on the IUCN’s Red List of Threatened Species. Their overall population has declined by 50% since the 1990s. Unprecedented human population growth as well as forest clearing for agricultural use or timber exploitation are the major contributing factors. Primary forest cover has decreased by almost 25% in Benin and by 80% in Togo over the last 30 years. The Niger Delta has been losing large surfaces of lowland rainforest, freshwater forest, and mangrove over the same period of time. Large scale infrastructure projects such as the development of the Adjarala storage hydropower plant on the Mono River are also threatening the Togodo Forest in Togo.  

Red-bellied monkey populations are shrinking due to habitat loss but also because the number of larger monkeys is decreasing and hunters default to hunting smaller primates for food. Red-bellied monkeys originally extended from the valley of the Couffo river in Southern Benin to the Nigerian border, but today they are only found in sacred groves, small swamp forests, and humid forest relics, of which Lama forest is the largest. The monkeys are also captured and killed inadvertently by snares farmers place close to their fields to protect their crops. Their meat is sold for food and their body parts for use in traditional rituals. Law enforcement against poaching is weak due to corruption, as well as lack of funds and staffing. Few local taboos have stopped hunters from targeting red-bellied monkeys. Only one may be acting as a deterrent to killing or eating monkeys—i.e., the belief that doing so could bring ill fate to families with twins. Incidentally, Benin has the highest number of twin births in the world.

Conservation Efforts

The red-bellied monkey is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES) and on Class A of the African Convention of Nature and Natural Resources.

Populations of red-bellied monkeys live in protected parks: Togodo Fauna Reserve and Godjin-Godjè sacred forest in Togo; Okomu National park in Nigeria; as well as Lokoli forest, Togbota Forest, and Lama Forest in Benin. As a matter of fact, the red-bellied monkey is the flagship species of the Lama forest, which is the largest contiguous dense natural and plantation forest in Southern Benin and has been identified as an important biodiversity hotspot. Teak plantations in the region can provide suitable habitat for these monkeys and other animals. They can also be used as corridors by many species, especially during the dry season when they need to migrate to more humid areas.

Urgent conservation action and regulations are needed in the countries where red-bellied monkeys are found. For instance, in Benin, there is no regulation clearly defining a protected forest; instead it can simply be declared as “sacred,” so forest protection is challenging. Local authorities and conservation organizations must collaborate to curb down illegal logging, deforestation, and hunting. Some projects are being implemented. A good example can be found in the Sitatunga Valley Community Nature Reserve in South Benin, where 25 acres (10 hectares) of fuelwood trees were planted to avoid illegal logging. Beekeeping is also being promoted to provide alternative source of income to the population.

  • IUCN Red List
  • – Distribution spatiale du singe à ventre rouge, Cercopithecus erythrogaster erythrogaster Gray et les menaces pesant sur sa conservation durable au Togo – K.G. Eric Agbessi, Moumouni Ouedraogo, Mouhameth Camara, Hoinsoudé Segniagbeto, Mariano B Houngbegji et André T. Kabre.  (2017)
  • Conservation Status of the Red-bellied Guenon (Cercopithecus erythrogaster erythrogaster) in the Western Dahomey Gap in Southwestern Benin and the Adjacent Togodo Forest Reserve, South Togo – M.G. Houngbédji, B.A.Djossa, A.C. Adomou, S.C.Dakpogan, B. Sinsin & kG. A. Mensah (2012) 
  • Diversité floristique des ressources alimentaires du singe à ventre rouge (Cercopithecus erythrogaster erythrogaster) dans les formations végétales de Togbota au Sud-Bénin – Ghislain O. Zoffoun, Georges Nobime, Sêdami Ajahossou et Gaudence Djego. (2018)
  • In Search of Rare Forest Primates in Nigeria – John F. Oates
  • Conservation of biodiversity in a relic forest in Benin – an Overview – Peter Nagel, Brice Sinsin, and Rafl Peveling
  • – Treeds and Bees Helping Red-Bellied Monkey Population in the Sitatunga Valley Community Nature Reserve (Benin)

Written by Sylvie Abrams, September 2021