Dryas monkey

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Dryas monkey [1]
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Family: Cercopithecidae
Genus: Cercopithecus
C. dryas
Binomial name
Cercopithecus dryas
Schwarz, 1932
Cercopithecus dryas distribution.svg
Geographic range of first-known population (a second population is to the southeast, near the edge of the square) [3]
  • Cercopithecus salongoThys van den Audenaerde, 1977

The Dryas monkey (Cercopithecus dryas), also known as Salonga monkey, ekele, or inoko, is a little-known species of guenon found only in the Congo Basin, restricted to the left bank of the Congo River. It is now established that the animals that had been classified as Cercopithecus salongo (the common name being Zaire Diana monkey) were in fact Dryas monkeys. [4] Some older sources treat the Dryas monkey as a subspecies of the Diana monkey and classify it as C. diana dryas, but it is geographically isolated from any known Diana monkey population.


While the Dryas monkey had been considered data deficient, evidence suggests it is very rare and its total population possibly numbers fewer than 200 individuals. Consequently, its status was changed to critically endangered in the 2008 IUCN Red List. [5] Along with being listed by the IUCN, this species is also listed on Appendix II of CITES. [5] However, in January 2019 the IUCN status was changed to endangered following the discovery of this species at eight locations in Lomami National Park. [6]

Physical description

An adult male Dryas monkey is characterized by its black muzzle, white whiskers, and short, white facial beard. The dorsal surface of its body, along with the coronal crown, is a grayish chestnut color. This species also has white on the ventral side of its body, tail, the bottom portion of the limbs, and the buttocks. The upper portion of the limbs resembles a similar color to the rest of its body, being a dark-grey/black-brown color. [7]

Adult females and offspring have smaller portions of their bodies that are white in color; the white color is not present around their shoulder areas or their buttocks. Another difference in coloration is present in the upper portion of the arms, which are lighter in color as compared to the males. [7] Body size varies from 40 to 55 cm, with a tail an additional 50–75 cm. Adults weigh between 4 and 7 kg, with marked sexual dimorphism. [8]


This species prefers secondary forest locations. Although secondary forests are said to be preferred, these monkeys may also inhabit lowlands, rivers, or swampy areas of the Congo. [7]

The diet of the Dryas is said to be made up of mostly plant foods, including fruits, young leaves, and flowers. Due to most of these foods being seasonal, this species also consumes small invertebrates, such as insects, as a supplement. [7]


This species is very social, and lives in groups that are either made up of their own species exclusively or within groups of mixed species. Visual and oral communication is very important, whether communicating to other Dryas monkeys or to other species. When living exclusively amongst each other, troops are made up of up to 30 individuals. Troops include many young offspring and females, but only contain one male. When females reproduce, they have only one young, and the gestation period lasts five months. Offspring are fully mature and ready to reproduce themselves after three years of life. The expected lifespan in the wild is 10–15 years, and because currently no Dryas monkeys are in captivity, that lifespan is unknown. [5] Their movement occurs with a gait pattern involving all four limbs (quadrupedal).

As communication is very important to this species, they have a unique way of communicating with one another. An example is staring, which is a display used as a threat. The eyes stay fixed as the eyebrows rise and the scalp is retracted. The facial skin becomes stretched and the ears move back. These movements expose the eyelids, which are a different color and heavily contrasts with their facial color. Staring with open mouth is another threat expression that often goes along with head-bobbing. Head-bobbing, another threat display, is thought to be more aggressive. Presenting behavior is used by females during the mating season, showing males they are ready to mate. [9]


While previously considered a member of the genus Cercopithecus, recent genetic studies indicates that it is instead a basal member of the Chlorocebus clade. [10] [11]


The IUCN estimates only 200 individuals are left, although because the species is rarely spotted, an actual number is not known, leading this species to be listed as critically endangered. Few speculations are given as to why this species has declined so rapidly and is not showing much progress towards making a comeback. Some reasons include: poaching of the species for meat, habitat loss due to logging and other human activity, and the lack of information and knowledge of this species makes them more susceptible to dangers. [5]

The community-managed Kokolopori Reserve in the north-eastern Democratic Republic of the Congo was initially considered a key to its survival and the only conservation efforts for the species. [5] A second population, about 400 km (250 mi) from the first and partially protected by the Lomami National Park, was discovered in 2014. [3] [12] [13]

Related Research Articles

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Vervet monkey Species of Old World monkey

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White-throated guenon Species of Old World monkey

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Preusss monkey Species of Old World monkey

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Grivet Species of Old World monkey

The grivet, also known as African green monkey and savannah monkey, is an Old World monkey with long white tufts of hair along the sides of its face. Some authorities consider this and all of the members of the genus Chlorocebus to be a single species, Cercopithecus aethiops. As here defined, the grivet is restricted to Ethiopia, Sudan, Djibouti, and Eritrea. In the southern part of its range, it comes into contact with the closely related vervet monkey and Bale Mountains vervet. Hybridization between them is possible, and may present a threat to the vulnerable Bale Mountains vervet. Unlike that species, the grivet is common and rated as least concern by the IUCN.

De Brazzas monkey Species of Old World monkey

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LHoests monkey Species of mammal

L'Hoest's monkey or mountain monkey, is a guenon found in the upper eastern Congo basin. They mostly live in mountainous forest areas in small, female-dominated groups. They have a dark coat and can be distinguished by a characteristic white beard.

Wolfs mona monkey Species of Old World monkey

Wolf's mona monkey, also called Wolf's guenon, is a colourful Old World monkey in the family Cercopithecidae. It is found in central Africa, primarily between the Democratic Republic of the Congo and Uganda. It lives in primary and secondary lowland rainforest and swamp forest.

Red-eared guenon Species of Old World monkey

The red-eared guenon, red-eared monkey, or russet-eared guenon is a species of primate in the family Cercopithecidae. It is found in Cameroon, Equatorial Guinea, and Nigeria. Its natural habitat is subtropical or tropical moist lowland forests. It is threatened by habitat loss, illegal bushmeat hunting and pet trade.

Olive colobus Species of Old World monkey

The olive colobus monkey, also known as the green colobus or Van Beneden's colobus, is a species of primate in the family Cercopithecidae. Its English name refers to its dull olive upperparts. It is the smallest example of all colobine monkeys and is rarely observed in its natural habitat because of its cryptic coloration and secretive nature. It is found in the rain forests of West Africa, ranging from southern Sierra Leone to Nigeria. As of 2019, the IUCN Red List classifies the olive colobus as vulnerable, with the cause of its decline attributed to habitat loss and hunting. Though much of the land within the range of the olive colobus has been affected by human activities, it retains its ability to thrive in small degraded forest fragments.

Roloway monkey Species of Old World monkey

The roloway monkey is an endangered species of Old World monkey endemic to tropical West Africa. It was previously considered a subspecies of the Diana monkey. It is classified as Critically Endangered due to habitat loss and continued hunting for the bushmeat trade. The roloway monkeys are mainly arboreal species, for the most part inhabiting forests in Ghana and some reserves in South-Eastern Côte-D'Ivoire. More specifically studies have shown that the C. diana roloway is mostly concentrated in Tanoé forest because of their heavy threats to extinction.

Bale Mountains vervet Species of Old World monkey

The Bale Mountains vervet is a terrestrial Old World monkey endemic to Ethiopia, found in the bamboo forests of the Bale Mountains. All species in Chlorocebus were formerly in the genus Cercopithecus. The Bale Mountains vervet is one of the least-known primates in Africa. They avoid tree-dominated and bushland areas as their habitat. These monkeys mainly reside in the bamboo forest of the Bale Mountains due their dietary specialization on bamboo, but other factors, such as climate, forest history, soil quality, and disease, are likely to play a role in their choice to inhabit this area. The Bale Mountains vervet have a very quiet behavior and tend to flee when encountering a human being. It is also known as the Bale monkey.

Tantalus monkey Species of Old World monkey

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Thollons red colobus Species of Old World monkey

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Lesula Species of Old World monkey

The lesula is a species of Old World monkey in the guenon family, found in the Lomami Basin of the Congo. Though known to locals, it was unknown to the international scientific community until it was discovered in 2007 and confirmed in a 2012 publication. The lesula is the second new species of African monkey to be discovered since 1984. This monkey is described to have human looking eyes and a blue bottom “And adult males have a huge bare patch of skin in the buttocks, testicles and perianal area,” said John A. Hart, the researcher who described the monkey. “It’s a brilliant blue, really pretty spectacular.”

Red-tailed monkey Species of Old World monkey

The red-tailed monkey, also known as the black-cheeked white-nosed monkey, red-tailed guenon, redtail monkey, or Schmidt's guenon is a species of primate in the family Cercopithecidae.

Lomami National Park

Lomami National Park is a national park located in the Democratic Republic of Congo in Central Africa. Situated within the middle basin of the Lomami River, it straddles the Provinces of Tshopo and Maniema with a slight overlap into the forests of the Tshuapa and Lualaba river basins. The National Park was formally declared on 7 July 2016. It is the 9th national park in the country and the first to be created since 1992.


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  2. IUCN (21 January 2019). "Dryas Monkey Cercopithecus dryas". IUCN Red List of Threatened Species . 21 January 2019. Retrieved 7 May 2019.
  3. 1 2 Hart, T. (11 September 2016). "Monkeys of the Lomami National Park". bonoboincongo.com. Retrieved 6 December 2017.
  4. Colyn, M.; Gautier-Hion, A.; Vanden Audenaerde, D. T. (1991). "Cercopithecus dryas Schwarz 1932 and C. salongo Vanden Audenaerde, Thys 1977 are the same species with an age-related coat pattern". Folia Primatologica. 56 (56): 167–170. doi:10.1159/000156543.
  5. 1 2 3 4 5 Hart, J.; Butynski, T.M. & Hurley, M. (2008). "Cercopithecus dryas". IUCN Red List of Threatened Species . 2008: e.T4216A10645463. doi: 10.2305/IUCN.UK.2008.RLTS.T4216A10645463.en . Database entry includes justification for why this species was listed as critically endangered
  6. Hart, Terese (14 April 2019). "Dryas monkey: Critically Endangered? Not anymore". TL2 Project. Retrieved 7 May 2019.
  7. 1 2 3 4 Reiko Goodwin © All the World's Primates(alltheworldsprimates.org) Downloaded 12/8/2011.
  8. Burton,F. 1995. the Multimedia Guide to the Non-human Primates. Prentice-Hall Canada Inc.
  9. Estes, R.D. 1991. The Behavior Guide to African Mammals . University of California Press.
  10. van der Valk, Tom; Gonda, Catalina M; Silegowa, Henri; Almanza, Sandra; Sifuentes-Romero, Itzel; Hart, Terese B; Hart, John A; Detwiler, Kate M; Guschanski, Katerina (1 January 2020). Yoder, Anne (ed.). "The Genome of the Endangered Dryas Monkey Provides New Insights into the Evolutionary History of the Vervets". Molecular Biology and Evolution. 37 (1): 183–194. doi:10.1093/molbev/msz213. ISSN   0737-4038. PMC   6984364 . PMID   31529046.
  11. Alempijevic, Daniel; Boliabo, Ephrem M.; Coates, Kathryn F.; Hart, Terese B.; Hart, John A.; Detwiler, Kate M. "A natural history of Chlorocebus dryas from camera traps in Lomami National Park and its buffer zone, Democratic Republic of the Congo, with notes on the species status of Cercopithecus salongo". American Journal of Primatology. n/a (n/a): e23261. doi:10.1002/ajp.23261. ISSN   1098-2345.
  12. Dasgupta, S. (3 February 2017). "New population of rare Dryas monkey videotaped for the first time". Mongabay. Retrieved 6 December 2017.
  13. "Secretive and colorful dryas monkey isn't as rare as once thought". Mongabay Environmental News. 23 July 2019. Retrieved 14 February 2021.