Hamlyn's monkey
Cercopithecus hamlyni Pocock, 1907
The hamlyn's monkey (Cercopithecus hamlyni) is a species in the family Cercopithecidae, order Primates. Recorded adults weigh 3.45 kg to 6.88 kg and live up to 28.5 years. Its IUCN Red List status is Vulnerable.

Quick facts about the hamlyn's monkey
- Weight
- 3.45 kg – 6.88 kgsrc for Weight
- Length
- Not recorded
- Lifespan
- 28.5 yearssrc for Lifespan
- Diet
- Herbivoresrc for Diet
- Longest recorded lifespan
- 28.6 years
- Main food
- Not recorded
- Habitat
- Not recorded
- Young per litter or clutch
- Not recorded
- Active
- By day (diurnal)src for Active
- Lifestyle
- Arborealsrc for Lifestyle
- Conservation status
- Vulnerable (IUCN)src for Conservation status
- Countries on record
- Not recorded
Where does the hamlyn's monkey live?
Not recorded
What is the hamlyn's monkey?
The Hamlyn's monkey (Cercopithecus hamlyni), also known as the owl-faced monkey, is a species of Old World monkey that inhabits the bamboo and primary rainforests of the Congo. This species is exceedingly rare and known only from a few specimens; little is known about it. However these specimens tend to be widely dispersed throughout the eastern part of Congo, from the Epulu River to the Lukuga River and from the Congo River to the Kabale Forest, with one example in northwestern Rwanda. Geographically it corresponds quite closely to another species of monkey, L'Hoest's monkey C. lhoesti. It travels on the ground, and researchers think that it may be awake primarily by night.
Schwarz (1928) grouped this species with C. l'hoesti, while Elliot (1913) noted its distinctive cusp pattern on the third molar, and reassigned it to a separate genus, Rhinostigma. This he believed to be an intermediate between Cercopithecus and Cercocebus. Hamlyn's monkey has one subspecies other than the nominate. In weight, the male is much larger than the female, with the average adult weighing 7 to 10 kg, while females weigh on average 4.5 to 6 kg. It is thought to be a frugivore-folivore in diet. Some published reports indicated that Hamlyn's monkey lives in small groups, of ten members or less, with one male and multiple females, with no data to show them occurring in monogamous groups. The species has been found only in higher elevations, above 900m and up to 4600m. In color it is generally dark gray, with a characteristic white stripe which extends from the root of the nose to the upper lip, giving it an owl-like appearance, hence the name "owl-faced monkey". The name "Hamlyn's monkey" and the scientific epithet "hamlyni" come from the animal dealer who first brought this species to the London Zoo. It has scent glands on its chest with which it marks its territory. Both sexes have bare, blue buttocks, and the mature male has bright red and blue genitals. The juvenile coloration is a yellow-brown coat and a pink face. In captivity it has been known to live for about 33 years. Like others of this genus, it covers a wide area in its daily travels, mostly in a search for food.
From the Wikipedia article “Hamlyn's monkey” (en.wikipedia.org/w/index.php?title=Hamlyn%27s_monkey&oldid=1384356239), by Wikipedia contributors, licensed under CC BY-SA 4.0 (creativecommons.org/licenses/by-sa/4.0). This block is kept separate from our own text.
What does the hamlyn's monkey sound like?
Is the hamlyn's monkey endangered?
The hamlyn's monkey is listed as Vulnerable on the IUCN Red List: it faces a high risk of extinction in the wild.
- LCLeast Concern
- NTNear Threatened
- VUVulnerable
- ENEndangered
- CRCritically Endangered
- EWExtinct in the Wild
- EXExtinct
Category via Wikidata (CC0). Find the full assessment on the IUCN Red List. See all Vulnerable species.
How is the hamlyn's monkey classified?
- kingdomAnimalia
- phylumChordata
- classMammalia
- orderPrimates
- familyCercopithecidae
- genusCercopithecus
- SpeciesCercopithecus hamlyni Pocock, 1907
Synonyms Cercopithecus hamlyni hamlyni, Cercopithecus hamlyni kahuziensis, Cercopithecus leucampyx aurora
Other names and names in other languages (24)
- Hamlyn s monkeyEnglish
- Hamlyn’s monkeyEnglish
- Hamlyn’s monkeyEnglish
- Owl-faced guenonEnglish
- Owl-faced guenonEnglish
- Owl-faced guenonEnglish
- Owl-faced monkeyEnglish
- Owl-faced monkeyEnglish
- غينون هاملينيArabic
- kočkodan HamlynůvCzech
- EulenkopfmeerkatzeGerman
- Cercopiteco de HamlynSpanish
- Cercopiteco del Congo OrientalSpanish
- juovanaamamarakattiFinnish
- Cercopithèque d'HamlynFrench
- Cercopithèque à tete de hibouFrench
- Cercopithèque à tête de hibouFrench
- フクロウグエノンJapanese
- HamlynmarekattNorwegian Bokmål
- UilenkopmeerkatDutch
- koczkodan sowiogłowyPolish
- Macaco-corujaPortuguese
- Совинолицая мартышкаRussian
- Hamlyns markattaSwedish
Relatives of the hamlyn's monkey
Other species in the same genus Cercopithecus.
Lesula
Cercopithecus lomamiensis

Diana monkey
Cercopithecus diana

Blue monkey
Cercopithecus mitis

De Brazza's monkey
Cercopithecus neglectus

Mona monkey
Cercopithecus mona

Red-tailed monkey
Cercopithecus ascanius
CompareHamlyn's monkey vs LesulaHamlyn's monkey vs Diana monkeyHamlyn's monkey vs Blue monkeyHamlyn's monkey vs De Brazza's monkey
Common questions
Answered only where our data holds the answer.
How big is the hamlyn's monkey?
An adult hamlyn's monkey weighs 3.45 kg – 6.88 kg, according to values recorded on Wikidata.
Is the hamlyn's monkey endangered?
The hamlyn's monkey is listed as Vulnerable on the IUCN Red List, meaning it faces a high risk of extinction in the wild.
How long does the hamlyn's monkey live?
The hamlyn's monkey has a recorded lifespan of 28.5 years.
What kind of animal is the hamlyn's monkey?
The hamlyn's monkey (Cercopithecus hamlyni) belongs to the family Cercopithecidae in the order Primates.
Sources and how to cite this page
Data as of 2026-11-11. How this page is put together.
- An amniote life-history database to perform comparative analyses with birds, mammals, and reptiles · CC0 1.0 · E096-269
Myhrvold, N.P., Baldridge, E., Chan, B., Sivam, D., Freeman, D.L. & Ernest, S.K.M. (2015) An amniote life-history database to perform comparative analyses with birds, mammals, and reptiles. Ecology 96: 3109. https://doi.org/10.1890/15-0846R.1. Data: https://doi.org/10.6084/m9.figshare.3563457.v1 - Catalogue of Life eXtended Release · CC BY 4.0 · 2026-10-16 XR
Catalogue of Life (2026). Catalogue of Life eXtended Release, version 2026-10-16 XR. Catalogue of Life Foundation, Amsterdam, Netherlands. https://doi.org/10.48580/dgzlf - Wikimedia Commons · per file (CC0 / public domain / CC BY green, CC BY-SA amber, anything else not displayed) · 2026-11-11
Wikimedia Commons contributors. Wikimedia Commons. https://commons.wikimedia.org (each file credited to its author under its own licence). - EltonTraits 1.0: species-level foraging attributes of the world's birds and mammals · CC0 1.0 · 1.0
Wilman, H., Belmaker, J., Simpson, J., de la Rosa, C., Rivadeneira, M.M. & Jetz, W. (2014) EltonTraits 1.0: Species-level foraging attributes of the world's birds and mammals. Ecology 95: 2027. https://doi.org/10.1890/13-1917.1. Data: https://doi.org/10.6084/m9.figshare.3559887.v1 - Wikidata · CC0 1.0 · 2026-11-11
Wikidata contributors. Wikidata. https://www.wikidata.org (data retrieved via the Wikidata Query Service). - Wikipedia (English) · CC BY-SA 4.0 · 2026-11-11
Wikipedia contributors. Wikipedia, The Free Encyclopedia. https://en.wikipedia.org (text under CC BY-SA 4.0; each block names its article and revision).
Embed a card for this animal on your own site
Copy this code. The card shows the photo with its credit, key facts and a link back to this page.
CreatureData. (2026). Hamlyn's monkey (Cercopithecus hamlyni). Retrieved from https://creaturedata.com/animals/hamlyn-s-monkey
“Hamlyn's monkey (Cercopithecus hamlyni).” CreatureData, 2026, https://creaturedata.com/animals/hamlyn-s-monkey.
@misc{hamlyn_s_monkey_2026,
title = {Hamlyn's monkey (Cercopithecus hamlyni)},
author = {{CreatureData}},
year = {2026},
url = {https://creaturedata.com/animals/hamlyn-s-monkey},
note = {Data as of 2026-11-11}
}