L'Hoest's monkeys live in groups consisting of a single male and 10 to 17 females and young, which form close bonds reinforced by mutual grooming. L'Hoest's monkeys have a more terrestrial lifestyle than many other monkeys, always travelling on the ground, and, unusually for primates, running to flee from predators such as crowned hawk-eagles (2) (4), a strategy that requires great collective coordination in order to keep together as a group. To feed and to sleep, the L'Hoest's monkeys will scale forest heights where they feed on the fruits of yellow wood, koso, parasol trees, wild custard apple, and the young leaves and shoots of various trees, shrubs and herbs. They also consume invertebrates (5), occasionally eat resins, bracken shoots, mushrooms and lichen (2), and have been seen carefully cleaning dirty dormant seeds that they have extracted from the soil (6). When sleeping, L'Hoest's monkeys frequent favourite tree spots, where they sleep as a group, out of reach of many predators. Newborn L'Hoest's monkeys are brown and acquire adult colours over the first two to three months. The young are frequently observed entwining their tail with their mother's (2).

One of Africa's most attractive primates, the L'Hoest's monkey possesses a brilliant white ruff that frames its delicate black face. Its second most distinctive feature is the deep-set, orange eyes, surrounded by bare skin that is pale violet in adult males. The body and long legs are black with grizzled grey, except for a chestnut coloured 'saddle'. The long tail is thick at the base and tapers to a black brush. Fully grown males can be twice the weight of females and have a conspicuous bright blue scrotum (2).

This species ranges from the eastern Democratic Republic of Congo, east of the Lualaba River through the Ituri Forest, Rwanda and western Uganda (south-west Kigezi District and the Ruwenzori Mountains), and south to the Itombwe Massif. The southern limits are poorly defined. Isolated populations occur east of the main block of the range, and include Kibale Forest National Park, Kalinzu Forest Reserve, Ruwenzori Mountains National Park, Maramagambo Forest Reserve and Bwindi Impenetrable National Park (Uganda), Nyungwe National Park (Rwanda), Virunga and Kahuzi-Biega National Park uplands (DRC), and Kibira National Park (Burundi; Barakabuye et al. 2007). Recently also recorded from Kahuzi-Biega lowlands (DR Congo) (J. Hall pers. comm.). This species is strongly sympatric with C. hamlyni, especially west of the Albertine Rift. It is found up to 2,900 m asl.

L’Hoest’s monkeys (Cercopithecus lhoesti) are found in montane forests of the Albertine Rift, including southwestern Uganda, Rwanda, Burundi, and Democratic Republic of the Congo.

Biogeographic Regions: ethiopian (Native )

Historic Range:
Upper eastern Congo R. Basin, Cameroon

Occurs in the Democratic Republic of Congo, western Uganda, Rwanda and Burundi (2).

L’Hoest’s monkeys are large, strikingly patterned monkeys with long limbs and a long tail. Females weigh approximately 3.5 kg, while males weigh approximately 6 kg. They are usually 31.7 to 68.6 cm in length, and tail length ranges from 48.3 to 99.1 cm. L'Hoest's monkeys are mostly covered in short dark gray fur, and they have a large chestnut saddle pattern on their back. There is also a distinctive large, conspicuous patch of white fluffy fur from the throat across the sides of the head almost to the ears. Their limbs and belly are black. Their face is mostly dark, with paler pinkish-white areas around the eyes and nose. Their long tail is medium gray, blacker near the tip, and is often held so the tip bends forward. Their eyes are bright orange. In males, the scrotum is bright blue in color, but otherwise both sexes are similar in coloration. L'Hoest's monkeys have narrow feet which aide running on the ground. They also have cheek pouches, used to carry food while foraging.

Range mass: 3.5 to 6 kg.

Range length: 31.7 to 68.6 cm.

Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful

Habitat and Ecology

Systems

• Terrestrial

L'Hoest's monkeys reside in montane tropical rainforests, including both primary and secondary forests. In secondary forests, they occupy the thick underbrush that grows where trees have fallen. L'Hoest's monkeys can be found at altitudes ranging from 900 to 2,500 m. The species is typically more terrestrial than other guenons.

Range elevation: 900 to 2500 m.

Habitat Regions: tropical

Terrestrial Biomes: forest ; rainforest ; mountains

L'Hoest's monkey inhabits forest up to altitudes of 2,500 metres (2).

The diet of L'Hoest's monkeys consists mainly of fruits, leaves, and invertebrates. Invertebrates typically constitute a little less than half of the diet, while fruits and plant materials make up over 50%. However, in some locations, the dietary percentage of invertebrates is as low as 9%. L’Hoest’s monkeys usually forage for mushrooms, terrestrial herbs, and arthropods in the lower strata of the forest and search the upper strata for small fruits, buds, flowers, young leaves (which have more protein than mature leaves), and herbaceous stems. They often look for arthropods in shallow streams, fallen leaves, trunks, and branches of the forests. L'Hoest's monkeys favor fruits of Myrianthus arboreus, Polycias fulva, Musanga leo-errerae, and Ficus spp. Some invertebrates in their diet include insects, earthworms, spiders, ants, and grasshoppers. L'Hoest's monkeys also have cheek pouches, in which they carry food while foraging.

Animal Foods: insects; terrestrial non-insect arthropods

Plant Foods: leaves; wood, bark, or stems; fruit; flowers

Other Foods: fungus

Primary Diet: carnivore (Eats non-insect arthropods); herbivore (Folivore , Frugivore , Lignivore); omnivore

Due to their semi-frugivorous diet, L’Hoest’s monkeys play a role in seed dispersal. Members of this species are known to host two types of gastrointestinal worm parasites, Strongyloides fulleborni and a species of Trichurus.

Ecosystem Impact: disperses seeds

Commensal/Parasitic Species:

• Strongyloides fulleborni
• Trichuris sp.

Predation of L'Hoest's monkeys by common chimpanzees has been observed in the Kahuzi forests in the Democratic Republic of Congo. Additionally, crowned hawk-eagles prey on guenons, including L'Hoest's monkeys. To escape eagles, they flee on the ground, which is uncharacteristic of primates. L'Hoest's monkeys are also hunted by humans for bushmeat.

Known Predators:

• Common chimpanzee Pan troglodytes
• Crowned hawk-eagle Stephanoaetus coronatus
• Humans Homo sapeins

L'Hoest's monkeys occassionally flee from predators while on the ground, which necessitates coordination, though the manner of this coordination is unknown. When females are ready to mate, they direct their hindquarters toward a male, know as presenting. L'Hoest's monkeys also utilize a variety of behaviors as a threat display. Staring involves fixing the eyes on a subject, raising the eyebrows, stretching the facial skin, and moving the ears back. Often, they open their mouth but do not display their teeth. Additionally, they may engage in head-bobbing, which often occurs with staring with an open mouth, and is also a threat display.

Communication Channels: visual ; tactile

Perception Channels: visual

The lifespan of L'Hoest's monkeys in the wild is currently unknown. One captive specimen lived to be 24.1 years of age.

Range lifespan

Status: captivity: 24.1 (high) years.

Maximum longevity: 24.1 years (captivity) Observations: One captive specimen lived 24.1 years (Richard Weigl 2005).

L'Hoest's monkeys are polygynous. A single male lives and mates with many females. When males have reached sexual maturity they leave the group. When females are ready to mate, they direct their hindquarters toward a male, know as presenting.

Mating System: polygynous

Female L’Hoest's monkeys usually give birth every other year at the end of the dry season. On average, females L'Hoest's monkeys produce a single offspring after 5 months of gestation. Infants are born with their eyes open and fully covered in brown fur. Their fur darkens to adult coloration around 2 to 3 months of age. Young L'Hoest's monkeys nurse until mothers birth another offspring, but frequency of nursing considerably decreases after the first few months. On average, weaning occurs around 1 year of age. When males reach sexual maturity, they leave the group.

Breeding interval: L'Hoest's monkeys usually breed every other year.

Average number of offspring: 1.

Average gestation period: 5 months.

Average weaning age: 24 months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); induced ovulation ; fertilization ; viviparous

After birth, a baby L'Hoest's monkey clings to its mother's belly while she licks it clean. Females in the group try to hold new infants. Because social groups are composed of related females and young, parental care likely occurs. Young L'Hoest's monkeys often entwine their tail with their mother's.

Parental Investment: female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); post-independence association with parents

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Species: 1
Species With Barcodes: 1

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

L'Hoest's monkeys are considered vulnerable by the ICUN Red List and endangered by the US Federal List. Populations are decreasing because of deforestation due to agricultural expansion as well as hunting. L'Hoest's monkeys were at one point listed in Appendix II by The Convention on International Trade in Endangered Species (CITES), which means international trade of this species is monitored. However, hunting of this species for bushmeat still occurs. L'Hoest's monkeys are most vulnerable to snares and shotgun hunting.

US Federal List: endangered

CITES: appendix ii

IUCN Red List of Threatened Species: vulnerable

Current Listing Status Summary

Status: Endangered
Date Listed: 10/19/1976
Lead Region: Foreign (Region 10) 
Where Listed:


Population detail:

Population location: entire
Listing status: E

For most current information and documents related to the conservation status and management of Cercopithecus lhoesti , see its USFWS Species Profile

Classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

Population

Population Trend

Major Threats

L'Hoest's monkey is a relatively little-known primate and so populations could be more threatened than is currently thought (6). Habitat loss, due to agriculture, mining and wood extraction (1), combined with hunting for bushmeat, is probably reducing population numbers in many areas (2). Even populations in protected areas are not safe from these threats; large-scale logging is known to have threatened this species in Kibale Forest, Uganda (2), and within Bwindi Impenetrable National Park, poaching, logging and the extraction of gold and charcoal occurs (7).

Conservation Actions

The Convention on International Trade in Endangered Species (CITES) lists L'Hoest's monkey on Appendix II, meaning that any international trade in this species should be carefully monitored (3), but this does little to control hunting for bushmeat. While this species does occur in some protected areas, such as Bwindi Impenetrable National Park (7), these populations still face threats, as mentioned above. While its large distribution and largely inaccessible forest habitat protects the species' short-term survival, the long-term prospects for the handsome L'Hoest's monkey are not so secure (2).

L'Hoest's monkeys are occasionally infected with Simian Immunodeficiency Virus, or SIV. When transmitted to humans, this virus becomes HIV.

Negative Impacts: injures humans (carries human disease)

L'Hoest's monkeys are hunted for bushmeat.

Positive Impacts: food