Cercopithecus lhoesti
L'hoest's monkey

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. (Tolo, et al., 2008)

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. (Tolo, et al., 2008; "L’Hoest’s monkey (Cercopithecus lhoesti)", 2007)

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. ("Oregon Zoo Animals", 2005; Flannery, 2007)

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. ("BBC Science & Nature: Animals", 2008; Flannery, 2007; "L’Hoest’s monkey (Cercopithecus lhoesti)", 2007)

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. ("BBC Science & Nature: Animals", 2008; "Oregon Zoo Animals", 2005)

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. ("BBC Science & Nature: Animals", 2008; "L’Hoest’s monkey (Cercopithecus lhoesti)", 2007)

The lifespan of L'Hoest's monkeys in the wild is currently unknown. One captive specimen lived to be 24.1 years of age. (de Magalhaes and Costa, 2009)

L’Hoest’s monkeys live in groups with a single male and 10 to 17 females or young, most of which are related. They forage and sleep as a group in trees, and also participate in mutual grooming, which solidifies close bonds within the group. They rarely associate with other guenons. L’Hoest’s monkeys are diurnal and are more terrestrial than most other guenons. They travel on the ground and, unusual for primates, may also flee from predators while on the ground. ("BBC Science & Nature: Animals", 2008; Flannery, 2007; "L’Hoest’s monkey (Cercopithecus lhoesti)", 2007)

Little information is available regarding the home range of L'Hoest's monkeys.

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. (Flannery, 2007; "L’Hoest’s monkey (Cercopithecus lhoesti)", 2007)

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. (Flannery, 2007; Tolo, et al., 2008)

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. (Basabose and Yamagiwa, 1997; Mitani, et al., 2001; "L’Hoest’s monkey (Cercopithecus lhoesti)", 2007)

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. (Gillespie, et al., 2004)

L'Hoest's monkeys are hunted for bushmeat. ("L’Hoest’s monkey (Cercopithecus lhoesti)", 2007)

L'Hoest's monkeys are occasionally infected with Simian Immunodeficiency Virus, or SIV. When transmitted to humans, this virus becomes HIV. (Beer, et al., 2000; Santiago, et al., 2003)

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. (Hart, et al., 2008; "L’Hoest’s monkey (Cercopithecus lhoesti)", 2007)

L'Hoest's monkeys, Cercopithecus lhoesti, were formerly classifed as a single speices with two other taxa of western Africa, Preuss's Monkey (Cercopithecus preussi) and Sun-tailed Monkey (Cercopithecus solatus). (Tolo, et al., 2008)