L'Hoest's guenon  (Cercopithecus lhoesti)

One of Africa's most attractive primates, the L'Hoest's guenon 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).

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

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

L'Hoest's guenons 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 guenons have a more terrestrial lifestyle than many other guenons, 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 guenons 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). Like many primate species, L'Hoest's guenons often forage with other monkey species, such as blue monkeys and black-and-white colobus monkeys, benefiting from extra eyes and ears to alert them of any predators (6).

When sleeping, L'Hoest's guenons frequent favourite tree spots, where they sleep as a group, out of reach of many predators. Newborn L'Hoest's guenons 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).

L'Hoest's guenon has been assessed as Lower Risk / Near Threatened on the IUCN Red List (1), but it is among the world's least known primates and so populations could be unknowingly facing great threats (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).

The Convention of International Trade in Endangered Species (CITES) lists L'hoest's guenon 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 guenon are not so secure (2).

For further information on L'Hoest's guenon see:

• Kingdon, J. (1997) The Kingdon Field Guide to African Mammals. Academic Press Ltd, London.

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