Western red colobus  (Procolobus badius)

The western red colobus is classified as Endangered (EN) on the IUCN Red List (1) and is listed on Appendix II of CITES (3). Three subspecies are currently recognised on the IUCN Red List: the bay colobus (Procolobus badius badius) and Temminck’s red colobus (Procolobus badius temminckii) are both classified as Endangered (EN), while Miss Waldron’s red colobus (Procolobus badius waldroni) is classified as Critically Endangered (CR) (1).

The western red colobus (Procolobus badius) is an attractive monkey which, like other colobus species, has just a bump in place of the thumb; indeed, ‘colobus’ means ‘docked’ in Greek, although the other fingers of these monkeys are particularly long. The western red colobus differs from other colobus species in having fur of even length over the whole body, with no tufts of longer fur. Whilst the subspecies differ in size and colouration, they are mainly black, grey or brown above with red or chestnut arms, legs and head (2).

Around the pubic area of this species the fur is white, and juveniles of both sexes have female-like genital swellings, possibly to prevent mature males evicting young males before they have matured (4). The western red colobus does not have cheek pouches (5).

The taxonomy of the western red colobus, like that of other red colobus species, is currently under debate, with some scientists placing it in the genus Procolobus while others place it in Piliocolobus (1) (6). Further evidence is required to resolve this issue (1).

The western red colobus occurs in West Africa, where the subspecies are confined to certain areas, many of which overlap. Miss Waldron’s red colobus (P. b. waldroni) was found in Côte d’Ivoire and Ghana but has not been seen alive since 1978 (1). However, recent evidence of a tail, a skin and a photograph suggest that a handful of individuals have remained undetected to this point in the extreme southeast of Ivory Coast (1) (7).

The bay colobus (P. b. badius) is found in the western Ivory Coast, Liberia and Sierra Leone (6). Temminck’s red colobus (P. b. temminckii) is found in Gambia, northern Guinea, Guinea-Bissau and southern Senegal (1) (6).

The western red colobus is found in tropical and gallery rainforests in all levels of the canopy (4).

The western red colobus forms large polyandrous groups of between 12 and 80 individuals (6). A diurnal species, it spends the day moving through the top of the canopy looking for leaves, shoots, fruits, and fungi. It has a complex stomach divided into sacs, as an adaptation to its diet. In the upper chamber of the stomach, foliage is fermented by bacteria, and once in the lower chamber it can be digested by acid. The stomach is particularly large so that it can take the large quantities of this low value food that are needed to provide the western red colobus with the necessary energy and nutrients to survive. More than a quarter of the body weight of an adult red colobus can be attributed to the food in its stomach (5).

Although not territorial, larger groups of western red colobus tend to have dominance over smaller groups when interactions occur. Mixed-sex groups contain more females than males, leaving bachelor groups of between 8 and 40 males. When ready to mate, females develop swollen genitals and will present to males to encourage mating. Each female may mate with many males, producing just one offspring every two years. Infanticide (the killing of infants) can occur, but the reasons for this are not fully understood. Once weaned, both male and female western red colobus will leave the group, but females will join another mixed-sex group, whereas males may join a bachelor group. A social monkey, the western red colobus conforms to a hierarchy, crouching to communicate submission, which may lead to ‘social’ mounting, not to mate, but as a prelude to social grooming (4).

One of the main causes of the decline in the western red colobus is hunting, especially in the eastern parts of its range. This species has been heavily impacted by both subsistence and commercial hunting, with the bay colobus (P. b. badius) and Miss Waldron’s red colobus (P. b. waldroni) particularly at risk (1). Hunting pressure is believed to have caused the possible extinction of Miss Waldron’s red colobus (8).

Compounding this threat is the loss of huge tracts of forest due to logging, charcoal production, and clearance for agriculture and plantations. Logging roads also open up forest interiors, improving access for hunters and so increasing hunting pressure on the western red colobus (1). Civil conflicts in much of the region inhabited by this monkey may also have had an impact on its populations, although the extent to which it may have been affected is not yet clear (1).

The western red colobus is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that any international trade in this species should be carefully regulated (3). It is also listed as a Class B species under the African Convention on the Conservation of Nature and Natural Resources, which means it should only be legally captured or killed with special authorisation (9). The western red colobus occurs in a number of protected areas throughout its range (1).

After surveys in the late 1990s, Miss Waldron’s red colobus (P. b. waldroni) was declared extinct in 2000, becoming the first primate to go extinct in the 20th century (8). However, more recent evidence from the forests of south-eastern Côte d’Ivoire suggest that a few individuals of this subspecies may remain (1) (7), although they may not represent a population that is viable in the long term (1). A priority for the conservation of the western red colobus is to undertake further survey work in this region to determine whether this highly endangered subspecies still survives in the wild (1).

View information on this species at the UNEP World Conservation Monitoring Centre.

Learn more about efforts to conserve endangered primates such as the western red colobus:

• IUCN/SSC Primate Specialist Group:
  http://www.primate-sg.org/pc.htm

More information on the western red colobus:

• BBC Wildlife Finder - Western red colobus:
  http://www.bbc.co.uk/nature/species/Western_Red_Colobus