Black Colobus

The black colobus is a tree-dwelling monkey that lives in small troops of 6 to 15 individuals, including one or more adult male (4). The majority of the diet consists of seeds and unripe fruits, but the black colobus also consumes leaves (6), as all colobus monkeys possess an unusual stomach that enables them to digest leaves more efficiently than other primates (2). The distinct high-pitched roar of the colobus can be heard across the forest as dawn breaks (3), and groups can also be heard calling to each other as they prepare to move or as they arrange their night-time sleeping positions (2).

The Gabon black colobus occurs in a number of protected areas, including Dja and Douala-Edea Reserves in Cameroon, Lopé National Park, Gabon, Monte Alen National Park in Equatorial Guinea, and the Gamba Reserve complex in Gabon (3) (5) (10) (11). The Bioko black colobus population is found entirely within two protected areas on Bioko Island, Pico Basile National Park and the Gran Caldera and Southern Highlands Scientific Reserve. However, these areas may offer little actual protection (5), and the subspecies is reported to have undergone the largest decline of all primates on the island, now being rare outside the Gran Caldera (1) (12). In 1986, the IUCN/SSC Primate Specialist Group compiled an Action Plan for African Primate Conservation in which a number of measures were outlined for the conservation of the black colobus. This plan was revised and the conservation recommendations reviewed in a 1996 publication. Further actions suggested included continued efforts to survey and develop the Dja Reserve and fully protect a core area of the Lopé Reserve. In addition, it was recommended that a management plan was developed for the Gamba Reserve complex, which included measures to reduce the impact of oil exploration occurring in the area (3). Working with local people in Bioko Island to find alternatives to bushmeat is also an urgent priority (7), to ensure the continued survival of the endangered Bioko black colobus.

The black colobus is one of the most threatened primate species in Africa (3). It is a large, heavily built monkey, with a glossy black coat and longer hair around the face and shoulders (2) (4). The hairs on its crown are semi-erect and point forward on the forehead (2). A unique feature of all Colobus monkeys is the reduced thumbs, in fact Colobus means 'docked' in Greek. As they leap through the forest habitat, the vulnerability of the thumb to injury is thought to outweigh the advantages of retention (2). Unlike all other species from the Colobus genus, in which the infant is born with a pure white coat, black colobus infants have brown coats (3).

The black colobus inhabits dense primary rainforest, as well as mature secondary rainforest, montane and swamp forest, and may also occasionally be found in coastal sand dunes and wooded meadows (4) (5).

Occurs in central-western Africa. There are two subspecies of the black colobus. The Gabon, or 'mainland', black colobus (C. s. anthracinus) occurs in Equatorial Guinea, east and south-west Cameroon, and Gabon, as far inland as Lope National Park. It may also occur in west Congo. The Bioko black colobus (C. s. satanas) is found only on Bioko Island, Equatorial Guinea (1) (5).

Classified as Vulnerable (VU) on the IUCN Red List (1). Colobus satanas satanas (Bioko black colobus) is classified as Endangered (EN) and Colobus satanas anthracinus (Gabon black colobus) is classified as Vulnerable (VU) (1).

Numbers of black colobus monkeys are declining, the result of both hunting and habitat destruction (3). The black colobus is a popular target for hunters, and is widely hunted with shotguns or bows and arrows (6). On Bioko Island, where bushmeat is a vital source of protein and cash for the locals, surveys indicate that the black colobus is becoming scarcer and is probably being hunted to dangerously low numbers (7). The black colobus appears to be more sensitive to habitat disturbance than other Colobus species and is rare or absent in forests that have been logged (3). This has resulted in the black colobus disappearing from many areas (8). Even protected areas in which the black colobus occurs are not safe from habitat degradation; for example, the Gamba Reserve complex is being impacted by unsustainable logging, agriculture and oil exploration (3) (9).