At 3,011 m Oku is, after Mount Cameroon, the highest mountain in West Africa. The site, also known as Kilum–Ijim, is a proposed Community Forest Reserve, the boundaries of which were largely agreed in 1988 and mostly follow the 2,200 m contour, but come down to 1,600 m at their lowest point. They enclose an area of c.20,000 ha, about half of which is montane forest, now the only extensive area of forest left anywhere in the Bamenda highlands. Important trees throughout include Carapa procera, Schefflera abyssinica, S. mannii and Syzygium guineense bamendae; Podocarpus latifolius is locally dominant at high altitudes and there is extensive Arundinaria bamboo forest above 2,600 m. The canopy of the forest is usually rather open and there are extensive shrubberies of Acanthaceae in the understorey. Habitats also include montane Sporobolus grassland, Gnidia woodland and montane Hypericum–Adenocarpus shrubland together with a few swamps (the main one is Afua at 2,100 m); Lake Oku (at 2,200 m and with a diameter of c.2,000 m) is in a cuvette entirely surrounded by forest. Average annual rainfall is over 2,000 mm. The slopes below the reserve (which were also forested in the past) are now almost entirely under cultivation.
See Box and Table 2 and 3 for key species. Some 170 species have been recorded from the reserve area. The forest holds the last major populations of Tauraco bannermani and Platysteira laticincta. The former is common throughout (to 2,950 m), and may number up to 2,000 pairs. T. bannermani competes with Tauraco persa locally up to 2,250 m.The wattle-eye is common up to 2,600 m and there are perhaps some 1,500 pairs. Several other Afromontane species endemic to the Cameroon–Nigeria chain occur in good numbers, including Andropadus montanus (widespread in open understorey and at edges up to 2,500 m), Bradypterus bangwaensis (widespread to 2,900 m), Ploceus bannermani (common at edges and in open understorey up to 2,900 m). On the other hand, Malaconotus gladiator is very scarce (2,220 m), as the altitude is rather too high for this species. In addition to the other species of global conservation concern, Circus macrourus has been recorded and is perhaps regular. Three species of the Sudan–Guinea Savanna biome (A04) and six of the Guinea–Congo Forests biome (A05) also occur (see Table 3). Up to 800 Tachybaptus ruficollis have been recorded on Lake Oku.
Non-bird biodiversity: Oku is very important for small mammals. The rodent Lamottemys okuensis (EN) represents a species and, indeed a genus, known only from Oku, and a golden mole and three other rodents apparently endemic are Chrysochloris balsaci, Lemniscomys mittendorfi (EN), Hylomyscus grandis and Lophuromys dieterleni. Three other Cameroon endemics, all of limited distribution in the country, also occur: the shrew Myosorex okuensis (VU), squirrel Paraxerus cooperi (VU) (common) and rat Hybomys eisentrauti (EN). Other mammals of note include Galagoides thomasi. Almost all large mammals have been hunted to extinction, although a few Cercopithecus preussi (EN) remain. Amphibians: several species of montane frogs have their centre of distribution in the Bamenda highlands; at least two Phrynobatrachus spp. tape-recorded at Oku appear to be unmatched vocally, but the taxonomy of this genus is confusing. A toad Wolterstoffina chirioi is apparently endemic. Butterflies: Charaxes tectonis and Bicyclus anisops are amongst the Cameroon–Nigerian forest endemics present. Plants: some 10 species new to science, including three trees, have been found recently in the Oku area. Several other plants are known only from Oku and one or two other sites. A checklist of plants, including those of conservation concern, has been prepared by the Royal Botanical Gardens, Kew.
Pressure/threats to key biodiversity
The Kilum–Ijim Forest Project has been operated by BirdLife International since 1987; a major achievement has been to get the local communities to agree on a limit beyond which no more forest is going to be cut down for cultivation. This largely follows the 2,200 m contour and the boundary has been clearly delineated, with some local tree species planted along it. The project now gives technical support to local communities to develop Community Forests, surrounding a Plant Life Sanctuary of about 500 ha around the crater lake. The forest is utilized in various ways, including trapping of small rodents for food and collection of honey from bee-hives; the latter is actively encouraged by the project. People do not hunt Tauraco bannermani as a rule, but the larger Corythaeola cristata was hunted to extinction in the 1980s. One of the main threats remains forest clearance for agriculture, should the community management system, currently being set up, not last. The plateau grasslands are at times grazed by large flocks of sheep and goats with resulting erosion and damage to the forest understorey; fires that get out of control in the dry season can also damage portions of the forest. Dead wood (standing or otherwise) is collected on a large scale for fuel; the gradual disappearance of standing dead trees is likely to affect populations of hole-nesting birds. This represents another major threat to the forest today, and as dead wood is not in sufficient supply live trees are also taken. More than 200,000 people depend on the forest for fuel and at the present rate of utilization the forest has probably no long-term future if an alternative source of fuel cannot be found. Other threats include over-harvesting of particular tree species for specific uses—Prunus africana, Podocarpus, etc.
BirdLife International (2019) Important Bird Areas factsheet: Mount Oku. Downloaded from
http://www.birdlife.org on 15/12/2019.