This EBA comprises the mountains which run south-west to north-east through western Cameroon and adjacent south-eastern Nigeria, and the mountains on the island of Bioko (or Fernando Po; politically part of Equatorial Guinea but lying c.30 km off the coast of Cameroon). These mountains are volcanic in origin, and both Mt Cameroon (at 4,095 m the highest mountain in West Africa) and Pico Basilé (Pico de Santa Isabel) on Bioko are still active.

There are considerable local variations in rainfall within the EBA, with a continuous wet rainy season on the coastal (southern) slopes of Mt Cameroon and the South Massif on Bioko, but progressively drier conditions further inland, which results in major differences in the altitude at which montane forest is found and in the forest type. On Mt Cameroon and the South Massif on Bioko, montane forest is found at relatively low elevations, generally above 800 m, but on the seaward (southern) slopes montane species of tree appear as low as 500 m; this is possibly because the extensive cloud cover and frequent mists caused by the proximity of the sea result in a severe reduction in the temperature (Tye 1986), or because of the exceptionally high rainfall (J. Pérez del Val in litt. 1993). Further inland, on Mt Kupe, montane forest is only found above 1,200 m. On nearby Mt Manenguba, the montane forest has rather a poor development of epiphytes, suggesting that this mountain is drier than Mt Kupe or Mt Cameroon. Further inland still, in the Bamenda-Banso highlands, montane forest is found from 2,000 to 2,950 m, and there is a transition to savanna (or now more usually farmland) at the base, rather than to the lowland rain forest found nearer the coast; the forest resembles the drier type found on Mt Manenguba, and a zone of mixed Podocarpus and bamboo appears above c.2,600 m (Thomas 1986). The Cameroon and Gabon lowlands (EBA 085) overlap geographically with the southern part of the present EBA, but the birds of the lowland EBA are generally found at lower altitudes, although there is some altitudinal overlap.

The monotypic genera Poliolais and Urolais are endemic to this EBA, and the genus Speirops is only found here and on the islands in the Gulf of Guinea (EBAs 082, 083). The restricted-range species present are all found within Afromontane habitats, principally montane forest, although several of them also range into more open areas. Many of the species appear to have wide altitudinal ranges, but this is largely because montane forest is found at different altitudes in different parts of the EBA. A few species range down into lowland forest in parts of their ranges, and several occur at or near sea-level on the seaward slopes of Mt Cameroon and on Bioko's South Massif.

The distributions of the restricted-range species of this EBA are relatively well known (see Stuart 1986), although recent fieldwork has extended the known ranges of several species in the northern part of the EBA (Smith and McNiven 1993) and Nigeria (Ash et al. 1989). Several species are highly localized in range: Batis poensis and Speirops brunneus are endemic to Bioko, and Francolinus camerunensis and Speirops melanocephalus to Mt Cameroon; Telophorus kupeensis is only known from Mt Kupe, where it is found around the transition from lowland to montane forest; Tauraco bannermani and Platysteira laticincta are restricted to montane forests in the Bamenda-Banso highlands; and Apalis bamendae to riverine vegetation at lower altitudes on the Adamawa plateau and the Bamenda-Banso highlands. Kupeornis gilberti has an unusual distribution in the central part of the EBA, being absent from Mt Cameroon and only recorded from the extreme south of the Bamenda-Banso highlands.

Another taxon confined to this EBA, considered by Sibley and Monroe (1990, 1993) to be a full species, is Cameroon Scrub-warbler Bradypterus lopezi, but it is here treated as a form of a more widespread species, Evergreen Forest-warbler B. lopezi, following Dowsett and Forbes-Watson (1993) and is therefore excluded from this analysis.

Forest loss is the main threat to the EBA. This is caused by unsustainable exploitation for timber and firewood, overgrazing, fire damage and agricultural encroachment, and is particularly serious in the Bamenda-Banso highlands (where it is estimated that half of the forest cover was lost between 1965 and 1985), the Obudu plateau and the eastern side of Mt Cameroon (Collar and Stuart 1988). Twelve of the restricted-range species are considered threatened, mainly those with particularly small ranges, or those which occur at low population densities and appear to be restricted to undisturbed forest.

Protected areas which may support some of the restricted-range birds include Cross River and Gashaka/Gumti National Parks in Nigeria (see IUCN 1992b), and several of these species occur in Nta Ali Forest Reserve between the Bakossi range and the Bamenda-Banso highlands (P. Rodewald in litt. 1993). However, most of the important sites in the EBA are not officially protected, including the areas which have their own endemic species: the Bamenda-Banso highlands, Mt Kupe, Mt Cameroon and Bioko. Mt Oku is the largest area of forest remaining in the Bamenda-Banso highlands, and represents the only hope for survival for Tauraco bannermani and Platysteira laticincta (Collar and Stuart 1988). BirdLife International has been running the Kilum-Ijim Mountain Forest Project to conserve the montane forests there for several years (Macleod 1987, Macleod and Parrott 1992, Alpert 1993, Edwards 1993a), and initiated a similar project on Mt Kupe (Bowden and Bowden 1993, Bowden and Andrews 1994) which is now managed by WWF. Mt Cameroon is particularly important because its southern slopes, between Batoke and Isongo, are mainland West Africa's best remaining example of an altitudinal gradient from lowland rain forest to montane forest and grassland (Thomas 1986), and a joint ODA/Cameroon Government project to protect a large section of the mountain has recently been started (L. D. C. Fishpool in litt. 1996). Pico Basilé and the South Massif on Bioko are also important because of their two endemic species, and because the forests on the southern slope of the latter are completely undisturbed from sea-level up to 2,200 m (J. Pérez del Val in litt. 1993). The montane habitats on Bioko remain largely intact, although fire may be a threat (Pérez del Val et al. 1994, Koster and Butynski undated). Other important forests in the EBA are on the Obudu plateau, Rumpi hills, Mt Manenguba, the Bakossi mountains and Mt Nlonako (Collar and Stuart 1988).

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Cameroon mountains. Downloaded from https://datazone.birdlife.org/eba/factsheet/81 on 23/11/2024.