Sites - Important Bird Areas (IBAs)

General characteristics 

This EBA includes the mountains which flank the Albertine Rift Valley in the Haut-Zare, Kivu and Shaba regions of eastern Zare, and in south-west Uganda, Rwanda, Burundi and extreme western Tanzania. It consists of a number of mountain ranges which vary considerably in extent and altitude. The highest peak is at 5,110m in the Ruwenzori range, but most of the mountain blocks reach maximum altitudes of between 2,000 and 3,500m.

There are several forest types: transitional forest, intermediate between lowland and true montane forest, is found at about 1,000-1,750m, mainly on the western flanks of the mountains in Zare; montane forest is found from about 1,600m to 3,500m, with bamboo and elfin forest above 2,400m (although bamboo is found as low as 1,600m on the Kungwe-Mahale mountains in Tanzania). Afroalpine moorlands are found above 3,500m, with a variety of ericaceous shrubs and grassland species (Britton 1980, White 1983, Dowsett 1985, Prigogine 1985, Sayer et al. 1992).

The Eastern Zare lowlands (EBA 107) lies immediately to the west of the western flanks of the Albertine Rift mountains. The birds of that EBA tend to occur at lower altitudes, but some range into the transitional forest zone and there is thus some altitudinal overlap between the two EBAs.

Restricted-range species 

The restricted-range species of this EBA include the monotypic endemic genera Pseudocalyptomena, Graueria and Hemitesia. They occur in a variety of Afromontane vegetation types, principally forest, although Bradypterus graueri is confined to highland swamps. Most of them occur in montane forest and range upwards into the bamboo zone, and a few also occur in Afroalpine moorland; Nectarinia stuhlmanni is mainly confined to the bamboo and moorland zones. Six species appear to have been recorded only in transitional forest, which is mainly confined to the western part of the EBA in Zare, although one of them, Glaucidium albertinum, also occurs in Rwanda. These include some poorly known birds which appear to be highly restricted in range: Sylvietta chapini is only known from the Lendu plateau and Chlorocichla prigoginei from the Lendu plateau (see Webb 1994) and the mountains to the west of Lake Edward; the recently described Caprimulgus prigoginei (Louette 1990) is only known from the Itombwe mountains. The montane Phodilus prigoginei has also been recorded definitely only from the Itombwe mountains (Butynski et al. 1997), although it probably occurs in Nyungwe and Kibira (Mt Heha/Ijenda and Teza forests) (J.-P. Vande weghe in litt. 1991). Other montane forest species with particularly restricted distributions are Nectarinia stuhlmanni, which is only known from the Ruwenzori range (but see Dowsett and Dowsett-Lemaire 1993 for a discussion of the unresolved taxonomy and distributions of this and other closely related forms), and Apalis kaboboensis, which is confined to Mt Kabobo. Apalis argentea has an unusual distribution, being found only in the south-eastern part of the EBA.

The form of Prigogine's Double-collared Sunbird Nectarinia prigoginei which is confined to the Marungu highlands in the south of the EBA was considered to be a full species by Collar and Stuart (1985), but is here treated as part of a more widespread species of the same name following Sibley and Monroe (1990, 1993).

Important Bird Areas (IBAs)

Threats and conservation 

The main threat to this EBA is deforestation, mainly as a result of encroachment for agriculture and unregulated timber felling (Howard 1991) which has recently been exacerbated by the effects of warfare (Kanyamibwa 1995), and there is some localized forest loss in Itombwe due to gold-mining (R. Beyers in litt. 1993). Rwanda and Burundi are small, very densely populated countries, and have already lost most of their forest (Dowsett 1985), as has south-west Uganda. Eastern Zare is more sparsely populated, and large areas of undisturbed montane forest still survive, but the transitional forest associated with the lower levels of the montane blocks is threatened because it is relatively accessible to local farmers. For example, the Maboya to Beni region, where Chlorocichla prigoginei is found, is densely populated and the area of transitional forest is shrinking rapidly (Prigogine 1985). Eleven of the restricted-range birds are threatened; these include those which are particularly restricted in distribution or habitat, or are known from just a few records, and are therefore judged to be most vulnerable to forest loss; one further species is classified as Data Deficient.

There are seven protected areas in this EBA (IUCN 1992b), and several forest reserves, but they do not cover all of the most important areas. The mountain ranges with their own endemic species of bird are of particular conservation concern: parts of the Ruwenzori range are included in the Virunga National Park in Zare and in the Mount Ruwenzori National Park in Uganda, but the Itombwe mountains, Lendu plateau and Mt Kabobo currently have no official protection. The Itombwe mountains are particularly important, as they contain the largest block of montane forest in the EBA (estimated to cover c.10,000km²) and support 31 of the restricted-range species; the available evidence suggests that habitat there remains reasonably intact (Collar and Stuart 1988, Wilson and Catsis 1990). The Lendu plateau is now largely deforested, and Djuga forest is perhaps the most important remaining site (see Webb 1994). At Mt Kabobo, montane forest covers no more than 2,000km², but its current status is unknown (Collar and Stuart 1988). The Itombwe mountains, and some other important parts of this EBA such as the Bwindi Impenetrable National Park, Kahuzi-Biega National Park (west of Lake Kivu) and the Virunga National Park, are exceptional in Africa in having an unbroken progression from lowland to montane evergreen forest; they are therefore important for the birds of both this EBA and the Eastern Zare lowlands (EBA 107). The threatened Nyungwe forest in Rwanda (see Dowsett-Lemaire 1990, Dowsett-Lemaire and Dowsett 1990, Gibson 1992), which has been proposed as a protected area but is not yet gazetted, and the adjacent Kibira National Park, are important for the conservation of Apalis argentea and many of the other restricted-range species. Another important area for A. argentea in the Kungwe-Mahale mountains in western Tanzania is included in Mahali National Park. Bwindi Impenetrable, Virunga and the Mgahinga Gorilla National Parks support most of the world population of mountain gorilla Gorilla gorilla berengei (Lee et al. 1988, I.S. Francis in litt. 1993).