The site is a mid-altitude tropical rainforest, the easternmost outlier of the Congo Basin forests. Its West African affinities are unique in Kenya, and the forest contains many species found nowhere else in the country. The forest lies in the Lake Victoria catchment, c.40 km north of Kisumu, and just east of the Nandi Escarpment that forms the edge of the central highlands. It was first gazetted as Trust Forest in 1933, and two small nature reserves, Yala and Isecheno (c.700 ha), were established within the Forest Reserve in 1967. In 1986, nearly 4,000 ha of the northern portion of the forest, along with the adjacent 457 ha Kisere forest, were gazetted as a National Reserve, managed by the Kenya Wildlife Service. Only an estimated 10,000 haof the overall gazetted area is still closed-canopy indigenous forest, of which some 3,200 ha is in the National Reserve. The remaining area consists of grassy and bushed glades (some natural, some maintained by fire or grazing), tea, cultivation and 1,700 ha of plantations of softwoods and commercially valuable hardwoods. Kakamega forest is an important water catchment; the Isiukhu and Yala rivers flow through the forest and gather tributaries from it. The terrain is undulating, with often steep-sided river valleys. The soils are well-drained, deep, heavily leached, clay-loams and clays, of generally low fertility. Rainfall is c.2,000 mm/year, decreasing from south to north, and apparently declining due to deforestation.
See Box and Tables 2 and 3 for key species. The avifauna is well known, rich, and unusual in its composition. Two globally threatened species occur, Muscicapa lendu (scarce resident) and Eremomela turneri (reasonably common). The 194 forest-dependent bird species (the highest total for any Kenyan forest) include many of Kenya’s Guinea–Congo Forests biome species, as well as 33 of Kenya’s 70 Afrotropical Highlands biome species. The mixture reflects Kakamega’s altitudinal position between lowland and montane forest. Kakamega’s avifauna is unique not only nationally, but continentally. Several species have isolated, relict populations here, including Andropadus ansorgei, Merops muelleri, Muscicapa lendu and Eremomela turneri, which are absent from all or nearly all of the superficially similar mid-elevation forests in Uganda. Muscicapa lendu is a restricted-range species that characterizes the Kakamega and Nandi forests Secondary Area, and is also present in the Albertine Rift mountains Endemic Bird Area. The presence of the eremomela indicates biogeographic links to the Eastern DR Congo lowlands Endemic Bird Area. Kakamega itself has few endemic taxa; among birds, there is an endemic subspecies (kavirondensis) of Andropadus ansorgei. At least 16 bird species occur in Kakamega but nowhere else in Kenya, and another 30 (such as Psittacus erithacus) are probably now confined to this site. The grassy glades have their own distinctive avifauna, with many moist-grassland species that are now rare elsewhere in western Kenya. Regionally threatened species include Circaetus cinerascens (fairly common resident), Hieraaetus ayresii (relatively abundant), Stephanoaetus coronatus (resident in small numbers), Tyto capensis (no recent records), Glaucidium tephronotum (widespread at low density), Indicator exilis (not uncommon), Indicator conirostris (uncommon), Prodotiscus insignis (rare, with few recent records), Phyllastrephus baumanni (not uncommon, but rarely recorded), Kakamega poliothorax (extremely local and generally scarce), Sheppardia polioptera (patchily distributed), Hyliota australis (uncommon in forest canopy), Dyaphorophyia concreta (very local), Campephaga quiscalina (rarely recorded) and Euplectes hartlaubi (local).
Non-bird biodiversity: Several West African forest mammals occur, including Potamogale velox (EN). The small mammal community is also very rich and shows strong affinities to the Congo basin. At least 28 snake species are recorded, including the rare Pseudohaje goldii and other West African species such as Philothamnus heterodermus carinatus, Hapsidophrys lineata, Dendroaspis jamesoni kaimosae, Atheris squamiger squamiger, A. hispida and Bitis nasicornis. Two notable and probably endangered forest amphibians, Leptopelis modestus and Hyperolius lateralis, are recorded. The forest’s butterfly fauna is very diverse and important, both regionally and continentally; around 350 species are thought to occur, including at least one endemic, Metisella kakamega, and a near-endemic, Euphaedra rex. Kakamega has a rich diversity of trees, although endemism is low, the only woody endemic being the liana Tiliacora kenyensis.
Pressure/threats to key biodiversity
Kakamega is a complex and fragmented forest, and one that has been under attack, from inside and out, for many years. Logging for commercially valuable timber, and clear-felling of indigenous forest to make way for plantations, was extensive under the colonial Forest Service and continued until the late 1980s. This began the process of isolating the northern and southern blocks. Excisions for settlement, schools and tea plantations (the ‘Nyayo Tea Zones’) have claimed additional chunks of the forest. Kakamega District is one of the most densely populated in Kenya, and human pressure on the forest is extremely intense. Local people are estimated to derive products worth c.US$1.7 million from the forest each year. Forest protection remains totally inadequate, especially in the southern sector under the management of the Forest Department. Agricultural encroachment has led to large-scale destruction (e.g. within Yala Nature Reserve) in recent years, and illegal tree-felling and charcoal burning are rampant. Forest and glade grazing of livestock, allowed once again by Presidential decree in 1994, prevents tree regeneration and causes policing problems. Hunting for bush-meat, debarking of certain trees for traditional medicine, and firewood collection (estimated at 100,000 m3/year) are also serious problems. Continuing forest fragmentation and destruction in Kakamega appears to have taken its toll on the avifauna. Some forest species, such as Ploceus tricolor, have not been recorded for many years, and may now be locally extinct. A number of montane forest birds that formerly occurred here, such as Tauraco hartlaubi and Campethera tullbergi, seem to have disappeared since the severing of forest connections with the nearby, higher altitude North Nandi forest (KE053). The Kenya Indigenous Forest Conservation Programme (KIFCON) developed an innovative conservation plan for Kakamega in the early 1990s, but this has never been implemented. The plan proposed a number of mechanisms for balancing the needs of biodiversity conservation and forest-adjacent communities, including a forest-zoning approach. These ideas should be revisited and, where appropriate, revived. An integral part of this plan was ecotourism development. The forest is one of Kenya’s top birdwatching destinations, and has enormous potential for tourism if properly protected. This is one obvious means of generating revenue to help conserve Kakamega’s immensely important biodiversity. A forest guides association, whose members are skilled local naturalists, already exists and has embarked on an ecotourist enterprise with GEF Small Grants support.