Sites - Important Bird and Biodiversity Areas (IBAs)
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Kenya, Rift Valley Province
35o 27.36' East 1o 6.12' North
2,000 - 3,365m
Year of IBA assessment
Site description The Cherangani Hills, an old fault-block formation of non-volcanic origin, form an undulating upland plateau on the western edge of the Rift Valley. To the east, the Elgeyo Escarpment drops abruptly to floor of the Kerio Valley, while westwards the land falls away gently to the plains of Trans-Nzoia District. The hills reach 3,365 m at Cheptoket Peak in the north-central section. The hills are largely covered by a series of Forest Reserves. These are made up of 13 administrative blocks, totalling 95,600 ha in gazetted area. Of this, c.60,500 ha is closed-canopy forest, the remainder being formations of bamboo, scrub, rock, grassland, moorland or heath, with c.4,000 ha of cultivation and plantations. Kapkanyar, Kapolet and Kiptaberr Forest Reserves together form a large western block of forest, totalling c.20,000 ha. To the east, the Forest Reserves of Lelan, Embotut, Kerrer, Kaisungor, Toropket, Chemurokoi, Kupkunurr, Cheboit, Sogotio and Kapchemutwa are less well connected. Apart from a large south-eastern block along the escarpment crest, the forests here are fragmented and separated by extensive natural grasslands, scrub and (especially in the central part) farmland. The hills are composed of metamorphic rocks, with conspicuous quartzite ridges and occasional veins of marble. The soils are well drained and moderately fertile, and annual rainfall varies from c.1,200 mm in the east to at least 1,500 mm in the wetter west, which catches the moist prevailing winds from Lake Victoria. The forests are of several different types. The lower western parts of Kiptaberr-Kapkanyar are clothed in Aningeria-Strombosia-Drypetes forest, with a large area of mixed Podocarpuslatifolius forest on the higher slopes. The southern slopes hold Juniperus–Nuxia–Podocarpus falcatus forest, with heavily disturbed Podocarpus falcatus forest on the eastern slopes. Valleys in the upper peaks area shelter sizeable remnants of Juniperus–Maytenus undata–Rapanea–Hagenia forest. Tree ferns Cyathea manniana occur in stream valleys, and there are patches of bamboo Arundinaria alpina, though no bamboo zone as such. In clearings, Acacia abyssinica occurs among scrubby grassland with a diversity of flowering plants. At higher altitudes, the forest is interspersed with a mixture of heath vegetation and swamps, the latter with Lobelia aberdarica and Senecio johnstonii. Much of this heathland may be maintained by burning and grazing. Relict Juniperus and Hagenia trees occur here and there. Especially in the east, there is a mosaic of vegetation types with little obvious altitudinal zonation, possibly a result of the hills’ varied topography and the long history of cultivation, grazing and fire. The Cherangani forests are important for water catchment, and sit astride the watershed between the Lake Victoria and Lake Turkana basins. Streams to the west of the watershed feed the Nzoia river system, which flows into Lake Victoria; streams to the east flow into the Kerio river system.
Key Biodiversity See Box and Table 3 for key species. The avifauna of the Cheranganis is characteristic of the highland forests of Kenya west of the Rift Valley, comprising both central highland species and western species. Ecological surveys have recorded over 73 forest-dependent species, none of which is presently globally threatened. Regionally threatened species include Gypaetus barbatus (one of the last breeding populations in Kenya, nesting on the high peaks), Stephanoaetus coronatus (widespread in small numbers), Glaucidium tephronotum (recently recorded in Kapkanyar), Campephaga quiscalina (uncommon and local; recent records from Kapkanyar) and Indicator conirostris (uncommon).
Non-bird biodiversity: The ungulate Tragelaphus eurycerus (LR/nt) has been recorded here in the past, but its current status is unknown. The butterfly Capys juliae is endemic to the Cherangani Hills. Two giant senecio taxa, Senecio johnstoniibattiscombei var. cheranganiensis and S. johnstoniibattiscombei var. dalei, are endemic to the Cheranganis. Two notable lobelias, Lobelia deckenii elgonensis and Lobelia cheranganiensis, are shared with Mount Elgon, as is Alchemilla elgonensis.