|Most recent IBA monitoring assessment|
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The Chyulu Hills are situated 190 km south-east of Nairobi and 30 km south-west of Kibwezi. They are of relatively recent volcanic origin, and the range is composed of ash cones and craters. The hills hold no permanent surface water, but rainfall percolating through the porous rock feeds many permanent fresh water sources in the surrounding plains, notably Mzima Springs and the Tsavo and Galana rivers. The hills are relatively undisturbed and still shelter indigenous vegetation and wildlife. Rough grassland and thicket give way to patches of montane forest along the spine of the hills, mainly above the 1,800 m contour; the largest tract of forest is around the highest peaks in the central-southern portion. Characteristic trees include Ficus spp, Neoboutonia macrocalyx, Tabernaemontana stapfiana, Prunus africana, Strombosia scheffleri, Cassipourea malosana, Olea capensis and Ilex mitis, with islands guarded by Erythrina abyssinica. Lower down, there are areas of Juniperus procera forest and, particularly on lava flows, forest dominated by the blue-stemmed Commiphora baluensis. The eastern flank of the hills, including about half the forested area, is in the 47,100 ha Chyulu East National Park, administered by Kenya Wildlife Service. The park boundary runs down the centre of the hills along the line of the peaks. The western half is part of the ungazetted West Chyulu Game Conservation Area, owned by several Maasai group ranches. At present, this area has no formal conservation status. The notional boundary of the IBA follows the 1,500 m contour, including an area of some 18,000 ha of which around half is included in the park and slightly under half (c.7,900 ha) is forested.
See Box and Table 2 for key species. The Chyulu Hills may be an important stopping-point (when forest trees are in fruit) for Cinnyricinclus femoralis as they move between forests on Mount Kilimanjaro and the central Kenyan highlands. The hills hold endemic races of Francolinus shelleyi (macarthuri), Pogonocichla stellata (macarthuri) and Zoothera gurneyi (chyulu). The race chyulu of the Bradypterus cinnamomeus is now generally merged with the race rufoflavidus of northern Tanzania, but Chyulu birds are darker. Van Someren (1939) named 22 further Chyulu Hills subspecies, and although most are no longer considered valid, definitive taxonomic work remains to be done. Regionally threatened species include Hieraaetus ayresii (status unknown); Stephanoaetus coronatus (status unknown) and Polemaetus bellicosus.
Non-bird biodiversity: A variety of large mammals occurs on Chyulu, including, at times, Loxodonta africana (EN). The rich butterfly life includes the endemics Pentila tropicalis chyulu, Acraea anacreon chyulu, Papilio desmondi desmondi and the near-endemic Amauris echeria chyuluensis. Ongoing research on the vegetation gives some 550 plant taxa, excluding the numerous grasses. Amongst these are 37 species of orchid, mostly epiphytes supported by the heavy mists and the rare saprophyte Epipogium roseum. Notable trees are Chionanthus mildbraedii and the most northerly population of Podocarpus usambarensis.
BirdLife International (2023) Important Bird Areas factsheet: Chyulu Hills forests. Downloaded from http://www.birdlife.org on 05/02/2023.