Sites - Important Bird and Biodiversity Areas (IBAs)
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Mrima Hill Forest
Kenya, Coast Province
39o 16.00' East 4o 28.00' South
100 - 300m
Year of IBA assessment
Site description This IBA consists of wet coastal forest on a small hill rising from the coastal plain some 60 km south-west of Mombasa, just west of the main Mombasa–Lungalunga road. The hill itself is a part of the alkaline igneous complex centred on Dzombo Hill (IBA KE010) and is known to have significant deposits of ores containing manganese and niobium. Mrima has been prospected over several times by geologists and there are many deep test holes, although no large-scale mining has yet taken place. Rainfall is at least 1,100 mm/year, and probably greater, since precipitation is produced as cloud rises over the slopes during the south-east monsoon. The forest is undifferentiated, with exceptional plant species diversity. Large trees include Combretum schumannii, Milicia excelsa, Terminalia sambesiaca, Nesogordonia holtzii, Sterculia appendiculata, Drypetes usambarica var. mrimae, Cordyla africana, Albizia glaberrima var. glabrescens, Newtonia paucijuga, Erythrina sacleuxii, Antiaris toxicaria, Lovoa swynnertonii, Zanha golungensis, Diospyros mespiliformis, Inhambanella henriquesii, Manilkara discolor, Mimusops aedificatoria and Synsepalum brevipes. Mrima Forest Reserve was gazetted in 1961, and the site was made a strict nature reserve under the Forests Act in the early 1980s. Mrima Hill is also a Kaya, recognized by the site’s gazettement as Mrima Hill Sacred Grove National Monument in 1992. The Kayas are relict patches of forest that once sheltered the fortified villages of the Mijikenda people (in Mrima’s case, the Digo) on the Kenyan coast. They have spiritual and ceremonial significance and are customarily protected by a Council of Elders.
Key Biodiversity See Box and Table 3 for key species. Mrima holds non-breeding populations of the globally threatened Zoothera guttata, and supports a rich avifauna characteristic of the East African coastal forests. The globally threatened Tauraco fischeri (also a restricted-range species) and Anthreptes reichenowi are both fairly common here. Forty-seven forest bird species are recorded. Pogonocichla stellata and Zoothera gurneyi are known from Mrima but no other Kenyan coastal forests. Both are probably altitudinal migrants. Regionally threatened species include Erythrocercus holochlorus.
Non-bird biodiversity: Mrima’s vegetation is exceptionally diverse. A 1989 expedition recorded over 270 taxa, including 25 that are globally or nationally rare. Among others, the rare trees Uvariodendron gorgonis and Gigasiphon macrosiphon are known from this site, though the latter was not relocated in 1989. The rare butterfly Eresinopsides bichroma also occurs. Mammals include the threatened Rhynchocyon petersi (EN), Galagoides zanzibaricus (LR/nt) and Colobus angolensis palliatus. Bats occur in the mineshafts, including the rare and localised Myonycteris relicta (VU).