Mrima Hill Forest (6408)
Kenya, Africa

Site overview

KBA status: confirmed

Year of last assessment: 2004

National site name: Mrima Hill Forest

Central coordinates: Latitude: -4.4667, Longitude: 39.2667

System: terrestrial

Elevation (m): 100 to 300

Area of KBA (km²): 3.76015

Protected area coverage (%): 95.77

KBA classification: Global/Regional TBD

Legacy site: Yes

Site details

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.

Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance because it meets one or more previously established criteria and thresholds for identifying sites of biodiversity importance (including Important Bird and Biodiversity Areas, Alliance for Zero Extinction sites, and Key Biodiversity Areas) KBA identified in the process of compiling the 2003 CEPF Ecosystem Profile of the Eastern Arc Mountains and Coastal Forests Hotspot (which was later [in 2005] split into two Hotspots, the East Afromontane and the Coastal Forests of Eastern Africa). Species taxonomy and threat category was based on IUCN Red List 2002.

Additional 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).

Habitats

Land use: forestry | nature conservation and research

IUCN Habitat	Coverage %	Habitat detail
Forest	100

Threats

Summary of threats to biodiversity at KBA: Despite its status as a strict nature reserve, and now a National Monument, Mrima has suffered badly from selective logging and pole cutting. Numerous Combretum schumannii and Milicia excelsa were being illegally felled in 1989 and 1992. The forest is severely degraded in many places, with an open canopy and dense thicket-like undergrowth. The population density around the hill is high, and there has been some encroachment on the lower slopes to the west. Prospective mining, which has carried on irregularly since 1919, has also affected the forest’s structure. Mrima is now littered with deep prospecting holes, each c.50 cm in diameter. Though some of these provide roost sites for bats, they act as effective pitfall traps for other vertebrates (including biologists!). The main threat to the forest remains the possibility of intensive mining for manganese or niobium. Given Mrima’s biological importance and its significance as a Kaya (or ‘sacred forest’) to the Digo community, any mining proposal should be very carefully evaluated. Certainly no opencast mining should be countenanced, as this would be extremely destructive to the forest. In the meantime, the Forest Department should recognize fully the conservation importance of this site, and work with the National Museums’ Coast Forest Conservation Unit and the Kaya Elders to maintain its integrity.

Threat level 1	Threat level 2	Threat level 3	Timing
Biological resource use	Gathering terrestrial plants	Unintentional effects (species being assessed is not the target)	Ongoing
Natural system modifications	Fire & fire suppression	Trend Unknown/Unrecorded	Only in the future
Invasive & other problematic species, genes & diseases	Invasive non-native/alien species/diseases	Named species	Ongoing
Residential & commercial development	Tourism & recreation areas		Ongoing
Energy production & mining	Mining & quarrying		Only in the future
Human intrusions & disturbance	Recreational activities		Ongoing
Human intrusions & disturbance	Work & other activities		Ongoing
Climate change & severe weather	Droughts		Ongoing

Additional information