Jachman, H., 1984. Status of the Mwabvi rhino (Diceros bicornis). Nyala 10 (2): 77-90, figs. 1-8, table 1
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| Location: |
Africa - Southern Africa - Malawi |
| Subject: |
Ecology - Population |
| Species: |
Black Rhino |
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The 6 or 7 rhino occupy an area of 52 km? , giving a density of 0.12 to 0.14/ km? . This compares with 0.32/ km? in Ngorongoro, 0.16/ km? in Olduvai Gorge, Tanzania (Goddard, 1967), 0.32/ km? in Tsavo National Park, Kenya (Goddard, 1969), 0.41/ km? in Luangwa valley, Zambia (Caughley, 1973), 0.14/ km? in Masai Mara, Kenya (Mukinya, 1973) and 0.05/ km? on the Serengeti plains in Tanzania (Frame, 1980). On account of differences in the vegetation structure, none of these areas are directly comparable. The rhino density in Masai Mara is similar to that of Mwabvi. However, the vegetation of Masai Mara consists of short grasslands, interrupted by stretches of riverine vegetation, generally containing low densities of the browsing black rhino. Olduvai Gorge also has a similar rhino density as Mwabvi. The vegetation is mainly Acacia and Coinmiphora, thornbush, roughly corresponding with the thicket vegetation in Mwabvi. The water supply is identical to that of Mwabvi, widely distributed and sparse during the dry season. As noted earlier, it is most likely that the water availability in Mwabvi is one of the main factors contributing to large home ranges, hence low rhino densities.
Parker (1967) estimated that one would expect Mwabvi Reserve (351 km? ) to contain 140 rhino, based on comparison with densities of rhino in the Luangwa valley, Zambia (Caughley, 1973). This is most unlikely, firstly because one year before Parker surveyed the Reserve, the extension area was still occupied by a large number of people, reducing the available rhino area to the size of the original Reserve (131 km? ). Secondly, poaching has always limited the available area for rhino within the original Reserve, which may be the main reason that rhino spend most of their time in the thicket vegetation. Thirdly, during the latter part of the dry season, the food availability for rhino is limited to mainly woody browse, imposing a nutritional constraint, upon their expansion. Parker (1967) suggested that the early burning policy is responsible for a possible nutritional constraint. However, the thicket vegetation does not bum at all, while most of the mopane woodland hardly burns because the shallow rooting system of the trees results in a low grass biomass. Fourthly, as mentioned before, the scarcity of water during most of the dry season may well be another factor contributing to low densities of rhino.
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Status of the Mwabvi rhino (Diceros bicornis)
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