 Reference Base  Observations on two introduced black rhinos in Liwonde Na... |
|
Bhima, R.; Dudley, C.O., 1996. Observations on two introduced black rhinos in Liwonde National Park, Malawi. Pachyderm 21: 46-54, figs. 1-3, tables 1-2
|
|
|
|
| |
| Location: |
Africa - Southern Africa - Malawi |
| Subject: |
Ecology - Habitat |
| Species: |
Black Rhino |
 |
|
Reintroduced Diceros bicornis in Malawi. The formula for preference index (PI), to determine habitat preferences. was adapted from Pienaar et al (1992) for this data set. The calculations in the formula are based on the proportional occurrence of each vegetation/ habitat type. A value of zero (0) indicates that a habitat type is used in the same ratio as expected from its proporuonal occurrence. A positive value (maximum + 1.0) indicates habitat use which is greater than expected from its proportional occurrence, while a negative value (minimum -1.0) indicates habitat use less than expected from its proportional occurrence.
Sanctuary vegetation
Three major vegetation communities were identified in the sanctuary. Two of these were further subdivided, as shown on the map in Figure 2. The most important in terms of plant cover is the mopane woodland complex which is sub-divided into four variants: mopane woodland with or without coppice (45 %); mopane woodland with Croton thicket (0.1 %); A. harveyi woodland (1%) and mopane clump savanna (9%). The second most dominant community is the tall, grass-tree savanna, which covers 35% of the sanctuary. At the edges of this community, the woodland is actively invasive and small, fire-coppiced woody plants are numerous. This may prove, ultimately, to be the most important area for rhino browse. The third community is the riverine forest/ thicket covering 10% of the sanctuary. Where this community has few trees, a second variant, riverine thicket is delineated (1 %).
Results
The adapted PIs for each vegetation type in the sanctuary are given in Table 1. The calculations indicate that the mopane-Croton thicket, the A. harveyi woodland, the riverine thicket and the riverine forest, were the most preferred habitat types for the rhinos. All these areas occupy small proportions of the sanctuary.
Table 1. Vegetation communities in the rhino sanctuary showing the proportion of sanctuary area, with rhino frequencies observed in each community and the calculated preference index (PI) for each community
Vegetation Proportion of Number of times Proportion Preference
Community Type sanctuary rhino seen count index
1. Riverine forest 0.09 8 0.1026 0.122
2. Tall grass tree 0.35 15 0.1923 - 0.451
savanna
3. Albizzia harveyi 0.011 7 0.0897 0.988
woodland
4. Mopane-Croton 0.001 7 0.0897 0.989
thicket
5. Riverine thicket 0.01 6 0.077 0.870
6. Mopane woodland 0.45 33 0.423 - 0.060
with coppice
7. Mopane termite 0.09 2 0.423 0.715
hill thicket
Discussion
The habitats preferred by the rhinos all occupy minor proportions of the sanctuary. However, this interpretation is based on a very limited number of observations and is only indicative of true preference. Despite this, the results bear some similarity to observations made by Emslie & Adcock (1994) in Hluhluwe-Umfolozi National Park in South Africa where dense, riverine forest was the most preferred rhino habitat. Riverine forest/thicket was also preferred by the rhinos in Liwonde. Emslie & Adcock (1994) also reported that very tall grassy areas were rejected by rhinos, which seemed to be the case in the sanctuary too.
The application of an adapted PI formula to this data worked well. However, more observations need to be included from vegetation communities which occupy larger proportions of the sanctuary in order to establish the validity of the Pls for the sanctuary.
|
|
|
File available
details
Original text on this topic: