- Suitable hippo habitats in the Caprivi -

Martin (2005) estimates that the Caprivi could support a hippo population of 5,000 animals if all limiting factors were favourable to hippo population increase.This estimate is based on the present population of Mamili National Park and extrapolating to other suitable habitats in the Caprivi. Any such estimate is speculative and requires a number of assumptions:

1. The population of Mamili is close to carrying capacity;
2. There is adequate water adjacent to all suitable habitats to meet the 'daily living space' requirement of hippos and this is not a limiting factor;
3. The habitats which are suitable for hippo in the Caprivi are all floodplains, riverine woodlands and open water areas;
4. The process which is underway at present whereby wildlife is valued through conservancy development will continue so that hippo are eventually able to occupy all available habitats;
5. Numbers of cattle will decrease as wildlife becomes the primary land use; and
6. Illegal hunting by citizens of neighbouring countries will become a minor factor through transboundary cooperation (a large assumption!).

Suitable Hippo Habitats in the Caprivi

Mendelsohn & Roberts (1997) give a detailed classification of the vegetation of the Caprivi including the area of each vegetation type and the proportions cleared for agriculture (Table 6).

The floodplain, riverine forest and open water areas appear in Table 6 and these areas are reconciled with Stander's (2004) survey strata in Appendix 6. Were there no people or cattle in the Caprivi, approximately 4,500km2 of suitable habitat would exist and, using the ratio derived from the hippo population of 560 animals estimated by Stander (2004) in Mamili National Park (320km2) which is all floodplain habitat, this would give a ceiling value of about 8,000 hippo.

This does not take into account the areas within these habitat types which have been cleared for agriculture. I have taken the proportions given by Mendelsohn & Roberts in 1996 and made allowance for a further decline in the available areas as a result of human population increase since 1996 assuming this will be directly proportional to the population growth rate of 4%. The recalculated area of 'pristine' habitat amounts to 3,181km2 (Table 6) which reduces the potential carrying capacity for hippo to about 5,600 animals.

Two habitats types appearing in the table are unlikely to contain hippo: the Bukalo- Liambesi grassland (120km2) is too far from surface water and the Okavango valley fields and shrubland (133km2) are settled and cultivated to the extent that this habitat type is unlikely ever to support more than a few hippo. Adjusting for this gives a potential hippo population of about 5,000 animals.

Table 6: Habitats suitable for hippopotamus in the Caprivi (Mendelsohn & Roberts 1997)