EVALUATING POPULATION PERSISTENCE OF CENSUSED AND UNMANAGED HERBIVOREPOPULATIONS FROM THE KRUGER-NATIONAL-PARK, SOUTH-AFRICA

The application of the Dennis et al. (Ecol. Monogr., 61, 1991) model t o data from 12 herbivore populations from the Kruger National Park, So uth Africa, introduces 'risk assessment' procedures into the conservat ion management of free-ranging species. The model enables one to predi ct the probability of reaching an arbitrarily defined threshold popula tion size using census figures from censused and unmanaged populations . It also provides an objective evaluation of population persistence b ased on past performance. Of the 12 species investigated, five (impala Aepyceros melampus, blue wildebeest Connochaetes taurinus, zebra Equu s burchelli, white rhinoceros Ceratotherium simum, giraffe Giraffa cam elopardalis) appear to be secure, four (kudu Tragelaphus strepsiceros, waterbuck Kobus ellipsiprymnus, warthog Phacochoerus aethiopicus, sab le antelope Hippotragus niger) are vulnerable and three species (tsess ebe Damaliscus lunatus, eland Taurotragus oryx, roan antelope Hippotra gus equinus) are at risk of declining by an order of magnitude within 100 years. Therefore, within data limitations, the KNP appears not to offer sufficient suitable habitat for a number of herbivore species de spite its considerable size, and a metapopulation approach may be requ ired for the effective conservation of some species. The model also al lows the principle of 'complementarity' to be extended beyond that of species composition. Objective evaluations of population persistence, of censused and unmanaged populations, as demonstrated here, mean that the principle of 'population viability' can help the design of effici ent regional reserve networks.