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Funston, P.J.; Hermann, E.; Babupi, P.; Kruiper, A.; Kruiper, H.; Jaggers, H.; Masule, K.; Kruiper, K.
Spoor frequency estimates as a method of determining lion and other large mammal densities in the Kgalagadi Transfrontier Park Kalahari Transfrontier Lion Project
2001 Full Book
Population size and trends of large low-density predators, like lions (Panthera leo), are difficult to monitor, a situation that is exacerbated in a semi-arid and vast area like the Kgalagadi Transfrontier Park (KTP, 36 000 kmý), South Africa/Botswana, where they occur at low densities. Mark-resighting studies conducted in 1976, and again in 1996, in the lower rainfall South African region of this transfrontier park (former Kalahari Gemsbok National Park) and adjoining area in the former Gemsbok National Park, Botswana (ñ 13000 kmý), indicated that lions occurred at very low densities (<1 lion/100 kmý). For effective conservation of lions in the KTP, and to evaluate the effect of persistent but low intensity boundary persecution, reliable estimates of population size and trends were required. Furthermore the adjoining area in the former GNP had never been surveyed (ñ 23 000 kmý). By adapting a technique whereby the correlation between spoor density (an indirect measure), and true density in various representative study areas, it was possible to extrapolate a density estimate for the entire park. True densities were determined by acquiring thorough knowledge of the population in each study area. This was done through a combination of marking individuals, radio-telemetry, ground observations, and attracting lions to 'call up' stations. Spoor density was determined through intensive spoor transects, conducted within the study areas (1382 ñ 215 km/study area). A total of 4078 km were conducted for comparative purposes outside the study areas. A strong linear correlation with increasing lion density and increasing spoor density was determined. The KTP was divided ecologically into dune- and tree savanna habitats, and separate population estimates were determined for each area. In the tree-savanna there was no significant difference between average spoor density within the study and other areas, prompting us to extrapolate the density estimates for the entire area (1.63 lions/100kmý). In the dune-savanna area, however, this was not possible. Having determined actual density not only the dune savanna study area, but for the dune-savanna areas as a whole, it was possible to interpret and accommodate these differences. Lion density was estimated to be 2.1 times lower in the dune-savanna (0.77 ñ 0.05 lions/100 kmý) than in the tree-savanna (1.63 ñ 0.11). Extrapolating this estimates resulted in population estimates of 122 - 128 lions in the dune-savanna, and 306 - 350 lions in the tree-savanna (428 - 478 for the KTP, 1.18 - 1.32 lions/100kmý). In the tree-savanna most of the variation in the spoor frequency estimate had been accounted for after 50 samples (1900km). A greater coverage was required in the dune-savanna; the variation in the estimate was only starting to level off after 3480 km (33 spoor samples). Spoor data fairly accurately described lion population structure, accounting more fully for the non-pride dwelling segment of the population. In assessing the possible use of this methodology of monitoring other species, a remarkable degree of correlation between estimates of true density of various large carnivores, and medium-to large- sized ungulates, was found. This suggests that this method may be productively utilized to monitor a much wider range of species than is currently possible with traditional ways of at least surveying large ungulates (e.g. aerial surveys).
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