Drivers of leopard population dynamics in the Kruger National Park, South Africa

Abstract

In the Kruger National Park (KNP), South Africa, five of the six extant members of the large carnivore guild: lions, Panthera leo, spotted hyaenas, Crocuta crocuta, leopards, P. pardus, cheetahs, Acynonyx jubatus, and wild dogs, Lycaon pictus, are sympatric. A priori and posteriori deductions dictate that lions maintain a balance in the top-down processes in the KNP ecosystem including population abundances and behaviour of the subordinate predators. The recent discovery of the extrinsic disease, bovine tuberculosis (bTB) caused by a bacterium Mycobacterium bovis, in lions suggests that potentially, lion population may decline. Further deductions dictate that the leopard population whereas at individual level may be affected, does not appear to be challenged by the disease. This presupposes that the balance in the top-down processes will potentially be affected. By specifically assessing how this change may affect the leopard population, two mechanisms, which in the context of the KNP are contradictory were invoked. The first mechanism is the meso-predator release hypothesis, which predicts that should the lion population decline, the leopard population would increase as a consequence. The second mechanism, niche packing hypothesis, predicts that the leopard population will not experience a change as a result of the lion population declining; it argues that leopards and lions have co-evolved and as a result have developed conflict avoidance life history, morphological and ecological patterns. Consequently, the thesis set out to investigate if these mechanisms were in effect in the KNP by: (i) designing a robust method to estimate leopard abundances; (ii) estimating leopard abundances throughout the KNP; (iii) comparing leopard abundances with abundances of other members of the large carnivore guild; and (iv) assessing how leopard movements responded to indices of resource distribution and models that predicted space use by lions. Results revealed that leopards responded to resource distribution more than in response to other carnivores and especially lions as was predicted. Accordingly, niche packing theory was selected over meso-predator release theory on the grounds that at population level leopards, at least as far as the KNP is concerned, are not affected by other carnivores. This study therefore, has direct implications on the large carnivore management in KNP. The present study suggests that the leopard population is mainly driven by resources and secondarily by lions. That means in the absence of factors such as human-induced effects, and diseases that are likely to threaten their resource base and them as a result, leopard population is likely to self-regulate in KNP.