THE RELATIONSHIP BETWEEN RAINFALL, LION PREDATION AND POPULATION TRENDS IN AFRICAN HERBIVORES

The relationship between rainfall, lion predation and population trend s in African herbivores, with special emphasis on buffalo, wildebeest and zebra, was studied in the central district of the Kruger National Park between 1968 and 1992. The study commenced at the end of a dry cy cle, and moved into a 10-year wet cycle that was followed by another 1 0-year dry cycle. Populations of the herbivores reacted differently to these cycles: those of wildebeest and zebra fluctuated inversely with rainfall, whereas those of buffalo and the other herbivores fluctuate d directly with rainfall to a greater or lesser degree. The proportion s in which some species were represented in lion kill samples followed a similar trend, with wildebeest and zebra being more vulnerable in t he wet cycle and buffalo and waterbuck being more vulnerable in the dr y cycle. Simulations of the buffalo, wildebeest and zebra populations suggest that buffalo are more heavily influenced by predation during p opulation declines than are the other two species, followed by wildebe est, with zebra experiencing the smallest influence. The driving force in the ecosystem, however, appeared to be rainfall.