Rapid growth rates of lion (Panthera leo) populations in small, fenced reserves in South Africa: a management dilemma

Managers of reintroduced lion (Panthera leo) populations in small reserves (<1000 km(2)) in South Africa are challenged by high rates of population increase and how best to control them. We combined data from 14 small, fenced reserves to evaluate growth rate parameters and compared them to those in larger and/ or open reserves. Growth rates of lions in small fenced reserves were only matched by those in Nairobi National Park (NP), which is relatively small and where the majority of the subadults emigrated away from the park. Initially, South African managers unconsciously mimicked this system by removing subadults to control population numbers, but increasingly chose euthanasia and hunting in the past decade, as the demand for wild lions for translocation decreased. They have, however, expressed a desire to use other methods of population control and mimic other open systems such as Kruger NP and Serengeti NP. Kruger NP had older ages of first reproduction and longer inter-birth intervals that could be mimicked through selective contraception. Alternatively, Serengeti NP had smaller litter sizes and lower cub survival, which could be mimicked through surgery to reduce litter sizes and, less attractively as it still involves lethal management and raises serious ethical concerns, selective culling of cubs. Mimicking Kruger NP may be more desirable as it is more ecologically similar to the small reserves than SerengetiNP. This understanding of the current situation, and howit could be altered to more closely mimic natural systems, will facilitate the development of a metapopulation-based management plan for lions in small reserves in South Africa.