Abstract

In 1993, 19 lions (Panthera leo) were introduced into the Pilanesberg National Park (PNP). The 500 km² PNP is entirely enclosed with predator-proof fencing (including electrification). No possibility exists for any natural movement of large predators in or out of the Pilanesberg system. An adaptive management and highly interventionist approach to lion population management has been applied in PNP. Lions were introduced into PNP primarily to contribute to the tourist experience, thereby generating income for the tourism industry in the region. The ecologic influence of lions on biophysical processes and ecosystem functioning can be considered as secondary objectives for maintaining a lion population in PNP. The cost of maintaining a lion population exceeds the direct financial return from the animals through live sales and trophy hunting. These forms of utilization are management tools rather than sustainable income-generating options. Population manipulation has been applied for a variety of management objectives. Pride size is kept small (5 adult females or less) to reduce impact on commercially valuable buffalo populations and to increase the relative number of prides PNP can accommodate. There is no indication that tourism sightability increases as pride size increases. Smaller prides have reduced reproductive potential, as there are fewer females to breed. Prides in remote regions are maintained at around 3 adult females to reduce impact on the prey base and trophies in the utilization areas where tourism sightings are not a consideration. Male coalitions are manipulated into pairs in order to increase the relative abundance of males, increase sightability, increase vocalization potential and increase the genetic potential of the population. Larger coalitions have proved to be likely to dominate the entire system. Dispersing subadults are made available for relocation in order to limit the potential of animals being forced through the perimeter fence and compromising the PNP relationship with neighbours. PNP has provided founder populations for 12 other reserves as well as supplying the population for Oklahoma City Zoo. Monitoring and management is dependent on individual recognition across the entire population. Vasectomies and more recently epididymectomies have been performed on key males within the population. This intervention has been designed primarily as a genetic management strategy. Over-represented males are thus permanently removed from the gene pool and a temporary reduction in population growth is experienced. The surgery is performed in the field. Despite initial concerns that behavioural and physiologic changes in the males would occur, there is no apparent change in roaring, mane growth and territoriality following the procedure. The ultimate objective with vasectomies is that PNP can apply assisted reproduction technology by using the mating males as indicators of the females’ reproductive state. Assisted reproduction technology will allow new genetic material to enter the population without the necessity for introducing new animals. New introductions are limited by animal availability, disease introduction potential, cost and life history limitations. Little progress has been made with lion assisted reproduction techniques thus far, however. PNP has maintained the lion population as an FIV-free population and other diseases, which are plaguing lion populations throughout Africa such as bovine tuberculosis and canine distemper, are also absent. Intensive human activity on the reserve’s periphery presents an ever-present threat and the development of early disease detection tools or sustained vaccination regimes on the reserve’s periphery is vital. No vaccination regime exists for the PNP lion population at present. A lion sightability index generated from game drive sightings allows some interpretation of the influence of management actions. Remote methods to gauge lions’ response to management interventions are being sought. The development of meta-population management strategies are being tested in PNP and Madikwe Game Reserve, which together contain approximately 30% of the remaining Etosha lion population. Increasing concern for the long-term survival of lion populations throughout their range is being expressed. The challenge to conserve and manage these animals on smaller, isolated conservation areas has therefore been identified as an important conservation strategy.