Context: Managed wild lions (Panthera leo) are lions found in smaller (<1000 km2), fenced protected areas that hold a substantial portion of South Africa's wild lion population. Because the natural population control mechanisms are compromised within these properties, managers must actively control population growth rates. Fecundity control is used by wildlife managers, but long-term, empirical data on the impact and consequences of such interventions in lions are lacking. Aims: The aim of the present study was to assess the effectiveness of two methods of contraception (deslorelin implant and unilateral hysterectomy) in reducing cub recruitment of managed wild lions. Methods: Survey data spanning 14 years from 94 managed wild lions on 19 protected areas were used to evaluate the effectiveness of deslorelin implant treatments and unilateral hysterectomies on population growth rates through mimicking open system cub recruitment. Key results: Deslorelin implants were effective at increasing the age of first reproduction and lengthening inter-birth intervals. There was also an unexpected decrease in litter size. Behavioural side-effects were recorded in 40% of individuals: 19% pride fragmentation 13% lack of receptiveness towards males 8% other. The more successive deslorelin implants a lioness had, the more likely it was that weight gain was reported. Unilateral hysterectomy resulted in a decrease in litter size post-surgery, but this was not statistically significant. No behavioural or physiological side-effects were noted after unilateral hysterectomy. Conclusions: Deslorelin treatment was more effective in reducing the reproductive output of managed wild lionesses than unilateral hysterectomy surgery. While more side-effects were associated with deslorelin implants than unilateral hysterectomies, a single deslorelin treatment is currently a good option for fecundity reduction. More research is required on unilateral hysterectomy surgery. Implications: Neither deslorelin implants nor unilateral hysterectomies offer a 'silver bullet' solution for reducing rapid population growth in managed wild lions. Reproductive control should be integrated with other best-practice approaches.
Bibliographical noteFunding Information:
We extend our greatest thanks and appreciation to all of the reserve staff involved in taking our survey and who contributed their time and support towards this project. Thanks to André Uys, Angela Gaylard, Clinton Wright, Dave Druce, Dave Zimmerman, Dusty Joubert, Gerrie Camacho, Hanno Kilian, Mariana Venter, Pieter Nel, Sam Davidson-Phillips, Simon Naylor and Craig Tambling for discussions at a LiMF meeting in October 2014, which led to the development of this paper. Thanks to Dr Peter Caldwell, Old Chapel Veterinary Clinic, for providing up-to-date quotes for both deslorelin implant and unilateral hysterectomy surgeries as well as details of modifications to the unilateral hysterectomy approach. Thanks to Drs Henk Bertschinger and Mike Toft for providing follow-up deslorelin implant size data. Thanks to two anonymous reviewers and the Associate Editor for helpful comments on earlier versions of this manuscript. This research paper forms part of a larger project assessing the management of free-roaming lions in small reserves across South Africa. OKMcE was sponsored by the National Research Foundation, SATIB Conservation Trust and the Lion Management Forum of South Africa. SMM was supported by a Clancey Trust Postdoctoral Fellowship.
- South Africa
- birth control
- population management