The use of contraceptive techniques in managed wild African lion (Panthera leo) populations to mimic open system cub recruitment.

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. African lion growth rates in smaller fenced protected areas are managed to prevent overpopulation. Using historical data, we found that deslorelin implants were more effective at reducing reproductive output than unilateral hysterectomy surgery. However, there were some undesirable side-effects associated with the implants. These findings advance the lion management practices on small fenced reserves; habitats that are becoming more valuable as larger lion populations are threatened across Africa. Photograph by Susan M. Miller. [ABSTRACT FROM AUTHOR]