Applicability of Age-Based Hunting Regulations for African Leopards

Abstract

In species in which juvenile survival depends strongly on male tenure, excessive trophy hunting can artificially elevate male turnover and increase infanticide, potentially to unsustainable levels. Simulation models show that the likelihood of safe harvests can be improved by restricting offtakes to males old enough to have reared their first cohort of offspring to independence; in the case of African leopards, males were ≥7 years old. Here, we explore the applicability of an age-based approach for regulating trophy hunting of leopards. We conducted a structured survey comprising photographs of known-age leopards to assess the ability of wildlife practitioners to sex and age leopards. We also evaluated the utility of four phenotypic traits for use by trophy hunters to age male leopards in the field. Our logistic regression models showed that male leopard age affected the likelihood of survey respondents identifying the correct sex; notably, males <2 years were typically misidentified as females, while mature males (≥4 years) were sexed correctly. Mature male leopards were also more likely to be aged correctly, as were portrait photographs. Aging proficiency was also influenced by the profession of respondents, with hunters recording the lowest scores. A discriminant model including dewlap size, the condition of the ears, and the extent of facial scarring accurately discriminated among male leopard age classes. Model classification rates were considerably higher than the respective scores attained by survey respondents, implying that the aging ability of hunters could theoretically improve with appropriate training. Dewlap size was a particularly reliable indicator of males ≥7 years and a review of online trophy galleries suggested its wider utility as an aging criterion. Our study demonstrated that an age-based hunting approach is practically applicable for leopards. However, implementation would require major reform within the regulatory framework and the hunting industry.

Effects of a protection gradient on carnivore density and survival: an example with leopards in the Luangwa valley, Zambia

“…Finally given the difficulty in aging leopards (Balme et al. 2012) documented by Ray (2011) in nearby Luambe National Park and the high potential for harvesting female leopards in trophy hunts (Spong et al. 2000), the impacts of past leopard harvests, particularly those that did not adhere to sex‐ or age‐based limits (Balme et al.…”

“…2000), the impacts of past leopard harvests, particularly those that did not adhere to sex‐ or age‐based limits (Balme et al. 2012), are likely to persist for several years. Despite these potential problems, our data provide no evidence that differences in management during the hunting moratorium directly affected leopard mortality rates.…”

“…We did not assign ages due to the limitations of image quality and the difficulty of aging leopards accurately (Balme et al. 2012). We created capture histories for each individual denoting detections (1) and nondetections (0) on each day of camera trapping.…”

Rosettes, Remingtons and Reputation: Establishing Potential Determinants of Leopard (Panthera pardus) Trophy Prices Across Africa

“…Leopard trophy size was also assessed by estimating the ages of leopards displayed on outfitter's online trophy galleries. Balme et al (2012) demonstrated that leopards could be accurately aged using morphological characteristics (e.g. dewlap size, facial scarring, ear wear) featured in photographs.…”

“…Poorly managed trophy hunting is a particularly important source of mortality in leopard populations, as leopards have naturally high rates of infanticide (e.g. Balme, Hunter, & Braczkowski, 2012; 40% in a protected population in the SabiSands). This is exacerbated by trophy hunting and may cause rapid population declines by artificial turnovers of adult males (Balme et al, 2009b).…”