Estimating leopard density across the highly modified human-dominated landscape of the Western Cape, South Africa

Apex predators play a critical role in maintaining the health of ecosystems but are highly susceptible to habitat degradation and loss caused by land-use changes, and to anthropogenic mortality. The leopard Panthera pardus is the last free-roaming large carnivore in the Western Cape province, South Africa. During 2011-2015, we carried out a camera-trap survey across three regions covering c. 30,000 km(2) of the Western Cape. Our survey comprised 151 camera sites sampling nearly 14,000 camera-trap nights, resulting in the identification of 71 individuals. We used two spatially explicit capture-recapture methods (R programmes secr and SPACECAP) to provide a comprehensive density analysis capable of incorporating environmental and anthropogenic factors. Leopard density was estimated to be 0.35 and 1.18 leopards/100 km(2), using secr and SPACECAP, respectively. Leopard population size was predicted to be 102-345 individuals for our three study regions. With these estimates and the predicted available leopard habitat for the province, we extrapolated that the Western Cape supports an estimated 175-588 individuals. Providing a comprehensive baseline population density estimate is critical to understanding population dynamics across a mixed landscape and helping to determine the most appropriate conservation actions. Spatially explicit capture-recapture methods are unbiased by edge effects and superior to traditional capture-mark-recapture methods when estimating animal densities. We therefore recommend further utilization of robust spatial methods as they continue to be advanced.

Automated summary

Leopards play a critical role in maintaining ecosystem health but are vulnerable to habitat degradation and mortality. A study in South Africa's Western Cape province found leopard density to be 0.35-1.18 individuals per 100 square kilometers, with a predicted population size of 102-345 individuals. Providing a baseline population density estimate is crucial for understanding population dynamics and conservation efforts.