Assessing the impacts of protection gradients on large African carnivore density and survival : an example with African lion and leopard in the Luangwa Valley, Zambia

Abstract

Large carnivores are in rapid global decline, primarily due to anthropogenic pressures. Human activities on the periphery of protected areas can limit carnivore populations, but measurements of the strength of such effects are limited. Both African lion (Panthera leo) and leopard (Panthera pardus) are declining throughout their ranges, and thus accurate monitoring of key populations is critical. Both of these species face pressure from encroaching human populations, particularly from trophy hunting, illegal bushmeat harvest, and human-carnivore conflict. In Zambia, South Luangwa National Park and its buffer areas are thought to contain the country's largest lion and leopard populations. However, this protection gradient is experiencing rapid human population growth and activities that are known to threaten large carnivore populations elsewhere. Here we examined the status and major anthropogenic drivers of the South Luangwa lion and leopard populations. First, we estimated population size, trends, survival rates and demography for the South Luangwa lion population from 2008 to 2012. These data indicated that trophy hunting was impacting the South Luangwa lion population, and potential management actions exist and should be implemented to mitigate impacts from trophy hunting. Second, we measured how the density and survival rates of South Luangwa's leopard population varied across this gradient of protection using remote camera trap surveys from 2012-2014 during a ban on trophy hunting. We estimated that leopard density was higher inside South Luangwa National Park as compared to an adjacent buffer area with lower levels of protection, but could not detect differences in leopard survival across these two areas. This difference in density was most likely driven by prey depletion in the buffer areas, and this limitation is likely an issue for other sympatric large carnivore species. Finally, we developed a rapid survey method based on pedigree reconstruction to estimate population size, with validation based on a simulated population. This method shows promise for surveying unstudied large carnivore populations. Overall, large carnivore populations face growing anthropogenic pressures worldwide, and management action to mitigate population declines must be informed by intensive monitoring of key large carnivore populations to identify the drivers and dynamics of such declines.