Edge effects and distribution of prey forage resources influence how an apex predator utilizes Sri Lanka's largest protected area

Abstract

AbstractApex carnivores are integral to effectively functioning ecosystems, but their populations are declining worldwide. To ensure the long‐term viability of top carnivore populations, it is important to understand their ecology and behavior throughout their remaining range, including in protected areas, as these can act as vital refuges. In Sri Lanka, an endangered, endemic leopard sub‐species (Panthera pardus kotiya) is the apex predator, and while its island‐wide distribution is influenced by forest cover and protection level of the landscape, ecological and anthropogenic influences of finer scale landscape utilization are poorly understood. In the interior of Sri Lanka's largest protected area, Wilpattu National Park, we used remote cameras and a spatially explicit capture‐recapture methodology to estimate leopard population density and quantify relative prey availability. We then employed linear models to compare four alternative hypotheses proposed to identify factors influencing observed leopard habitat selection within the PA. Adult leopard density was estimated at 10.4 individuals/100 km2 which is at the higher end of the global spectrum of recorded leopard densities, and only marginally lower than other Sri Lankan National Parks which appear to have considerably higher available prey abundance. Leopard site utilization increased with increasing distance from park boundaries, suggesting the presence of edge effects due to anthropogenic disturbance. Leopard occurrence was also higher close to grazing lawns used by prey but not areas of higher prey abundance, evidence of ‘leap‐frogging’, whereby carnivores bias movement toward spatially anchored preferred resources of their prey instead of prey directly. The relatively high core area leopard density, combined with avoidance of boundary areas and frequent observation of injuries suggests the possibility of density‐dependent intra‐specific competition and needs to be further investigated. These results illuminate essential aspects of leopard ecology in a key part of its remaining Sri Lankan range, providing important insights for protected area management.