Coexistence of Sympatric Large Carnivores: Spatio-Temporal Interactions Between Tigers and Leopards in Parsa National Park, Nepal.

Understanding interspecific interactions between tigers () and leopards () is crucial for effective conservation planning. However, most studies have been conducted only in well-known protected areas, leaving knowledge gaps in other parts of their overlapping range. This study investigates the spatial-temporal interactions between sympatric carnivores (tigers and leopards) in Parsa National Park (PNP), Nepal. Camera trap data obtained from 157 sampling sites (2 × 2 km grid cells) were used to assess daily temporal activity patterns, single-species occupancy, and density of tigers and leopards using spatially explicit capture-recapture models (SECR) to further examine their coexistence mechanism in light of the recent recovery of tiger populations in PNP. In general, our findings indicate that both species co-detected at 44 camera locations, demonstrating that they spatially share habitats inside the park. However, leopards avoid peak tiger activity periods, which is likely to reduce competitive interactions. The SECR model estimated a leopard density of 3.09 individuals per 100 km whereas tiger density was 1.25 individuals per 100 km within the study area. The model-averaged occupancy probability of leopards in PNP was 0.45 (CI: 0.30, 0.64). The normalized difference vegetation index (NDVI) had a strong correlation with leopard occupancy, while the tiger relative abundance index (RAI) had minimal impact, reflecting the importance of high-quality habitats in protected areas for conserving both species. Conservation initiatives targeting to strengthen the tiger recovery plans should incorporate thorough studies of interspecific interactions between sympatric large carnivores like tigers, leopards, and their prey base on a fine-grain scale to ensure effective management strategies.