Coexistence of two sympatric flagship carnivores in the human-dominated forest landscapes of Northeast Asia

Context: Understanding how large carnivore guilds survive in human-dominated landscapes is key to inform strategies for their conservation in the face of global carnivore declines. Amur tigers and leopards are recovering across the China-Russia border. However, knowledge is limited about competitive interactions between two large cats in Northeast Asia. Objectives: To assess the spatial, temporal and combined spatiotemporal behavioral mechanisms potentially allow co-occurrence between tigers and leopards in a human-dominated forest landscape. Methods: Based on a large-scale camera-trapping data set in Northeast China, we used three different approaches for quantifying spatiotemporal associations: one spatial method (two-species occupancy model), one strictly temporal method (activity pattern overlap), and one spatiotemporal method based on multi-response permutation procedures at shared camera trap sites. Results: Spatially, leopards showed no avoidance of the areas highly used by dominant tigers, but their diurnal activity pattern was significantly different from that of tigers. Spatiotemporal overlap analysis showed fine-scale behavioral avoidance when both co-occurred at camera locations, which further facilitates sympatry. Tigers spatially overlapped with humans, but they were less active during the day when human activities were more frequent. In areas with high cattle density, low occurrence of tigers and leopards may reflect the absence of sika deer, an important prey item for both species. Conclusions: This study provides the first empirical evidence that tigers do not limit leopard distributions, at least in our study area in Northeast Asia. Our results highlighted temporal segregation, not large-scaled spatial avoidance, as a key mechanism promoting coexistence of two large carnivores. Understanding these fine- spatial scale (i.e., camera locations) interactions between sympatric carnivores can help devise management strategies for predator guilds in human-dominated landscapes, currently a major global challenge.