Narrow dietary niche with high overlap between snow leopards and Himalayan wolves indicates potential for resource competition in Shey Phoksundo National Park, Nepal

Understanding species' dietary ecology and inter-specific interactions is crucial for multi-species conservation planning. In Central Asia and the Himalayas, wolves have recolonized snow leopard habitats, raising considerable concern about resource competition between these apex predators. Using micro-histological analysis of prey species remains (e.g., hair) in their fecal samples, we determined the prey composition, dietary niche breadth, and the extent of diet overlap between these two apex predators in Shey Phoksundo National Park, Nepal.  We analyzed 152 scat samples collected along 89 survey transects from April to June 2021. Our findings reveal a significant overlap in their diets (Pianka’s index= 0.93), with snow leopard and wolf scats containing the remains of 11 and 10 prey species, respectively. However, the interspecific difference in prey selection was apparent with significant deviations between observed and expected prey use indicating non-random prey selection relative to availability: snow leopards exhibited a higher occurrence of wild prey items in their diet (55.28%), primarily blue sheep (Pseudois nayaur) (24.83%), whereas wolves relied predominantly on domestic livestock (67.89%), with goats (Capra hircus) accounting for over one-fourth of their diet (29.15%).  Yaks (Bos grunniens) comprised a significant portion of the biomass consumed by both predators, with higher for wolves (43.68%) than snow leopards (36.47%). Overall, the narrow dietary niche breadth with high overlap indicates potential resource competition between snow leopards and wolves.  However, a comprehensive understanding of resource competition will require further study on other axes of niche partitioning, including habitat and time. Nevertheless, the region's low prey richness means that, with increasing human influence, any reduction in wild prey or increase in livestock could intensify competition between snow leopards and wolves, which could have implications for livestock depredation.

Methods
The scat samples of snow leopards and Himalayan wolves were collected from the field surveys in Shey Phoksundo National Park, Dolpa, Nepal. From those collected scats, micro-histological analysis was done in the laboratory.