Searching for a needle in a haystack: Population estimation of snow leopards in the western Mongolian Altai by means of camera-trapping

Apex carnivores such as the snow leopard are notoriously difficult to monitor, and gathering abundance data presents technical and analytical challenges. Such information is scarce for the snow leopard ( Panthera uncia ), which is threatened by habitat degradation, decline of wild prey, and retaliatory killing. With this study, we fill a knowledge gap by conducting camera-trapping surveys in two national parks (NPs) and one Strictly Protected Area (SPA) in previously under-surveyed habitats in the western Mongolian Altai. We report low detection rates in the two NPs, respectively 14 detections in the Silkhem-B (513 km 2 ) and two detections in Tavan Bogd (720 km 2 ), preventing us from adopting spatial capture-recapture frameworks (SCR). In the Khork Serkhe SPA, we surveyed an area of 811 km 2 and tested the effect of elevation on the density parameter (D) and explored relationships between the encounter probability (λ 0 ) and the ranging parameter (σ) with behavioral, topographical, and biotic covariates. We also evaluated the effect of topography in determining movements across activity centers. We obtained 32 detection events of 10 adult snow leopards. Snow leopard density (95 % CI) estimates from the first two top models were 0.93 (0.45–1.8) and 0.92 (0.48–1.9) individuals/100 km 2 . Density from the best models was weakly dependent on elevation. Baseline encounter probability varied with the behavioral response covariate (bk), indicating changes in detection probability after initial capture, and activity centers were influenced by ruggedness. This study represents an additional effort toward establishing robust density data for the elusive and threatened snow leopard, confirming previous observations of low densities in the Westernmost Altai Mountains. By providing site-specific population estimates in this area, it contributes to the PAWS initiative, enhancing our understanding of snow leopard population densities and distribution in this critical part of their range.