New elevational limits of Himalayan mammals in eastern Sikkim, India

The eastern Himalaya is recognised as one of the most important biodiversity hotspots in the world. There is a limited understanding on the mammalian distributions in its high-altitude landscapes. To address the knowledge gap, we conducted extensive camera-trap surveys across protected and adjoining non-protected landscapes of eastern Sikkim, India, a part of this eastern Himalayan biodiversity hotspot between February 2023 and May 2026. The survey resulted a total 20,411 trap nights efforts from a total 64 camera traps stations across elevation range between 1,800 and 4,200 m, and documented 30 mammal species. We observed eleven notable mammalian records including five new elevational records and six first photographic records from eastern Sikkim. Gaur Bos gaurus was recorded at 3,542 m in Pangolakha Wildlife Sanctuary which is the highest verified photographic record of the species globally. Tiger Panthera tigris presence at 3,966 m in the Kyongnosla region is also one of the highest documented elevations for the species in the Himalaya. Additional records included Sambar Rusa unicolor at 3,050 m, Golden Jackal Canis aureus and Red Panda Ailurus fulgens at 4,100 m. Other notable records are the Spotted Linsang Prionodon pardicolor at 2,939 m, Clouded Leopard Neofelis nebulosa at 3,189 m. These findings emphasise the ecological importance of eastern Sikkim as a high-altitude biodiversity rich area facilitating movement of several rare endangered and threatened species between the protected areas of India, Bhutan, and Tibet. The findings also demonstrate the value of systematic camera-trap monitoring for documenting mammalian distributions across this relatively lesser studied landscape and provide a foundation for evaluating the influence of habitat availability and environmental change on species occurrence. The study also emphasizes the conservation importance of both protected and adjoining non-protected forests for maintaining habitat connectivity and conserving Himalayan mammalian diversity.