Predicting the potential habitat of bears under a changing climate in Nepal

In Nepal, the distributions of three bear species vary: sloth bears (Melursus ursinus) in the lowlands, Asiatic black bears (Ursus thibetanus) in the mid-hills, and brown bears (Ursus arctos) in the high Himalayas. We utilized 179 occurrence points for sloth bears, 199 for Asiatic black bears, and 41 points for brown bears to construct a habitat model incorporating climate and topographic variables. Employing various species distribution modeling algorithms in BIOMOD2, the model predicts suitable habitats spanning 10,971.75 km² for sloth bears; 29,470.75 km² for Asiatic black bears; and 6152.97 km² for brown bears. Within protected areas, the habitat for sloth bears is 4120.56 km², that for Asiatic black bears is 9688.67 km², and that for brown bears is 4538.67 km². Chitwan National Park emerged as the prime sloth bear habitat with a core area of 918.55 km² and a buffer zone of 726.485 km². The Annapurna Conservation Area was deemed suitable for Asiatic black bears and brown bears, covering 2802.23 km² and 2795.91 km², respectively. The models projected a significant reduction in the habitat of these bear species both inside and outside protected areas. As predicted under the Shared Socioeconomic Pathways (SSP)2-4.5 scenario, sloth bears may experience 54.9% (2050) and 44.7% (2070) losses, respectively, of habitat; Asiatic black bears, 11.2% (2050) and 16.8% (2070); and brown bears, 68.41% (2050) and 82.20% (2070) losses. The overlap between sloth bears and black bears spans 38.7 km², and that between brown bears and black bears is 26.6 km². Notably, all three bear species exhibited suitability correlations with the intermediate temperature of the driest quarter. Examining current and projected habitats provides essential information for guiding conservation strategies and ensuring the conservation of these bear species in the face of climate change.