Habitat occupancy of sloth bear Melursus ursinus in Chitwan National Park, Nepal

Abstract

Mammals around the world face serious threats and experience massive decline in their populations and geographic ranges. The sloth bear has become extinct from two of five range countries and the existing population face serious conservation threats. Despite being endangered in Nepal, decades of conservation obliviousness have hindered their conservation and management. We assessed the distribution and habitat use by sloth bears in relation to landscape, environmental, and anthropogenic factors in Chitwan National Park, Nepal. We conducted a sign survey from March-June 2020 in 4*4 km2 grids (n=45) in a checkerboard approach. An observation was spatially replicated four times by recording information in four continuous search trails of 1 km each. We recorded presence/absence of sloth bears, termites, fruits and disturbance in the field and extracted information on tree cover, terrain ruggedness and vegetation index from remotely sensed image of the study area. The data was analyzed using single species-single season occupancy method in PRESENCE software. By using repeated observations these models account for imperfect detectability of species to provide robust estimates of species occupancy. Averaged habitat occupancy estimate obtained from the best models was Ѱ = 0.53 ± 0.04SE with detection probability p = 0.44 ± 0.1SE. Selection of variable based on summed AIC weight from the top models (AIC<2) showed that presence of termites (ƩWi=0.66) significantly influenced sloth bear habitat occupancy. Habitat occupancy was positively influenced by termites followed by fruits, disturbance, terrain ruggedness and vegetation productivity, whereas, it was negatively influenced by tree cover. We suggest that future conservation interventions and action plans aimed at sloth bear management must adequately consider these requirements and issues.