Habitat suitability modeling for the endangered Bengal slow loris (Nycticebus bengalensis) in the Indo-Chinese subregion of India: a case study from southern Assam (India).

Abstract

The Bengal slow loris (Nycticebus bengalensis) is an endangered nonhuman primate distributed in Southeast Asia, including India. The species is facing sharp population decline throughout its range, largely due to acute habitat loss and fragmentation. IUCN revised the threatened status of the species from vulnerable to endangered in 2020. In the present study, habitat suitability modeling was conducted in southern Assam (India) to analyze the suitable habitat for the Bengal slow loris. The modeling analysis was performed using MaxEnt software. Using a reconnaissance field survey and questionnaire, data on the presence of 30 Bengal slow lorises were collected and run along with seven biophysical factors. The area under the curve (AUC 0.825) indicated high predictive performance of the model. A jackknife test revealed that all seven biophysical factors were important (scores greater than 0.1). The contribution of forest pattern, normalized difference vegetation index, elevation, slope, distance from cropland, normalized difference built-up index and distance from roads were found to be 35.3%, 34.9%, 9.3%, 5.9%, 5.7%, 4.6%, and 4.3%, respectively. Based on thresholds including minimum training presence, tenth percentile training presence, and equal training sensitivity and specificity, this model indicates that 49.91%, 38.30% and 20.37% of the land, respectively, was suitable for the slow loris in southern Assam. This finding regarding habitat distribution and suitability is essential for identifying priority areas for future research and for focusing survey efforts for the long-term conservation of the species.