Predicting the distribution and habitat suitability of the smooth-coated otter (Lutrogale perspicillata) in lowland Nepal

Abstract

Ever increasing anthropogenic pressures and natural threats to freshwater ecosystems are impacting global biodiversity. Otters are an indicator species that have an important role in maintaining the integrity and stability of wetland ecosystems. A lack of information on essential variables of otter ecology in the Himalaya range, including suitable potential habitat and site occupancy, hampers otter conservation. In this study, we analyze the geographic range, habitat suitability, and landscape connectivity for the smooth-coated otter (Lutrogale perspicillata) in lowland areas of Nepal. Using 655 presence points collected between 2010 and 2018, we created habitat suitability models using an ensemble of small models (ESMs) derived from MaxEnt techniques to understand the variables influencing smooth-coated otter distribution in the country. The model predicted the distribution of smooth-coated otters with high accuracy (AUC = 0.89 ± 0.03, Boyce’s Index = 0.95 ± 0.02). The model identified distance to water, precipitation in the driest month, Normalized Difference Vegetation Index, precipitation in the warmest quarter, and precipitation in the driest quarter, as the top five weighted variables that highly influenced the habitat suitability of smooth-coated otters, and identified 12 core areas with 14 potential connectivity linkages in only 2374 km2 of highly suitable habitat in Nepal. Importantly, suitable habitat was found to be highly concentrated in protected areas, particularly in Bardia and Shuklaphanta National Parks, having the only significant permeability of linkages between these core areas. All seven provinces had very small amounts of highly suitable habitat, likely due to the low abundance of natural freshwater lakes and aquaculture ponds, with the exception of Sudurpaschim Province, with only 19.82%, and Lumbini Province, with 5.18%, of highly suitable habitat. While accounting for little land area, the aquaculture ponds may provide important prey sources for otters, and consequently may create conflict with local farmers in the future. Appropriate management intervention, including habitat restoration, the integration of otter conservation strategies into wetland policies, specifically in the Ramsar site management plans, are urgently needed for the survival of the species in Nepal.

Keywords

• Smooth-coated otter
• Nepal
• Habitat suitability
• Ensemble of small models