Modeling Distribution and Habitat Suitability for the Snow Leopard in Bhutan

Dechen Lham,Sonam Wangchuk,Stefan Sommer,Namgay Wangchuk,Phuntsho Thinley,Arpat Ozgul,Gabriele Cozzi

doi:10.3389/fcosc.2021.781085

Abstract

The snow leopard (Panthera uncia) is one of the world's most elusive felids. In Bhutan, which is one of the 12 countries where the species still persists, reliable information on its distribution and habitat suitability is lacking, thus impeding effective conservation planning for the species. To fill this knowledge gap, we created a country-wide species distribution model using “presence-only” data from 420 snow leopard occurrences (345 from a sign survey and 77 from a camera-trapping survey) and 12 environmental covariates consisting of biophysical and anthropogenic factors. We analyzed the data in an ensemble model framework which combines the outputs from several species distribution models. To assess the adequacy of Bhutan's network of protected areas and their potential contribution toward the conservation of the species, we overlaid the output of the ensemble model on the spatial layers of protected areas and biological corridors. The ensemble model identified 7,206 km2 of Bhutan as suitable for the snow leopard: 3,647 km2 as highly suitable, 2,681 km2 as moderately suitable, and 878 km2 as marginally suitable. Forty percent of the total suitable habitat consisted of protected areas and a further 8% of biological corridors. These suitable habitats were characterized by a mean livestock density of 1.3 individuals per hectare, and a mean slope of 25°; they closely match the distribution of the snow leopard's main wild prey, the bharal (Pseudois nayaur). Our study shows that Bhutan's northern protected areas are a centre for snow leopard conservation both at the national and regional scale.

Highlights

Understanding species distribution and habitat suitability are crucial for species management (Aryal et al, 2016; Bai et al, 2018)
To predict snow leopard distribution from the spatially filtered occurrence records, we formed an ensemble of species distribution models (SDMs) using the R package BIOMOD2, version 3.4.6 (Thuiller et al, 2020)
We used true skills statistics (TSS) and the area under the receiver operating characteristic (ROC) curve to assess the effectiveness of each modeling technique (Thuiller et al, 2009; Ahmad et al, 2020)

Summary

Introduction

Understanding species distribution and habitat suitability are crucial for species management (Aryal et al, 2016; Bai et al, 2018). Managing species is increasingly important due to the growing anthropogenic pressure on natural habitats and the impending threats from climate change (Forest et al, 2012; Aryal et al, 2016; Watts et al, 2019) The latter is expected to be most severe on species that inhabit mountain ecosystems (Forest et al, 2012; Aryal et al, 2016); a prime example of such a species is the snow leopard (Panthera uncia) (Ghoshal et al, 2019). The population estimates are yet to be updated, the global snow leopard population is currently estimated at 2,710–3,386 mature individuals (McCarthy et al, 2017)

Methods

Results

Conclusion