West to east shift in range predicted for Himalayan Langur in climate change scenario

Abstract

The group of langur species in the Himalayan range, comprising Semnopithecus ajax, Semnopithecus hector and Semnopithecus schistaceus, now proved to be one single species, were earlier thought to be different species. Their taxonomic confusion has led to deficiency in the understanding of their geographic range and their vulnerability to future climate has not been studied. This study attempts to map their distribution in the face of changing climate. The Western Indian Himalayas and Nepal were considered as the study area for this work. An ensemble model approach for Species Distribution Modelling (SDM), for estimating the habitat loss risks of the Himalayan Langur (HL) in the event of climate change was adopted in this study. Patch metrics and corridor analysis were used to understand fragmentation of suitable habitat. The suitable habitat area for HL was predicted to be 24,240 km2 in the present scenario. It is predicted to decline by 64.6% in 2050; 64.1% 2070 (RCP 4.5); and 63.6% in 2050, 20.3% in 2070 (RCP 8.5). A minimum shrinkage by 58% in the mean habitat patch size is predicted. A list of protected areas important for conservation of the species from the habitat connectivity perspective was extracted. The HL was predicted to shift both longitudinally as well as along the latitude, in the landscape, confirming effects of climate change on the species. The HL was also predicted to find refuge under climate change in areas that are not presently protected forests, suggesting management of the refugia would be needed in future.

Keywords

• Climate change
• Ensemble modelling
• Himalaya
• Langur
• Patch metrics
• Protected areas