Future simulated landscape predicts habitat loss for the Golden Langur (Trachypithecus geei): A range level analysis...

Trachypithecus geei Khajuria, 1956 or Golden langur are an endangered colobine primate species that are distributed in the transboundary region of Bhutan and India. The species is severely threatened because of increasing habitat fragmentation and isolation across its entire range, especially the populations in Assam, India. The distribution range of the species has not been updated for the last two decades, nor is there any proper evaluation of the habitat requirements for the species. Therefore, we mapped the habitat suitability for the species across its entire distribution and projected its habitat suitability on the simulated landscape for the future (2031). The results indicate that out of the total range extent (66,320 km²), only 12,265 km² (18.49%) is suitable for the species at present, which will further be reduced to 8884 km² by the year 2031, indicating major range contraction. These suitable habitats are largely scattered and fragmented in southern range of the species. Among the predictors used, the distance to evergreen and deciduous broadleaf forest was the strongest predictor out of the 35 used for model building. Moreover, land use and land cover were found to be more informative than the climatic variables. Much of the suitable habitats of the species are located outside the protected area network in the landscape. Therefore, we identified landscape configurations and suitable habitat areas for the future conservation and monitoring of Golden Langur in the protected areas of its range.