Patterns and determinants of mammal species occurrence in India

Abstract

1. Many Indian mammals face range contraction and extinction, but assessments of their population status are hindered by the lack of reliable distribution data and range maps. 2. We estimated the current geographical ranges of 20 species of large mammals by applying occupancy models to data from country-wide expert. We modelled species in relation to ecological and social covariates (protected areas, landscape characteristics and human influences) based on a priori hypotheses about plausible determinants of mammalian distribution patterns. 3. We demonstrated that failure to incorporate detection probability in distribution survey methods underestimated habitat occupancy for all species. 4. Protected areas were important for the distribution of 16 species. However, for many species much of their current range remains unprotected. The availability of evergreen forests was important for the occurrence of 14 species, temperate forests for six species, deciduous forests for 15 species and higher altitude habitats for two species. Low human population density was critical for the occurrence of five species, while culturally based tolerance was important for the occurrence of nine other species. 5. Rhino Rhinoceros unicornis, gaur Bos gaurus and elephant Elephas maximus showed the most restricted ranges among herbivores, and sun bear Helarctos malayanus, brown bear Ursus arctos and tiger Panthera tigris were most restricted among carnivores. While cultural tolerance has helped the survival of some mammals, legal protection has been critically associated with occurrence of most species. 6. Synthesis and applications. Extent of range is an important determinant of species conservation status. Understanding the relationship of species occurrence with ecological and socio-cultural covariates is important for identification and management of key conservation areas. The combination of occupancy models with field data from country-wide experts enables reliable estimation of species range and habitat associations for conservation at regional scales.