Determinants of habitat occupancy and spatial segregation of primates in the central Western Ghats, India.

Abstract

Primates are among the globally imperiled fauna requiring urgent conservation interventions to protect their habitat. Information on species distribution and factors influencing it are vital to species management and habitat protection. In this study, we assessed habitat occupancy of the lion-tailed macaque (Macaca silenus), bonnet macaque (M. radiata), and black-footed gray langur (Semnopithecus hypoleucos) that occur in the Kudremukh Wildlife Division, a large protected area network in the central Western Ghats. We examined the influence of habitat variables on the occupancy probability of these primates. We carried out four temporally replicated detection/non-detection surveys to assess detection probability and site occupancy of the primate species. We surveyed 244 sites of 5 Km2, with each site surveyed for 4 days, to assess detection probability and site occupancy. Among the three species, the langur had the highest habitat occupancy estimate (0.66 ± 0.05SE) and the lion-tailed macaque had the lowest estimate (0.28 ± 0.08SE). The habitat occupancy estimate for the bonnet macaque was (0.56 ± 0.05SE). Wet and semi-evergreen forest cover and mean elevation positively influenced the lion-tailed macaque's occurrence. Covariates influencing bonnet macaque's occurrence were plantations, semi-evergreen and moist deciduous forests, and non-forest areas. Mean elevation negatively affected its occurrence. Wet evergreen forests and plantations positively influenced the occurrence of the langur. We examined spatial segregation between the species based on their site occupancy. Pairwise comparisons revealed a significant negative association between the bonnet macaque and the other two primates. However, we found a significant positive association between the lion-tailed macaque and the langur. We discuss these results and their implications for conservation of primates in the region. Given the cost-effectiveness of carrying out surveys at large spatial scales, we recommend occupancy surveys for future surveys of forest primates.