Far from home: The synurbisation of a rainforest-evolved primate, the lion-tailed macaque Macaca silenus, and its recent adaptations to anthropogenic habitats in southern India

Abstract

The lion-tailed macaque is an endangered species, endemic to the Western Ghats of southern India. The Anamalai hills harbour 63 groups of the species, several of which occur in rainforest fragments, amidst tea and coffee plantations, on the Valparai plateau. Being highly arboreal, these populations have always been assumed to be largely restricted to their fragmented forest patches and possibly unable to navigate successfully through the surrounding plantation–human habitation matrix. While adult males have occasionally been sighted along roadsides between forest fragments, we now provide evidence for the emigration of an entire troop out of a forest fragment into nearby human settlements, leading to the inclusion of areas completely devoid of natural vegetation into the core home range of the troop. We argue that a combination of hostile inter-troop encounters, a natural urge to expand their range and the discovery of novel and relatively easily accessible food resources may have led to such unusual ranging patterns, accompanied by significant changes in troop behavioural profiles, which we consider as inexorable processes of synurbisation.