Habitat use by western purple-faced langurs Trachypithecus vetulus nestor (Colobinae) in a fragmented suburban landscape

Abstract

As natural habitats around the globe disappear, humans and non-human primates become increasingly engaged in complex interactions, both peaceful and hostile. Sri Lanka's endemic western purple-faced langur Trachypithecus vetulus nestor persists in the majority of its range in complete sympatry with humans. Listed as Critically Endangered by the IUCN and one of the world's top 25 most endangered primates, their survival appears dependent on the tolerance of humans with whom they coexist. Our aims were to augment the limited information on T. v. nestor focusing on group composition and behavioural adaptations in relation to its heavily fragmented habitat. Research was carried out in Talangama Wetlands, Sri Lanka in 2007. The 5 groups varied in size from 11 to 19 individuals Monkeys regularly used fences, rooftops, power lines, and agricultural trees. Two groups of 19 and 16 individuals had home ranges of 3.06 and 2.86 ha respectively. They consumed a variety of foods including fruits, showing dietary flexibility; the fruits and leaves of Arctocarpus heterophyllus were the langurs' most frequently consumed foods. The langurs seem to be adapting to these human-modified environments. Notwithstanding, areas for concern include potentially fatal dangers when crossing between fragments, increasing human-primate conflict and intergroup conflict, and permanent genetic isolation. © Inter-Research 2010.