Habitat selection of Western purple faced langurs (Semnopithecus vetulus nestor) in relation to land use patterns
University Of Colombo
Semnopithecus vetulus nestor is an endemic primate of Sri Lanka that is listed as critically endangered and one of the 25 most endangered primates in the world. Majority of its population survive in an area with high human density and therefore its habitat is subjected to constant change due to anthropogenic activities. This research was carried out to study habitat selection of these langurs with relation to different land use types.
Study focused on two langur groups, Malabe-M1 (high human use) and Pannipitiya-P1 (Low human use) from May to August 2012. Data were collected using scan sample method. Group was observed for 5 minutes followed by a 10 minute break from 0600h to 1800h. In each scan sample GPS point of the location, land use type, substrate occupied and behaviours of each individual were recorded. Habitat and substrate selection was evaluated using Manly-Chesson selectivity index.
There is definite habitat selection despite the availability of it in the home range. This behaviour is influenced by presence of canopy cover, level of human activities and food plant distribution. The composition of the diet of the two groups showed that there is high adaptability to the food plants available in specific habitat types and shows high amount of flexibility.
Home range of both groups had distinct boundaries, beyond which the home range cannot be expanded due to the presence of uninhabitable land use types such as paddy fields and marsh lands. Current development pattern of the area shows that available habitat types may further change due to human activities that will result in fragmentation of home ranges, which could lead to the disappearance of these animals from those areas.