Ranging Pattern of Western Purple-Faced Langurs (Semnopithecus vetulus nestor) in Human Modified Landscapes
Presented by: Chathuranga Deshapriya
University Of Sri JayewardenepuraAuthors
S. J. Cabral, C. I. Deshapriya, D. K. Weerakoon, S. W. Kotagama
Introduction: What conservation problem or question does your study address?
The western purple-faced langur (Semnopithecus vetulus nestor) is endemic to Sri Lanka and is considered as critically endangered. It has been considered as one of the 25 most endangered primates in the world due to rapid human induced habitat alterations. The aim of this study was to determine the ranging behavior with relation to food and substrate availability in human modified sub urban landscapes.
Methods: What were the main research methods you used?
Study was focused on two langur groups, M01 and P01 in two suburban habitats located in Malabe and Pannipitiya respectively in the Western Province of Sri Lanka. Data were collected using scan sample method, from May to August 2012. Group was observed for 5 minutes followed by a 10 minute break from 0600 hrs to 1800 hrs. In each scan sample GPS point of the location, land use type, substrate occupied and behaviors of each individual were recorded.The daily travel routes and home range maps were created and analysed using Arc GIS.
Results: What are your most important results?
Travel routes fall over arboreal pathways connecting canopy areas and buildings. Canopy of M1 are more fragmented resulting to travel longer distances to reach a particular part of the home range compared to P1. Canopy is over utilized while buildings and other substrates are underutilized. Use of substrates such as telephone wires, posts and ground were for traveling when other arboreal paths (canopy or buildings) were not available and it was too far to jump across.
Discussion: What are your important discussion points and what is the relevance of your results to conservation (if any)?
These primates are under threat as their arboreal paths are being disturbed by fragmentation. They sometimes even tend to use unsuitable substrates such as electric wires and the ground which exposes them to dangers such as electrocution and being chased and bitten by dogs. Although they are adapted to survive in urbanized landscapes their home range size could reduce in considerable proportions due to disappearance of canopy that keep their home range intact.