RESEARCH ARTICLE

GROUP CHARACTERISTICS AND HOME RANGE SIZE OF THE WESTERN PURPLE-FACED LANGUR (Semnopithecus vetulus nestor) IN A HUMAN-MODIFIED LANDSCAPE

Abstract

The endemic Western Purple-faced Langur, Semnopithecus vetulus nestor, distributed in the south-western wet zone of Sri Lanka, has been categorized as one of the 25 most threatened primates in the world. The present study sought to examine group size and composition and home range size of selected langur groups in human-modified landscapes within the Colombo district. Six groups inhabiting the area from Delkanda to Homagama were selected for the study conducted during April to November 2016. The animals were observed from 0600 to 1800 h and the locations of each group were geo-referenced every 15 mins over six consecutive days. The group size of the six groups varied from 5 to 18, with a mean group size of 10.7 individuals. With the exception one group, there were more adults than sub-adults or juveniles. The overall sex ratios of the groups deviated from 1:1, moving towards a polygyny structure. Home ranges varied in size from 0.51 to 4.32 ha, and they represented a mosaic human-modified landscape. No significant relation was found between group size and the extent of the home ranges. It was interesting that only between 7.6 to 21.2 % of the home ranges were utilized intensively by the langurs. These core areas, where use was intensive, consisted of relatively small patches spread across the home range. A comparison of the space use patterns of the langurs as observed in the present study with those of langurs inhabiting the remaining wet zone forests would shed some light on the factors that drive home range use.

Keywords: group size, home range, Semnopithecus vetulus nestor, urban landscape

How to Cite: Weerakkody,W.A.D.S.N,Weerakoon,D.K,Wijesinghe,M.R, (2018). GROUP CHARACTERISTICS AND HOME RANGE SIZE OF THE WESTERN PURPLE-FACED LANGUR (Semnopithecus vetulus nestor) IN A HUMAN-MODIFIED LANDSCAPE.WILDLANKA, 6(2):Pages 036-047

Published On:2018-06-30

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