The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)


Living together in the night: abundance and habitat use of sympatric and allopatric populations of slow lorises and tarsiers (Nycticebus and Tarsius)

RACHEL A. MUNDS1, K.A.I NEKARIS2, VINCENT NIJMAN2 and BENOIT GOOSSENS3,4.

1Anthropology, University of Missouri, 2Anthropology and Geography, Oxford Brookes University, 3Danau Girang Field Centre, Sabah Wildlife Department, 4Organims and Environment Division, Cardiff University

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Throughout much of Asia slow lorises (Nycticebus) and tarsiers (Tarsius) live allopatrically but on several islands they occur in sympatry. As habitats dwindle, competition for resources may increase within the area of sympatry. An understanding of how they are coping with competition is necessary for conservation measures. To address this we gathered data on the abundances and vertical strata preferences of slow loris and tarsier species from the literature. We predict sympatric species will favour different heights from congeners. Allopatric species will have lower abundances compared to sympatric species. In addition, we studied tarsiers and lorises in sympatry in Sabah, Borneo. We estimated abundances of Bornean lorises (Nycticebus menagensis) and Western tarsiers (Tarsius bancanus borneanus) and investigated habitat use. Through the literature review we found lorises do not vary in densities, whether allopatric or sympatric. Abundances of sympatric and allopatric tarsiers were significant (sympatric: 3-27 individuals/km2, allopatric: 57-268 individuals/ km2). Vertical strata use of sympatric and allopatric tarsier populations was not significant, but was for sympatric and allopatric loris populations (p=0.036). On a small scale estimated densities of Bornean lorsies were 5.105 slow lorises/km² and 3.646 individuals/km² for Western tarsiers. Slow lorises favoured the upper and middle level of the forest (10-30 m) and tarsiers the lower levels (<5 m). In our analysis of vegetation plots we found that tree heights and diameter at breast height preferences differed between genera. Results indicate sympatric genera are able to share their nocturnal environment due to niche separation.

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