ESR 24:95-103 (2014)  -  DOI: https://doi.org/10.3354/esr00585

Densities, distribution and detectability of a small nocturnal primate (Javan slow loris Nycticebus javanicus) in a montane rainforest

K. Anne-Isola Nekaris1, Jarot Arisona Aji Pambudi2, Dwi Susanto2, Ridwan Djaffar Ahmad1,2, Vincent Nijman1,*

1Noctural Primate Research Group, Oxford Brookes University, OX3 0BP Oxford, UK
2Department of Biology, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok 16424, Indonesia
*Corresponding author:

ABSTRACT: Nocturnal mammals can be challenging to survey and, especially for many species that live in dense forest habitats, limited information is available on densities and distributions. We surveyed the endemic Javan slow loris Nycticebus javanicus in the montane forests of Mount Gede Pangrango, West Java, Indonesia. Surveys were conducted on 23 transects (260 h covering some 93 km) walking at variable speeds between 200 and 800 m h-1. Densities on individual transects varied from 0 to 52 ind. km-2, with an overall density of 15.6 ind. km-2 (95% CI 9.7 to 25.2 ind. km-2). Encounter rates per kilometre were strongly influenced by the speed at which transects were walked, with fewer lorises detected at higher speeds. This effect was absent when considering encounter rates per hour. Detectability and behavior of Javan slow lorises were not affected by the amount of lunar light and, in contrast to studies of some of their congeners, we found no evidence of lunar phobia or lunar philia. Our study shows that slow lorises are not homogeneously distributed in their montane habitat and occur at intermediate densities. However, encounter rates did not differ between disturbed and primary forest. Analysis of data from multiple surveys of lorisforms, including this one, reveals no statistically significant relationship between survey effort or the speed at which transects are walked and estimated densities, but speed is positively correlated with encounter rates.


KEY WORDS: Indonesia · Survey methods · Lunar phobia · Mammal · Conservation · Ecology


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Cite this article as: Nekaris KAI, Pambudi JAA, Susanto D, Ahmad RD, Nijman V (2014) Densities, distribution and detectability of a small nocturnal primate (Javan slow loris Nycticebus javanicus) in a montane rainforest. Endang Species Res 24:95-103. https://doi.org/10.3354/esr00585

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