Population assessment methods for the sunda colugo Galeopterus variegatus (Mammalia: Dermoptera) in tropical forests and their viability in Singapore

Abstract

Colugos are arboreal folivores and are found in tropical rainforests of Southeast Asia. Despite their discovery roughly 200 years ago, colugos attracted relatively little scientific attention. Given the importance of population estimates in conservation decision-making, it is surprising that no colugo has been surveyed in tropical forest habitats. In this study, we assessed the possibility of using distancesampling for estimating population size of Sunda Colugo (Galeopterus variegatus) in the protected forests of Singapore, and also compared this method with estimates from fixed-width strip transect. We found that key assumptions of distance-sampling were not violated and the method provided relatively more precise estimates than fixed-width strip transect. The population density estimate obtained was 0.535 (± 0.104) individuals per ha, and this translates to an estimated 1,074 ± 209 individuals within the 2,007 ha of protected forests in Singapore. We recommend the use of distance-sampling for the long-term monitoring of colugo populations and also discuss the viability of the species in Singapore. © National University of Singapore.