Distribution of arboreal nocturnal mammals in northern Borneo

This study aimed to determine the distribution of arboreal nocturnal mammals in northern Borneo, in particular the Bornean Striped Palm Civet Arctogalidia stigmatica, Philippine Slow Loris Nycticebus menagensis, Western Tarsier Cephalophacus bancanus, Bornean Colugo Galeopterus borneanus and Island Palm Civet Paradoxurus philippinensis. Nocturnal mammals were surveyed at six sites in northern Borneo of varying habitat types and patterns of disturbance. Standardised point and line transects following predetermined paths were used and mammals searched for with the aid of a thermal imaging camera, a red-filtered head lamp and alternatively, a white light head lamp. With 49% of the observations, A. stigmatica (36 individuals/6 sites) was the most common species across the study sites, followed in abundance by N. menagensis (16/5), C. bancanus (14/3), G. borneanus (11/3) and P. philippinensis (2/2). The highest arboreal mammal density of 4.4 individuals/km was found at our Kiudang study site in Tutong District. In addition to the five focal arboreal mammals, 20 additional species were observed throughout the study. This study reveals variation in arboreal nocturnal mammal presence with habitat type that is likely influenced by diet preferences, habitat fragmentation, and the level of hunting pressure. Further surveys combined with arboreal camera trapping will be necessary to study the secretive and easily disturbed arboreal nocturnal mammals of Borneo.