Use of space by proboscis monkey (Nasalis larvatus Wurmb) on to Isolated Habitat in Kuala Samboja, East Kalimantan

Abstract

Proboscis monkeys (Nasalis larvatus Wurmb) is an endemic primate species to the island of Borneo and has been classified as endangered species by IUCN. Fourty percent of this habitat has been lost and only 4.1% of this habitat occurs within designated conservation areas. Kuala Samboja River is an unprotected habitat of proboscis monkey. This area was narrow, isolated, and fragmented. The objectives of the research were to obtain habitat conditions, population, food source, and space use. Data were collected through vegetation analysis by line-plot sampling method, activity budget and use of space by instantaneous sampling method, whereas food sources by individual activity records of feeding (IARF) method. The groups were observed were Stan, Zacky, and Raja. The results of this study showed that the community of habitat are dominated by Sonneratia caseolaris, Cerbera manghas, Vitex pinnata, and Elaeocarpus stipularis. Twenty one of plant species were found as food sources, five of those were preferred i.e. S. caseolaris, V. pinnata, Deris sp., Hevea braziliensis, and Avicenia cf. officinalis. The population of proboscis monkey more than 143 monkeys, 98 monkeys divided to 9 groups (6 one-male groups, 3 all-male groups), whereas 45 monkeys unidentified. Generally, the monkeys spent more time for feeding in the morning and afternoon and resting in noonday. Feeding and moving activity of female greater than male but resting was lesser, whereas social activity was done by female only. Each mean daily range groups were 289 m (Stan), 260 m (Zacky), and 449 m (Raja), while home range size were 4.92, 4.52, and 6.92 ha, respectively. The groups of Stan, Zacky and Raja spent most of their time at heights of 9-12 m, 0-6 m, and 3-9 m, respectively. Use of canopy stratum influence by habitat conditions, temperature, blown of wind, and predators.