Abstract
To clarify the present distribution of Proboscis Monkey Nasalis larvarus from the River Mahakam to the Bay of Balikpapan, about 500,000 ha was surveyed.
Forest of rivers, swamp, mangrove and lowland were researched by using a boat or walking. When the monkeys were observed, first individual numbers were recorded, then I tried to identify sex and age. Also field signs were collected.
In total Proboscis Monkeys were confirmed at 88 points, and 67 of them were the groups, 11 were subgroups and l0 were solitaries. Population size was l0-35, and the average was l5.2 individuals. More than one male adult were observed in seven of 40 groups in which male adults were confirmed.
Only in the Mahakam delta, the habitat is kept in good condition for Proboscis Monkeys, and also many groups were distributed there. Although it is a desirable condition now for monkeys, there are many possibilities that it will be developed for cultivation of shrimp in future. So we should make a good plan in order to realize the coexistence development for people and the preservation of Proboscis Monkeys. For that purpose, detailed all-out research of this area is certainly needed in future.
