Population of Proboscis Monkey (Nasalis lavatus) in Manggar River, Balikpapan City, Indonesia

Abstract

A population estimation of proboscis monkeys (Nasalis larvatus) has been conducted in Manggar River, Balikpapan. In this non-conservation area, the anthropogenic activities threaten the proboscis monkey habitat. Boat survey technique was applied along ± 17 km of the river in the morning and evening. The number of proboscis monkeys in the surveyed area was estimated to range from 57 to 69 individuals with estimated population density of 4.75 individuals/Km2. Moreover, the population of this primates was divided into 4 groups and the sex ratio between adult males and females was 1:2.33. The proboscis monkeys were distributed in the middle of the river to the upstream. The highest population was found in the upstream area with less human activities. Conservation efforts in the Manggar River need to be carried out considering the proboscis monkey habitat in the area has been fragmented and isolated. These efforts could involve local economic communities.

Habitat use of proboscis monkey (Nasalis larvatus) in production forests of West Kalimantan, Indonesia

“…Proboscis monkey habitat was, however, distributed in the middle to the upper reaches of the river, with the upper reaches of the river almost never being traversed by humans. This is in accordance with the findings of Mediawati et al (2021) that the distribution of proboscis monkeys tends to be upstream because it avoids human activities on the Manggar River.…”

Locating the unique biodiversity of Balikpapan Bay as an ecotourism attraction in East Kalimantan, Indonesia

“…Data were collected using a Boat Survey method by tracking along the Bay and the river flowing into it (Atmoko et al 2014(Atmoko et al , 2021Lahjie et al 2019;Mediawati et al 2021a;Mediawati et al 2021b). The direct field observations included 10-19 observation points.…”

“…Natural ecosystems in the Balikpapan Bay area offer many opportunities for development as tourist attractions. The Bay provides a unique natural panorama that includes tropical rain forest, mangrove forest, freshwater swamp forest, sandy beaches, and beautiful estuaries, all of which can be found within the area between the hinterland and coastline of the Bay (Mediawati et al 2021a;Mediawati et al 2021b). Kristiningrum et al (2019) stated that in Mentawir Village, which is one of the villages included in the Balikpapan Bay area, there is a mangrove forest with 12 mangrove species.…”