Proboscis Monkey

Project Description

Proboscis monkey / Bangkatan / Monyet Belanda (Nasalis larvatus)

IUCN Red List category & criteria: Endangered A2c ver 3.1

Recent publications:

Nasalization by Nasalis larvatus: Larger noses audiovisually advertise conspecifics in proboscis monkeys.

Habitat use and movement of proboscis monkeys (Nasalis larvatus) in a degraded and human-modified forest landscape.

Combining drones and satellite tracking as an effective tool for informing policy change in riparian habitats: a proboscis monkey case study.

Evaluating methods for estimating home ranges using GPS collars: a comparison using proboscis monkeys (Nasalis larvatus).

Use and Selection of Sleeping Sites by Proboscis Monkeys, Nasalis larvatus, along the Kinabatangan River, Sabah, Malaysia.

Endemic to the Island of Borneo, the proboscis monkey (Nasalis larvatus) is an endangered primate species, mostly threatened by the habitat loss and fragmentation. They are found in riverine, mangrove, freshwater and peat swamp forests, areas which tend to be first colonized, farmed, industrialized and least protected by man. Although the movement and dispersal of proboscis monkeys is not restricted by water, populations become isolated due to the increasing loss of habitat by logging and agriculture (palm oil plantations). Proboscis monkeys are selective feeders that follow the leaf-eating pattern among colobines, therefore increasing their vulnerability to habitat loss and degradation.

Proboscis Monkey Conservation Program

Principal Investigator: Benoît Goossens

In 2005, an extensive state wide survey was conducted to establish the population status and to assess the threats to the survival of this species in Sabah (Sha et al. 2008). The population size was estimated to a minimum of 5,907 individuals found along major coastal river systems in Sabah. The distribution of the proboscis monkeys appeared highly fragmented, with only five major centers of continuous distribution (three on the east coast, one on the west coast, and one in the south of the state) and numerous small isolated populations. Moreover, only 15.3% of the population estimated was found within protected forest reserves, with much of the species’ diminishing range habitats exposed to further conversion, extraction and disturbance.

The Proboscis Monkey Conservation Program aims to gain better understanding of the current demographic, genetic and health status of this species populations.

Main objectives:

1) Research and conservation of one of the most charismatic (and endemic) primate species of Borneo, the proboscis monkey.

2) Rescue and translocation operations of pocketed populations of proboscis monkeys in unviable habitats.

3) Promote the restoration and re-establishment of wildlife corridors along large rivers in Sabah that will be emphasized during an international workshop at the end of the project.

4) Increase the capacity in conservation biology and wildlife management within the Sabah Wildlife Department through high-education training of a senior wildlife officer, one SWD/DGFC veterinarian, and one international PhD student.

Samples and data are being collected from proboscis monkeys from all the five major centres throughout Sabah. The project team is capturing and sampling between 5 and 15 individuals per population. The samples include blood, saliva, urine and faeces; ecto-parasites and morphometric data are also being collected. Some of the analyses being made include blood biochemistry, nutrition, population genetics, and parasite and virus identification. In addition, satellite collars were deployed on individuals from different populations, and the forest quality and its level of disturbance is being quantified with the aid of drones (Unmmaned Aerial Vehicles).

In February 2017, an international workshop has been held on the conservation of the proboscis monkey in Borneo to present the results of the work carried out on the species and to discuss these results with all stakeholders involved in the conservation of the proboscis monkey. A Population and Habitat Viability Assessment (PHVA) for the taxon was also carried out before the workshop encompasing population-specific management goals, the results of the PHVA have also been presented at the workshop. Two significant outputs resulting from this workshop will be the production of a Resolution to be tabled before the State Cabinet of Sabah and the production of a final State Action and Management Plan for the proboscis monkeys. We will also stress out the importance of wildlife corridors along the main rivers in the country that will benefit not only for the proboscis monkey but also for other endangered species such as orang-utans, Bornean elephants, eight species of hornbills, etc.

Projects within the Proboscis Monkey Conservation Program

Eco-ethology of proboscis monkey, Nasalis larvatus, and assessment of its role in forest regeneration along the Kinabatangan River

PhD Candidate: Valentine Thiry

Institution: Université Libre de Bruxelles

Supervisors: Martine Vercauteren, Roseline C. Benudel-Jamar, Benoît Goossens

Duration: October 2014 – October 2018

Valentine is studying proboscis monkeys, and their feeding ecology in particular. She makes her behavioural and ecological observations along the Kinabatangan riverside, and collects faecal samples every morning at sleeping sites. She will study proboscis monkey’s diet using the DNA metabarcoding methodology by comparing short chloroplast DNA sequences found in faeces to a plant DNA Database (a database she builds along the way for this purpose). Her aim is to identify proboscis monkey’s food items in the Kinabatangan fragmented landscape and to study the seasonal dietary variations throughout the year. Interested in the role proboscis monkeys could potentially play in seed dispersal, she will also investigate faecal samples for their content in seeds and set up different germination tests. Finally, she will study how the phytochemical composition of leaves varies between consumed and not-consumed plant species, with a gradient distance to the river.

The project aims to determine which the key plant species for N. larvatus are in the fragmented landscape of the Lower Kinabatangan Wildlife Sanctuary and to contribute to the conservation of this endangered species.