Presbytis potenziani

Taxonomy (Name)

Picture

Distribution, Range

This species is found on the Mentawai Islands, off the western coast of Sumatra, Indonesia (Fuentes 1996). The subspecies P. p. potenziani is found on Sipora, North Pagai, and South Pagai Islands, while the subspecies P. p. siberu is found on the island of Siberut (Brandon-Jones 1993).

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Map

Country

Brunei Darussalam
Cambodia
China
Indonesia	IUCN
Japan
Lao PDR
Malaysia
Myanmar
Mongolia
Philippines
Singapore
Republic of Korea
Thailand
Vietnam

Status

International Status

IUCN Red List Category

ENIUCN

Justification

The species is considered Endangered due to a past and continued population decline, estimated at more that 50% over the past 40 years (approximately 3 generations) due to hunting and loss of habitat (Whittaker 2006).

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CITES

CMS

National Status

Ecology Discription

Appearance

Habitat

These animals are found predominantly in primary forest areas, but also utilize secondary and cultivated habitats to a lesser extent. They are arboreal and favor the middle and upper canopies.

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Population size

The Siberut subspecies is estimated to comprise 1,600-9,500 individuals (Whittaker 2006), based on a population density estimate of 1 to 4 individuals/km2 (Paciulli 2004). The southern subspecies has a much smaller population of only 100-800 individuals across the three islands. In 1980, there were an estimated 46,000 individuals on Siberut, representing a decline of 83 to 97% (Whittaker 2006). Further consideration had determined that these estimates may be higher due to difficulty of detection, and that the actual decline is closer to 50% (Whittaker pers. comm.). However, the animals may have adapted to hunting by becoming cryptic, causing current population estimates to be low (Whittaker 2006). Thus, there may be as many as 36,000 individuals for the species as a whole, representing a decline of only 43% (Whittaker 2006). They appear to reach their highest densities in forests logged 10 years ago (Whittaker 2006).

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Behavior

Its home range in a site on North Pagai Island was 25-40 ha (Fuentes 1996); elsewhere the home range has been recorded as 11.5-40 ha.

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Diet

As a colobine monkey, P. potenziani is highly folivorous, feeding on leaves (55% of diet), fruits and seeds (32%), and or flowers, bark, and sap (13%) (Fuentes 1996). A large proportion of its total diet, up to 35%, consists of "climber"-type vegetation.

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Reproduction

Threat

Major Threat(s)

This species is threatened mainly by hunting and commercial logging (Whittaker 2006), as well as conversion to oil palm plantations, forest clearing, and product extraction by local people (Whittaker 2006). Recently, hunting pressure has intensified because of increased access to remote areas due to logging roads and tracks, as well as the replacement of bows and arrows with .177 caliber air rifles, anything larger is illegal in Indonesia (Whittaker 2006). Also, local rituals and taboos that formerly regulated hunting have been replaced by Christianity (Whittaker 2006). The pet trade constitutes a minor threat to this species (Whittaker 2006).

Conservation and Measurement

International

This species is listed on CITES Appendix I.IUCN

National

This species is protected by Indonesian law.IUCN

Conservation law

Protected Area

It is only known from one official protected area, Siberut National Park. There are no specimens in captivity.

IUCN

Other Coservation Projects

Whittaker (2006) suggests the following conservation actions: increased protection for Siberut National Park, which currently lacks enforcement; formal protection of the Peleonan forest in North Siberut, which is home to unusually high primate populations and is easily accessible; protection of areas in the Pagai Islands by cooperating with a logging corporation that has practiced sustainable logging technique there since 1971; conservation education, especially regarding hunting; the development of alternative economic models for the local people to reduce the likelihood of selling off their lands to logging companies.

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Citation

Brandon-Jones, D. 1993. The taxonomic affinities of the Mentawai Islands sureli, Presbytis potenziani (Bonaparte, 1856) (Mammalia: primates Cercopithecidae). Raffles Bulletin of Zoology 41(2): 331?357.

Fuentes, A. 1996. Feeding and ranging in the Mentawai Island langur (Presbytis potenziani). International Journal of Primatology 17(4): 525 ? 548.

Groves, C. P. 2001. Primate taxonomy. Smithsonian Institution Press, Washington, DC, USA.

Paciulli, L. 2004. The effects of logging, hunting, and vegetation on the densities of the Pagai, Mentawai Islands primates. Thesis, State University of New York.

Tilson, R. 1976. Infant coloration and taxonomic affinity of the Mentawai Islands leaf monkey, Presbytis potenziani. Journal of Mammalogy 57(4): 766 ? 769.

Watanabe, K. 1981. Variations in group composition and population density of the two sympatric Mentawaian leaf-monkeys. Primates 22(2): 145?160.

Whittaker, D. 2006. A conservation action plan for the Mentawai primates. Primate Conservation 20: 95-105.

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