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Presbytis thomasi

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA PRIMATES CERCOPITHECIDAE

Scientific Name: Presbytis thomasi
Species Authority: (Collett, 1892)
Common Name/s:
English Thomas’s Langur, North Sumatran Leaf Monkey, Thomas's Langur, Sumatran Grizzled Langur, Thomas's Leaf Monkey
French Semnopithèque De Thomas
Spanish Langur De Thomas
Synonym/s:
Presbytis nubilus Miller, 1942

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2c ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor/s: Supriatna, J. & Mittermeier, R.A.
Reviewer/s: Mittermeier, R.A. & Rylands, A.B. (Primate Red List Authority)
Justification:
The species is considered Vulnerable due to past and continued population declines, estimated at more that 30% over the past 40 years (3 generations) due to loss of habitat, especially to logging and oil palm plantations.

Geographic Range [top]

Range Description: This species is found in northern Sumatra (Indonesia) in Aceh Province north of the rivers Simpangkiri and Wampu (Wilson and Wilson 1976), where the range has recently been discovered to extend to the south bank of the Simpangkiri River (Aimi and Bakar 1996). A study on the behaviour of this species was performed at Ketambe Research Station, Leuser Ecosystem, Sumatra, Indonesia (3°41 N, 97°39 E) (Sterck et al. 2005). Another study on its behaviour was performed at two sites in Leuser Ecosystem, northern Sumatra, one of which was also Ketambe, and the other was Bukit Lawang (3°30 N, 98°6 E) (Wich and de Vries 2006).
Countries:
Native:
Indonesia (Sumatera)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: During a study of this species? behaviour by Sterck et al. (2005) 163 different individuals were recorded, in a study area of 200 ha.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species has been recorded from undisturbed primary rainforest near Ketambe Research Station in Sumatra (Sterck et al. 2005). It has also been recorded from a mosaic of primary and secondary forest with rubber plantations on its fringes (Wich and de Vries 2006), and in rubber tree plantations (Gurmaya 1986). It ranges in elevation from 0 to approximately 1,500 m, and the home range has been observed to be 12.3-15.7 ha.

These animals are primarily folivorous (Ungar 1995) but also feed on fruits and flowers, and occasionally on toadstools and the stalks of coconuts (Gurmaya 1986), as well as gastropods such as ground snails (Steenbeek 1999). Females are considered adult at an age of 60 months, roughly one year before the average age at which infants were born (74 months), and the youngest age at which a female in a study population gave birth (Sterck et al. 2005).
Systems: Terrestrial

Threats [top]

Major Threat(s): Hunting does not seem to be a significant threat, but loss of primary habitat due to logging and conversion to oil palm plantations is probably displacing some populations.

Conservation Actions [top]

Conservation Actions: This species is listed on CITES Appendix II and is protected by Indonesian law. It is known to occur in at least one large national park, Gunung Leuser.
Citation: Supriatna, J. & Mittermeier, R.A. 2008. Presbytis thomasi. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 18 April 2014.
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