Spectactled langur

Scientific name:

Trachypithecus obscurus

Threat level:

Near threatened

Authority:

Thomas & Wroughton, 1909

Common names:

• Dusky leaf monkey (English)
• Spectacled leaf monkey (English)
• Spectacled langur (English)
• Dusky leaf monkey (English)
• Dusky langur (English)
• Dusky leaf-monkey (English)
• Langur obscuro (Spanish)

Taxonomy:

It may be that the blackish insular subspecies (halonifer, carbo, styx, seimundi) represent a distinct taxon which has been entirely replaced on the mainland by the contrastingly toned T. obscurus.

Taxonomy synonyms:

Version:

3.1

Year assessed:

2008

Assessor(s):

Boonratana, R., Traeholt, C., Brockelmann, W. & Htun, S.

Evaluator(s):

Mittermeier, R.A. & Rylands, A.B. (Primate Red List Authority)

Justification:

Considering the extensive habitat loss that has taken place within the range of the species, there is reason to believe that this species is in decline, probably at a rate of less than 30% over three generations (approximately 30 years), thus qualifying if for listing as Near Threatened. Almost qualifies as threatened under criterion A2cd.

Geographic ranges:

• Malaysia (Native)
• Myanmar (Native)
• Thailand (Native)

Population:

On the mainland, at five sites surveyed (Kuala Lompat, Pasoh, Sungai Kenyam, Ulu Sebol, and Lesong) the density was estimated 1.8-7.3 groups/km², with an average group size of 14. A population at Khao Lommuak (11°49’N) numbered 80 individuals in an area of 0.5 km². The population status of several of the insular forms (Penang, Langkawi, Dayang Bunting, Terutau, East Perhentian, Pennan) is unclear, but most are presumed to be stable.

Population trend:

Decreasing

Habitat and ecology:

This species prefers closed primary forests, but is also found in old-growth secondary and disturbed forests, urban areas, and parks. It is diurnal, primarily arboreal, and folivorous, although the diet is relatively varied and the animals will also consume fruit, flowers and other items. They are able to take advantage of unripe fruit, which have chemical defenses, by the same means that they break down toxins in plant leaves, using the bacteria found in their digestive system (MacKinnon and MacKinnon 1980).

Ecosystems

• Terrestrial

List of habitats:

• Forest
• Subtropical/Tropical Moist Lowland
• Subtropical/Tropical Moist Montane
• Artificial/Terrestrial
• Rural Gardens
• Urban Areas
• Subtropical/Tropical Heavily Degraded Former Forest

Major threats:

Hunting for food is a major threat, as is habitat loss and degradation due to expanding oil palm plantations, agriculture, and urbanization. In Peninsular Malaysia the animals are frequent victims of road-kill.

List of threats:

• Residential & commercial development
• Housing & urban areas
• Agriculture & aquaculture
• Annual & perennial non-timber crops
• Shifting agriculture
• Small-holder farming
• Agro-industry farming
• Wood & pulp plantations
• Agro-industry plantations
• Transportation & service corridors
• Roads & railroads
• Biological resource use
• Hunting & trapping terrestrial animals
• Intentional use (species is the target)
• Motivation Unknown/Unrecorded

Conservation actions:

This species is listed on CITES Appendix II. It is known to occur in a number of protected areas, including: Krau Wildlife Reserve, Taman Negara National Park (Malaysia); Kaeng Krachan National Park, Khao Sam Roi Yot National Park, Khao Sok National Park, Taratau National Park (Thailand). It is relatively common in captivity. There is a need for further survey work to determine the current population status of the insular forms.

List of conservation actions:

• Land/water protection
• Site/area protection
• Land/water management
• Site/area management
• Species management
• Species management
• Harvest management
• Law & policy
• Legislation
• National level