Hylobates klossii 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Primates Hylobatidae

Scientific Name: Hylobates klossii (Miller, 1903)
Common Name(s):
English Kloss’s Gibbon, Dwarf Gibbon, Kloss's Gibbon, Mentawai Gibbon
French Siamang De Kloss
Spanish Siamang Enano

Assessment Information [top]

Red List Category & Criteria: Endangered A2cd ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Whittaker, D. & Geissmann, T.
Reviewer(s): Mittermeier, R.A. & Rylands, A.B. (Primate Red List Authority)
Listed as Endangered due to a past and continued populations decline, estimated at more that 50% over the past 45 years (approximately 3 generations) due to hunting and loss of habitat.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is endemic to the four Mentawai Islands (Siberut, Sipora, North Pagai and South Pagai) off the west coast of Sumatra, Indonesia (Geissmann 1995; Groves 2000; Marshall and Sugardjito 1986).
Countries occurrence:
Indonesia (Sumatera)
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Whittaker (2005a,b) gathered population estimates on all four Mentawai Islands, using loud-call monitoring and forested area estimates to census the animals. The species population is estimated at 20,000 to 25,000 individuals remaining on the Mentawai Islands, where they are endemic (Whittaker 2005b, 2006), which amounts to a reduction in numbers of up to 50% since the last survey in 1980 (World Wildlife Fund 1980; MacKinnon 1986, 1987). Throughout the Mentawai Islands, density averaged 12 individuals/km2 (Whittaker 2005a, b). The largest remaining population, 13,000-15,000 individuals, is found in Siberut National Park (Whittaker 2005b, 2006).
Current Population Trend:Decreasing
Additional data:
Number of mature individuals:20000-25000
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This species is arboreal, diurnal, and omnivorous, though predominantly frugivorous (Whitten 1982a). Although disturbance levels in H. klossii habitat on the different islands are variable, a recent survey detected similar population densities in un-logged forests, forests logged 10 years ago, and those logged 20 years ago (Whittaker 2005; Paciulli 2004).

Gibbons in the Siberut area studied by both Tenaza (1974, 1975) and Tilson (1980) had unusually small average home ranges of 7-11 ha. A gibbon group studied in a different area on Siberut had a home range size of 32 ha, similar to that in other species of the genus Hylobates (Whitten 1980, 1982b).

Use and Trade [top]

Use and Trade: This species is collected for the pet trade.

Threats [top]

Major Threat(s): This species is threatened mainly by hunting and commercial logging (Whittaker 2006). It is also threatened by conversion to oil palm plantations, and forest clearing and product extraction by local people (Whittaker 2006). Recently, hunting pressure has increased 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 (Whittaker 2006). Also, local rituals and taboos which formerly regulated hunting have been replaced by Christianity (Whittaker 2006). The pet trade is also a threat to this species (Whittaker 2006). Although this may be a greater threat to this species than to other gibbons (D. Whittaker pers. comm.), it is rarely seen in the pet-trade in Java (Nijman 2005).

The extent of the threats from logging, hunting, and the pet trade faced by this species varies depending on location. The very large population in Siberut National Park, on central Siberut, lives in a protected area but is subject to moderate hunting pressure from local people. In the Peleonan forest, northern Siberut, the habitat was logged 20 years prior but faces low hunting pressure. This area is significant because four of the endemic Mentawai primates (H. klossii, Simias concolor, Presbytis potenziani and Macaca siberu) exist here in high densities. Populations in Saureinu, Sipora are subject to traditional use by locals but limited logging. In South Pagai, forest plots are selectively logged but there is high hunting pressure. Animals on North Pagai were not censused, but logging and hunting occurs there as well (Whittaker 2005b).

Conservation Actions [top]

Conservation Actions: This species is listed on CITES Appendix I, and is protected by Indonesian law. More than half of the remaining Kloss's gibbons reside in Siberut National Park, a government protected area. Whittaker (2005b, 2006) suggested the following conservation actions: 1) increased protection for Siberut National Park, which currently lacks enforcement, 2) formal protection of the Peleonan forest in North Siberut, which is home to unusually high primate populations and is easily accessible, 3) protection of areas in the Pagai Islands by cooperating with a logging corporation that has practiced sustainable logging technique there since 1971, 4) conservation education, especially regarding hunting, and 5) the development of alternative economic models for the local people to reduce the likelihood of selling off their lands to logging companies (Whittaker 2006).

Classifications [top]

1. Forest -> 1.6. Forest - Subtropical/Tropical Moist Lowland
suitability:Suitable  major importance:Yes
1. Land/water protection -> 1.1. Site/area protection
1. Land/water protection -> 1.2. Resource & habitat protection
2. Land/water management -> 2.1. Site/area management
3. Species management -> 3.1. Species management -> 3.1.1. Harvest management
4. Education & awareness -> 4.1. Formal education
4. Education & awareness -> 4.3. Awareness & communications
5. Law & policy -> 5.4. Compliance and enforcement -> 5.4.2. National level

In-Place Research, Monitoring and Planning
In-Place Land/Water Protection and Management
  Occur in at least one PA:Yes
In-Place Species Management
In-Place Education
  Included in international legislation:Yes
  Subject to any international management/trade controls:Yes
2. Agriculture & aquaculture -> 2.1. Annual & perennial non-timber crops -> 2.1.1. Shifting agriculture
♦ timing:Ongoing    
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

2. Agriculture & aquaculture -> 2.1. Annual & perennial non-timber crops -> 2.1.2. Small-holder farming
♦ timing:Ongoing    
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

2. Agriculture & aquaculture -> 2.1. Annual & perennial non-timber crops -> 2.1.3. Agro-industry farming
♦ timing:Ongoing    
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

2. Agriculture & aquaculture -> 2.2. Wood & pulp plantations -> 2.2.1. Small-holder plantations
♦ timing:Ongoing    
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

5. Biological resource use -> 5.1. Hunting & trapping terrestrial animals -> 5.1.1. Intentional use (species is the target)
♦ timing:Ongoing    
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

5. Biological resource use -> 5.3. Logging & wood harvesting -> 5.3.5. Motivation Unknown/Unrecorded
♦ timing:Ongoing    
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

1. Research -> 1.2. Population size, distribution & trends
1. Research -> 1.5. Threats
1. Research -> 1.6. Actions
3. Monitoring -> 3.1. Population trends

♦  Food - human
 Local : ✓   National : ✓ 

♦  Pets/display animals, horticulture
 Local : ✓   National : ✓ 

Bibliography [top]

Fuentes, A. 1997. Current status and future viability for the Mentawai primates. Primate Conservation 17: 111-116.

Fuentes, A. and Ray, E. 1996. Humans, habitat loss and hunting: the status of the Mentawai primates on Sipora and the Pagai Islands. Asia Primates 5: 5-9.

Geissmann, T. 1995. Gibbon systematics and species identifications. International Zoo News 42: 467-501.

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

Kawamura, S. and Megantara, E. 1986. Observation of primates in logged forest on Sipora Island, Mentawai. Kyoto University overseas research report of studies on Asian non-human primates, Kyoto University Primate Research Institute, Kyoto, Tokyo.

Keith, S. 2006. Conservation status of the Kloss's gibbon (Hylobates klossii) in the Mentawai Islands, Indonesia. Gibbon Journal 2: 29-32.

MacKinnon, K. 1987. Conservation status of primates in Malaysia, with special reference to Indonesia. Primate Conservation 8: 175-183.

MacKinnon, M. 1986. The conservation status of nonhuman primates in Indonesia. In: K. Benirschke (ed.), Primates. The road to self-sustaining populations, New York and Berlin.

Marshal, J. T. and Sugardjito, J. 1986. Gibbon systematics. In: D. R. Swindler and J. Erwin (eds), Comparative primate biology: Systematics, evolution and anatomy, pp. 137-185. Alan Liss, New York, USA.

Mitchell, A. and Tilson, R. 1986. Restoring the balance: Tradtitional hunting and primate conservation in the Mentawai islands, Indonesia. In: J. Else and P. Lee (eds), Primate ecology and conservation, Cambridge University Press, Cambridge, UK and London, UK.

Nijman, V. 2005. In full swing. An assessment of the trade in orangutans and gibbons on Java and Bali, Indonesia. TRAFFIC South-east Asia Report, Kuala Lumpur.

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.

Tenaza, R. 1974. Monogamy, territory and song among Kloss' gibbons (Hylobates klossii) in Siberut Island, Indonesia: II. Kloss' gibbon sleeping trees relative to human gradation implications for the socio-ecology of forest dwelling primates. Ph. D. Thesis, University of California.

Tenaza, R. 1975. Territory and monogamy among Kloss' gibbons (Hylobates klossii) in Siberut Island, Indonesia. Folia Primatologica 24(1): 68-80.

Tenaza, R. 1987. The status of primates and their habitats in the Pagai Islands, Indonesia. Primate Conservation 8: 104-110.

Tenaza, R. 1988. Status of primates in the Pagai Islands, Indonesia: A progress report. Primate Conservation 9: 146-149.

Tenaza, R. 1991. Conservation of Mentawai Islands primates. In: A. Ehara, T. Kimura, O. Takenaka and M. Iwamoto (eds), Primatology today, Amsterdam.

Tenaza, R. 1991. The Mentawai Islands: A case study in conservation of rainforest primates and archaic culture. AAZPA (American Association of Zoological Parks and Aquariums) regional conference proceedings: 602-606.

Tenaza, R. and Hamilton, W. 1971. Preliminary observations of the Mentawai Islands gibbon, Hylobates klossii. Folia Primatologica 15(3-4): 201-211.

Tenaza, R. and Mitchell, A. 1985. Summary of primate conservation problems in the Mentawai Islands, Indonesia. Primate Conservation 6: 36-37.

Tenaza, R. and Tilson, R. 1985. Human predation and Kloss's gibbon (Hylobates klossii) sleeping trees in Siberut, Indonesia. American Journal of Primatology 8(4): 299-308.

Tilson, R. 1980. Monogamous mating systems of gibbons and langurs in the Mentawai Islands, Indonesia. Ph.D. Thesis, University of California.

Tilson, R. 1981. Family formation strategies of Kloss's gibbons. Folia Primatologica 35: 259 - 287.

Tilson, R. and Tenaza, R. 1982. Interspecific spacing between gibbons (Hylobates klossii) and langurs (Presbytis potenziani) on Siberut Island, Indonesia. American Journal of Primatology 2: 355-361.

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Whittaker, D. 2000. The Kloss's gibbon (Hylobates klossii). The Gibbon's Voice 4(1): 1-2.

Whittaker, D. 2005. Evolutionary genetics of Kloss's gibbons (Hylobates klossii): systematics, phylogeography and conservation. Ph.D. Thesis, City University.

Whittaker, D. 2005. New population estimates for the endemic Kloss's gibbon Hylobates klossii on the Mentawai Islands, Indonesia. Oryx 39(4): 458-461.

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Citation: Whittaker, D. & Geissmann, T. 2008. Hylobates klossii. The IUCN Red List of Threatened Species 2008: e.T10547A3199263. . Downloaded on 23 November 2017.
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