|Scientific Name:||Hylobates klossii|
|Species Authority:||(Miller, 1903)|
|Red List Category & Criteria:||Endangered A2cd ver 3.1|
|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.
|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).|
|Range Map:||Click here to open the map viewer and explore range.|
|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).|
|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).
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:||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).|
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. P. 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.
Waller, M. 2006. Rain and Kloss?s gibbons: A travelogue from the Mentawai islands in Indonesia. Gibbon Journal 2: 25-28.
Weitzel, V. 1982. Mentawai Island primates face problems. Newsletter International Primate Protection League 9: 13.
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.
Whittaker, D. 2006. A conservation action plan for the Mentawai primates. Primate Conservation 20: 95-105.
Whitten, A. 1980. Arenga fruit as food for gibbons. Principes 24: 143-146.
Whitten, A. 1980. The Kloss gibbon in Siberut rain forest. Ph.D. Thesis, University of Cambridge.
Whitten, A. 1982. Diet and feeding behaviour of Kloss gibbons on Siberut Island, Indonesia. Folia Primatologica 37: 177-208.
Whitten, A. 1982. Home range use by Kloss gibbons (Hylobates klossii) on Siberut Island, Indonesia. Animal Behavior 30: 182-198.
Whitten, A. 1982. The role of ants in selection of night trees by gibbons. Biotropica 14: 237-238.
Whitten, A. 1984. Ecological comparisons between Kloss gibbons and other small gibbons. In: H. Preuschoft, D. Chivers, W. Brockelman and N. Creel (eds), The lesser apes. Evolutionary and behavioural biology, Edinburgh.
Whitten, T. 1982. The gibbons of Siberut. J. M. Dent, London, UK.
Whitten, T., Whitten, J. and House, A. 1979. Solution for Siberut? Oryx 15: 166-169.
World Wildlife Fund. 1980. Saving Siberut: A Conservation Master Plan. Bogor, WWF Indonesia Programme.
|Citation:||Whittaker, D. & Geissmann, T. 2008. Hylobates klossii. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 22 May 2013.|
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