Hylobates pileatus

Taxonomy (Name)

Picture

Distribution, Range

The range of this species includes southeastern Thailand, a portion of southwestern Lao PDR (west of the Mekong), and western Cambodia (west of the Mekong). In Thailand, the western limit may once have been the Bang Pakong River, extending north to Khao Yai National Park, east of the Lam Takhong watershed, and all forested areas east and south of the Moon River (Geissmann 1995; Groves 2001; Marshall and Sugardjito 1986). In Khao Yai, the limit is Khao Rom Mountain and the upper reaches of the Lam Takhong river on the north side (Brockelman 1975; Marshall et al. 1972).

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Map

Country

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

Status

International Status

IUCN Red List Category

ENIUCN

Justification

This species is listed as Endangered as it is believed to be experiencing a decline of more than 50% incorporating a time frame of three generations (45 years) for the period 1970-2015, due to rampant forest loss and loss of mature individuals due to hunting.

IUCN

CITES

Appendix IIUCN

CMS

National Status

Ecology Discription

Appearance

Habitat

This species is found in moist, seasonal evergreen and mixed deciduous-evergreen forests and have been recorded to about 1,500 m in Cambodia, and to around 1,200 m in Thailand.

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Population size

In Cambodia, the primary area of importance is the Cardamom Mountains, in the south-western part which is relatively intact, where densities are on the order of 1-2 groups/km2, with an estimated 20,000 individuals (Traeholt et al. 2005). Populations in the north, where the habitat is similar but more open, with a very small percentage of evergreen forest, are smaller. Bokor National Park in southwestern Cambodia has an estimated 1,000 groups and is likely to be isolated from the remainder of the range (Traeholt et al. 2005). Pileated gibbons might number more than 35,000 individuals in Cambodia in total (Traeholt et al. 2005).

In Lao PDR the population is significantly smaller, mainly since it comprises a smaller part of the range (Duckworth et al. 1999).

In Thailand, there are an estimated 12,000 individuals (3,000 breeding groups) surviving in the four largest forest areas including five major protected areas (Khao Yai National Park, Thap Lan National Park, Khao Ang Ru Nai Sanctuary and Khao Soi Dao Sanctuary), based on an auditory census in 2004?2005, plus around 1,000 to 2,000 individuals in 15 other scattered and highly fragmented smaller protected areas (Phoonjampa and Brockelman unpub. data). Population densities are generally low, averaging close to one group (average 4 individuals)/km2, with pockets of higher density populations in some remote mountain areas (Brockelman and Srikosamatara 1993). An earlier study generated a total population estimate of 30,000 pileated gibbons for Thailand (Tunhikorn et al. 1994).

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Behavior

Researchers find the species somewhat shyer and more elusive than H. lar (W. Brockelman pers. comm.).
Average group size in Thailand is four individuals (Brockelman and Poonjampa unpubl. data). There has been no long-term study of behavior and life history.

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Diet

This species is similar to H. lar in diet and general ecology, consuming mostly fruits, shoots, and some immature leaves, as well as insects (Srikosamatara 1980, 1984).

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Reproduction

Threat

Major Threat(s)

This species is threatened by both hunting, primarily for subsistence, and severe habitat fragmentation and degradation (Duckworth et al. 1999; Traeholt et al. 2005). In Thailand all populations are now within protected conservation areas and the era of logging and slash-and-burn agriculture (Brockelman 1983) is now mostly over. Nevertheless, severe encroachment has occurred in eastern Khao Yai Park and other major protected areas, and subsistence hunting by minor forest product collectors is still uncontrolled (Phoonjampa and Brockelman unpubl. data). In Cambodia, however, habitat destruction is a more immediate threat than poaching, especially in remote areas. Most populations are not yet secured in protected areas, and the main threats are habitat loss due to logging, agricultural conversion, hydroelectric development, and new human settlements (W. Brockelman pers. comm.).

IUCN

Conservation and Measurement

International

CITES, Appendix I. IUCN

National

In Cambodia the major stronghold is three contiguous protected areas, including Samkos and Aural Wildlife Sanctuaries, and the Central Cardamom Protected Forest. This last area contains about 3,350 km2 of gibbon habitat and a population of nearly 7,000 groups. This potentially could ensure the long-term survival of the species if effectively managed. The Cambodian Forestry Administration in collaboration with Conservation International is developing a management plan for this area, and ranger units have been established to stop illegal poaching and logging. Gibbons also occur in Bokor National Park (1,220 km2 of habitat), which is generally well managed.
As in Thailand, numerous smaller fragmented areas also contain pileated gibbons, most with low long-term prospects. In Cambodia there is a need to strengthen protected area administration and protection activities, and to halt logging and development activities in important conservation areas (Brockelman pers comm.; Traeholt et al. 2005).
In southeast Thailand, all populations are included within protected areas, but more effort needs to be made to change the behavior of local villagers who hunt. The largest protected forest areas are the Tab Lan National Park, Pang Sida National Park, Ta Phraya National Park, Khao Ang Ru Nai Sanctuary, and Khao Soi Dao Sanctuary, totaling greater than 3,000 km2 of forest habitat in three blocks (Phoonjampa and Brockelman unpubl. data).

IUCN

Conservation law

Protected Area

Other Coservation Projects

Citation

Anonymous. 1995. More on Thai gibbon PHVA. Asian Primates 4(4): 8-10.

Braendle, C. and Geissmann, T. 1997. Behavioural development of a pileated gibbon. International Zoo News 44(1): 4-16.

Brockelman, W. 1975. Gibbon populations and their conservation in Thailand. Natural History Bulletin of the Siam Society 26: 133-157.

Brockelman, W. 1978. Preliminary report on relations between the gibbons Hylobtes lar and H. pileatus in Thailand. In: D. Chivers and K. Joysey (eds), Recent advances in primatology, vol.3: Evolution, London, UK and New York, USA.

Brockelman, W. 1983. In search of the elegant ape. Animal Kingdom 85(6): 34-39.

Brockelman, W. and Gittins, S. 1984. Natural hybridization in the Hylobates lar species group: Implications for speciation in gibbons. In: H. Preuschoft, D. Chivers, W. Brockelman and N. Creel (eds), The lesser apes. Evolutionary and behavioural biology, Edinburgh.

Brockelman, W. and Srikosamatara, S. 1993. Estimation of density of gibbon groups by use of loud songs. American Journal of Primatology 29: 93-108.

Brockelman, W., Damman, D., Thongsuk, P. and Srikosamatara, S. 1977. Pileated gibbons survey at Khao Soi Dao Sanctuary, Thailand. Tiger Paper 4(4): 13-15.

Duckworth, J. W., Salter, R. E. and Khounbline, K. 1999. Wildlife in Lao PDR: 1999 Status Report. IUCN, Vientiane, Laos.

Geissmann, T. 1991. Sympatry between white-handed gibbons (Hylobates lar) and pileated gibbons (H. pileatus) in southeastern Thailand. Primates 32(3): 357?363.

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

Geissmann, T. and Braendle, C. 1997. Helping behaviour in captive pileated gibbons (Hylobates pileatus). Folia Primatology 68: 110-112.

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

Lekagul, B. and Mcneely, J. A. 1988. Mammals of Thailand. White Lotus Press, Bangkok, Thailand.

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.

Marshall, J. and Brockelman, W. 1986. Pelage of hybrid gibbons (Hylobates lar x H. pileatus) observed in Khao Yai National Park, Thailand. Natural History Bulletin of the Siam Society 34: 145-157.

Marshall, J., Ross, B. and Chantharojvong, S. 1972. The species of gibbons in Thailand. Journal of Mammology 53: 479-486.

Ruggeri, N. and Timmins, R. 1996. An initial summary of diurnal primate status in Laos. Asian Primates 5(3-4): 1-3.

Srikosamatara, S. 1980. Ecology and behavior of the pileated gibbon (Hylobates pileatus) in Khao Soi Dao Wildlife Sanctuary, Thailand. M. A. Thesis, Mahidol University.

Srikosamatara, S. 1984. Ecology of pileated gibbons in south-east Thailand. In: H. Preuschoft, D. J. Chivers, W. Y. Brockelman and N. Creel (eds), Evolutionary and behavioural biology, Edinburgh.

Srikosamatara, S. and Brockelman, W. 1987. Polygyny in a group of pileated gibbons via a familial route. International Journal of Primatology 8: 389-393.

Traeholt, C., Bonthoeun, R., Rawson, B., Samuth, M., Virak, C. and Sok Vuthin. 2005. Status review of pileated gibbon, Hylobates pileatus, and yellow-cheeked crested gibbon, Nomascus gabriellae, in Cambodia. FFI Cambodia Programme Office, Phnom Penh, Cambodia.

Tunhikorn, S., Brockelman, W., Tilson, R., Nimmanheminda, U., Ratanakorn, P., Cook, R., Teare, A., Castle, K. and Seal, U. S. 1994. Population and habitat viability analysis report for Thai gibbons: Hylobates lar and H. pileatus. IUCN / SSC Conservation Breeding Specialist Group, Apple Valley, Minnesota, USA.

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