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Hylobates pileatus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA PRIMATES HYLOBATIDAE

Scientific Name: Hylobates pileatus
Species Authority: (Gray, 1861)
Common Name(s):
English Pileated Gibbon, Capped Gibbon, Crowned Gibbon
Spanish Gibón De Cresta Negra
Taxonomic Notes: This species forms a narrow area of sympatry and hybridization with H. lar in Khao Yai National Park, Thailand (Brockelman 1978, Brockelman and Gittins 1984, Marshall and Brockelman 1986, Marshall and Sugardjito 1986), specifically in the headwaters of the Takhong-Mun-Mekong River system (W. Brockelman pers. comm.). Until at least 1925, an area of sympatry apparently existed in the region of Sriracha, about 80 km southeast of Bangkok. Therefore, a large zone of overlap in the distribution of the two species may originally have existed. In most parts of this hypothetical zone, gibbon habitat appears to have been destroyed, with the Khao Yai Park possibly representing the last remnant of the once large contact zone (Geissmann 1991).

Assessment Information [top]

Red List Category & Criteria: Endangered A4cd ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Brockelman, W., Geissmann, T., Timmins, T. & Traeholt, C.
Reviewer(s): Mittermeier, R.A. & Rylands, A.B. (Primate Red List Authority)
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.
History:
2000 Vulnerable
1996 Vulnerable
1994 Endangered (Groombridge 1994)
1990 Endangered (IUCN 1990)
1988 Vulnerable (IUCN Conservation Monitoring Centre 1988)
1986 Endangered (IUCN Conservation Monitoring Centre 1986)

Geographic Range [top]

Range Description: 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).
Countries:
Native:
Cambodia; Lao People's Democratic Republic; Thailand
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: 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).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: 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. 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). 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.
Systems: Terrestrial

Threats [top]

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.).

Conservation Actions [top]

Conservation Actions: This species is listed in CITES Appendix I. 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).

Citation: Brockelman, W., Geissmann, T., Timmins, T. & Traeholt, C. 2008. Hylobates pileatus. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 19 December 2014.
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