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Hoolock leuconedys

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA PRIMATES HYLOBATIDAE

Scientific Name: Hoolock leuconedys
Species Authority: Groves, 1967
Common Name(s):
English Eastern Hoolock Gibbon, Eastern Hoolock
Synonym(s):
Bunopithecus hoolock subspecies leuconedys Groves, 1967
Taxonomic Notes: This taxon is monotypic; it was formerly considered a subspecies of H. hoolock. The previous generic name, Bunopithecus, was changed by Mootnick and Groves (2005) to Hoolock (Haimoff et al. 1984).

Assessment Information [top]

Red List Category & Criteria: Vulnerable A3cd ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Brockelman, W. & Geissmann, T.
Reviewer(s): Mittermeier, R.A. & Rylands, A.B. (Primate Red List Authority)
Justification:
Listed as Vulnerable because it is suspected that a population decline, projected to be more than 30%, would be met over the next three generations (approximately 40 years), inferred from habitat loss and hunting.
History:
2000 Endangered

Geographic Range [top]

Range Description: This species is found in southern China (western Yunnan) and northeastern Myanmar (east of the Chindwin River). In China it is found as far east as the Salween River, and north to nearly 26°N (Groves 2001). Das et al. (2006) reported the discovery of a population of H. leuconedys in eastern Arunachal Pradesh, north-east India, which has traditionally been considered to be part of the distribution area of H. hoolock. This record has yet to be proven (T. Geissmann pers. comm.).

The boundary between the two species of hoolock gibbon is uncertain in the Chindwin headwaters in the north, and possibly includes a zone of intermediates or variable population (T. Geissmann pers. comm.). More fieldwork is needed to investigate populations on both sides of the river and in the headwaters of the Chindwin, where there is likely to be one or more hybrid zones or clines (W. Brockelman pers. comm.).
Countries:
Native:
China (Yunnan); Myanmar
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: There are an estimated 50-300 individuals in western Yunnan province, China (Lan 1994; Tian et al. 1996; Zhang 1998; Zhang et al. 2002). In India, a population of about 170 gibbons, which have been tentatively identified as H. leuconedys, occurs in the Mehao region, in eastern Arunachal Pradesh state (Das et al. 2006), but further surveys are needed (J. Das pers. comm.).

The total population of H. leuconedys in Myanmar is over 10,000 individuals, and perhaps up to 50,000 or so; however, much more survey work is needed. There have been some Wildlife Conservation Society surveys in Hukaung Valley Wildlife Sanctuary, which have approximately two groups/km2 (Htun pers. comm. 2006). There are approximately two groups/km2 in Mahamyaing Wildlife Sanctuary based on vocal surveys, with a total population of 4,000–8,100 individual gibbons (about half of which would be adult animals) (Brockelman 2006 unpub. draft).

The species is doing relatively well in Myanmar, but there is no guarantee of continued political protection in the next few decades (W. Brockelman pers. comm.). Political instability is presently slowing down logging (W. Bleisch pers. comm.).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This gibbon is a forest-dweller that inhabits primary evergreen, scrub and semi-deciduous hill forest, as well as mountainous broadleaf and pine-dominated forest. It ranges up to 2,700 m in elevation, as reported by the Vernay-Cutting expedition (Anthony 1941), in mixed pine/broadleaf forest in northeastern Myanmar.

It is a frugivorous species, with ripe fruits composing a majority of its diet. Individuals also eat a large proportion of figs and some amount of leaves, shoots, and petioles. This diet contributes to a relatively large home range of some populations.

No intensive studies have been carried out on the behaviour or ecology of H. leuconedys, but it may be assumed to be similar to that of H. hoolock, with diet varying somewhat by habitat (W. Brockelman pers. comm.).
Systems: Terrestrial

Threats [top]

Major Threat(s): Eastern hoolocks are threatened by habitat loss and hunting, both for meat as well as for use in traditional “medicine” (M. Richardson pers. comm.). In Myanmar, commercial logging may eliminate most forest habitats outside of protected areas, but in and around Mahamyiang Sanctuary, selectively logged forests (with dipterocarps removed) still contain many gibbons. The more than 50,000 people settled in the Hukaung Valley Tiger Reserve constitute a threat to all wildlife in the area, and the future of the reserve will depend on the ability of the government as well as international conservation groups to curtail hunting. Gold mining has become a threat to conservation in Kachin State (W. Brockelman pers. comm.).

Conservation Actions [top]

Conservation Actions: This species is listed on CITES Appendix I. In China there are two nature reserves with eastern hoolocks (Gaoligongshan and Tongbiguan National Nature Reserves). In Myanmar, the Mahamyaing Sanctuary was created in part as a gibbon refuge, and the species occurs as well in the Bumhpabum, Hponkan Razi and Htamanthi Wildlife Sanctuaries, and in the Hukaung Valley Tiger Reserve (W. Brockelman unpub.). Unfortunately, there is no viable protected area in Myanmar between the northern Ayerawady and Salween Rivers, near the borders with Yunnan and Thailand. Gibbons in this zone could be genetically different from those along the Chindwin; therefore, it is critical to save the small numbers that survive west of the Salween River in Yunnan. A project has been implemented by Wildlife Conservation Society to help educate local residents – especially school children – around Mahamyiang Sanctuary, and to urge them not to hunt wildlife. The project also provides some support to the wildlife sanctuary for increased patrols. Such projects need to be implemented in the Hukaung Tiger Reserve as well, in order to reduce hunting pressures. At present tourism is not promoted in the Hukaung Valley because it is a politically sensitive area, but there is great potential for tourism to have a positive impact on local development in the future. In the meantime, alternative sources of income are needed to compensate for the bans on direct resource exploitation (W. Brockelman pers. comm.).

Citation: Brockelman, W. & Geissmann, T. 2008. Hoolock leuconedys. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 22 September 2014.
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