Vietnam Primate Conservation Status Review 2002 - Hoang Lien ...

Ha Tay Province 20 O 34’-21 O 17’N / 105 O 18’-105 O 58’E
3.5 GREY LANGUR - Trachypithecus crepusculus
Grey langurs were reported in Ha Tay Province in the Red Data Book of Vietnam (Ministry of Science,
Technology and Environment, 1992). However, this location is given without reference. Regarding the
extent of forest currently remaining in the province, it is doubtful that a significant population of the
species still occurs.
Thanh Son District (PHU THO) ca. 21 O 21’N / 104 O 59’E
Grey langurs were reported in Thanh Son District (Phu Tho Province) by Dang Huy Huynh et al.
(1994). However, no reference is given and the information cannot be considered as reliable. The
species was not recorded during the FFI survey in Xuan Son Nature Reserve in November 1999
(Nguyen Xuan Dang & Lormée, 1999).
Kon Cha Rang - Kon Ka Kinh area (GIA LAI) 14 O 09’-14 O 35’N/108 O 16’-108 O 39E
The report of Grey langur in Kon Cha Rang-Kon Ka Kinh area by Lippold (1995b) is considered to be
“incongruous” by Fooden (1996). This occurrence would be a considerable extension of T. crepusculus
range to the south and there must be repeated sightings before it can be classified as confirmed.
3.5.5 Status
Not enough data are available to assess correctly the Grey langur status in Vietnam. In fact, no
surveys, however short, have been carried out with a special emphasis on this species.
Grey langur is now very scarce and shy in Vietnam. In ten years, only five confirmed records have
been documented, and there are only 12 localities with provisional occurrence.
In China, the range of the species is restricted. In Honghe County it is extirpated from most places
(Zhang et al., 1992). Ma et al. (1988) gave an estimation of 11,500 to 17,000 individuals. If this
number was not overestimated, the population in China has dropped to 5,000-6,000 individuals
(Wang Yingxiang et al. 1998). Zhang Yongzuo et al. (2002) estimate 5,400 individuals (of both taxa,
shanicus and crepusculus). The subspecies shanicus occurs in three protected areas, the subspecies
crepusculus in eight protected areas.
No research on the species is planned at the moment in the country (Li Zhaoyuan, pers. comm., 2000).
Despite its wide distribution in Lao PDR, there are less confirmed records of the Grey langur than of
any other primate species. Although Nam Et, Phou Louey and Nam Ha NBCAs are located in its
range, it has not been recorded, even provisionally. Its occurrence was recently confirmed in only
three locations. Furthermore, it has not been found common in any surveyed area. It may be the
most threatened primate in Lao PDR. It is locally considered “At Risk” (Duckworth et al., 1999).
The major threat it currently faces is from hunting. Grey langur is heavily hunted throughout their
range. This species often develops gallstones as large as golf balls, possibly due to drinking in the salt
springs of mountainous areas. These “bezoar” stones are much sought-after by the Chinese for
medicine production (Lekagul & McNeely, 1988).
Indeed, although the species can live in a disturbed habitat, where it may even be found in higher
densities (MacKinnon & MacKinnon, 1987), the hunting pressure is so great in northern Vietnam
that its population can be considered to be on the way to extinction. Being a large prey, it is a prime
target for hunters and, like other primates, it constitutes valuable merchandise for wildlife trading.
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