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

Vietnam Primate Conservation Status Review Part 2: LEAF MONKEYS
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Buon Ma Thuot (DAK LAK) ca. 12 O 45’N/108 O 05’E
Six adults and two infant Black-shanked douc langurs were collected in Buon Ma Thuot in March
1937 by W. H. Osgood (FMNH 46510 to 46518). However, Buon Ma Thuot is an important trading
locality in the area and no precision is given about the exact origin of the specimens.
4.4 Status
All three douc langur species were once widely distributed in Vietnam and common throughout their
range. After several decades of intense human pressure, populations have been reduced and
fragmented.
Hunting is currently the major threat. Douc langurs have probably undergone a more significant
decline than other diurnal primate species in Vietnam, partly as a result of behavioural characteristics
which make them easy to hunt. They remain motionless but they are still easily seen by humans
(Timmins et al., 1999; Pham Nhat et al., 2000). Douc langur meat is not considered tasty by Kinh
people (Eames & Robson, 1993), but minorities in the south appreciate the meat for food (Ha Thang
Long & Le Thien Duc, 2001). Most animals are hunted for traditional medicine and sometimes also
for sale as pets, even if they do not have much chance of long survival in captivity.
One of the main contributing factors to the rapid decline of the douc langur population in Vietnam is
the removal of its natural habitat. A large portion of forest in the centre and south of the country
suffered from the massive wartime damage. Post-war human demographic explosion and extensive
logging for coffee, rubber and cashu plantation reduced the natural habitat.
The core population of Red-shanked douc langur now resides in Lao PDR. These langurs are still
common in some areas of Lao PDR, in particular in the eastern part of the country, south of 18 0 45’N.
However, they are absent or very rare northwest of Nam Kading NBCA (Bolikhamxai Province) and
further to the south and west of Xe Pian NBCA (Champaxac Province). Nakai-Nam Theun NBCA and
the adjacent Hin Namno NBCA together may possess the largest population of Red-shanked doucs
remaining in the world (Timmins & Duckworth, 1999). Doucs have been eradicated from disturbed
and fragmented forest. They are particularly susceptible to exploitation in the wildlife trade. Most
animals are probably traded in Vietnam and in Thailand. With regard to the status of the taxon in
Vietnam, the conservation of Red-shanked douc langurs in Lao PDR is a global priority (Duckworth
et al., 1999).
From Lao PDR the distribution area extends along the Annamite Mountain Chain to central Vietnam.
This remaining natural habitat is now confined on a narrow band near the Lao PDR border. Most
forest at lowland levels has been cleared and no forest remains undisturbed. The eastern slope of the
Annamite Chain is still subject to human pressure. Between 1985 and 1998, in some locations, such
as Anh Son and Con Cuong Districts (Nghe An Province), and Huong Son and Huong Khe Districts
(Ha Tinh Province), the quality of the habitat has been dramatically reduced.
Even in areas which maintain a relatively large and undisturbed habitat, such as Phong Nha or Vu
Quang, the populations of douc langur seems to be very small in relation to the same habitat in Lao
PDR. For instance, in Phong Nha-Ke Bang National Park, only one small group of douc langur was
seen, despite four months of intensive surveying by FFI in 1998.
The Black-shanked douc langur has a fragmented distribution area in south Vietnam. Many
subpopulations are under pressure due to forest conversion into plantations and agricultural land
and hunting. High hunting pressure along the border with Camdodia originates in army stations (Ha
Thang Long & Le Thien Duc, 2001).