WASHINGTON, Aug. 28 (Xinhua) -- Surprisingly large populations of two globally threatened primates have been discovered in a protected area in Cambodia, the Wildlife Conservation Society (WCS)reported on Thursday.

    The report counted 42,000 black-shanked douc langurs along with2,500 yellow-cheeked crested gibbons in Cambodia's Seima Biodiversity Conservation Area, an estimate that represents the largest known populations for both species in the world.

    WCS scientists conducted the surveys with the Cambodian government across an area of 789 square km within a wider landscape of 3,000 square km. The scientists believe total populations within the wider landscape may be considerably greater.

    "Now we must put into place the management to truly protect these populations and apply the approach to other regions where primates are in trouble," said John Robinson, an executive vice president at WCS.

    The two primate species are found in much lower numbers at other sites in Cambodia and in Vietnam. Prior to the recent discovery in Seima, the largest known populations were believed to be in adjacent Vietnam, where black-shanked douc langurs and yellow-cheeked crested gibbons hover at 600 and 200 respectively. The total population of the two species remains unknown.

    According to the WCS, a combination of factors account for such high numbers of primates: successful long-term management of the conservation area; cessation of logging activities; a nation-wide gun confiscation program implemented in the 1990s; and habitat where there is plenty of food.