The Wildlife Conservation Society Cambodia Programme (WCS) Biodiversity Team, in collaboration with the Preah Vihear provincial Department of Environment, have initiated a six-month research project that involves a survey of pileated gibbons in the northern province's Phnom Tbeng Natural Heritage Park.

The pileated gibbon (Hylobates pileatus) is listed on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species as "Endangered".

Launched early this month, the project aims to determine the distribution and population density of the thickly-coated lesser apes, and develop an initial conservation management plan to protect and preserve the species.

The survey will be conducted by The Northern Plains Landscape REDD+ project (NPL REDD+), and supported by the US Fish and Wildlife Service, a bureau under the Department of the Interior.

Populations of pileated gibbons are found in western Cambodia, southeastern Thailand and southwestern Laos, the NPL REDD+ said in a Facebook post.

Ministry of Environment spokesperson Neth Pheaktra recently said Cambodia is believed to have the highest population of pileated gibbons worldwide, at about 35,000, which is 53.8 per cent of the IUCN's 65,000 global estimate.

In Cambodia, he said, the highly-arboreal apes mainly live in the forest, particularly in protected areas, and above all in the Cardamom Mountains.

There are around 30,000 pileated gibbons in the eastern part of neighbouring Thailand, and just a small number believed left in southwestern Laos, Pheaktra said.