Gibbon surveys have been conducted in Preah Vihear Protected Forest and its periphery from 2006 to 2009, with important populations discovered in the area. Pileated gibbons feed mostly on fruits and shoots, and unsurprisingly the majority were found in denser, evergreen and riverine forest. However, an important number were also found in drier deciduous forest. The density was estimated at 0.3 groups per km2. This is low compared to other sites, but may reflect the large proportion of dry forest in this site. The actual density inside preferred evergreen forest may therefore be higher.
Further surveys of Pileated Gibbons are planned in 2010 in Kulen Promtep Wildlife Sanctuary and periphery, which lie west of Preah Vihear Protected Forest. This area is known to contain gibbons, but has never been properly surveyed. It will also provide information on the distribution of other species such as gaur, banteng and silvered langurs.
Pileated Gibbons Hylobates pileatus are endangered in their small range in mainland South-East Asia as a result of habitat loss and hunting. Much of their former habitat in the region has been cleared and the gibbon populations that remain are threatened as fragmentation of the forest increases access for hunters. The Northern Plains of Cambodia are one of the most important remaining landscapes for this species, indeed many agricultural and social concessions are planned for the north of the country and this may be one of the few sites which protects this species in this region.