Thirty-two percent of bird species in South-East Asia are likely to become extinct by the end of this century. However, due to a lack of data this number may be an underestimate. The Chestnut-headed Partridge Arborophila cambodiana found in south-west Cambodia’s Cardamom Mountain range is a largely unknown potentially at-risk species. We used line transects and camera traps to survey A. cambodiana in four protected areas in the Cardamom Mountains to estimate population densities. We also assessed their current distribution range and broad scale habitat changes from 1996 to 2016. We found A. cambodiana in evergreen and semi-evergreen forest at a density of 1.23 calling males/km2, and at altitudes above 400 m and where the slope was between 11 and 43o. From 1996 to 2016 A. cambodiana’s potential habitat decreased by 11%, whilst the total evergreen forest cover in the Cardamom Mountains decreased by 20%. A. cambodiana has a very restricted range within which the habitat has been fragmented. Compounded by human disturbance and development activities that negatively affect the species, we suggest a revision of its IUCN Red List status from ‘Least Concern’ to ‘Near Threatened’ as it partially meets a range of threatened Red List species criteria.