Key Biodiversity Together with the adjacent Nam Nao National Park (IBA TH017), Phu Khieo Wildlife Sanctuary is one of the most important sites for the conservation of the globally endangered White-winged Duck Cairina scutulata in Thailand. The total population in the two contiguous IBAs was estimated at c.24 individuals in 1993. Two other globally threatened species have been recorded at the site, although neither is thought to occur regularly in significant numbers. In addition, the site supports significant populations of four globally near-threatened species: White-rumped Falcon Polihierax insignis, Siamese Fireback Lophura diardi, Great Hornbill Buceros bicornis and Brown Hornbill Anhorrhinus tickelli. A fifth globally near-threatened species, Oriental Darter Anhinga melanogaster, has been recorded at the site but is not confirmed to regularly occur in significant numbers. Furthermore, both Green Peafowl Pavo muticus and Spot-billed Pelican Pelecanus philippensis, two globally vulnerable species, are regularly recorded near the wildlife sanctuary headquarters. However, these records are believed to refer to released birds.