The bird sanctuary at the Prek Tuol core area of the Tonle Sap Biosphere Reserve has been called “the single most important breeding group in South-east Asia for globally threatened large waterbirds”. The Biosphere covers 31,282 hectares at the northwest tip of the Tonle Sap Lake and plays host to species including Greater and Lesser Adjuncts, Black-headed ibis, Painted Stork, Milky Stork, Spot-billed Pelican, Grey-Headed Fish Eagle and many more species. Of the three Biosphere core area on the Tonle Sap lake,

Prek Tuol is the most accessible from Siem Reap and the most popular with birdwatchers. The best time of year for viewing is the dry season from December to June when flocks of migratory birds congregate at Prek Tuol. As the dry season progresses and the water recedes, the number of birds increases but the travel to some of the more important viewing area becomes more difficult. There are also basic overnight accommodations at the Research Station if you want to stay the night to take full advantage of the sunset and early morning viewing hours.