Swans, ibises, pelicans, storks and other waders, some endangered, are among the waterfowl of Tonle Sap and today protected thanks to its status as a biosphere reserve. The park is divided into three sectors, including the Prek Toal area to the west of the lake and mouth of River Sangker, home to a bird sanctuary that you can observe by boat, during an excursion between Siem Reap and Battambang. Migratory birds are the most numerous between January and June.