Every year, from September to April the following year, migratory birds from Europe, Western Asia and India fly to evade the winter season to the tropical weather of Sri Lanka. During this season, flocks of birds can be seen gathered around the villus, tanks and the mud flats of the Kala Oya estuary. A few examples of migratory birds are the Northern Pintail, Garganey, Lesser Sand Plover, Black-tailed Godwit Marsh Sandpiper and several species of Gulls and Terns.