Sri Lanka is a small island with a very rich diversity of eco systems. In Sri Lanka between October to late April or early May is best for visiting birders. This period is best because all the winter visitors to the country are present and there is a very good chance of seeing a load of wintering waders and some spectacular migrants such as Indian Pitta, Pied Thrush, Kashmir Flycatcher, Orange-headed Thrush etc. If the visitor is not so much interested in the migrants, May, June and July are also good time to arrive in the island.
There are many good birding sites but Sinharaja World Heritage Wilderness area, Bundala, Yala and Uda Walawe National Parks; Horton Plains are imperative for any birder.
Kumana is also a popular attraction and bird sanctuary because of its lake populated by large flocks of migratory waterfowls and other species of wading birds.