Bundala National Park is also known as Bundala Ramsar Wetlands. This is the very first wetland declared as a Ramsar Wetland under the Ramsar Convention. Here is a full list of Ramsar Wetlands in Sri Lanka: http://www.ramsar.org/wetland/sri-lanka
Bundala is a famous area to watch water birds and winter migrant waders. From November to April there are thousands winter migrant birds such as plovers, sandpipers, various types terns and ducks can be seen.