Anawilundawa is made up of nine tanks linked together to form a unique irrigation system. The six large tanks – Pinkattiya, Maradansola, Anawilundawa, Mayyawa, Surawila and Vellawali – and three smaller peripheral tanks, exist as a single system and are located close to Nalladarankattuwa. Although there is no longer a definite trace of the waterways that fed the system, the system is now watered by the flood waters of the Deduru Oya brought to the area via the Sengaloya scheme. The Anawilundawa tanks abound with birdlife and is one of the three RAMSAR wetlands in the country.
Birdwatching, or birding, is a form of wildlife observation in which the observation of birds is a recreational activity. It can be done with the naked eye, through a visual enhancement device like binoculars and telescopes, by listening for bird sounds, or by watching public webcams.
Birdwatching often involves a significant auditory component, as many bird species are more easily detected and identified by ear than by eye. Most birdwatchers pursue this activity for recreational or social reasons, unlike ornithologists, who engage in the study of birds using formal scientific methods.
Sri Lanka is a remarkable country for birds. Although small, it has a wide range of climate and habitat and over 435 species of birds. Out of these,235 are resident and these include the most important 33 species that are recognizes as endemic to the country. A further 198 species have been recorded as migrants to country. The majority of these migrate to Sri Lanka during the northern winter and present from about August/September to April/May. In contrast, pelagic species of seabirds like Shearwaters, Petrels, Storm-Petrels etc migrate to Sri Lankan waters from southern oceanic islands during the southern hemisphere`s winter. Of the migrants, about 100 species regularly visit the country. The rest are occasional visitors and vagrants.