Vaduvur bird sanctuary spreads over an area of 112.638 ha, is a large human-made irrigation tank and shelter for migratory birds as it provides a suitable environment for food, shelter, and breeding ground. It is situated in Needamangalam taluk, Thiruvarur district. Surrounding vast agricultural fields during monsoon and abundance of aquatic insects attracts numerous birds making it a favourable feeding place. It is 20 km away from Thanjavur town. The site is rich in aquatic flora and fauna including migratory species. It is part of the Cauvery delta and hence dependent on the release of water from Mettur dam. The southern branch of the Cauvery drains into the districts of Thanjavur, Trichy, and Tiruvarur and has a lot of smaller rivers and tributaries referred to by local, historical names. The Kannanar and Vadavar canals are the main source of water to Vaduvur, in addition to the North-East monsoon. Locally known as the Old Vadavar canal and Kannanar pallam, the drainage is all along the Western border of the wetland (North-West to South-West). Being a freshwater habitat, no seasonal fluctuation in salinity is observed. It is surrounded by a large bund on the southern side and a short bund on the northern side, as the elevation serves as a natural bund. Bunds help in holding the water up to a depth of 2.5 m. Four outlets and discharge canals are present. Potable groundwater is available at a depth of about 20-50m. The peak flow into the canal is for a period of 15-20 days post-mid-June every year when water from Mettur dam is released. From Vaduvur, the water drains on easterly drainage into a series of wetlands such as Edaimelayur, Edaikeelayur, Kattakudi eri, Karakotai eri, Ponnaganni Eri, Sirumanaglam eri, Minal eri, etc. Due to increasing anthropogenic pressure, irreparable damage to this fragile ecosystem including the flow and character of the river has occurred. To conserve this ecosystem, powers conferred by Section (3) of the Environment (Protection) Act 1986 (29) of 1986, the Govt. of India vide its notification dated 13th September 2019, Vaduvur Bird Sanctuary has been declared as an Eco-sensitive zone from an ecological and environmental point of view. Besides, it is considered an area of national importance by MoEFCC, India, and internationally, as an Important Bird and Biodiversity Area (IBA) and also a Key Biodiversity Area

A wetland should be considered internationally important if it contains a representative, rare, or unique example of a natural or near-natural wetland type found within the appropriate biogeographic region.

A wetland should be considered internationally important if it supports vulnerable, endangered, or critically endangered species or threatened ecological communities.

A wetland should be considered internationally important if it supports populations of plant and/or animal species important for maintaining the biological diversity of a particular biogeographic region.

A wetland should be considered internationally important if it supports plant and/or animal species at a critical stage in their life cycles, or provides refuge during adverse conditions.

A wetland should be considered internationally important if it regularly supports 20,000 or more waterbirds.

A wetland should be considered internationally important if it regularly supports 1% of the individuals in a population of one species or subspecies of waterbird.

A wetland should be considered internationally important if it supports a significant proportion of indigenous fish subspecies, species or families, life-history stages, species interactions and/or populations that are representative of wetland benefits and/or values and thereby contributes to global biological diversity.

A wetland should be considered internationally important if it is an important source of food for fishes, spawning ground, nursery and/or migration path on which fish stocks, either within the wetland or elsewhere, depend.

A wetland should be considered internationally important if it regularly supports 1% of the individuals in a population of one species or subspecies of wetland-dependent nonavian animal species.