Therthangal Birds Sanctuary, located at N 09º27.499’ Latitude and E 078 º 45.536’ Longitude, is part of Therthangal Vi lage in Ramanathapuram District of Tamil Nadu. The wetland is a situated in rural area. The Therthangal wetland was declared as a bird sanctuary in the year 2010, with an estimated area of 29.295 ha. It is notified as a bird sanctuary with the meaning and scopes of Section 18 (1) of Wildlife Protection Act 1972, through the G.O Ms. No 220/W6, Environment and Forest Department (FRV) dated 15.12.2010. Most notable feature of the sanctuary area is the prominent growth of Babul (Acacia nilotica) trees. The sanctuary offers conducive breeding and feeding grounds for the birds, especialy the migratory birds, which use the site as foraging ground. The Babul trees (Acacia nilotica) planted in the wetland act as nesting sites. The sanctuary includes earthen embankments, bunds and the seasonaly water holding marshy lake, which is equaly beneficial for the birds as wel as the vi lagers. Excess water that is stored during rainy season within the bunds is later utilized for agricultural purposes. The sanctuary acts as a store space for an efficient flood and inundation control mechanism. The sanctuary controls the natura ly occurring soil erosion. It also acts as a natural filtration system for nutrient removal from agricultural runoff and wastewater systems. The sanctuary is home for many threatened species including Black-headed ibis (Threskiornis melanocephalus), Spot-bi led pelican (Pelecanus philippensis), Oriental darter (Anhinga melanogaster) and Pa lid harrier (Circus macrourus) among others. The sanctuary also harbours rich biodiversity particularly among the lower vertebrate groups such as amphibians and reptiles (herpetofauna) as wel as invertebrates. This sanctuary supports about 96 bird, 57 butterfly, 7 mammal, 11 reptile, 6 amphibian and 133 plant species.

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.