Ranganthittu bird sanctuary is located in Mandya district, of the state of Karnataka, India. The major islands and islets of Ranganathittu bird sanctuary are located in the mid-stream of river Cauvery, and form part of the wetland system. The wetland can be divided into three parts. The first part is the riverine area around Devaraja islands (59.08 ha) situated 1.60 km downstream of Krishna Raja Sagara dam. The second part is the riverine area around the most popular Puttaianakoppalu Island (202.82 ha) situated 8.30 km downstream of Krishna Raja Sagara dam. The third part is the riverine area around Gendehoshally Islands (255.79 ha), situated 30 km downstream of Krishna Raja Sagara dam. The total area of the site is 517.70 ha located between 12.422750°N, 76.587040°E and 12.357411°N, 76.809090°E. The site represents a unique riverine ecosystem comprising flora and fauna that survive in complete harmony and maintain a natural balance. The site has been enlisted as one of the Important Bird Areas (IBA) in Karnataka and India by Bombay Natural History Society. It is an ecologically important riverine wetland of India, rich in biodiversity, with 188 species of plants, over 225 species of birds, 69 species of fishes, 13 species of frogs, and 30 species of butterflies. The site is an important breeding site for about 20 species of waterbirds of which, 17 species breed on trees growing on the islands of Ranganathittu bird sanctuary. The site supports several threatened taxa which include two critically endangered species of fishes, six endangered species (bird: 1, fishes: 4, frog 1), and nine species of vulnerable species (mammal:1., reptile: 1, birds 5, fishes: 2). Besides, it also supports one species each of endangered, vulnerable, and endemic plant species, and about 98 medicinal plant species. This proposed site supports healthy populations of mugger crocodiles (Crocodylus palustris), smooth-coated otter (Lutrogale perspicillata) and the river waters harbour the endangered hump-backed masheer (Tor remadevii). The site supports over 1% of the world\'s population of Asian openbill, spotbilled pelican, and black-headed ibis.

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.