Ranganathittu Bird Sanctuary is a bird sanctuary located near the town of Srirangapatna in the Indian state of Karnataka. It is situated on the banks of the Cauvery River and is a popular spot for bird watching and photography.  It is situated 4 km. from Srirangapatna and 19 km. from Mysore. The Bird Sanctuary is named after Sri Ranganatha Swamy, an incarnation of the Hindu God Vishnu. It is an island on the river Cauvery and it is spread over an area of 40 acres. The Sanctuary includes six islands and was declared a bird sanctuary in 1940.

Ranganathittu Bird Sanctuary is an important nesting and breeding ground for thousands of bird species. Ranganathittu Bird Sanctuary witnesses the arrival of a large number of migratory birds of different flocks from as far as Siberia, North America, and Australia. The migratory birds start arriving at the Ranganathittu Bird sanctuary in December and the breeding season starts during the winter months they finally migrate back with their nestlings in August.

The islands host numerous mammals and migratory birds. Some of them are Bonnet Macaque, colonies of Flying Fox, and common small mammals like the Indian Gray Mongoose, the monitor lizard, and the Civet. The Marsh Crocodile also called the Mugger Crocodile is a common inhabitant of the riverine reed beds. Migratory water birds include the Painted Stork, Asian Open bill Stork, Common Spoonbill, Woolly-necked Stork, Black-headed Ibis, White Ibis, Lesser Whistling Duck, Indian Shag, Stork-billed Kingfisher, and other common birds like egrets, cormorants, Oriental Darter, and herons. The Great Stone Plover and River Tern also nest here. It is home to a large flock of Streak-throated Swallows.

Ranger-guided boat tours of the islands are available throughout the day and are a good way to watch birds, crocodiles, otters, and bats. The seasons for visiting the park are June - November (during the nesting season of the water birds).