Ranganthittu Bird Sanctuary, Bird sanctuary in Mandya district, India.

Ranganathittu Bird Sanctuary covers about 40 acres (16 ha) across six islets in the Kaveri River, 3 km from Srirangapatna. Flat-topped rocks break the water's surface, and the low banks are thick with broadleaf trees, bamboo and pandanus, where white birds perch. Among the leaves, spot-billed pelicans show bare orange heads, pinkish-red throat patches and long pale yellow bills.

The reserve was established in 1940 after ornithologist Salim Ali persuaded the king of Mysore to protect the islands. These islands had formed in the 17th century following a man-made embankment that altered the river course.

The name comes from Ranganatha, a form of the god Vishnu whose temple stands nearby. Local people often call the reserve "Pakshi Kashi of Karnataka", with Pakshi meaning bird and Kashi referring to its spiritual importance.

Ranger-guided boat tours of the islets run through the day; when the Kaveri floods after water is released from the Krishna Raja Sagara dam, boating is suspended and birds are watched only from a distance. There is no lodging inside the sanctuary, so visitors stay in Srirangapatna, 3 km away, or Mysuru. The nesting season runs June to November, and migratory birds are usually best in December.

The mugger crocodile, also called the marsh crocodile, inhabits the riverine reed beds, and Ranganathittu holds Karnataka's largest freshwater crocodile population. The painted stork began nesting here again after 1996–97, and spot-billed pelicans after 2009–10.