Ranganathittu Bird Sanctuary, also known as Pakshi Kashi of Karnataka, is a bird sanctuary in the Mandya District of the state of Karnataka in India. It is the largest bird sanctuary in the state, 40 acres (16 ha) in area, and comprises six islets on the banks of the Kaveri river.

Ranganathittu is located 3 kilometres away from the historic town of Srirangapattana and 16 kilometres (9.9 mi) north of Mysore. The sanctuary attracted about 3 lakh visitors during 2016–17. Ranganathittu’s islets were formed when an embankment across the Kaveri river was built between 1645 and 1648 by the then king of Mysore, Kanteerava Narasimharaja Wadiyar.These islets, originally numbering 25, soon started attracting birds.