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, only 0.67 km2. in area, which is about 40 acres and comprises six islets on the banks of the Kaveri river. Ranganathittu is located three kilometers away from the historic town of Srirangapatna and 16 kilometres (9.9 mi) north of Mysore. 

Roughly 170 birds have been recorded here. Of these, the painted stork, Asian openbill stork, common spoonbill, woolly-necked stork, black-headed ibis, lesser whistling duck, Indian shag, stork-billed kingfisher, egret, cormorant, Oriental darter, and heron breed here regularly. The great stone plover, and river tern also nest here. The park is home to a large flock of streak-throated swallows. During the months of January and February, more than 30 species of birds are found and the season of the sanctuary is from November to June. About 50 pelicans have made Ranganathittu as their permanent home.

The islands are host to numerous small mammals, including bonnet macaque, colonies of flying fox and common small mammals like common palm civet and Indian gray mongoose and the monitor lizard. The mugger crocodile or marsh crocodile is a common inhabitant of the riverine reed beds and Ranganathittu has largest fresh water crocodile population in Karnataka state