The swelling of Cauvery river has become a cause for concern for migratory and Indian birds at Ranganathittu Bird Sanctuary in Srirangapatna, with hundreds of nests and fledglings being washed away in the last 24 hours.

The Irrigation Department lifted the sluice gates of the Krishnaraja Sagar (KRS) upstream on Saturday following a significant rise in water inflow. Whilst water was being let out at the rate of 50,000 cusecs at 1 p.m. on Saturday, the outflow was increased to the rate of 1,19,947 cusecs at 6 a.m. on Sunday. Turbulence in the Cauvery has caused damage to the islands at the sanctuary, according to officials of the Forest Department.

Entry of tourists into the bird sanctuary was restricted and boats were anchored when this correspondent visited on Sunday morning. Water could be seen entering walkways, garden areas, the ticket counter, watch towers and other areas. Almost all the 34 islands were submerged.

The breeding season of a majority of the birds is over and they have left the islands. However, several hundreds of black ibis, cormorants, little egrets, intermediate egrets, cattle egrets, pond herons and night herons, river turns, kingfishers and some other birds were there when the sluice gates were lifted, officials said.

According to them, many birds nesting on or between rocks, on the grounds, and on branches near the water flow have been washed away. Some trees have also been uprooted and swept away.

Meanwhile, according to officials, several hundreds of local and migratory birds at many places — along the Cauvery river course between Ranganathittu and Gaganachukki waterfalls — are also bearing the brunt of the swollen Cauvery.