Thousands of migratory birds and their fledgling offspring have been affected along the downstream of the Krishnaraja Sagar (KRS) as their nests and eggs have been washed away following an increase in the discharge of water from the reservoir.

At least 25 places downstream of the reservoir attract hundreds of species of birds from far and wide. Thousands of migratory birds had made Ranganathittu Bird Sanctuary their home. A large number of migratory birds roost at 25 more places between Ranganathittu and Gaganachukki waterfalls in Mandya district.

Swollen river

Cauvery Neeravari Nigam Ltd. (CNNL) authorities opened the crest gates of the KRS on July 22 after the water-level reached the full reservoir level. Since then, the authorities have been discharging a huge volume of water into the river. The discharge from the reservoir into the river was at 15,000 cubic ft a second (cusecs) on July 22 midnight. However, it was at 33,298 cusecs on July 24 and increased to 62,181 cusecs on July 26.

The situation, however, became precarious on the evening of August 2 with CNNL increasing the outflow to over 88,000 cusecs. As a result, the water-level in the Cauvery rose drastically and the embankments of the mini-islets of the bird sanctuary got flooded.

As the sanctuary has been inundated, most of the adult birds have moved to higher reaches, P. Lakshmeesha, Deputy Range Forest Officer (in-charge of the sanctuary), said.

He told The Hindu on Saturday, “At present, the sanctuary has around 6,000 birds of various species.”

The officer, who has been monitoring the flood situation, said there were not many nestlings. Around 4,000 varieties of bats, 1,000 black and white ibis, 500 cormorants and around 300 night herons could be seen. Also, some local birds have roosted at the sanctuary for breeding.

“Majority of the birds have left the sanctuary. But, around 5 to 10 per cent of the fledgling birds might have been affected because of the floods,” the officer said.

25 more places

Meanwhile, Forest Department authorities have noticed the impact of floodwaters on migratory birds at around 25 more places downstream of the KRS.

Ornithologists have identified at least 234 species of birds at Gende Hosahali Bird Sanctuary, Hasiru Bore Halla, Honge Halla, Akkikallu, Bavihalla, Padadahare, Addahare, Jenukallu Wade, Doddamakali, Moogana Kallu, Gavi Kallu, Vamada Kallu, Chikka Makali, Kitaki Palu, Kootale, Balumadu, Aira, Tirumadu, Bagemarada Halla, Ittale Kallu near Bheemeshwari fishing camp, Doddamaralu, Bommana Hole near Muthathi, Kirumadu, Muniyappana temple, Mosale Halla, Mosale Guddi near Galibore fishing camp, Mekedatu, Gaganachukki waterfalls, Balamuri waterfalls, and at other places along the Cauvery between the KRS and Gagana Chukki waterfalls.

“We [forest officials] have also identified 11 varieties of eagles and 10 varieties of owls at the above mentioned places,” another senior forest officer said.

Swift, River Tern, Great Stone Plovers, and several other species which settle on rock-beds, breeches of rocks and on the ground had washed away in flood water with their nests at these places, he said.