The pattern of migratory birds at the Okhla Bird Sanctuary is rapidly changing. The number of the winged visitors is also coming down. And all this can be attributed to climatic changes and local disturbances.
Only 15 species of winter migratory water birds have so far arrived at the sanctuary. Birdwatchers say arrival of many species -- such as Greater Flamingo, Wollynecked Stork, Ferruginous Pochard, Blacktailed Godwit and Tufted Duck -- has been delayed.
The sanctuary -- spread over an area of 3.5 sqkm on the Yamuna -- has been a heaven for waterbirds and a favourite among birdwatchers with more than 300 species spotted so far. After the construction of a barrage and the resulting lake in 1986, birdwatching activity increased.
T K Roy, ecologist and conservationist, said, "The temperature is not as low as it used to be around this time of the year a few years ago. Winter birds used to come here by early November and stay till February -- sometimes March. But now they come late and leave early."
"Yamuna has also become extremely polluted. Plus, there's noise pollution because of vehicles and the annual Diwali blitzkrieg. High-tension electric wires run through the sanctuary. There are mobile towers in the vicinity that affect movement of birds," he said.
"During the last summer, winter migratory birds -- Greater Flamingo, Great White Pelican and Cotton Pygmy Goose -- were spotted at the sanctuary. This was again unusual. These birds had deserted the sanctuary. But they reappeared in the scorching heat. This was because of changing climatic conditions globally," said another birdwatcher.
JM Banarjee, range officer at the sanctuary, however, said, "High-tension wires are every where. We have rare migratory birds visiting the sanctuary but we don't have powerful cameras to capture them. We're satisfied with the pattern and numbers."