Unseasonal rain, release of water from dams make region unsuitable for birds
Climate change, coupled with shifting agricultural conditions, has affected avian migration to the wetlands of Mysore and surrounding regions.
As a result, the number of migratory birds that come here to roost during their annual winter sojourn has plummeted to a new low.
The change has been precipitated by unseasonal rain that lashed the south-interior parts of Karnataka before the advent of winter, followed by the release of water from the dams of the region that have filled lakes to the brim.
This has affected the natural cycle of growth and flowering of hydrophytes (plants that grow in water or under moist conditions) that sustain insect life on which the birds prey.
Global phenomenon
K. Manu of the Mysore Amateur Naturalists (MAN) told The Hindu that the phenology (natural cycle of events dictated by climatic conditions) of bird migration had altered owing to changes in the weather conditions.
“This is a global phenomenon and has been observed across the world but is now evident in Mysore and surrounding regions that have received unseasonal rains this year. As the lakes are full, they support only fish-eating birds. The migratory birds that survive on insects have to fly on looking for an ideal habitat,” he explained.
“As against nearly 1.25 lakh to 1.5 lakh birds that could be counted in the wetlands across Mysore region during this period, we hardly see 40,000 birds this year,” said Mr. Manu, who is an ornithologist and recipient of the Sanctuary ABN Amro Wildlife Award for his contribution to the conservation of birds.
Large flocks
The winter migration is heralded by the arrival of large flocks of gargeney, Northern Pintail duck, shoveler, a variety of sandpipers, snipe, plover, curlew as well as the local River Tern.
A few species fly in from the Baltic region, Russia, Central Europe and Mongolia, crossing the Himalayas in the process. The Bar-headed Geese even have a stopover at the Mt. Everest base where the temperature is -20 degree C to -40 degree C.
After a brief stop in the North, the birds enter Karnataka. Major roosting sites in are near Belgaum, Haveri and parts of Deccan.
By the time the birds fly into Somnathapura, it is late December or early January.
Major lakes in south Karnataka that sustain the bird population are Kaggalipura, Narasambudhi, Kuttur and Kallur, Kesthur and Yellandur, according to Mr. Manu.
The migration of birds is triggered by the onset of winter when the duration of daylight declines. “Birds, on an average, have to consume one-third of their body weight every day. This is impossible when the daylight hours are less. Hence during this time, large flocks of birds fly south where there is an abundance of daylight,” the ornithologist says.
