Heavy rains, coupled with the flooding of waterbodies this year, is set to disrupt the arrival and distribution pattern of migratory birds in the State.
Winter migration commences during the second and third weeks of November and reaches a peak in December. Karnataka plays host to winged beauties from European and Central Asian countries and from the trans-Himalayan region. The bar-headed geese from Mongolia fly over the Himalayan mountains and come to roost in different parts of the State after a brief sojourn in the central Indian plains.
The wetlands and marshy habitats in the northern parts of Karnataka, Mandya, Kolar and Mysuru-Chamarajanagar belt play host to birds during winter. Hadinaru lake in Nanjangud taluk is a favourite among the bar-headed geese. “But their arrival may be delayed or the distribution may be more widespread, thus making the bird count more difficult [to narrow down],” said Rajkumar of Wildlife Conservation Foundation.
He said almost 75% of the migratory birds are waders that do not venture into the deep waters. Hence, the bird population could disperse to other regions in search of food and marshy ecosystems. “The monsoon was active till October, followed by a cyclonic affect that led to a few more rainy days across the State. This has led to a situation wherein most lakes are flooded, leaving them not ideal for migratory birds,” Mr. Rajkumar explained.
He added that if the northeast monsoon gains more vigour and rainy days continue in south Karnataka, the concentration of migratory birds in the region is expected to further reduce.
C.S. Kulashekar, an avid birder and amateur ornithologist, pointed out that not all birds prey on fish and many species are dependent on insects, whose presence is assured in shallow waters, provided there is scope for the growth of hydrophytes or vegetation. Also, the periodical release of water from reservoirs fills up waterbodies downstream of the command area, disrupting vegetation growth, and this may force the birds to disperse to areas beyond their normal foraging range, he said.
Lakes flush with water also give an impetus to fishing and human presence, tending to disrupt migratory bird populations, according to bird-watchers.
