Erratic monsoon upsets migratory pattern of birds

KOCHI: Vagaries of monsoon have upset the life pattern of a large number of migratory birds.

While a few species chose to arrive early in Kerala this year, some others delayed the annual visit by a few months due to the extended showers. It was the wetland-dependent migrants that came late by nearly two months whereas the forest birds reached their favourite spots well in advance.

The migratory species have evolved a voyage pattern for themselves wherein they reach the wetlands and forest regions of the State by September and return to their native grounds by April. They complete a crucial phase of their lives in the water bodies and forests of Kerala.

The international migrants come all the way from places like Siberia whereas some other migrants reach here from the northern regions of the Himalayas. Some feathered friends come from Europe when life becomes difficult in the intense winter months there. The arrival of commensal migrants, which are found near human habitations, like Ashy drongo, Golden oriole and Greenish leaf-warbler was also delayed this year, said P.O. Nameer, State coordinator of the Indian Bird Conservation Network and Important Bird Area Programme.

Most of the migratory species that used to reach the kol wetlands, Peechi Wildlife Sanctuary and the Kerala Agricultural University campus, Mannuthy, by September came nearly two months late. The delayed arrival was striking as the water birds came in large congregations, Dr. Nameer said.

One of the reasons for the delayed appearance can be the excess monsoon the State received this year. It is to be seen whether the birds will overstay the migratory season. The birds go back when the breeding instincts urge them to hit the return path, he said.

The delayed arrival of birds was conspicuous in the wetlands of Kottayam district also, said Dr. B. Sreekumar, president of the Kottayam Nature Society.

“Kumarakom, Veeyapuram, Mangottuchira, Aayaaparambu, Karuvatta and Polachery are some of the favourite spots of migrant species in the district. Lesser whistling ducks and Egrets are among those who came late. Though delayed, a few species have started arriving in good numbers at Thollayiram Kayal and some other areas of the district,” he said.

Good monsoon in neighbouring States means less appearance of the migrant birds species in Kerala. A drought in Tamil Nadu four years back had brought more birds to Kerala, he said.

Early arrival

Contrary to the delayed presence of wetland birds, the forest species chose to arrive well in advance at the Salim Ali Bird Sanctuary, Thattekad. Some species like Warblers and Wagtails reached the sanctuary as early as September as against October, said R. Sugathan, ornithologist associated with the sanctuary.

Last year, the birds kept the date. They came and departed on time, he said.

Earlier studies have recorded the presence of more than 100 migratory birds in the sanctuary.

The excess rains could be one of the deciding factors as it might have ensured availability and supply of food for the birds. The changing patterns of flowering and fruiting of trees due to global warming would also have telling effect on the lives of several bird species, Dr. Sugathan said.