Kochi: It was a tradition in Kerala to wait for the vitthum kaikottum (seed and spade) call of the Indian cuckoo, which was the indication for farmers to begin sowing operations as the rains would not be long in coming. But that was then. Today, new species of birds have descended on the state, some never sighted here before. And climate change is said to be the reason. “The Aquila type of eagle, not historically reported in Kerala, is now commonly found.
These are commonly found in the very dry areas of Gujarat, Rajasthan and Punjab and have migrated to Kerala. The sparrow type wheatear or buntings noticed in the dry areas of central and north-western parts of the country have also been spotted across Kerala in the last few years,” says professor at the College of Forestry of Kerala Agriculture University, P.O. Nameer.
This is a new phenomenon and the presence of these birds is an indication that they are equally comfortable in the southern tip of the country as in northern parts which were their original homeland.
Ornithologist R. Sugathan says these are indications of global warming. "Birds do not migrate or come for fun. When a moist deciduous forest changes into deciduous, shedding its moist tag, a new set of birds and animals takes the place of the old. This is obvious in the changing pattern of migration of birds to Kerala. Some of them are now found going to places in neighbouring Karnataka and Tamil Nadu in search of food and breeding grounds."
Suganthan had worked closely with Indian's birdman, Salim Ali, who first trekked the forests of Kerala and recorded its birds and was followed by K.K. Neelakantan, better known by his pen name Induchoodan, whose work Birds of Kerala is still the Bible for birdwatchers.
Climate change and loss of food and habitat have affected the pattern of bird migration in the state. "Take the case of birds that feed on nectar. A change in flowering season owing to the change in climate makes things difficult for them. This has forced them to migrate to areas where there is sufficient nectar available," Sugathan points out. Bird watchers from other parts of the state also confirm that the delayed arrival of birds was conspicuous in their areas, especially the wetlands of Kottayam district.
The effect of climate change on bird behaviour is part of an agri-ornithology study by the Kerala Agriculture University. Mani Chellappan, who is part of the study team, points to the very early arrival of birds like teals from Europe. They used to arrive some time in February and their breeding season was up to April, after which they left.
But now they come earlier, in October-November, and leave by January, he says. The presence in Kerala of birds such as the stonechat, blue throat and wheatear, which are found in temperate regions, is a further indication of how changing climate conditions have impacted the existence of animals.
Migratory birds chart a new flight
There is no significant decrease in the number of birds visiting the state, but their migration pattern has changed significantly, says ornithologist R. Sugathan, who has worked closely with the renowned ornithologist Salim Ali, and is now associated with the Salim Ali Bird Sanctuary at Thattekkad near here.
Places like Thattekkad and Kumarakom, which play host to a number of resident and migratory birds, have registered significant changes in the time they arrive from and return to their distant homes. This could be the result of drying up of water bodies, change in the flowering time of trees and extreme weather conditions.
“While some species choose to come late, some others delayed their annual visit by a few weeks. The migration season, which usually extends to about six months, has reduced to three months. However, there is no decrease in the number of species coming to Thattekkad. The total number of bird species here is 322,” said Sugathan.
The international migrants come all the way from Siberia and Britain, others from the northern regions of the Himalayas. Thattekkad and Kumarakom are favourite destinations for both tropical and wetland birds during summer and winter.
A comprehensive bird census to assess the increase or decrease in the number of birds is yet to be held, says Sugathan, but with the sanctuary becoming a plastic-free zone and the restriction of entry to its eastern side, the bird population has increased.
Wagtails from Siberia, which are water birds, come annually to Thattekkad by the second week of October and return by March. This year, they came in December and are overstaying. Another species, the Golden Oriole, coming from Britain and Siberia, have vanished very early from the sanctuary due to lack of food.
These birds feed on small worms found on teak tree leaves in the sanctuary. This year, the leaves dried and fell quite early as there were scanty rains. As there was no food, the birds went back early, Sughatan said.
Among the migratory bird species coming to Thattekkad to eat and breed are terns, egrets, herons, teals and other duck varieties. The avian visitors cannot go back to their homelands till the climate there is suitable.
In an effort to take stock of the number of birds in the sanctuary, Sugathan began a detailed study last year. "To get the precise number of birds, it is necessary to monitor them throughout the year. We are now registering the time a migratory bird is first and last seen during the year.
The time, atmospheric temperature and velocity of the wind also are important. Through this study, the exact time of visit of migratory birds can be assessed," he adds.