After false starts, winter season is slowly getting back on track

After false starts, the winter season seems to be getting back on the rails for the Perumbakkam wetland. The fine points of seasonal tenancy by long-distance and local migrants is being inked in afresh, after the details of the earlier agreements were washed away by a succession of harsh weather systems in November.

What occupants of nosebleeds are to a sporting event, migratory ducks are to a wintering ground. They bring the numbers and the noise to a wetland. And this week, on the northern side of the wetland, which clasps the Sholinganallur-Medavakkam road in a tight embrace, there is finally something to quack about — signs of migratory ducks, largely northern pintail from whatever can be viewed from the road.

Towards the end of October, northern shovelers seemed to be leading the influx, but the back-to-back weather systems saw the wetland swell with water and the early birds recede from the scene. Except for the blue-tailed bee-eater and a handful of resident bird species, the wetland looked as stark as Thomas Moore’s “banquet-hall deserted”.

There are points to ponder. How filled with bird choruses would this banquet-hall be this season, after it picks up momentum? Would similar back-to-back late starts in the future disturb bird migration patterns, getting chunks of migrant populations to be acclimatised to other winter hangouts?

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When the wintering season arrived, the wetlands had surplus water harvested from unexpectedly good rains in June, July and August. The more water-filled a wetland is, the more of an anathema it would be to a vast majority of waterbirds — particularly the waders and dabbling ducks — which prefer the shallows. So, the first arrivals in Perumbakkam would have already been scattered. This November in Chennai, which made it to the record books for being one of the wettest Novembers in 100 years, further scattered the other batches of migrants headed this way.

“With the excess rain, and water being found everywhere, you may not find them in such concentration in one place as you would in a drought year. The same number of birds — or even more — would be present but spread out to various wetlands. Of course, the sudden increase in water levels due to the weather systems may have also forced them to go to other places,” notes ornithologist V Santharam.

Two “scatterings” is not good news for the nosebleeds. Though the water levels have subsided this week, one may expect a considerably piped-down birdsong this season. There is strong scaffolding for this belief. Ducks and waders are what make the Perumbakkam wetland a hugely occupied space in winter. Unfortunately both are hardly pin-ups for site loyalty.

“Flycatchers and raptors such as the peregrine falcon feel impelled to return to the same spot, migratory season after season, going over much of the covered ground, including habitual perches. Ducks and waders do not have the same commitment, their choice of place being hugely dictated by circumstances. As long as the circumstances are favourable, they will return to the same wintering grounds. When the situation shifts, they would also easily shift their loyalty to another place,” says eBird reviewer Gnanaskandan Keshavabharathi.

He adds: “There is a high probability that between February and March, the wintering season at Perumbakkam wetland would pick up. The ducks and waders would have settled down in and around the region. Probably a little later, when the water levels drop, they may come back. On the return migration, during February and March, there is a fair chance of bird numbers going up at this habitat. But if rain extends upto January, one cannot be sure.”

Risk factors

The two rainfaIl-created scenarios mirror elective and emergency surgeries. Birds that arrived early to the sight of filled wetlands would have had sufficient response time to choose what are possibly the best alternative locations. The ones that were buffeted around by the inclement weather systems would have been in a less enviable position. Would some of these have settled for sub-optimal locations?

Santharam says: “With increased rainfall, I am sure there is enough food wherever they go — because we are not talking in terms of Chennai area alone — they are capable of flying over long distances to find alternative places. They may even go as far as Tirunelveli — the possibility is there. They could spread and scout for places that are profitable. Due to the rains, there should be food in more places than there were earlier. So, the tendency is to scatter and feed in certain places so that they do not have to compete with other individuals. Once the water level drops at a particular habitat and the food depletes, they will move to another place — they will not settle in sub-optimal places unless there is no other option.”

However, being “buffeted around” can take a toll on the birds.

Santharam explains: “Every time, they have to travel from one place to another, they have to expend energy. And if the unpredictability persists, besides the birds expending energy on movement, there is also the possibility of some of them getting killed. These are however part of the natural cycle — our coast is known for cyclones, and they may have to be prepared for it.”

Answering the other unanswered question — whether there would be any long-term impact on winter turnouts if a geography keeps throwing up challenging circumstances for a disturbingly long succession of seasons — circle back to the Gnanaskandan’s observation about the lack of site fidelity among ducks and waders.