Gulls for weather updates

The annual return of gulls and terns are a sign of calmer waters and better catch. And proof that urban spaces can be unexpected sanctuaries for wildlife

March 01, 2024 10:08 am | Updated 03:32 pm IST

Terns in flight

Terns in flight

This year, winter came on the night of Deepavali, in a sky torn by incessant explosions of colour and light. It came on the wings of a huge, slow moving flight of egrets swimming south, hugging the coast, undeterred by the umbrellas of falling fire.

This extraordinary tableau was a reminder that our cities, for all their hazards, are not the sterile spaces we believe them to be. Increasingly, evidence points to non-human life actively finding ways to thrive in urban areas, often without our knowledge. One global study (started in 2017), which tracked 529 bird species, found that an incredible 66 were found only in urban areas. As agriculture becomes increasingly mono-cropped and chemical-dependent, even bees may be more abundant in cities than rural scapes.

Egrets flying across a Deepavali sky

Egrets flying across a Deepavali sky

Many of those egrets probably settled down with long-distance migrants around the Muttukad backwaters, to the south of Chennai. On Margazhi mornings, the widening strands of yellow sand and restless waves in the creek are alive with white. While gulls slice inland, terns rove bay-wards. Spot-billed pelicans kiss the waves like flying boats. Cormorants dip and dive while elegant painted storks and great egrets meditate in the shallows. Nervous sandpipers stalk at the edges, hopping away from the surf. A dowdy pond heron abruptly bursts into brilliant light on an upturned boat. A hefty Eurasian curlew, a sand and pebble-winged wader with feet the colour of the waves, is nearly invisible till it tilts its head to unveil a slender down-curved bill.

An egret

An egret

Sign of calmer waters

Why are so many sea birds coloured like they are? The answer may lie in who is looking at them. Seen by prey from underwater, their white bodies merge with the bright sky. And when seen by predators from above, their greys meld into the waves below. Melanin makes the wing tips black and abrasion resistant.

Gulls and terns are interesting to observe because of their diet and habits. Their population and movement patterns are good indicators of ecosystem health, weather patterns, and even ocean currents and fish movement. Experienced fishermen often track tides and fish by relying on their activity.

A seagull

A seagull

At first, there is little to distinguish between gulls and terns; both largely white and grey with dark wing patches. Look closer and they reveal themselves to be very different creatures. Terns are delicate; sleek and streamlined with thin, sharp bills and wings. Sweeping the creek on forked tails, 30 feet above, peering intently below for prey which they strike with steep dives. When not flying, terns rest on sandbars on short, non-webbed feet.

Nearly a dozen tern species are seen in Chennai during winter. Many are migratory, like the elegant greater crested tern, the pigeon-sized gull-billed tern, and the smaller whiskered tern. The most impressive representative though is the Caspian, the largest of its kind, with a long flaming bill contrasting with its black capped head. These birds undertake their long annual migrations at night on 4.5-ft wings, with young birds relying on male parents to successfully complete their pilgrimage.

A tern

A tern

The sturdy gulls, meanwhile, are a bizarre blend of angel with devil. They glow with a translucent, other-worldly quality while meandering up and down on angled wings. Perfect, spotless beings, till they swoop down on an unsuspecting cormorant to steal its catch. They are raucous thieves and scavengers, not averse to bullying crows and humans.

They do fish, often by ducking their head under the surface and paddling around like ducks on webbed feet. Here, the most numerous brown-headed gulls from Ladakh are in mixed flocks with their black-headed brethren from central Asia.

Alternate habitats

Bird behaviour is always in tune with their ecosystems. This year, migrants seem more numerous to the south of Chennai, due to the oil spill near Ennore in north Chennai. Gulls are smart and adaptable; many European gull populations are now exclusively inland, urban, and thrive on waste. Tern numbers, meanwhile, are falling. The recent State of India’s Birds report indicates a 70%-80% long-term decline for many of these once common species, a worrying sign for fishermen.

Such changes also raise questions on how cities are evolving. By 2050, it is estimated that there will be 9.5 billion of us, with 68% living in cities. We now know that cities contribute to the resilience of at least some species. Perhaps we could, with some planning and prioritisation — such as mapping and preserving existing vegetation and habitat, or having dedicated green spaces with native species — enable cities to become havens for migratory stopovers, and provide conditions to adapt to our ‘development’ and climate change.

The first in a series that looks at urban spaces as havens for biodiversity and often overlooked species.

The writer is an amateur birder based in Chennai.

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