Winter is prime birdwatching season in northern India. It is the time of the year scores of migratory birds from the North fly down to wetlands in the Indian plains to escape the harsh winter in their native habitats. They then wait out the cold season before they head homeward again.

But something is changing.

On December 2, when Kanwar B Singh, an avid birdwatcher, and his team, hosted a bird count event in Delhi, they counted 255 migratory bird species in multiple locations across the National Capital Region. This includes areas around the Yamuna river, Sultanpur and Okhla in Delhi, and parts of the satellite cities of Noida and Greater Noida.

“We noted a fluctuation of two – that is 255 [species] against 253 in the previous year,” said Singh. “That is considered normal.”

He added: “But the bigger concern is the severe depletion in the visible population of birds of different varieties.”

Explaining what has changed, Singh said that about six years ago any birdwatcher could easily spot at least 500 flamingos in the Okhla Bird Sanctuary, a four sq km expanse on the banks of the Yamuna, straddling the Delhi-Noida border. “This season, we spotted 10 flamingos there,” he said. “Such is the depletion in numbers.”

Nikhil Devasar, avid birdwatcher and founder of a conservation network called DelhiBird, had a similar story about migratory ducks.

About 15 to 17 varieties of migratory ducks are usually spotted in Delhi-NCR in this season. “There was a time when we could not see the water in certain areas of the Yamuna in December because of the presence of varieties of migratory ducks,” he said. “Today, we have to make an effort to spot them.”

He added: “Of all birds, ducks are the easiest to monitor and keep count of. Their population has depleted to one-fourth of what it used to be around 10 years ago, which was close to 25,000.”

Devasar listed the tufted duck and common pochards as duck varieties whose numbers have severely depleted, while Singh said it was now getting difficult to spot northern shovelers and northern pintails.

But it is not just ducks and flamingos whose numbers are falling. Jayantika Dave, an avid birder, said that all species of migratory birds in Delhi-NCR have witnessed a significant depletion in numbers in the past few years.

Causes behind the depletion

Could this fall be attributed to the severe air pollution that has gripped the region over the past few years?

Both Singh and Devasar said that this was difficult to say as there has been no research on the subject so far. But though Singh was inclined to be open to that possibility, Devasar was sceptical. “If birds can survive the toxic gases of the Yamuna, it is unlikely that their migration will be significantly affected by the smog and air pollution,” he said.

Birders say that the loss of habitat has been identified as the primary reason behind the decline in the number of migratory birds in the region.

Singh gave the example of the Bil Akbarpur wetland in Greater Noida, which used to be a refuge for animals like the protected blackbuck, as well as migratory birds. The wetland has nearly been obliterated today, said Singh. In 2012, the Uttar Pradesh government sold area to a private developer.

“Another recent example would be the damage caused to the Yamuna floodplain by the Art of Living event in March 2016,” said Singh.

Environmentalists have said that the three-day festival organised by spiritual leader Sri Sri Ravi Shankar’s Art of Living foundation on the banks of the Yamuna in Delhi destroyed the riverbed habitat – home to several species of birds – by removing reeds, filling in mini ponds and flattening and hardening the ground.

On Thursday, the National Green Tribunal held that the Art of Living was responsible for damaging the floodplains during the festival. The tribunal also censured the Delhi Pollution Control Committee for granting permission for the extravaganza.

Workers make arrangements for the three-day festival organised by the Art of Living foundation on the banks of the Yamuna in March 2016. (Photo credit: PTI).

Dave cited the Basai wetland in Haryana’s Gurugram district as an example of another bird habitat lost to development. Several multi-storeyed buildings have been constructed around it over the past few years, she said. Similarly, the Okhla Bird Sanctuary has high voltage transmission towers that disturb the birds that take refuge there.

Dave added that this year several geese arrived at Okhla only to take-off a few days later. “Bar-headed geese, which had just arrived in November, waited only for a couple of days and fled because they could not find sufficient water to survive,” she said.

Climate change is another factor. It has affected bird migrations all over the world, leading to the depletion in numbers and varieties of birds, said Devasar. “The Spanish sparrow is a classic example,” he said. “The temperatures in their usual habitats in southwest and Central Asia do not drop enough for them to migrate so far away.”

Every winter, these sparrows are usually spotted in northwest India, in the states of Haryana, Gujarat and Rajasthan. Birders say that these are one of the species whose numbers have fallen substantially.