Bird Flu: Bar-headed Geese Worst Hit in Himachal's Pong Dam Wetlands
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Nestled in the sylvan surroundings of the Kangra valley in Himachal Pradesh, the Pong Dam wetlands in the foothills of the Himalayas are normally agog with flapping of feathered guests each winter.
Its silvery green waters, verdant forests, shrubbery islands, grassy swamps and aquatic life make the reservoir a paradise for migratory birds.
But this winter, for the first time in recent decades, birds in the 307-square km Pong wetlands are hit by avian influenza H5N1. And the worst affected species is one of world's highest-altitude fliers, the bar-headed goose, an endangered species that regularly descend in India.
The Pong wetlands, one of the largest man-made wetlands in northern India, have emerged as the preferred wintering ground of the bar-headed goose.
At the annual waterfowl estimation coordinated by the state wildlife wing in 2015, a staggering 71,800 bar-headed geese, probably half their numbers globally, were recorded in the Pong wetlands, an all-time high till date.
A total of 49,496 bar-headed geese were recorded in January 2020. Around 23,000 and 28,160 geese were recorded in 2009 and 2008, respectively.
The gregarious goose feeds at night in the grasslands on riverbanks and breeds in high-altitude lakes in Central Asia, including Tibet and Ladakh.
With the death toll of migratory waterbirds in the Pong wetlands rising to 4,020, and almost 90 per cent of them being notable visitors, the bar-headed goose, the state wildlife authorities blamed the avian influenza (H5N1) for the disaster.
Principal Chief Conservator Forest, Wildlife, Archana Sharma, told IANS that 318 dead birds were found in the Pong catchment on Saturday and with them the total number of mortality of birds rose to 4,020.
She said the ICAR-National Institute of High Security Animal Diseases (NIHSAD) based in Bhopal has confirmed that avian influenza virus (H5N1) was responsible for their mortality.
The first death was reported on December 28 last year.
However, Pong heaved a sigh of relief as fatality cases are falling now.
"Most of the carcasses that were collected in the past two-three days were of those who died quite a long time back and they were retrieved from dense forest and muddy terrain," she said.
"The decayed carcasses indicate that the mortality has declined," Sharma said.
But wildlife experts are concerned over a large number of species that have started migrating from Pong to nearby wetlands, lakes and water bodies owing to stress and trauma by seeing influenza-hit birds dying and behaving unnaturally.
Some birds -- including the bar-headed geese - were seen acting strangely before their deaths, Chief Conservator Wildlife (Pong wetlands) Upasna Patyal, told IANS.
"When you're seeing that birds are not able to take the flight despite healthy wings, it's really disturbing. At some distance, you find their carcasses," she said.
Besides the bar-headed goose, the other species that died owing to the influenza were the shoveler, the river tern, the black-headed gull and the common teal.
The dead included a lesser white-fronted goose that was visiting the Pong wetlands alone for the past three years.
Crossing national and international boundaries, millions of migratory birds of several species descend on various water bodies and wetlands in the region. They start returning by the end of February or the beginning of March.
At the last waterfowl estimation conducted in Pong on December 15, nearly 57,000 waterbirds were recorded that comprised 27,000 bar-headed geese.
"Our current estimation indicates the presence of a small population of migratory birds in Pong of all prominent species as most of them have moved to nearby water bodies possibly due to psychological stress," a wildlife official, who didn't wish to be identified, told IANS.
He said it is still doubtful that the birds infected with H5N1 are able or willing to embark on long-distance migration. "This needs further surveillance, at least months, as there are chances of the presence of the virus in nature. This disaster may also cause stopping of arrival of the bar-headed goose for some years. For this, we need drastic habitat restoration too."
Listed under Schedule IV of the Wildlife Protection Act, 1972, the global population of the bar-headed geese, known for two distinctive black bars across their neck, is believed to be around 130,000, wildlife experts say.
Bombay Natural History Society (BNHS) Deputy Director S. Balachandran, who was earlier tracking migratory routes of the geese and duck species through satellite and leg-rings in Pong, told IANS over the phone that Pong is the only wintering ground in the globe to hold such a large congregation of bar-headed geese.
"Most of the water bodies and lakes across the country have been getting bar-headed geese every winter. Their number is between 3,000 and 4,000 in each water body. But Pong is the only place which is getting the largest influx of bar-headed geese, largely from Tibet and Ladakh," he said.
Even their breeding grounds spread over Tibetan plateau do not support such a large number of the geese at one point in time, he added.
Besides the bar-headed goose, other prominent species that regularly descend on Pong, some 250 km from Himachal Pradesh capital Shimla and 190 km from Chandigarh, are the coot, common pochard, red-crested pochard, great cormorant, gadwall, northern pintail, river tern and the spotbill duck.
Other species recorded are the common shelduck, the greater white fronted goose, the black bellied tern, the Sarus crane, the lesser white-fronted goose, the osprey, the buff bellied pipit and water rail. These species are not common visitors in other wetlands in India.
In Pong, influx of the bar-headed geese can be spotted in marshy areas along the reservoir like Nagrota Suriyan, Nandpur Batoli, Chatta, Jambal and the Rancer island, say wildlife officials.
The Pong wetlands are also home to many native birds like the red jungle fowl, large Indian parakeet, Indian cuckoo, bank mynah, wood shrike, yellow-eyed babbler, black ibis, paradise flycatcher, crested lark and the crested bunting.
A total of 425 species of birds, both migratory and local, 18 of snake, 90 of butterfly, 24 of mammals and 27 of fish have been recorded so far in Pong.