Tagged by BNHS on city’s coast, bird sighted in China

MUMBAI: A curlew sandpiper (a medium-sized wader bird native to Russia’s Arctic tundra), which was tagged by the Bombay Natural History Society (BNHS) in Navi Mumbai over two years ago, was seen again over 4,500km away, in China’s Tianjin province last month.

The bird was seen in the Tangu Saltpans on May 7, marking the first international re-sighting of a bird tagged on the Mumbai coast, BNHS officials said.

The bird was captured and tagged at the TS Chanakya wetland near Palm Beach Road in Nerul on March 18, 2019, and was subsequently resighted on January 12, 2020, at the Bhandup pumping station.

Curlew sandpipers tagged by BNHS, as part of various studies to learn more about birds migratory routes, have earlier been resighted around the city.

During the current migratory season, birds tagged by BNHS at different locations in India have been resighted across the world. For instance, a Terek sandpiper tagged in the Gulf of Kutch, Gujarat, was resighted in Jandola, Pakistan, last month.

“An isolated resighting does not tell us much because the tags are not like radio collars which allow us to track the journey of the bird. But it is still extremely exciting because of how rarely it happens. Taken together, resightings provide important insights about the political boundaries that birds may cross, and the potential hurdles they face on their often long migratory routes,” said Dr Bivash Panday, director, BNHS.

Each year, an estimated 50 billion birds undertake such migrations across the world, and their preferred routes, the timing of travel and the ecology of migration is surrounded by intrigue. The bird ringing-recapture/resighting method is a commonly used method to study this process, and involves banding a bird with a light-weight metal ring (with a unique alpha-numeric code). When enough data through this method is collected, it allows scientists to discern the migratory ‘flyways’ of the birds.

Bird-ringing studies were first initiated by BNHS in India in 1927, while large-scale studies relying on this method first began in 1959. They were also carried out extensively at Point Calimere in Tamil Nadu, Keoladeo National Park in Rajasthan, Harike Lake in Punjab, and Chilika Lake in Odisha among other places during the 80s and 90s, and have been monitored for resightings. Along the Mumbai coast, such exercises have been carried out intensively for about seven years.

In Mumbai alone, since 2018, about 10,000 birds belonging to 36 species have been ringed (or colour flagged). Resighting and recapture records of these marked birds, experts said, have provided valuable insights into their migratory routes, site fidelity and turnover rates. “This information would be useful for proposing species specific conservation actions in future,” BNHS said in a statement.

As part of other studies, various species including gulls, terns, shorebirds and flamingos ringed in Central Asia, the Persian Gulf, eastern Asia and along the islands in the Indian Ocean have been recorded along the coast of Maharashtra.