Mumbai: Bird-ringing exercise identifies Akshi Beach as crucial habitat for migratory waterbirds
Of 105 migratory water-birds that were ‘ringed’ or tagged as part of a Bombay Natural History Society (BNHS) study at Akshi Beach in September 2019, 31 specimens were resighted at the same location during subsequent months, between October and December 2019. At least two birds that were previously tagged in Mumbai, were also recorded at Akshi during the study period.
Experts said this indicates that the Akshi beach, along with Alibag beach in the north and Nagaon beach in the south, is a crucial wintering ground for migratory birds, including at least two species that are globally threatened. The area, BNHS’s report points out, also requires protection from significant anthropogenic stressors, including pollution, tourism and free-ranging dogs, which may pose a threat to its rich avifauna.
Hindustan Times had reported, on March 6, that a BHNS and Mangrove Cell study has recorded over 70 species of waterfowl across 99 monitoring sites across the Maharashtra coast. However, bird-banding exercises were carried out only at Akshi, which is about 50kms aerial distance from Mumbai.
“We picked Akshi beach for this exercise because it is the only wetland outside of Mumbai that harbours such large congregations of migratory birds. We wanted to gauge the interconnectivity of these wetlands by seeing if birds visiting Akshi were also visiting Mumbai and vice versa,” said Tuhina Katti, a research scientist who worked on the study.
Bird ringing, also known as banding, is a well-established wildlife surveillance tool in which individual specimens are tagged with a small plastic or metal ring, make it easier for researchers to individually identify them. The method has long been used by scientists to understand the movement patterns and life cycles of birds.
In September 2019, a total of 105 individuals belonging to 15 bird species, including 65 Lesser Sandplover, 10 Kentish Plover, 7 Ruddy Turnstone and 6 Terek Sandpiper were ringed at Akshi. “One individual each of near-threatened Bar-tailed Godwit and Eurasian Oystercatcher were also ringed,” the study notes.
Of these 105 birds, 31 birds were resighted multiple times in the area, indicating that they have a high fidelity toward the local ecosystem. The time elapsed between resightings ranged from as little as 13 days to as many as 84 days, indicating strongly that birds were not just staging (or resting) at Akshi, but that they had established themselves there for the winter season. The black-tailed godwit, one of two threatened species that were tagged, was seen in the area after nearly two months.
Conversely, the birds were not observed to be moving between Akshi and Mumbai. Only a single Kentish Plover, “ringed in Akshi on September 24, 2019, recorded at Merces Beach in Vasai on October 17, 2019,” the report notes. However, two birds who had been tagged in Mumbai during previous studies were resighted at Akshi between October and December 2019.
“This tells us that the birds visiting Akshi are highly partial to that ecosystem. To answer why requires more studies over a longer period,” said Katti, adding that the BNHS has proposed to conduct similar exercises at other wetlands in Maharashtra. “Permission for the same could not be obtained due to the bird flu outbreak last year but we are hoping to start soon,” she added.
Virender Tiwari, additional PCCF (mangrove cell), said that the findings of the Akshi beach study are encouraging enough to commission more comprehensive bird-ringing studies in other areas as well. Tiwari reiterated his comment to Hindustan Times on March 5, saying, “The wildlife department has tabled a proposal with the state to monitor not just coastal wetlands, but all wetlands in the state. The budget for this second study is ₹2.77 crore. We are awaiting in-principle approval.”