Coimbatore records drop in migratory birds

Coimbatore: There is a sharp decline in the arrival of migratory bird species to the wetlands in the district, according to a recent study conducted by the Coimbatore Nature Society. The study revealed that only 25 migratory bird species were present in the wetlands of the district, compared to 47 species in January this year.

The study, conducted systematically across the wetlands of the district from November 12 to 17, involved 35 birders with the Coimbatore Nature Society (CNS).

P R Selvaraj, president, CNS, said it was evident from the data and analysis compiled by senior bird watcher A Pavendhan that there was a steep decline in the arrival of migratory birds - both in species diversity and individual numbers - to the wetlands of Coimbatore, compared to the same period last year.

"In the recent exercise, CNS members observed a total of 7,054 individual birds belonging to 131 species across 30 wetlands in the district. In January, they had spotted 16,069 individual birds belonging to 201 species during a synchronized bird survey," he said.

The count of migratory bird species also dropped significantly, with only 25 species recorded this time, against 47 in January. The number of individual migratory birds observed declined to 1,060 from 2,816 in January. Among the 25 migratory bird species identified, eight were waterbirds, while the remaining 17 were terrestrial species, Selvaraj said.

"This year, we received very good rainfall and as a result almost all wetlands are filled with water. This is not only true for Coimbatore, but also for neighbouring districts. During the years of good rainfall, migratory birds tend to disperse rather than congregate in a location. This could be a reason for the reduced numbers of migratory birds observed. The upcoming migratory bird estimate in January is expected to provide further validation," said G Prakash, a senior member of CNS.

P B Balaji, another senior member of CNS, said the unchecked discharge of untreated domestic and industrial sewage into the wetlands had deteriorated water quality and led to growth of invasive water hyacinths. "This has adversely affected the fish populations, which are a primary food source for many birds. Additionally, domestic waste is often dumped along the paths and bunds leading to the wetlands. Human interventions in these areas are another cause for concern."

Balaji emphasised that the long-term management of wetlands was crucial to reversing the decline in migratory bird species and numbers. "If the Noyyal system tanks have to host a diverse bird population, they must be scientifically managed with input from all stakeholders."