Wintering duck numbers dwindle in B'luru lakes

Maqsood Maniyar | NT

The numbers of migratory duck species in Bengaluru’s lakes have seen a steep decline as another winter rolls in, thanks to the ecological changes in the city's water bodies. The same pattern had been noticed in past winters. An ornithologist said that one of the main reasons for this is the change in the structure and ecology of the lakes.

They were once seasonal water bodies but have become perennial because they are being dug up to uniform depths by authorities. This caused biodiverse shallows around these lakes, where many birds did their feeding to disappear. Heterogeneous and dynamic lake habitats have been turned into homogeneous and stagnant ones.

This has swallowed the shallows as well. Other factors include inflow of domestic waste water instead of clean monsoon run-off from surrounding catchments, the disappearance of paddy cultivation and constructions around the waterbodies.

City-based ornithologist, Dr S Subramanya said that many migratory birds like pintails, shovelers, pocahards and teals that were common in these lakes have declined in their numbers by over 90 per cent.

“For example, Bellandur lake, which is one of the most polluted lakes in the city today, had accounted for over 50,000 ducks in 1994. I don’t know how many ducks you see there now, maybe in double digits. We have been studying these lake habitats since the late 1980s,” he said. “Hebbal lake used to attract 8,000 to 10,000 ducks during winter. Those numbers and patterns have changed,” he added

Paddy fields to concrete jungles

The bird watcher said that the ecology of the lakes was negatively affected by urbanization. “Earlier, the lakes were not being let out for commercial fishing. Once the paddy cultivation disappeared, the land that was being used (for irrigation) was bought and builtup. Even the catchment areas around the lakes have been completely built up,” Subramanya said.

“There are fewer ducks in these lakes now. There are still some lakes where you can see ducks. When you go to Hesaraghatta lake or Madhure kere, which is behind the Hesaraghatta lake, where there is no sewage pollution and are still seasonal waterbodies, you still get to see ducks. They are not the kind of numbers that you used to find earlier because, one of the main feeding areas (paddy fields) has disappeared from around these lakes,” Subramanya said.

Bird watcher Prashanth Badrinath confirmed that he had observed migratory bird species such as sandpipers, harriers and warblers wintering in Bengaluru. “They are the more common (migratory) birds. They keep coming,” he said.