How tiny trackers are helping unravel mysteries around bird migration

Scientists at BNHS leverage cellular technology to chart their global journeys

- Anjana Vaswani

From the second week of October to November, north-eastern India bears witness to an awesome spectacle: the world’s greatest gathering of raptors. Nagaland’s Doyang reservoir is a pit stop for Amur falcons on a migratory route that takes them from Siberia to South Africa and back. Over a million falcons arrive here, then move through India sightings have been reported from Maharashtra and Karnataka to Kerala before flying across the Arabian Sea, non-stop, for some three to four days, until they arrive on the eastern coast of Africa. From here, they migrate to the south of the continent before returning to Siberia,” says ornithologist Bikram Grewal, while pointing out that these birds follow an elliptical migratory route, bypassing India on their way back.

Why do birds stick to these routes and what sort of in-built navigation system allows them to zero in on locations year after year? These are some of the mysteries that scientists at Bombay Natural History Society hope to unravel by tagging migratory birds with electronic tracking devices, a practice they have undertaken since January this year.