Vishvendra S Poonia

Annual bird migration is a beautiful yet mysterious phenomenon. Hundreds of species of birds migrate long distances with great precision every year. Some of them even spend six to eight months a year in flight. Despite several attempts to understand the underlying biophysical mechanism, it has been one of the least understood natural phenomena till date.

The magnetic field of the Earth helps many organisms (e.g. sea turtles, sharks, etc.) navigate large distances. It turns out that migratory birds also use geomagnetic field for navigation, albeit in a complex way. That is why this phenomenon is also termed as avian magnetoreception and the migratory birds are said to possess a ‘compass’.

In order to better understand the phenomenon of avian magnetoreception, behavioural experiments have been performed where a migratory bird is captured and kept in a big wooden chamber. During the migratory season, the bird develops ‘migration anxiety’ where it instinctively tries to fly. During this ‘compulsive’ flight, the characteristics of the birds’ migration are studied by artificially manipulating the magnetic field in the chamber and observing the bird’s flight behaviour. Following characteristics have been observed in these…read more on NOPR