Birdwatchers get very excited when a ‘rare’ migratory bird makes landfall having been blown off-course and flown beyond its normal range. But these are rare for a reason; most birds that have made the journey before are able to correct for large displacements and find their final destination.
Now, new research by an international team shows for the first time, how birds displaced in this way are able to navigate back to their migratory route and gives us an insight into how they accomplish this feat.
Writing in Current Biology, the team from Bangor and Keele Universities describe how reed warblers can navigate from a ‘magnetic position’ beyond what they have experienced in their normal migration route, back towards that correct route.
Adult birds already familiar with their migration route, and its general magnetic signatures, were held in captivity for a short period before being released back into the wild, and exposed to a simulation of the earth’s magnetic signature at a location thousands of miles beyond the birds’ natural migratory corridor.
Despite remaining physically located at their capture site and experiencing all other sensory clues about their location, including starlight and the sights, smell and sounds of their actual location, the birds still showed the urge to begin their journey as though they were in the location suggested by the magnetic signal they were experiencing.
They oriented themselves to fly in a direction which would lead them ‘back’ to their migratory path from the location suggested to them by the magnetic signals they were experiencing.