Birds can read the earth’s magnetic signature to get back on track

Bird watchers get very excited when a ‘rare’ migratory bird lands the country, that it is blown off the runway and has flown outside its normal fly. But this is hardly for a reason; most birds that have made the journey before can correct for large displacements and find their final destination.

Now, new research by an international team shows for the first time how birds that are displaced in this way are able to move back to their migratory route and give us an insight into how they achieve this feat.

Subscribe Current biology, the team from Bangor and Keele universities describes how reed grasses can move from a ‘magnetic position’ as they experienced in their normal migration route, back to the right route.

Different parts of the earth have a clear ‘geomagnetic signature’ according to their location. It is a combination of the strength of the geomagnetic field, the magnetic slope or the immersion angle between magnetic field lines and the horizon and the magnetic declination, or the angle between directions to the geographic and magnetic North Pole.

Adult birds already familiar with their migratory pathways and their general magnetic signatures were briefly imprisoned before being released back into the wild and exposed to a simulation of the earth’s magnetic signature at a site. thousands of miles beyond the birds’ natural migration.

Despite staying physically at their capture site and experiencing all other sensory cues about their location, including starlight and the sights, smells and sounds of their actual location, the birds still showed the urge to begin their journey as if they were on the place was represented by the magnetic signal they experienced.

They orientated themselves to fly in a direction that would lead them ‘back’ to their trek path from the place they imagined by the magnetic signals they were experiencing.

This shows that the earth’s magnetic field is the key factor in guiding reed storms when they are blown off course.

“The main impetus was to respond to the magnetic information they received,” explains Richard Holland of Bangor University’s School of Natural Sciences.

What our current work shows is that birds are able to realize that they are outside the bounds of the magnetic fields known to them due to their movements throughout the year, and that they can adequately extrapolate their position from the signals. . This fascinating ability enables birds to move to their normal migratory route. ‘

Dr. Dmitry Kishkinev from Keele University’s School of Life Sciences explained:

“What these birds achieve is ‘true navigation.’ or information provided during the external journey. ‘

Florian Packmor of Bangor University added: “We have already shown that reed stormers use the same magnetic cues they experience within their natural range, but this study shows that they can extrapolate what they understand about how the magnetic field in space different, beyond any previous experience they had. ‘

However, there are still questions about whether the birds have an accurate ‘map’ or just use a ‘rule of thumb’ measurement to determine the general travel direction needed to get back on course.

The Eurasian reed star was selected for the research, but the findings could probably be applied to other migrating songbirds.