A new study shed shed light on how birds navigate back to their breeding site after flying across two continents. The study has been published in the journal Science.
University of Oxford and University of Oldenburg scientists suggested that information extracted from the Earth’s magnetic field tells birds where and when to stop migrating. It allows them to precisely target the same breeding site year-on-year from thousands of kilometers away.
It has been the subject of intense research of how birds sense the Earth’s magnetic field. Birds even ‘see’ magnetic field lines. They use this ability to both determine the direction they’re facing in and where they are.
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Scientists analyzed data from nearly 18,000 reed warblers to investigate. They found out if the birds used the Earth’s magnetic field when finding their breeding site. Reed warblers are tiny songbirds that fly across the Sahara Desert every year to spend the summer in Europe.
Scientists found out the magnetic field of Earth moved slightly. The sites to which birds returned moved with it. This suggests that birds homed to a moving magnetic target. Birds used magnetic information as a ‘stop sign’.
It has magnetic inclination in particular telling birds that they had arrived at their breeding location. Scientists utilized ‘ringing’ data. Scientists have uniquely numbered metal rings have been attached to the legs of birds from across Europe.
Why use the magnetic field to inform return migration?
Magnetic information seems to be pretty stable, meaning the magnetic field doesn’t change very much in a given location year-on-year. Aiming for a specific magnetic value during migration might make sense then, and the cue we think birds are using, inclination, appears the most stable aspect of the magnetic field. We think this gives the birds the best chance of making it back to the breeding site.Dr. Wynn