Scientists from Bangor University believe they have revealed how some migrating birds navigate on their journeys.
One aspect of the system used by some birds has been revealed for the first time and involves detecting the declination or variation that occurs because the geographic ‘true’ north pole and magnetic north are not in the same place.
In Europe, this difference between the true and magnetic north, increases as you move from east to west.
Writing in Current Biology (August 2017), an international team of biologists, including Richard Holland and Dmitri Kishkiniev of Bangor University in the UK, explain how they identified for the first time, that mature Reed Warblers are able to detect the declination from magnetic north, and use the scale of the declination or change from true north to geo-locate themselves to a longitude, from which they orient themselves towards their autumnal migration from Russia to Africa.
Dr Richard Holland of Bangor University said: “It seems that a bird as unassuming as the Reed Warbler, may have a geographic map or memory that enables it to identify its longitudinal position on the globe, only by detecting the magnetic north pole and its variance from true north. This, combined with other external cues, which may include the strength of the magnetic field, star positions or smells enables it to locate its current position and orient itself during a long migration.”
Their work also suggested that the birds learn from experience, with immature birds struggling to navigate.