Migratory birds rarely reach an area outside of their normal range. Why? Because almost everyone knows how to get back on track if they lose it. To analyze this, a team looked at how they used magnetism to orient themselves. That would explain how migratory birds are managed.
Magnetic signatures
The researchers come from the British universities of Bangor and Keele. They describe how the warbler begins his navigation from a “magnetic position” outside the route. From there they return to the correct route. Their study is published in Current Biology.
Different parts of the earth have different “geomagnetic signatures” depending on their location. This combines several elements. Geomagnetic field strength, magnetic inclination, angle between the directions to the geographic and magnetic north pole.
Adult birds that were already familiar with their migration route were used for the tests. They were subjected to a simulation of the Earth’s magnetic signature. It was taken at a location thousands of kilometers behind the birds’ natural migration corridor.
They experienced all of the other sensory cues of its location. Even the starlight and the sights, smells and sounds of your actual location. And the birds kept showing the urge to begin their journey as if they were in the place indicated by the magnetic signal.
Navegantes choice
The magnetic signals they experienced influenced their decision. It is the key factor in guiding warblers when they deviate from their course. “The main impetus was to respond to the magnetic information they received.” Richard Holland explains it in a statement. She is from Bangor University College of Natural Sciences.
What these birds do is real navigation. They are returning to a known destination after traveling to a completely unknown location. They do not depend on familiar surroundings, signs, or information gathered during the trip. It is clear how migratory birds are managed.
Warblers use the same magnetic signals that occur in their natural range. However, this study shows that they can extrapolate what they understand about the variation in the magnetic field in space. Far beyond any previous experience.
