How do migrating birds steer using Earth's magnetism?
Birds' Magnetic Eyes
How do migrating birds steer using Earth's magnetism?
Every fall, a tiny warbler no bigger than your fist flies from Canada to Central America — two thousand miles, much of it over open ocean, no GPS, no map, no road signs. How does it know where to go? The answer is inside its eyes.
Earth is a giant magnet. Invisible magnetic field lines loop out from the North Pole, arc through the sky, and dive back in at the South Pole — like huge, curved wires you can't see or feel. We ignore them. Birds see them.
