How do birds navigate? They steer by landmarks and by the sun and stars. A keen sense of smell helps some birds chart their course. And, it turns out, migrating birds also find their way by responding to the magnetic field of the earth.

Iron-rich magnetic crystals inside the upper beak of this Bobolink help the bird orient itself to Earth’s magnetic north. Also, light hitting a specific protein in a bird’s eye may trigger a chemical reaction that varies depending on the direction of the earth’s magnetic field. And “birds may actually see Earth’s magnetic field in the form of changing dark areas across one eye.”

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