Migrating birds may rely on a special molecule discovered in their eyes that allows them to perceive the Earth’s magnetic field lines as a kind of road map, new research shows. The molecule may help birds navigate much the same way humans follow lines to stay on a highway lane, said the study in the journal Nature.
It's not clear how the molecule functions—whether it affects sight or simply orientation. “It could be a bright or dark spot that would move around,” said the lead researcher. Another biophysicist theorized that a bird’s inner magnetic compass might make it feel the way airline passengers do during a drastic descent if it started flying off course.