SOME birds, especially those that migrate at night, use the Earth’s magnetic field to find their way. They presumably sense the north-south direction of the field and use that as a reference to find the direction they need to fly. But no one knows how they do it, or even where the magnetic sensor is.
Now German researchers have shown that the European garden warbler turns its head to detect the Earth’s magnetic field, adding to evidence that the birds detect magnetic fields with their eyes.
Henrik Mouritsen and colleagues at the University of Oldenburg in Germany filmed warblers during…
