Every year, migratory birds travel thousands of kilometres across landscapes they may never have encountered before, yet many can maintain remarkably consistent directions. Scientists have long known that birds can use Earth’s geomagnetic field as a source of navigational information. What remains fascinating is how they detect something humans cannot see or feel. Research points toward magnetoreception, a biological sensory ability that may allow birds to extract directional information from the planet’s weak magnetic field. One leading explanation involves light-sensitive proteins called cryptochromes in the retina and a quantum-chemical process known as the radical pair mechanism.
