MIGRATING birds probably use a chemical compass to navigate with, rather than a physical one.
Pigeons have particles of magnetite in their beaks, which some researchers have suggested could align with the Earth’s magnetic field and give birds a directional cue. But a study of European robins (Erithacus rubecula) indicates that birds are more likely to rely on chemistry.
Thorsten Ritz of the University of California at Irvine and his colleagues placed captive robins in cages and manipulated the length of their days and nights to simulate the onset of spring. By altering the lighting, the researchers could cause the…
