Very weak radiation can have a profound influence on a robin’s magnetic compass. A group led by Prof. Thorsten Ritz has shown that 7 MHz signals of less than 100 nanowatts per square centimeter can disorient the bird’s migratory flight. The new findings appear in the May 13 issue of Nature.
It is not clear what the mechanism of interaction may be, but Ritz thinks that it is unlikely to involve magnetite. Rather, he believes that a radical pair mechanism — that is a chemical reaction — is at work. “Since the artificial field’s oscillations were too rapid to influence magnetic material like magnetite, it suggests that the most likely mechanism for magnetic orientation in these birds involves tiny changes to magnetically sensitive chemical reactions, possibly occurring in the eyes of the birds — we are not sure,” Ritz noted in a press release issued by the University of California, Irvine, where he teaches biophysics. “These very weak oscillating fields block the ability of the birds to sense the static field,” Ritz told Microwave News.