Paul Boxley

Robins can see magnetic fields

It's fairly well known that birds use magnetic fields to navigate, but recent research has shown that it is linked to the chemical cryptochrome which is present in birds' retinas.

When cryptochrome is struck by blue light, it shifts into an active state where it has an unpaired electron – these particles normally waltz in pairs but here, they dance solo. The same thing happens in a companion molecule called FAD. Together, cryptochrome and FAD, both with unpaired electrons, are known as a “radical pair”. Magnetic fields act upon the unpaired electrons and govern how long it takes for the radical pair to revert back to their normal, inactive state. And because cryptochrome affects the sensitivity of a bird’s retina, so do magnetic fields.