Sixth Sense Migration

Researchers have known that built-in biological compasses tell migrating birds which way to fly, but the details of how birds detect magnetic fields have been elusive. It was proposed that iron-based receptors in cells found in the upper beaks of some migratory birds sensed the magnetic field and sent that information along the trigeminal nerve to the brain. A new study published in the October 29th edition of Nature provides evidence that instead of their beaks, it's a light-processing area of the brain called cluster N that is the birds’ migratory sixth sensor.

The hypothesis is that light-sensing cells in birds’ eyes sense the magnetic field and send the information along a different route to cluster N. When light reaches the proteins, it produces a pair of free radicals, highly reactive molecules with unpaired electrons. These electrons have spin which may be sensitive to Earth’s magnetic field. Signals from the free radicals may then move to nerve cells in cluster N, telling the birds where north is.

Scientists are hopeful that this new discovery will help us begin to understand the mysterious magnetic sixth sense. One possible goal of the research will be to trick re-located migratory birds (who often fly back to their original location) into staying in their new, safer home.

"Noche de luna Llena--Full Moon Night" by Flowery L*U*Z*A* on Flickr courtesy of Creative Commons Licensing.