14 DAY TRIAL // In a new scientific study that may improve conservation efforts for migratory birds, scientists demonstrate that, in European robins, a visual center in the brain and a special type of light-sensing cells in the eyes play a much more important part in guiding the bird on its migratory path than magnetic-sensing cells in the beak. The study appears in the October 29 issue of the respected scientific journal Nature, Wired reports.
“This is really fascinating science,” University of Illinois in Urbana-Champaign (UIUC) biophysicist Klaus Schultenof says. The expert has been among the first scientists ever to suggest that birds can sense a magnetic field. Other studies that have followed have discovered that the creatures may be orienting themselves in regards to the planet's magnetic lines, when moving from one location to the other. Regardless of the amount of work that has been poured in the investigations, scientists have never been able to determine precisely how birds detect the magnetic fields.
“This is basically the sixth sense of biology, but no one knows how it works. The magnetic sense is by far the least-understood sense in the natural world,” German expert Henrik Mouritsen, from the University of Oldenburg, says. He is also the co-author of the Nature paper. The expert believes that the role of the magnetic-sensing cells in the beaks of some migratory birds may be related to picking up minor changes in the strength of the magnetic field along a North-South axis, as the creatures fly to their destinations. “This is an important advance in what we know about these systems,” Virginia Tech neuro-ecologist John Phillips says.
In the experiments, the team demonstrated that a light-processing part of the brain, called cluster N, might play a significant role in the light-mediated, magnetic-sensing ability some birds had. In a rather cruel, yet necessary, approach to finding out how the birds oriented themselves, the scientists damaged the cluster N region in some European robins, and then analyzed their flight patterns. It was immediately obvious that the birds had no idea as to where they were going. The work “nicely confirms that the trigeminal nerve is not involved in this direction sensing,” Phillips says. This specific nerve connects magnetic-sensing cells in the beak to the brain.