Birds navigate by being able to SEE Earth’s magnetic field with their right eye.
Researchers led by Katrin Stapput of Goethe-Universitat in Frankfurt, Germany, put goggles on the European Robins and found that if the right eye was covered by a frosted goggle, the birds could not navigate effectively. The scientists think the migrating birds actually see the magnetic fields with their right eye giving information to the left side of their brain.
It has been known since 1968 that birds were able to sense magnetic fields and use them to navigate when migrating south for the winter. Now this new study shows that the internal compass also depends on the birds having clear vision in their right eyes.
The ability is believed to be linked to specialized molecules in the birds' retinas that allow them to literally see the magnetic fields, which appear as patterns of light and shade superimposed over the regular image from light. The shadings change as the bird turns its head, giving it a visual compass.
Read more: http://www.physorg.com/news197872356.html
Study information: Magnetoreception of Directional Information in Birds Requires Nondegraded Vision, Katrin Stapput et al., Current Biology, doi:10.1016/j.cub.2010.05.070