The magnetic compass orientation of birds is light dependent and is primarily mediated by the right eye. These findings make it likely that magnetic compass information is actually “seen” by the bird as a local change in its visual percept. The superiority of the right eye / left hemisphere in this process could then be a consequence of the superiority of the left hemisphere in discrimination tasks requiring object vision. Scientists from Frankfurt University and Biologists and Biopsychologists from Bochum have now conducted tests in the local geomagnetic field with European robins wearing goggles equipped with a clear and a frosted foil of equal optical translucence. Robins with a clear foil on the right eye and a frosted foil on the left eye oriented in the migratory direction as well as birds using both eyes. Birds with a frosted foil that blurred vision on the right eye and a clear foil on the left eye, in contrast, were disoriented. The publication in Current Biology is the first to show that avian magnetoreception requires, in addition to light, a nondegraded image formation along the projectional streams of the right retina. This suggests that the conversion of magnetic input into directional information requires processes that are also relevant for visual pattern recognition.

Stapput, K., Güntürkün, O., Hoffmann, K.-P., Wiltschko, R. and Wolfgang, W. (2010). Magnetoreception of directional information in birds requires non-degraded object vision. Curr. Biol., 20, 1259-1262.