Сухов И. Б.

The ability of birds to sense the magnetic field has been discussed in the scientific context since the 19th century. However, until the second half of the 20th century the researchers of this subject encountered skepticism from the colleagues. In the 1960ies behavioral experiments in migratory birds showed unequivocally that birds can use the geomagnetic field as a global compass cue. The sensory mechanism of magnetoreception remained elusive. At least two independent systems of magnetoreception are currently believed to exist in birds, based on different biophysical principles, located in different parts of their bodies, and with different neuroanatomical mechanisms. One magnetoreceptory system is located in the retina, and may be based on photochemical reactions on the basis of cryptochrome. It is often assumed to process compass information. The second magnetoreceptory system is probably based on biogenic magnetite, located in the upper beak (its exact location and ultrastructure of receptors remain unknown) and innervated by the ophthalmic branch of trigeminal nerve. Information from this receptor might participate in spatial representation.