IRON MINERAL BASED MAGNETORECEPTION MECHANISM IN BIRDS

In an earlier work, it was suggested that the “magnetic sense” in birds may be mediated by the blue light receptor protein, cryptochrome, which is known to be localized in the retinas of migratory birds. The present contribution discusses an alternative mechanism of avian magnetoreception based on the interaction of two iron minerals (magnetite and maghemite), recently found in subcellular compartments within the sensory dendrites of the upper beak of several bird species. The analysis of forces acting between the iron particles shows that the orientation of the external geomagnetic field can significantly change the probability of the mechanosensitive ion channels opening and closing. Our theoretical analysis shows that the suggested magnetoreceptor system might be a sensitive biological magnetometer providing an essential part of the magnetic map for navigation.