Iron containing short nerve branches in the upper beak of birds may serve as a magnetometer to measure the vector of the Earth magnetic field (intensity and inclination) and not only as a magnetic compass, which shows the direction of the magnetic field lines. Whether this magnetic map is consulted, strongly depends on the avian species and its current motivation to do so...research has...suggested that magnetic compass and magnetic map sense are based on different mechanisms and are localized at different sites: The magnetic compass resides in the eye, the magnetometer for the magnetic map lies in the beak.
Dr. Gerta Fleissner
So that's it then, lovebird of mine:
our eyes alone won't do it. Point A
to B, I see it, sure,
but won't find my way to it.
I'll fly and fight and never tire
until this ocean's crossed;
but 'til we're mouth
to mouth, my dear, I'll be
as good as lost.
original bird-compass article here.
photograph by Claire
