Sense
Magnetoception (or magnetoreception) is the ability to detect the direction one is facing based on the Earth's magnetic field. Directional awareness is most commonly observed in birds, which rely on their magnetic sense to navigate during migration. It has also been observed in insects such as bees. Cattle make use of magnetoception to align themselves in a north-south direction. Magnetotactic bacteria build miniature magnets inside themselves and use them to determine their orientation relative to the Earth's magnetic field.
Magnetoreception
Maghemite has been observed in platelets concentrated along the dendrites of the upper beak, consistently in the nanoscale. When in the nanoscale, iron oxides will remain permanently magnetized at lengths greater than 50 nm and will become magnetized at lengths smaller than 50 nm. Since these platelets have been observed in collections of 5-10, they are thought to form dipoles local to the dendrite they are present in. These local magnetic changes then cause a mechanical response along the membrane of the nerve cell, leading to a change in ion concentrations. This ion concentration, with respect to the other dendrite clusters is believed to form the magnetic sense.