Earth's magnetic field Migratory Animals
Animals that undergo long migrations depend on the magnetic field for a guide. The magnetic field is used for many things in these migratory animals. Migratory animals know their locations by the intensity of the field. They know the time because of circadian rhythms the field produces. Migratory animals are born with a magnetic map in their head that allows them to migrate great distances safely. Their ability to sense the magnetic field is because of magnetic particles. Other animals have a chemical compass based on a radical pair mechanism.