Bat
Microbats make use of magnetoreception, in that they have a high sensitivity to the Earth's magnetic field, as birds do. Microbats use a polarity-based compass, meaning that they differentiate north from south, unlike birds, which use the strength of the magnetic field to differentiate latitudes, which may be used in long-distance travel. The mechanism is unknown but may involve magnetite particles.
Magnetoreception
Then there is the distinction of magnetic usage. Some species may only be able to sense a magnetic compass to find north and south, while others may only be able to discern between the equator and the pole. Although the ability to sense direction is important in migratory navigation, many animals also have the ability to sense small fluctuations in earth’s magnetic field to compute coordinate maps with a resolution of a few kilometers or better. For a magnetic map, the receptor system would have to be able to discern tiny differences in the surrounding magnetic field to develop a sufficiently detailed magnetic map. This is not out of the question, as many animals have the ability to sense small fluctuations in the earth's magnetic field. This is not out of the question biologically, but physically has yet to be explained. For example, birds such as the homing pigeon are believed to use the magnetite in their beaks to detect magnetic signposts and thus, the magnetic sense they gain from this pathway is a possible map. Yet, it has also been suggested that homing pigeons and other birds use the visually mediated cryptochrome receptor as a compass.