Magnetic Orientation in a Small Mammal, Peromyscus leucopus

We displaced white-footed mice (Peromyscus leucopus) 40 m away from their home areas and released them in a circular arena. Mice concentrated their exploratory and escape activity in the portion of the arena corresponding to home direction. In another group of mice, we reversed the horizontal component of the geomagnetic field surrounding them during displacement. These individuals concentrated their activity in areas of the circular arena opposite home direction. Mice were not likely using visual, chemical, or kinesthetic cues to establish home direction. Tissues of P. leucopus exhibit strong isothermal remanent magnetization and may contain biogenic ferrimagnetic material. Our results suggest that white-footed mice have a magnetic sense and use the geomagnetic field as a compass cue.