No expression of magnetic compass orientation in Clethrionomys glareolus in total darkness (Rodentia: Cricetidae)

Our knowledge about magnetoreception in mammals remains limited. Among rodents, magnetic compass orientation has been documented in four subterranean mole-rats and four epigeic (i.e., active above ground) species. While it is well established that the magnetic compass of mole-rats is light-independent and magnetite-mediated, recent evidence suggests that a radical pair-based mechanism may underlie magnetic orientation in epigeic rodents. To determine whether the magnetic compass of epigeic rodents is light-dependent, which is thought to be an inherent feature of radical pair-based magnetoreception, we investigated the ability of the bank vole Clethrionomys glareolus (Cricetidae) to use magnetic compass orientation in total darkness. The voles, which were allowed to explore/build a nest overnight in a circular arena, did not exhibit any directional preference in the initial stage of the experiments; later they tended to prefer the southern sector of the arena irrespective of magnetic field direction, implying that they relied on nonmagnetic orientation cues. Previous tests (Oliveriusová et al. 2014) in the same environment, but under lighting, showed a significant reaction to a change in the orientation of the magnetic field. On the basis of the presented study in comparison with the previous one, it can be concluded that bank voles do not use the magnetic compass for near-space orientation in darkness and thus support evidence for light-dependent magnetoreception in a mammal.