Learned magnetic compass orientation by the Siberian hamster, Phodopus sungorus

Magnetic compass orientation in C57BL/6J mice

“…The mean vector length (r) was obtained by dividing the length of the resultant vector calculated for each distribution by the sample size; r provides a measure of r the clustering in the distribution of bearings, ranging in value from 0.0 for a uniform distribution to 1.0 for a distribution in which all the bearings are in a single direction. The Rayleigh test was used to (Deutschlander et al, 2003), we used the method of doubling the angles to test for bimodality (r bimodal r r r unimodal r r ); the Rayleigh test was used on the distribution of doubled bearings to test for bimodal orientation (Batschelet, 1981). A 95% confidence interval around the mean bearing was used to test whether the clustering in the distribution of bearings plotted relative to the trained magnetic direction was consistent with orientation in the trained direction.…”

“…The procedures for both training and testing were derived from earlier experiments in our laboratory with Siberian hamsters (Deutschlander et al, 2003). The mice were trained individually in separate cages (48 25.5 16 cm) with a layer of pine shavings as bedding and were provided with three nestlets (pulped, sterilized, cotton fiber pressed into flat, 5 5 cm pieces; Ancare) for nest building and with food and water ad lib.…”

“…On the basis of our earlier experiments with hamsters (Deutschlander et al, 2003) and preliminary experiments with mice (Edgar, 2004), we established the following testing criteria. (1) We did not test on nights when thunderstorms were in the area and excluded tests carried out during nights when a thunderstorm unexpectedly occurred (n 2).…”

“…Siberian hamsters also use magnetic compass cues to position nests and can learn to position nests d along an arbitrary axis with respect to the magnetic field (Deutschlander et al, 2003). In contrast to mole rats, however, the hamsters' responses are relatively weak and bimodally distributed.…”

Extremely low-frequency electromagnetic fields disrupt magnetic alignment of ruminants

“…Despite being phylogenetically widespread, magnetic compass orientation has been convincingly demonstrated in only a few species of mammals representing only 2 taxonomic groups: rodents (4)(5)(6)(7)(8) and bats (9,10). Not surprisingly, all these model species are small mammals amenable to experimental manipulation of the ambient magnetic field.…”