Figure 2.

Control experiments showed that the birds were in migratory mood and able to perform magnetic compass orientation. (a) Our garden warblers oriented in their typical south-westerly migratory direction in autumn in the NMF when no hood was attached to their head. (b) The same birds’ orientation without hoods in a magnetic field turned 120° counterclockwise (CMF). mN, magnetic North. The arrows indicate the group mean vectors. The inner and outer dashed circles indicate the radius of the group mean vector needed for directional significance according to the Rayleigh test (p < 0.05 and p < 0.01, respectively). The radial lines flanking the group mean vector indicate the 95% confidence intervals for the group mean direction.