Figure 1.
Orientation of European robins during spring migration in the local geomagnetic field (control, C) and, after pre-exposure, in the 4 µT field (4 µT), in this field with a radiofrequency field of 1.315 MHz, 480 nT added (4 µTRF), and with the skin of the upper beak locally anaesthetized by Xylocaine (4 µTXy). The triangles at the periphery of the circle mark the mean headings of the individual birds, the arrows represent the grand mean vector in relation to the radius of the circle = 1, and the two inner circles are the 5% (dashed) and the 1% border of the Rayleigh test [22].