Fig. 1. Orientation behavior of silvereyes during the control phase (A) after exposure to the biasing field of 1 mT (B) and after treatment with a brief, strong magnetic pulse in the presence of the same biasing field (C). Left: PAR birds where the pulse was parallel to the biasing field; right: ANTI birds where the pulse was antiparallel to the biasing field. In A, the arrows represent mean vectors of up to six recordings per individual bird, drawn proportionally to the radius of the circle; the symbols at the periphery mark the mean headings. In B and C, symbols at the periphery represent headings of individual tests (in C: outside=day 1; inside=day 2), and the arrows give the axial vector of the respective data.