Fig. 3. Orientation of 17 pied flycatchers tested under a rotating planetarium sky, where the stars were turned 180° in the middle of the night. (A) The orientation of the birds before the turn (first 5.5 h of the night). (B) The orientation of the same birds after the celestial cues were turned 180° (last 5.5 h of the night). (C) Comparison on an individual basis of the orientation after the turn relative to the orientation before the turn of the celestial cues. Each individual bird’s orientation before the turn is defined as 180°. Thus, a direction of 360° indicates a 180° turn in orientation of the individual bird, equivalent to the turn of the celestial cues. The inner and outer dashed circles indicate the radius of the group mean vector needed for significance (P<0.05 and P<0.01, respectively) according to the Rayleigh Test of uniformity. mN, magnetic north; cN, celestial north.