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. 2016 Jan 25;113(6):1654–1659. doi: 10.1073/pnas.1513391113

Fig. S2.

Fig. S2.

Illustration of the training and testing procedure and the data analysis used in the spatial orientation assay. The figure is an example of a training to magnetic compass cues in the presence of overhead polarized light aligned parallel to the magnetic field, followed by a probe trial for magnetic compass orientation in the presence of overhead polarized light aligned perpendicular to the magnetic field. The bird is trained to find the food reward at mS and along the polarized light axis. (A) In training trial 1, the reward (red rectangle) is located in the maze arm at gS and the magnetic field (green arrow with mN) points toward gN, with the overhead polarized light axis (pink double arrow) aligned along the gN/gS axis. (B) In training trial 2, the food reward is moved 90° clockwise to the gW arm and the magnetic field is shifted accordingly. (C) In the probe trial the day after training, the bird is tested (without reward) for magnetic compass orientation in the presence of overhead polarized light aligned perpendicular to the magnetic field that is pointed in either one of four geographic directions (mN at gN, gS, gE, or gW; in the example mN = gS). (D) Original path of the bird in the maze as tracked by the computer program. The green star gives the start of the track when the bird enters the first arm; the red star gives the end of the track after 90 s. (E) Calculation of the individual mean orientation. The number of frames in each arm (displayed outside of the circle) are automatically determined by the computer program and summed by vector addition to give the individual mean orientation and mean vector length (in red). The number in brackets in the center of the circle gives the number of frames the bird spent in the center of the maze. (F) Recalculation of the mean orientation relative to gN to the orientation relative to the polarized light axis, with the east end of the polarized light axis defined as 0°, and relative to the trained polarized light axis, with the north end of the axis defined as 0°. Recalculation of the mean orientation relative to gN to the orientation relative to mN and the trained magnetic direction.