Fig. 9. Error angles. (A) The remaining angle β (in degrees) between the actual turning angle and the extended line between the owl's flight path and the center of the in-flight target speaker was measured, as shown in Fig. 2J. The error angle did not depend on the in-flight stimulus delay. Plotted is the mean ± s.d. Due to technical limitations, only in-flight stimulus delays larger than 700 ms were considered for the analysis, as far as the owl's turn was visible from above on the video recording. The number of trials, N, is given at the base of each column. (B) For pooled data from all owls and delays, the error angles are significantly larger (t-test, P0.0003) for the 100 cm distance between speakers than for the 50 cm distance.