Example of a flight trajectory.

A: Position and head orientation of a bird shown every 4 ms within the middle division of the flight arena. Dots indicate beak tip position; lines indicate horizontal beak orientation and, thus, gaze direction in the middle section of the flight arena. The bird contour is taken from the first frame analysed and approximately sized relative to the indicated cage dimensions. Origin of XY plane is the front left corner of the middle division. Positions of entrance, exit and obstacle are marked. B: Time-dependent beak angle relative to long axis of flight arena over time. The dotted line indicates raw data and the solid line indicates filtered data.