Table 2. Flight metrics.

Seven metrics of collision avoidance were computed from birds three-dimensional coordinates, related to flight velocity, distance from speaker and collision hazard, and change in flight trajectory.

Metric description	Calculation method
1. Within-flight change in velocity (m/s)	Average velocity in final third of flight minus average velocity in first third of flight
2. Average velocity (m/s)	Average velocity over the entire course of the flight
3. Minimum distance from obstacle (m)	Smallest distance measurement between the bird and the obstacle
4. Minimum distance from speaker (m)	Smallest distance measurement between the bird and the speaker
5. Distance from obstacle when bird makes greatest adjustment in flight trajectory (m)	Distance between the bird and the obstacle at frame when change in flight trajectory is greatest (both curvature and angle of inflection are maximized)
6. Distance from speaker when bird makes greatest adjustment in flight trajectory (m)	Distance between the bird and the speaker at frame when change in flight trajectory is greatest
7. Proportion of flight completed when bird makes greatest adjustment in flight trajectory	Frame number at which greatest change in flight trajectory occurs divided by total number of frames in flight