Behaviour 2019
Evaluating the use of acoustic warning signals to reduce avian collision risk
Robin G. Thady1, Lauren C. Emerson1, John P. Swaddle1,2. 1College of William & Mary Department of Biology, Williamsburg, VA, United States; 2Institute for Integrative Conservation, Williamsburg, VA, United States

Collisions with humanmade structures are responsible for billions of bird deaths each year, resulting in ecological consequences as well as regulatory and financial burdens to many industries. Acoustic warning signals can alert birds to obstacles in their flight paths in order to mitigate collisions, but these signals should be tailored to the sensory ecology of birds in flight. I evaluated the ability of four sound signals to elicit collision-avoidant flight behaviors from birds released into a corridor containing a physical obstacle. I selected signals to test multiple frequency levels (4-6 kHz and 6-8 kHz) and temporal modulation patterns (broadband and frequency-modulated oscillating) to determine which combination of sound attributes elicits the strongest collision avoidance. I found that all sound treatments cause birds to maintain a greater distance from hazards and to adjust their flight trajectories before coming close to obstacles. In addition, the 4-6 kHz frequency-modulated oscillating signal elicited the strongest avoidance. These findings can be used to design effective warning signals and to demonstrate the value of using behavioral data to assess collision risk.