Cowbird behavioral responses to lights tuned to their visual system: Implications for bird-aircraft collisions
Collisions between birds and aircraft cause extensive monetary expenses and are a risk to human lives, as well as the lives of endangered and threatened birds. Birds are highly visual organisms with visual system substantially different from humans. Previously, studies show that the use of white broad-spectrum lights have the potential to enhance bird avoidance behavior; however, no study has investigated the effects of light colors that would be more salient from the avian perspective. The purpose of this project was to assess detection and avoidance responses of brown-headed cowbirds exposed to a radio-controlled (RC) aircraft with a lighting system with high visual saliency from their visual perspective (blue LED lights, 470 nm). In the first experiment (RC aircraft static), we found that birds showed alert behaviors more quickly in response to the RC aircraft with the lights on compared to that with the lights off. In the second experiment (RC aircraft approaching the animals), we found a significant speed effect. Cowbird alert responses were delayed at higher speeds when the RC aircraft had the lights off. However, the speed effect diminished with the type of light. We found a less pronounced (but still significant) speed effect when the lights were pulsing, but when the lights were steady, the speed effect was no longer significant. Time to "collision" at avoidance was only significantly affected by ambient noise. Our findings suggest that developed to maximize avian visual systems can attract their attention to the aircraft and potentially enhance the ability of birds to detect the aircraft even at high speeds, particularly when the lights are steady.
Fernandez-Juricic, Purdue University.
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