Defining Mechanistic Pathways for Anthropogenic Noise Impact on Avian Species

This review collates and analyses data on noise exposure of birds in relation to avian hearing system performance. It provides new insights into the mechanistic pathways of anthropogenic noise impact on avian species. Noise impacts both humans and wildlife. Birds are of conservation concern, given the recent reports of major global declines in bird populations and that one in eight bird species is threatened with extinction. Studies of noise impacts on birds have been, and continue to be, published. Whilst many of these studies report associations between noise and a response in birds, relatively few provide clear demonstration of the mechanisms of impact. Anatomical and physiological datasets were compiled for species representing nineteen avian orders. Information on noise sources, propagation path and habitat selection was also collated. Bird order was not a good predictor of bird hearing frequencies, but body dimensions were. In general, smaller birds were found to have higher peak hearing frequencies than larger birds. Cranium height was the strongest predictor of peak hearing frequency for birds. These findings provide mechanistic context to noise impacts on birds and a potential basis for predicting responses of avian species to different noise environments.