Warning sounds and color for reducing bird and bat mortality at wind turbines

The large number of bird and bat fatalities by wind turbines has slowed the installation of new turbines, and even prompted the dismantling of turbines with high casualty records. The sights and sounds of turbines, while considered an infringement on the environment, are seldom recognized as a visual and auditory warnings to birds and bats. Declining bird casualties in successive years implies a learning process in the birds where the view and noise of turbines have taught remaining birds and bats to stay away. This paper discusses providing additional auditory and visual stimuli that will further catch the attention of the birds, helping associate the sights and sounds with mortal danger. Sounds such as screeching and gunshots are recommended, based on what would be disturbing and repelling to birds and bats, and not much audible beyond the immediate vicinity of the turbine. Different sounds may be generated for different species, such as ultrasonic sounds for bats. Ultra-violet patterns painted on the blades may catch the visual attention of the birds, without being too obstrusive to human vision. Warning visual patterns and bird-repelling sounds should be similar for turbines, so that birds do not have to re-learn the warnings for different turbines. As birds are globally mobile, there can even be convergence towards a common world standard for warning colors and bird-repelling sounds.