Experimentally Broadcasted Wind-Turbine Sound Drastically Alters Songbirds' Habitat Selection and Vocal Communication in a Natural Environment

The sound of wind turbines is a potential threat to songbirds, who use vocal communication to transfer information and rely on acoustic cues from the environment. Previous studies have shown decreased bird density around wind-farms, but the exact causes for this decline have not yet been fully recognized. We investigated the effects of wind-turbine sound on songbird populations by deploying a "Phantom Turbine": broadcasting wind-turbine sound (102dB) at a site without actual turbines. We conducted the experiment in cycles of three stages: 'before', 'noise-treatment', and 'after'. We monitored birds' abundance using mist-netting and recorded freely-flying birds' communication and background noise levels using calibrated automated recorders. Wind turbine noise caused a significant decrease of approximately 45% in the mean number of Sardinian Warblers (Corruca melanocephala momus) and a significant reduction in the number of detected calls compared to the control stages. The broadcasted sound overlapped birds' known hearing range and measured vocalization frequency range, providing possible explanations for birds' avoidance. These findings provide evidence of a strong negative impact of wind-turbine sound on habitat selection and vocal communication in a songbird population, emphasizing the need to consider noise impacts when planning wind farms or other noisy infrastructures in natural environments.