Wind is a clean, renewable energy resource that is expanding rapidly in California and nationwide. However, high numbers of fatal bird and bat collisions with wind turbines have led to cancellations or permitting delays for many wind energy projects. Because the likelihood of such fatal collisions depends upon complex interactions between site characteristics, turbine design, and animal behavior, the two most promising approaches to reducing collisions risks are to carefully site new wind turbines and to develop new wind turbines designs that reduce collision risk.
The original goal of this study was to test whether a new shrouded wind turbine design would reduce avian and bat collisions; unfortunately, before installation of the new wind turbines could occur, the wind project was cancelled. Following this, the researchers then analyzed the collected data to explore whether variation in fatality rates can be explained by bird and bat flight patterns and avoidance behaviors. This information was then used to map collision hazards in the study portion of the Altamont Pass Wind Resource Area to inform the siting of new and repowered wind turbines. The researchers also sought to improve collision risk estimation methods by conducting integrated trials to determine bird and bat carcass detection probabilities, assessing whether body mass can serve as a predictor of detection rate variables, quantifying species identification, and reducing estimation errors when fatality rates occur. The results of this research improve current understanding of bird and bat mortality rates at wind turbine sites and provide a template for guiding the siting of new and repowered turbines to minimize wildlife fatalities throughout the state.