The Moore Charitable Foundation
Energy Siting Resource Library

Estimates of bird collision mortality at wind facilities in the contiguous United States

Wind energy has emerged as a promising source of renewable energy, but its effects on birds are not fully understood. Prior studies estimate that between 10,000 and 573,000 birds die annually from collisions with wind turbines in the United States. However, these studies do not differentiate between turbines with a monopole tower – which now dominate the wind energy industry – and those with a lattice tower – which are known to be especially dangerous to birds and are largely being de-commissioned.

In this 2013 study published in Biological Conservation, Dr. Loss and his colleagues at Smithsonian’s Migratory Bird Center generate the first estimates on bird mortalities from collisions with monopole wind turbines. By systematically extracting data from peer-reviewed articles and unpublished industry reports, the authors estimate that between 140,000 and 328,000 birds are killed each year by collisions with monopole turbines in the contiguous U.S. A significant correlation was found between increasing turbine height and increasing bird mortality, although this could be explained by a number of factors such as pole diameter and location. Mortality rates differed among regions, with per turbine mortality lowest in the Great Plains. Patterns such as this could help in broad-scale decisions about wind facility siting, although the authors emphasize the importance of species-specific and local-scale assessments for all wind developments. They also join previous authors in calling for increased transparency in collision data reporting from the wind energy industry. (PDF 528KB)

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