Drivers of fatal bird collisions in an urban center Benjamin M. Van Doren, David E. Willard, Mary Hennen, Kyle G. Horton, Erica F. Stuber, Daniel Sheldon, Ashwin H. Sivakumar, Julia Wang, Andrew Farnsworth, Benjamin M. Winger Proceedings of the National Academy of Sciences Jun 2021, 118 (24) e2101666118; DOI: 10.1073/pnas.2101666118
Collisions with built structures are an important source of bird mortality, killing hundreds of millions of birds annually in North America alone. Nocturnally migrating birds are attracted to and disoriented by artificial lighting, making light pollution an important factor in collision mortality, and there is growing interest in mitigating the impacts of light to protect migrating birds. We use two decades of data to show that migration magnitude, light output, and wind conditions are important predictors of collisions at a large building in Chicago and that decreasing lighted window area could reduce bird mortality by ∼60%. Our finding that extinguishing lights can reduce bird death has global implications for conservation action campaigns aimed at eliminating an important cause of bird mortality.