New Study Provides Most Comprehensive Analysis Ever of Bird Fatalities at Wind Energy Facilities

September 15, 2014

Media Contact: Lauren Flinn,, 202-448-8780

New Study Provides Most Comprehensive Analysis Ever of Bird Fatalities at Wind Energy Facilities 

Cell Towers, Buildings, Other Threats Are Much Greater 

Washington D.C. – A comprehensive peer-reviewed study released today provides the most detailed analysis to date of the impact of bird fatalities at wind energy facilities in North America, and is the first to measure the relative impact of those fatalities on populations of small passerines, including songbirds.

The study finds that, of the more than 5 billion small passerines in North America, an estimated 134,000-230,000, or less than 0.01%, collide annually with wind turbines. Overall, the study authors estimate that all bird fatalities from wind turbines range from 214,000 to 368,000 annually–a small fraction compared with the estimated 6.8 million fatalities from collisions with cell and radio towers, 1.4 to 3.7 billion fatalities from cats, and of the many other, much larger threats that birds face today.

“While total fatality numbers inform the scale of the issue, one of the most important scientific contributions from this research is our new understanding  of the level of impact on individual songbird and other small passerine species,” said Wallace Erickson, West, Inc., the study’s lead author. “Using conservative assumptions, we estimate that on an annual basis, less than 0.1% (and typically less than 0.01%) of songbird and other small passerine species populations in North America perish from collisions with turbines.”

“This study provides the most up-to-date and comprehensive analysis of small passerine fatalities from wind turbines in North America, including an assessment of potential impacts on populations,” said Taber Allison, Director of Research and Evaluation for the American Wind Wildlife Institute (AWWI), which supported the study. “The conclusion is that small passerines will benefit from conservation actions that focus not just on wind turbines but on the many threats that are far more serious in terms of their effect on the populations of these birds.”

“These findings come just a week after new reports on some of the truly major threats that all bird populations face today, including climate change, and provide a solid and useful perspective on the relatively minor impact that wind turbines have on populations of birds,” said Terry Root Senior Fellow/University Faculty at Stanford University. “With comprehensive measures to further minimize impacts on birds, wind power is a growing solution to some of the more serious threats that birds face, since wind energy emits no greenhouse gases that accelerate climate change and backs more and more of those and other pollutants out of our energy mix.”

On September 8, a report by the National Audubon Society for the U.S. Fish and Wildlife Service found that climate change threatens the survival of more than half of all species of birds in North America.  On September 9, State of the Birds 2014, a report prepared by a 23-member partnership of government agencies and bird conservation organizations, documented the decline of many bird species in North America, particularly from loss of habitat in the arid lands and grasslands of the U.S. due to conversion of wild lands to agriculture and suburban development, among other causes.

The study released today on bird fatalities at wind turbines was supported by the American Wind Wildlife Institute, a non-profit that brings together the wind industry, wildlife management agencies, and science and environmental organizations to facilitate timely and responsible development of wind energy while protecting wildlife and wildlife habitat.

In order to reach the most reliable numbers possible, the authors took into account the various methods used to improve the accuracy of fatality counts from the field.  Such methods, or estimators, adjust for the fact that not all birds killed by collision with wind turbines can be detected during surveys; some carcasses may disappear through scavenging, decompose before they are counted, or be missed by surveyors/monitors.

In next steps, AWWI is working with its partners to sponsor additional studies, including on eagles and prairie birds, and to establish a first-of-its-kind initiative to bring together data collected from wind energy projects across the U.S.  When completed, this Research Information System will further expand the amount of data for understanding and minimizing risks and impacts to wildlife from wind turbines.

The study, entitled “A Comprehensive Analysis of Small-passerine Fatalities from Collision with Wind Turbines at Wind Energy Facilities,” by Wallace P. Erickson, Melissa M. Wolfe, and Kimberly J. Bay of WEST, Inc.; Douglas H. Johnson, U.S. Geological Survey; and Joelle Gehring, Federal Communications Commission, is published in PLOS ONE.

The study is available online at


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