Governors' Wind Energy Coalition

A new study that evaluated bird mortalities at wind farms across North America found that collisions with wind-turbine blades annually kill less than 1 percent of the smallest and most common birds on the continent, a conclusion that the study’s sponsors say points to the need to focus bird conservation on climate change, loss of habitat and other more significant threats.

The study, using existing data and other studies on bird mortalities, found that of the more than 5 billion small songbirds like tree sparrows and black-throated blue warblers that are the most commonly killed at wind farms, no more than 230,000 are killed by wind-turbine collisions each year.

“Using the most conservative estimates, we determined the continent-wide effect from collisions with turbines for each species to be much less than 1 percent annually,” according to the peer-reviewed study, published this month in the journal PLOS ONE. “This means that less than one-tenth of one percent of the continent-wide population for each species is estimated to be killed annually by collisions with wind turbines.”

The study also estimated that overall, no more than 368,000 birds are killed annually by wind turbines in North America, a small fraction of the estimated 6.8 million fatalities caused by bird collisions with cellphone and radio towers — or cats — the study says.

The study was conducted by researchers at Cheyenne, Wyo.-based Western EcoSystems Technology Inc. and the U.S. Geological Survey. The study’s authors say it is the first to look at fatalities of small birds across North America.

The study was sponsored by the American Wind Wildlife Institute (AWWI), a nonprofit that brings together the wind industry, science groups and environmental groups, such as Defenders of Wildlife, the Audubon Society and the Natural Resources Defense Council, to help balance wind energy development and wildlife protection.

“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,” Taber Allison, AWWI’s director of research and evaluation, said in a statement announcing 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.”

Terry Root, a biologist and senior fellow at Stanford University who is familiar with the study, said it provides “a solid and useful perspective on the relatively minor impact that wind turbines have on populations of birds,” whereas climate change will have far greater impacts to birds.

A study released last week by the National Audubon Society with input from the Fish and Wildlife Service reported that more than half of the bird species in North America face severe decreases in population by 2080 if the world maintains the current pace of global warming (Greenwire, Sept. 9).

“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,” Root said.

But not everyone agrees with the conclusion that growing wind power and commercial-scale wind farms are a relatively minor threat to birds.

The American Bird Conservancy, one of the nation’s largest bird conservation groups, said the study has flaws. ABC has lobbied for years for regulators to take stronger actions to ensure wind farms are sited in places that have the least impact on birds.

“Unfortunately the study does not account for the expected tripling of wind turbines in the near future. Estimates for mortality when wind is fully built-out range from a low of around 1 million birds (extrapolating from this study), to around 2.5 million,” Mike Parr, ABC’s vice president, said in an emailed statement. “One [million] to 2 million birds is a very large number by any measure, but given that many of these could be from species with very small populations, the assertion that this mortality is insignificant in comparison to other causes of mortality is very concerning.”

A peer-reviewed study published last year and led by researchers at the Smithsonian Conservation Biology Institute’s Migratory Bird Center and the Fish and Wildlife Service reported that despite the wind power industry’s assurances that turbines kill a smaller volume of birds than cellphone towers, feral cats and other bird hazards, “mortality at wind facilities should not be dismissed offhand,” according to the study (E&ENews PM, Dec. 10, 2013).

If the nation meets the Energy Department’s goals of wind power producing 20 percent of the nation’s electricity by 2030, the estimated “mean annual mortality estimate” jumps to 1.4 million birds, that study said.

“Multiscale decisions about where to site wind facilities and individual wind turbines in the context of risks to individual bird species will be crucial to minimizing this mortality,” the study said.

Parr added: “Notably, these deaths also do not include collisions with the many miles of transmission lines that will be required to support the wind build out. Of the threats mentioned, wind turbine collision is also among the most easily addressed — and could be solved before wind build out is complete — by requiring siting for wind turbines to avoid the most high-risk areas.”