Bird collisions happen because birds see the world differently.

 ~ The American Bird Conservancy

“Creak, creak, creak…” lazily interrupted the silence of the prairie. Another hot day quail hunting, we walked up to the ancient windmill where the dogs could get water and tried futilely to avoid stepping in the cow pies where the cattle had congregated around the water tank. We were all sweating heavily, but the spinning blades cast only a small shadow that provided little relief from the hot sun.

Concerns about alternative energy sources often focus on the relative risks associated with various factors. Coal has emissions problems and mining is extremely destructive to the local environment. Nukes are, supposedly, catastrophically dangerous. Solar energy is land intensive and only available when and where the sun shines. Likewise, wind power is available when it blows and is reported to cause lots of deaths of birds and bats.

For many of the concerns about alternative power sources, data has not always been available or used to support the arguments. Studies have, however, been collected for bird deaths from turbines.

Simon Chapman summarized three studies from around the world (U.S., Europe, Canada) that collected actual bird-death data related to wind farms. He concluded, “Wind turbine blades do indeed kill birds and bats, but their contribution to total bird deaths is extremely low.” He reported on a 2009 study using US and European data on bird deaths that estimated the number of birds killed per unit of power generated: “Wind farms and nuclear power stations are responsible each for between 0.3 and 0.4 fatalities per gigawatt-hour (GWh) of electricity while fossil-fueled power stations are responsible for about 5.2 fatalities per Gwh.”

In fact, the studies showed that there are many things more dangerous to birds than wind farms. Collisions with buildings, power lines, vehicles and communication towers caused far more bird deaths than wind turbines. The greatest cause of bird deaths was feral cats, followed closely by domestic cats. (I don’t think domestic cats actually follow feral cats around, though.)

This appears in contrast to data collected by John Marzluff that showed the greatest diversity of bird life to be in the suburbs, despite the reportedly high predation of domestic cats. Apparently, predation by house cats and feral suburban cats, while sad, is not totally devastating to the bird population.

Of course, the data doesn’t imply that siting, design and operation of wind farms to minimize bird collisions is unnecessary. In migration paths and other sensitive places, attention to bird and bat habits and habitats is crucial. Per Emma Bryce, “There is one easy way wind companies can avoid bird deaths: Put wind farms in places where birds are unlikely to fly in the first place.”

Dustin Solberg notes, “Research shows those (grassland) bird species tend to avoid these giant wind turbines …The continent’s grassland birds are declining more rapidly than shorebirds, forest songbirds, or any others, for that matter.” He suggests, “why not concentrate new wind farms in places that are already developed? Farm fields and former oil and gas installations, say, rather than native grasslands. This both saves habitat and lessens the risk of bird strikes.”

The American Bird Conservancy agrees, “The most critical component of Bird-Smart Wind Energy (the Conservancy’s protection program) is proper siting. Wind energy projects should not be placed in sensitive areas for birds, including key migratory routes and stopover sites; breeding and nesting sites; areas where large numbers of birds congregate for feeding; or in sensitive habits, such as wetlands.”

And technology may also play a role. Emma Bryce reported on several technologies being considered for wind farms to reduce bird death:

Cameras, Radar, and GPS: “The most advanced and widespread technologies are those that use radar and GPS to detect incoming flocks and turn off the turbines in time for the birds to fly through.”

Smart Blades: “Help to detect approaching birds and bats.”

Bright Blades: “Purple wind turbines would in theory cause fewer bird strikes than the typical white ones…because white blades attract insects, and insects attract foraging birds.”

Bright Lights: “… as a deterrent tool, UV lighting could be used to deter bats and birds from wind farm sites.”

Turbines That Look Like Trees: “… vertical axis turbines, whose “blades” circulate around a central spire, can be easily camouflaged.”

More data is needed to completely understand bird movements relative to turbines and the effectiveness of mitigation measures. However, one thing we do know is that the turbines, as well as the controversy, will continue to go around and round.

Additional information:

The American Bird Conservancy, Wind Energy and Birds, 2018

Emma Bryce, Will Wind Turbines Ever Be Safe For Birds?, March 16, 2016, Audubon

Simon Chapman, Wind Farms are Hardly the Bird Slayers They’re Made Out to Be. Here’s Why. June 16, 2017, The Conversation

John Marzluff, Welcome to Subirdia, 2014

Dustin Solberg, Wind’s Big Footprint: Clean Energy Still Needs Safeguards for Nature, November 29, 2017, CoolGreenScience,