E3: Do wind turbines kill birds?

LHF: Hi, I’m Laur Hesse Fisher, and from MIT, the Massachusetts Institute of Technology, this is Today I Learned: Climate.
In our last episode, we took a pair of questions from Julie G. of California, who has some concerns about the wind energy that is being rapidly built in this country and around the world. In that episode, we talked about how wind turbines perform in cold weather.

For this episode, we’re taking on an especially thorny question: do wind turbines kill birds?

You might have heard news stories like this one, from KGW, a local TV station in Oregon:

KGW: Thousands of wind turbines dot the landscape, each generating energy, offering a clean, green alternative to fossil fuel. The problem, studies have shown, those huge turbine blades kill hundreds of thousands of birds every year, including some that are endangered.

LHF: We talked to Prof. Michael Howland about this—he studies renewable energy projects at the MIT Department of Civil and Environmental Engineering. And Prof. Howland told us that that news report is… correct. Much of the data about bird deaths at wind facilities come from studies published in 2013 and 2014, which concluded that somewhere between 150 thousand and 700 thousand birds were killed by wind turbines each year when birds run into them. Those numbers are likely to be higher today, because many more wind farms have been built in the past decade.

So yes, wind turbines do kill birds—and bats as well, including some whose populations are in decline. But don’t stop the episode here, because that’s not the whole story. Unfortunately, many, many things that humans build kill birds. And wind turbines are not at the top of the list. Here’s Prof. Howland:

MH: Wind turbines result in far less bird mortalities than from habitat loss, cats, windows, vehicles, toxins, electrical lines, and communication towers.

LHF: Power lines are a useful comparison here: we need them for any kind of electricity generation, not just wind. And researchers have concluded that those power lines kill tens of millions of birds a year—potentially hundreds of times more than are killed by wind turbines.

And unfortunately, that’s just scratching the surface. Studies show that buildings—just, birds colliding with our homes and office towers—kill hundreds of millions of birds a year, perhaps almost a billion. And the greatest human threat to bird populations? Have a guess? It’s housecats. At the upper end of estimates, our pets may kill four billion birds a year. We’ll have links to all these studies in our show notes on tilclimate.mit.edu.

We cite all these figures not to brush off the birds killed by wind turbines, but to put those numbers into context. If you are really concerned about birds – who control pests, and pollinate plants, and inspire us, and provide many other services – then you should be even more concerned about the things that threaten them the most, like power lines, buildings, house cats – and, also, burning fossil fuels.

MH: When assessing electricity generation technologies, it’s important to evaluate against baseline generation alternatives, because electricity generation is a requirement of modern society. Fossil fuels contribute to climate change, increased air pollution, and negative impacts on human health, among other issues. Wind energy is an electricity generation technology that significantly reduces such environmental and health impacts.

LHF: And bird deaths are among those environmental impacts. Even if we set aside the effects of pollution from burning fossil fuels, or the damage coal mines have done to bird habitats, fossil fuels—unlike wind turbines—are changing our climate.

According to the IPCC—that’s the United Nations’ worldwide body of climate scientists who review climate research—if we do no more to stop climate change than we’re doing now, more than one in five bird species will likely be at high risk of extinction by the end of this century.

That would make climate change itself the greatest human threat to birds.

That’s why there are researchers who have concluded that wind turbines, by replacing climate-warming fossil fuel plants, actually save far more birds than they kill.

Of course, it’s still important, as we build more and more wind farms, to work to minimize the harm they do to bird populations.

MH: Further research continues to develop methods to reduce the frequency of wind turbine interactions with birds and bats, including wind turbine design and appearance modifications to mitigate such interactions.

LHF: For example, scientists have found that painting one blade of a turbine black can increase its visibility and reduce bird fatalities by 70 percent. Some wind companies are even experimenting with using artificial intelligence to sense a bird’s approach, powering turbines down to avoid collisions. And decision-makers can limit the number of wind turbines that are being built in important bird habitats or flight paths.

So Julie, as you have identified, wind energy – like any energy source – comes with its complications. And we should be honest about those complications. And we should also be honest about the full story, and we hope we did that for you today.

Do you have a question about climate change? Maybe we answered it as part of our Ask MIT Climate series at climate.mit.edu. If we haven’t, ask us! Visit https://climate.mit.edu/ask or leave us a voicemail message at 617 253 3566. Whether it's simple or sticky, about science or solutions — we work with faculty and scientists from MIT and beyond to give you clear, no-nonsense answers grounded in the best scientific information. We’ll be releasing answers as episodes here on TILclimate as well as at climate.mit.edu. 

And we love hearing from our listeners! Send us a message at climate@mit.edu, and let us know who you are, what you’re working on, and why you listen to the show. We so look forward to hearing from you.

TILclimate is the climate change podcast of the Massachusetts Institute of Technology. Aaron Krol is our Writer and Producer. David Lishansky is our Sound Editor and Producer. Michelle Harris is our fact-checker. Sylvia Scharf is our Climate Education Specialist. The music is by Blue Dot Sessions. And I’m your Host and Executive Producer, Laur Hesse Fisher. 

A big thanks to Prof. Michael Howland for speaking with us, and to Julie G. – and all of you, our listeners – for your climate curiosity.