Reducing Bird Deaths Caused by Wind Turbines

According to the United States Fish and Wildlife Service, about 300,000 birds were killed by wind turbines in the US in 2015. Another study estimated that wind turbines killed about 500,000 birds and 900,000 bats in the US in 2012.

This sounds bad. But it’s actually tiny compared to some other causes of death! A 2014 paper estimated that power lines kill somewhere between 12 and 64 million birds each year in the US. And another paper estimates that between 1.3 to 4 billion birds are killed by domestic cats each year in the US.

So if you really want to save birds, do something about cats. But it’s interesting to read that there may be an easy way to reduce bird mortality due to wind turbines. Just paint one blade black!

That’s what this laboratory study suggested, back in 2003:

• W. Hodos, Minimization of motion smear: reducing avian collisions with wind turbines, National Renewable Energy Laboratory, NREL/SR-500-33249, August 2003.

Hodos studied the perceptual psychology of birds and recommended field testing. And that’s what these folks did, with a nice hat tip to the Rolling Stones song:

• Roel May, Torgeir Nygård, Ulla Falkdalen, Jens Åström, Øyvind Hamre and Bård G. Stokke, Paint it black: Efficacy of increased wind turbine rotor blade visibility to reduce avian fatalities, Ecology and Evolution 10 (2020), 8927–8935.

With a rather small sample size, they concluded that painting one blade of a wind turbine black reduced the fatality rate by about 70% compared to to the neighboring unpainted turbines. And the treatment had the largest effect on reduction of raptor fatalities.

Audubon Magazine is cautiously optimistic… but the Federal Aviation Authority would need to be persuaded:

The results are promising, says Garry George, director of Audubon’s Clean Energy Initiative, but they’re also preliminary. Eight turbines—half of which were treated with black paint—is not a large sample size, he says, and the researchers found relatively few bird carcasses both before and after painting the blades: A total of 42 dead birds, found at all eight turbines during the study period, were included in the analysis. It’s also not clear if the paint solution achieves the same results across various species of birds. May himself agrees: “Although we found a significant drop in bird collision rates, its efficacy may well be site- and species-specific,” he says. “It is surely not a golden egg solving all bird-collision problems in the world.” He recommended that more turbine operators test the approach around the world to see whether it works in different places and with different bird species.

If it does work, Allison says, painting blades black would be an effective, low-cost solution. But giving birds visual cues with paint isn’t the only solution researchers are testing. More thought is being put into siting, or figuring out where to physically place turbines. By studying nesting areas and common flight paths near potential wind farm locations, Allison says, wind companies can build turbines as far as possible from frequented bird routes. Additionally, wind farms are experimenting with radar, camera, and GPS tech to track birds and automatically shut off turbines as the birds approach. Still, since birds use wind to navigate and soar, there’s inevitably going to be some overlap between the best locations for wind farms and the best migratory pathways for birds.

Researchers are also experimenting with deterrence systems. “When you detect something that you think might be an eagle within a certain distance of a turbine, you emit sounds that will first alert the bird,” Allison says. “If the bird keeps coming, you send a second signal that—you know, the hope is it will persuade the bird to change its flight path.” The turbines will, in essence, scream at birds to stay away, and a report published by AWWI suggests this method could reduce collisions by somewhere between 33 and 53 percent.

Future research might prove that black turbine blades are the wind energy panacea we’ve been waiting for, but for now the idea of seeing painted blades dotted across the landscape is still up in the air in the United States. That’s because painted turbine blades are currently prohibited by Federal Aviation Administration (FAA) regulations, in part due to concern about reduced visibility for aircraft flying at night. “However, we do have a process for considering such changes,” an FAA spokesperson wrote in an email to Audubon—which sounds like they might consider changing their rules.

• Neel Dhanesha, Can painting wind turbine blades black really save birds?, Audubon, 18 September 2020.

6 Responses to Reducing Bird Deaths Caused by Wind Turbines

  1. aranjedeath says:

    Other turbine designs help as well. VAWTs don’t have nearly the issue the big pinwheels do because the blades pass through space frequently enough the birds see it and avoid it.

  2. Supernaut says:

    This is good news. However, with respect to the relative number of bird deaths, one has to keep in mind that the birds the wind turbines kill are different than the birds killed by cats, for instance. The former tend to be large birds (ie raptors) and the latter, abundant and small bird species like sparrows.

    • John Baez says:

      It’s true: cats here kill lots of lizards and I bet also lots of finches and sparrows, but probably never any hawks. The “Paint it Black” study claimed that painting one blade of wind turbine black is especially good at preventing raptor deaths. I’ve also read it’s important to keep rodents from nesting near the base of the wind turbine.

      • Jason Erbele says:

        If the raptor death reduction bears out in larger trials, that is very good news. “It’s also important to keep rodents from nesting near the base of the wind turbine.” Sounds like a problem where cats would be a good solution. (:

      • John Baez says:

        Apparently rodents find it easy to dig burrows in the ground loosened by constructing the turbine, and this attracts raptors:

        This picture is from a webpage claiming there’s massive under-reporting of bird deaths due to wind turbines:

        Wind farms: a slaughter kept hidden from the public, Windmills Kill.

        The issue has become politicized so everything everyone says needs to be taken with a grain of salt, and of course a single picture of a rabbit near a wind turbine proves little. However, I once read from a trustworthy source that keeping rodents from nesting near the base of wind turbines was important.

  3. Apparently the rationale for painting one-blade-black approach works is because it reminds birds of predators that attack by striking down. Painting both blades black doesn’t provide the same tomahawk motion visual cue.

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