• Energy

Some evidence that wind turbines can harm eagles, but more are killed by other causes

Posted on:  2025-02-03

Key takeaway

Some evidence, if not conclusive evidence, suggests that eagles are disproportionately likely to die from colliding with a wind turbine and that some eagle populations are in decline as a result. But it’s important to put these claims in the context that wind turbines aren’t the only eagle-killers. Eagles can also die from automobiles, power lines, guns, and the effects of climate change. We’re building wind turbines in part to reduce our dependence on fossil fuels and alleviate climate change. Furthermore, people who claim that wind turbines are harming eagles may be acting in bad faith – their goal may not be to save wildlife, but to oppose wind energy development at all costs.

Reviewed content

Lacks context

Windmills are a threat to eagles’ population.

Source: Instagram, X/Twitter, Social media users, 2025-01-16

Verdict detail

Overstates scientific confidence:

There is some evidence that eagles and other large birds are vulnerable to wind turbines, and there is some evidence that building more wind turbines has caused the population of at least one eagle species to decline. However, we need more research to understand the connection.

Lack of context:

There are other ways human activity can kill eagles – electrocutions and poisonings, for example, and shootings, not to mention the effects of human-caused climate change. Moreover, if we look at all birds, not merely eagles or large birds, wind turbines kill hundreds to thousands of times fewer birds than fossil fuels, buildings, or cats do.

Full Claim

Windmills kill our eagles; Windmills and wind turbines are environmental disasters, killing our birds and eagles.

Review

A common critique of onshore wind power is that wind turbines kill eagles. It’s a claim made by well-established environmental groups who otherwise support wind energy. But it’s also a claim made by explicitly anti-wind outlets like National Wind Watch and the Institute for Energy Research, an organization that has received funding from fossil fuel interests and has frequently downplayed the human role in climate change. Sometimes, the claim is expanded to include all birds, as Science Feedback has previously reviewed.

Perhaps the most notable figure claiming that wind turbines kill eagles is U.S. president Donald Trump. For example, Trump claimed in 2023 that wind turbines are killing “thousands” of bald eagles each year. Trump’s sentiment continues to spread online – for example, see this Instagram post by a social media user, who quotes an unrelated Trump complaint about wind energy to reassert that, “Not only are windmills [sic] an absolute waste of money, but they kill our eagles.” The Instagram post has collected more than 200,000 views since being uploaded on 16 January.

There is evidence that eagles are more vulnerable to wind turbines than smaller bird species, for example, but further research is needed, as is more context. We explain below.

Wind turbines are far from the leading bird-killer, but turbines may disproportionately affect eagles and other large birds

When we zoom out to consider all birds, as Science Feedback has previously written, the science is clear: wind turbines are responsible for a very tiny fraction of bird deaths. The author of a 2012 study estimated that, in 2009, wind turbines killed around 46,000 birds in the U.S., while fossil fuel power plants, pesticides, building windows, and feral cats each killed tens of millions.

The authors of a 2015 study, combining estimates from several other studies, also concluded that wind turbines killed far fewer birds than other sources (Figure 1). They attributed approximately 460,000 to 680,000 bird deaths to U.S. wind turbines annually[1]. The range, while higher than the earlier study’s figure, is dwarfed by the later study’s estimates of birds killed by electrocutions (between 920,000 and 11.5 million each year in the U.S. alone), collisions with buildings (between 365 million and 988 million), and cats (between 1.3 billion and 4.0 billion)[1].

Plot of estimated numbers of birds killed in the U.S. by different sources. Cats kill more than two billion; building windows and automobiles each kill hundreds of millions; while wind turbines kill less than a million each year, according to estimates.
Figure 1 – Estimated numbers of all birds – not just eagles – killed annually by different sources in the U.S. as of the early 2010s. Source: Loss et al (2015)[1].

But what about eagles – some of the largest birds – in particular? Large birds tend to be overrepresented in wind turbine casualties. According to a 2021 report from the Renewable Energy Wildlife Institute (a think tank partly funded by the renewable energy industry), diurnal raptors (birds of prey who are active during the day, such as falcons, kestrels, vultures, hawks, and, indeed, eagles) account for 7% of recorded bird fatalities from wind turbines. According to the report, this is “more than expected” given the proportion of diurnal raptors in the bird population, though the report suggests that humans are more likely to find and record larger birds’ bodies.

In a 2022 study, authors from the U.S. Fish and Wildlife Service tracked and modeled the population of one species, the golden eagle, in the western U.S. They estimated that around 31,800 golden eagles lived in the U.S. and that human activities killed about 2,572 each year between 1997 and 2016 – if that number seems large, it’s actually modest enough to keep the golden eagle population stable. Shootings accounted for 26% of those deaths, “collisions” for 23%, electrocutions for 20%, and poisonings (mainly from lead) for 17%[2]. The authors classified deaths by wind turbine as “collisions”. Though they didn’t separate collisions with wind turbines from collisions with vehicles, power lines, or others, their data clearly attributes only a small fraction of U.S. golden eagle deaths between 1997 and 2016 to wind turbines[2].

But the number of wind turbines in the U.S. has grown since 2016. Has the risk to eagles also risen? Some evidence suggests it has. The authors of a 2025 study modeled where and when golden eagles were likely to collide with wind turbines in the western U.S. The authors estimated that, as more wind turbines were built in the region, the number of golden eagles they killed rose from 110 per year in 2013 to 270 per year in 2024, though the authors’ collision estimates had a large degree of uncertainty[3]. If more golden eagles really are dying, then the golden eagle’s population may be shrinking, though further monitoring is needed to confirm whether this is the case[2].

A similar story may be playing out in Europe with a different species, the white-tailed eagle. A 2019 study of white-tailed eagle deaths and wind turbines in Northwest Germany found that the eagles were more likely to die in areas with higher densities of turbines. An eagle’s risk of death further increased if wind turbines were built on land that served as useful habitat[4]

Models of potential futures support the idea that wind turbines may put pressure on the populations of large birds. The authors of a 2021 study estimated how existing and planned wind turbines in the U.S. would impact the populations of several different large bird species, including golden eagles (Figure 2). They estimated that existing wind turbines might push the golden eagle population into a slight decline, steepening if all planned wind turbines were built[5]. Again, further research is needed to confirm if a decline is occurring, and these estimates are only for one eagle species.

A plot showing estimated population change rates of different large bird species in the U.S., in three different scenarios: no wind energy, moderate wind energy, and high wind energy. An increase in wind energy lowers most species' growth rates, though the uncertainty is large.
Figure 2 – Estimates of how the populations of different large bird species in the U.S. will change under different scenarios: one without any wind turbines (pale bar, “No wind”); one with the wind turbines that existed as of 2021 (orange bar, “106 GW”); and one with those wind turbines plus those in the development queue as of 2021 (red bar, “241 GW”). A growth rate of 1.00 represents an unchanging number of birds – increasing populations have a growth rate above 1, and shrinking populations have a growth rate below 1. There’s significant uncertainty, however, as researchers are often unsure of the likelihood of wind turbines killing certain birds. Source: Diffendorfer et al (2015)[5]

That said, researchers warn that it’s hard to make definitive statements about eagles. We don’t always find eagles’ carcasses. Even when we do, eagles are migratory and quite mobile, and the body may have fallen at a great distance from its cause of death. Moreover, different wind farms, even within the same region, may count eagle deaths in different ways[5].

Climate change also affects eagles

Even if wind turbines do harm eagles, it’s misleading to imply that wind turbines are the chief cause of deaths and disregard other ways human activity can harm eagles. We’ve already talked about some of them – shootings, poisonings, electrocutions, collisions with non-turbine objects. However, we also have to account for the effects of climate change. 

Climate change impacts all life on Earth, not just eagles or other large birds; but researchers suggest that a changing climate is making large birds more vulnerable to diseases, altering their breeding patterns, and shifting where they migrate, all of which can be deadly to eagles. A warming climate can also reduce eagles’ food supply – eagles often scavenge on animal carcasses for food, and models suggest that scavenging will become less viable in the future[6].

Eagles are also vulnerable to climate change’s indirect effects. For instance, wildfire risk rises in a warming world, especially in the western U.S. where many eagles and other large birds live. Wildfires can tear through ecosystems and disrupt eagles’ food supply. A 2021 study found that golden eagles in a post-burn landscape were more likely to see their young die in the nest[7].

When we zoom out to consider all birds, researchers from the U.S. National Audubon Society found that, in a climate change scenario similar to the world’s current trajectory, two-thirds of North America’s bird species will have limited ability to adapt to changing conditions[8].

We’re building wind turbines in large part to prevent the effects of climate change from worsening. The largest contributor to climate change is the greenhouse gas emissions created by human activities, such as burning fossil fuels[9]. And when we look at all bird species, we find that fossil fuels kill considerably more birds than wind turbines do. This isn’t just because the world gets more energy from fossil fuels. The aforementioned 2012 study estimated bird fatalities per gigawatt-hour – enough to power a medium-sized city for a year – finding that wind turbines caused 0.3 bird fatalities per gigawatt-hour on average, while nuclear power stations caused 0.6 and fossil-fuel power plants caused 9.4. 

The high rate of fossil fuel deaths isn’t just from the physical fossil fuel plants themselves. The count also includes birds killed by fossil-fuel-related pollution and birds affected by fossil fuel extraction, which can clear a great deal of natural habitat in order to mine coal or pump oil and gas. In fact, one study found that, in North America, shale oil and gas production reduces local bird populations by 15%[10].

Eagles are often a convenient excuse for obstruction

As we’ve shown, there is real reason to worry about how eagles will fare in landscapes dominated by wind turbines. Many who scrutinize how wind turbines could harm birds are voicing genuine concerns. That’s why scientists are studying the issue, and that’s why wind turbine operators are taking steps to reduce the risk of large bird collisions – for instance, siting wind turbines away from known habitats or giving turbines the capability to detect nearby eagles and shut off if one flies too close.

But others appear to be less interested in protecting eagles (or other threatened species, like whales) than in simply obstructing renewable energy. For these opponents, protecting wildlife may be little more than a convenient excuse. If they really had birds’ best interests in mind, rather than simply singling out wind turbines, they might follow the science and call for stronger oversight on power lines, stronger controls on cats, or even stronger interdictions against shooting sensitive eagle species (which is already illegal in the U.S.).

In 2021, Brown University researchers charted a network of anti-wind groups linked to fossil fuel interests, who provided funding, shared legal support, or shared advisory personnel. Many of the organizations in this network appear to be community groups or wildlife defenders, but the report’s authors say, “Knowingly or not, they are executing a strategy laid out for them by climate obstructionists in 2012.”

So, if you see a claim that wind turbines kill birds, it’s good to check if the claim has scientific evidence. If you can’t find any, then it’s a red flag that someone is pushing the claim in bad faith.

Conclusion

When we talk about all birds, the evidence is very clear that wind turbines kill a tiny fraction of the number that other threats do, like electrocutions or feral cats. When we talk about eagles in particular, the story may be different. Large birds like eagles may be more likely to die from colliding with turbines, and there’s some – if inconclusive – evidence that turbines have pushed the population of at least one eagle species into decline.

However, singling out wind turbines for scrutiny ignores other ways in which eagles and other large birds can die: electrocutions, poisonings, shootings, and more. Moreover, we’re building wind turbines to mitigate something else that can harm eagles – the substantial consequences of climate change driven by human activities, especially burning fossil fuels.

References:

  1. Loss et al. (2015) Direct Mortality of Birds from Anthropogenic Causes. Annual Review of Ecology, Evolution, and Systematics.
  2. Millsap et al. (2022) Age-specific survival rates, causes of death, and allowable take of golden eagles in the western United States. Ecological Applications.
  3. Gedir et al. (2025) Estimated golden eagle mortality from wind turbines in the western United States. Biological Conservation.
  4. Heuck et al. (2019) Wind turbines in high quality habitat cause disproportionate increases in collision mortality of the white-tailed eagle. Biological Conservation.
  5. Diffendorfer et al. (2021) Demographic and potential biological removal models identify raptor species sensitive to current and future wind energy. Ecosphere.
  6. Marneweck et al. (2021) Predicted climate-induced reductions in scavenging in eastern North America. Global Change Biology.
  7. Heath et al. (2021) Golden Eagle dietary shifts following wildfire and shrub loss have negative consequences for nestling survivorship. Ornithological Applications.
  8. Bateman et al. (2020) North American birds require mitigation and adaptation to reduce vulnerability to climate change. Conservation Science and Practice.
  9. IPCC. (2022) Climate Change 2022: Impacts, Adaptation and Vulnerability.
  10. Katovich E. (2023) Quantifying the Effects of Energy Infrastructure on Bird Populations and Biodiversity. Environmental Science & Technology.

Science Feedback is a non-partisan, non-profit organization dedicated to science education. Our reviews are crowdsourced directly from a community of scientists with relevant expertise. We strive to explain whether and why information is or is not consistent with the science and to help readers know which news to trust.
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