Birds die in numbers and in ways that can boggle the imagination.
President Donald Trump, for one, prefers to blame wind turbines.
“They kill all the birds,” Trump told a Miami Beach audience last February, echoing a dubious assertion he made in October 2022, when he told a Michigan audience that wind turbines are “destroying your fields. They’re destroying everything, killing all the birds.”
They certainly can be lethal. The Fish and Wildlife Service estimates that an average of 234,000 bird deaths each year are caused by collisions with wind turbines on land.
But while Trump attributes his animus toward wind power in part to the industry’s impact on birds, there are bigger threats.
Cats are the leading threat to birds. In the United States alone, felines account for an estimated average of 2.5 billion — that’s billion with a B — bird deaths a year. The estimates range from a low of 1.7 billion to a high of 3.4 billion. Collisions with building windows, which Trump might be familiar with from his real estate development days, also racked up a sizable death toll.
Other causes that are known to be significant, such as habitat modification or destruction, nonetheless defy enumeration.
And there is a caveat. The Fish and Wildlife Service’s numbers are dated. They rely in part on a 2015 study. Their accuracy matters, in part, because the estimates can drive regulatory and policy decisionmaking.
On the policy front, Trump used a Jan. 20 directive to focus on the relationship between wind power and bird deaths, and among other steps he ordered federal agencies to assess “the environmental impact of onshore and offshore wind projects upon wildlife, including, but not limited to, birds and marine mammals.”
Interior Secretary Doug Burgum followed up in late July, announcing the start of a “careful review of avian mortality rates associated with the development of wind energy projects located in migratory flight paths.” The review will include an assessment of whether the Migratory Bird Treaty Act might apply to birds unintentionally killed at wind power sites, although the administration has separately sought to constrain the law protecting migratory birds.
Last month, FWS began to survey wind developers about eagle deaths, which are monitored under the Bald and Golden Eagle Protection Act.
“By their very nature, wind projects are located in high wind areas where eagles are also prevalent,” Interior spokesperson J. Elizabeth Peace said Tuesday, adding that FWS must rely on companies to self-report eagle fatalities.
Peace said that “unfortunately, multiple wind projects have chosen not to apply for eagle permits and face legal and financial consequences if they do self-report. As a result, eagle fatalities from wind projects are under-reported most likely by orders of magnitude.”
The Interior Department and FWS both declined to comment on the administration’s perspective concerning other, numerically more significant, causes of bird deaths. The White House also did not respond to a question about the data for other causes of bird deaths.
But a White House spokesperson said birds are part of the equation in the president’s moves to stop wind projects. The administration has moved to block both onshore and offshore projects.
“While unleashing America’s energy dominance, President Trump has paused certain wind projects that are detrimental to our beloved wildlife including birds and whales. President Trump supports commonsense policies, which is why these harmful wind turbines, whose harmful environmental impacts outweigh their benefits, have been put on pause,” White House spokesperson Taylor Rogers said.
Here, then, are the leading human-related causes of bird deaths, according to the Fish and Wildlife Service.
Building windows
Window collisions account for between 365 million and 988 million bird deaths annually in the United States, according to FWS. This is, by far, the single biggest human-caused source of bird deaths.
The problem, in part, is that birds generally cannot see clear or reflective glass. This creates the daytime appearance of airspace into which the bird attempts to fly. Other building dangers arise at night, when lights lure birds to their doom.
“By using materials that conceal indoor lighting to the outside, we can dramatically reduce the frequency of birds colliding with glass buildings,” said Rep. Mike Quigley (D-Ill.).
For many years, Quigley has pushed legislation designed to help federal buildings become safer for birds. He has, for instance, sought to spell out requirements for use of everything from netting, screens, shutters and exterior shades “in order to reduce bird risk.”
In May, Quigley joined Rep. Morgan Griffith (R-Va.) as a co-sponsor of H.R. 3268, the latest version of what the lawmakers call the “Federal Bird Safe Buildings Act of 2025.”
Vehicle strikes
Collisions with vehicles account for an estimated average of 214.5 million bird deaths annually, with the estimates ranging from 89 million to 340 million.
Electrical line problems
Electrical line collisions kill an estimated average of 25.5 million birds in the United States annually, with the estimates ranging from 8 million to 57.3 million. The Fish and Wildlife Service’s numbers also include a distinct category of bird deaths attributed simply to “electrocution,” which the agency puts at an average of 5.6 million annually.
The potential risk to birds will likely increase as the grid grows with more electrical transmission lines. In 2024, according to the Federal Energy Regulatory Commission, a total of 888 miles of new high-voltage transmission lines were constructed, and a 2024 Energy Department study called for at least a doubling of the current U.S. regional transmission capacity.
At the same time, the National Audubon Society notes the transmission line risks can be lessened or offset through strategic bird-friendly route planning, warning devices and other means.
Wind turbines
The average annual death estimate of 234,012 birds killed by land-based wind turbines falls between the low and high estimates of 140,438 and 327,586.
Lewis Grove, energy director with the American Bird Conservancy, said that two competing forces influence the relative risks to birds. The overall growth of wind energy has caused “increased concerns for particular species,” he said, noting the deaths of “hundreds of adult golden eagles” annually.
“Areas like southeastern Wyoming, which have seen rapid wind energy build-out, have likely become a continental-scale population sink,” Grove said.
At the same time, Grove added, “mitigation technology has improved” to lessen the harm from turbines.
There is no similar overall estimate cited by FWS for deaths caused by ocean-based wind turbines. The Biden administration approved 11 offshore wind projects. Six of them have started construction, but the Trump administration has also moved to revoke three of the permits.
The Trump administration’s stop-work orders and legal filings on major offshore wind projects in the Atlantic Ocean have made little or no reference to bird deaths as a reason to block wind turbines, instead citing issues like national security.
Biological opinions prepared for individual offshore projects acknowledge that the turbines will affect bird species but do not estimate total avian casualties.
For instance, the Fish and Wildlife Service’s biological opinion for the offshore Empire Wind project off New York states that “wind turbines are likely to affect Atlantic Coast piping plovers throughout their annual cycle via the risk of collisions, although the magnitude of this effect remains unknown at this time.”
Oil pits
FWS says that oil pits account for an estimated average of 750,000 bird deaths annually, with estimates ranging from a half-million to 1 million.
The estimate is based on a 2006 study by the agency’s own now-retired forensic ornithologist, Pepper Trail.
“Birds visit these fluid-filled pits and tanks — oil pits — which often resemble water sources, and may become trapped and die,” Trail wrote, adding that “even the lower-end estimate of 500,000 birds is a very high annual toll for a human-caused, preventable source of mortality on U.S. native birds.”
