Well before he became a presidential candidate, Donald Trump professed a deep concern about the welfare of birds endangered by wind turbines:

“[Wind power] kills all the birds,” Trump told 2012 Republican presidential candidate Herman Cain on the latter’s radio show Tuesday. “Thousands of birds are lying on the ground. And the eagle. You know, certain parts of California — they’ve killed so many eagles. You know, they put you in jail if you kill an eagle. And yet these windmills [kill] them by the hundreds.”

Wind turbines do kill birds — but not in the numbers Trump claims.

The U.S. Fish & Wildlife Service reported in 2018, based on data published between 2008 and 2015, that:

Bird/turbine collisions in California are estimated to be an average 7.85 birds/turbine/year, higher than in the East (6.86 birds/turbines/year), the West (4.72 birds/turbine/year), and the Great Plains (2.92 birds/turbine/year).

The agency says that in aggregate:

The most comprehensive and statistically sound estimates show that bird deaths from turbine collisions are between 140,000 and 500,000 birds per year. As wind energy capacity increases under the DOE’s mandate (a six-fold increase from current levels), statistical models predict that mean bird deaths resulting in collisions with turbines could reach 1.4 million birds/year.

But during his first year in office, it was clear how much concern Trump actually had about birds. In December, 2017, Huffpost reported:

In a reversal of yet another Obama-era rule, the Trump administration has moved to protect energy companies and other parties from being prosecuted for unintentionally killing migratory bird species.

The Migratory Bird Treaty Act of 1918 only prohibits the intentional hunting, capturing or killing of bird species, according to a legal opinion the Interior Department’s solicitor’s office published Friday. Accidental deaths, including those caused by oil rigs, wind turbines and power lines, will no longer violate federal law.

So where does Trump’s opposition to wind turbines come from? The clearest articulation of his concern almost certainly relates to the value of his golf courses and his expectation that their appeal to customers would diminish if wind turbines were allowed to spoil the surrounding views.

As Trump wrote to Scotland’s First Minister Alex Salmond in 2012:

Wind turbines in inappropriate locations are a disastrous mistake for Scotland. They will certainly be very destructive to major golf resorts (such as mine) and tourism will greatly suffer.

Trump made no reference to the threat to birds.

In another letter to Salmond, Trump predicted that the installation of wind turbines would result in Scotland becoming “a third world wasteland that global investors will avoid.” Again, no mention of birds.

Among the human-caused threats to birds, the greatest currently comes from domestic cats that kill an estimated average of 2.4 billion birds a year in the U.S. After that, the largest hazard is posed by buildings — especially the kind that Trump owns — that kill an estimated average of 600 million a year. Moreover, as The Guardian now reports, that figure may be as high as a billion:

Scientists estimate that at least 100 million and maybe as many as a billion birds die each year in the US when they collide with buildings, especially glass-covered or illuminated skyscrapers. And, in a new report, conservationists now have a better idea which American cities are the deadliest for those on the wing.

Chicago, with its many glass superstructures that spike into what is the busiest US avian airspace during migration, is the most dangerous city for those feathered travelers. More than 5 million birds from at least 250 different species fly through the Windy City’s downtown every fall and spring.

They journey twice a year, many thousands of miles, going north in the spring from Central and South America, across the Great Lakes to Canada, and back south in the fall.

So wherever Trump brags about owning the tallest building, it’s reasonable to also infer it’s the building that kills the most birds.