For the Birds

Painted Bunting. Courtesy John Heino

A number of years back I recall reading about a North Dakota wind turbine firm that was fined a million dollars because their wind turbine killed a predator bird of some kind that was an endangered species. I've forgotten the details now, but do recall the size of the fine.

That story came mind this morning as I read another story about how hazardous wind turbines are to birds. This prompted me to dig a little deeper into hard numbers, and here is what found. Instead of focusing on win turbines I looked at skyscrapers, windows and other human actions that kill birds. 

Actual numbers vary widely depending on the source, but here's a general summary based on the best available research.

Bird deaths from building and window collisions

It is estimated that between 365 million and 1 billion birds are killed annually by birds crashing into windows. Most deaths occur from collisions with residential and low-rise buildings, not skyscrapers. This happens because birds often cannot perceive glass as a barrier, especially when it reflects sky, trees or other vegetation.

Bird deaths from wind turbines
The estimated annual deaths from wind trbines in the U.S. is around 140,000 to 500,000 birds. In other words, wind turbines account for a much smaller fraction of total human-related bird mortality compared to buildings, cats, and vehicles.

Bird deaths from cats and cars

For comparison, outdoor cats kill an estimated 2.4 billion birds annually in the U.S. We have one cat and it's true, cats are quite skilled at reducing the bird population. As much as we love birds, we do not have a bird feeder outside our window for that very reason.

And then you have cars and trucks, which kill about 89–340 million each year. Cars are more aerodynamically designed now, but I remember how when we drove home from Grandma's house in the Fifties, my dad frequently pulled a dead sparrow from the grill of the car. It was a grim business. Back then cars had those wide, flat grills to provide airflow and keep the engine cooler. 

Bottom Line

Wind turbines do kill birds, but windows and other human-related factors like habitat loss and predation by domestic cats are far greater threats to bird populations.