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.