Studies have found that the bright lights and glazing of towering structures in US cities including New York, Chicago and Los Angeles are causing millions of migratory birds to die each year.
A study published by Cornell Lab of Ornithology this week ranked 125 US cities based on the danger they pose to birds. It found that Chicago is one of the most popular migration paths for birds in the US, and therefore the most dangerous.
The dense metropolitan areas of New York City and Los Angeles, which features hundreds of glass skyscrapers, are also deadly.
Migratory birds prone to deadly building collisions
This recent research is a continuation of a 2014 study produced in The Condor: Ornithological Applications journal, which estimated that between 100 million and one billion birds are killed annually in the US. "Building collisions, and particularly collisions with windows, are a major anthropogenic threat to birds, with rough estimates of between 100 million and 1 billion birds killed annually in the United States."
Migratory birds are at most risk, the study found, because they are attracted to the great building's artificial light during nocturnal flight in big cities.
Another study published this week by the University of Michigan follows this analysis and reveals that certain type of migrating birds tends to collude with illuminated buildings more often.

The university, which also investigated Chicago along with Ohio city Cleveland, found that songbirds, s...