It's migration time for North America's birds, with many already journeying north for their summer stay, and one US city has taken a seemingly unusual step to light our feathered friends' way: It's turning off its lights. About 20 buildings in Philadelphia are taking part in "Bird Safe Philly," a voluntary initiative that involves dimming the city's skyline from April 1 through May 31 so that the 100 million birds passing over the City of Brotherly Love can do so safely, without being distracted by bright lights that can prove fatal. CNN notes that turning the lights down low or off completely in atriums and lobbies, especially on higher floors, may seem like a counterintuitive move—after all, how can the birds then see the buildings?—but Robert Peck of the Academy of Natural Sciences of Drexel University explains that birds typically use the natural light of the sun, moon, and stars to navigate.
However, during migration time, birds often end up flying at lower altitudes due to seasonal fog and rain, and the emergence of bright city lights can confuse them. "Suddenly they have all these lights coming at them from different directions. It's overwhelming," Peck says, noting the disoriented birds then end up smashing into buildings and walls. Bird Safe Philly came to be after what it describes on its site as a "mass collision event" that happened last fall: On Oct. 2, "thousands" of birds ended up perishing after crashing into buildings in the Center City District. That's why, from 12:01am until 6am each day through the end of May, participating buildings are dimming any lights that aren't needed overnight. Texas News Today notes that a "lights out" program for just this purpose was launched in Chicago in 1999, and that dozens of cities have duplicated the effort since. "It's a tough trip," Peck tells CNN. "The last thing [the birds] need to do is encounter brightly lit buildings." (Read more Philadelphia stories.)