Turn the Lights Out. Here Come the Birds. Buildings, landmarks and monuments are turning off lights to prevent fatal impacts as birds set off on spring migration. Each year, about 365 million to one billion birds die by smacking into reflective or transparent windows. Credit...Matt Slocum/Associated Press April 10, 2021, 8:00 a.m. ET Dozens of American cities are being transformed this spring, enveloped in darkness as the lights that usually brighten up their skylines are turned off at night to prevent birds from fatal impacts during their annual migrations. Each year, an estimated 365 million to one billion birds die by smacking into reflective or transparent windows in deadly cases of mistaken identity, believing the glass to be unimpeded sky.