Updated

More than 1,000 birds were killed or injured in window collisions around Chicago during the evening of October 16, when more than five million birds were estimated to have flown through Cook County, propelled by favorable winds from a cold front, according to Smithsonian Magazine. The incident highlights the dangers that migrating birds face from human infrastructure, particularly during peak migration season when birds navigate through cities at night. Window collisions remain one of the leading human-caused threats to bird populations during migration.