At least 1,000 migratory birds died slamming into Chicago’s skycrapers over the weekend, with heartrending photo showing their corpses placed in tiny bags

More than 1,000 migratory birds died after striking buildings in Chicago over a busy autumn migration weekend, according to local bird safety advocates. The deaths highlight the risks glass-fronted skyscrapers pose along a major route used by millions of migrating birds.

About 25 volunteers searched downtown Chicago and nearby Evanston on Saturday, taking more than 1,000 birds to the Field Museum for research and helping over 250 injured survivors reach a wildlife treatment centre. Cornell Lab BirdCast data suggested more than five million migratory birds passed through the area on Friday alone; advocates say the reported toll may be higher. They are urging the city council to require bird-safe measures, such as textured glass, in new buildings.