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Twice a year, millions of birds migrate north in the spring to breed, then fly south for the winter. And in Chicago, thousands die every year when they fly into glass buildings. But Juanpablo Ramirez-Franco of member station WBEZ and Grist has this report on efforts to try to protect the birds.
JUANPABLO RAMIREZ-FRANCO, BYLINE: Larita Clark looks straight up, then to her right and then her left. As far as she can see, it's all glass. She's standing outside Lakeside Center, one of the four massive buildings that make up Chicago's McCormick Place, the largest convention center in all North America.
LARITA CLARK: Yes, this is the building that has two football fields' worth of glass surrounding it, which are the windows.
RAMIREZ-FRANCO: Clark is the CEO of the Metropolitan Pier and Exposition Authority. That's the organization that owns the convention center just south of downtown Chicago. Currently, Clark is overseeing a sort of polka-dot makeover that she and others around the city hope will make the windows of the more than 2-million-square-foot lakeside building safe for birds.
CLARK: To me, it's just a bunch of dots, but it's also something that the birds can recognize so they know that there's something there, and they won't collide with the building.
RAMIREZ-FRANCO: Many birds travel by night. They navigate using the stars and the moon. That can turn into a lethal problem for migratory birds approaching the Windy City. A dizzying multitude of lights behind glass windows can disorient them. Between 500 and a thousand migratory birds crash at McCormick Place annually.
Just up the street at the Field Museum, scientists have been monitoring this situation for more than 40 years. John Bates is a curator of birds with the museum. He walks me through a long hallway of floor-to-ceiling filing cabinets before stopping at one and sliding out what he calls the gee-whiz drawer.
JOHN BATES: These are all window kills of different species that have hit. So you've got things like - here's a ruby-throated hummingbird, which is the only hummingbird in eastern North America.
RAMIREZ-FRANCO: There are birds as small as a pinky finger and others that are bigger than a fist in this drawer - all kinds of colors - and all of them were found lifeless outside of McCormick Place. Bates estimates that over 200 different species make the trek through Chicago every year. But this past fall was one for the record books.
BATES: It was a migration that was bigger, in terms of numbers and individuals moving along the shores of Lake Michigan, than colleagues of mine have seen in 45 years of monitoring that area.
RAMIREZ-FRANCO: Close to a thousand birds crashed into McCormick Place in one night. Another 1,600 birds were found scattered around downtown Chicago. In the days that followed, more birds turned up, too. Annette Prince was out early that morning, trying to rescue as many birds as she could. She works with Chicago Bird Collision Monitors, a group that collects dead and injured birds in downtown Chicago.
ANNETTE PRINCE: They were filling garbage bags. One garbage bag had so many birds in it, you couldn't lift it.
RAMIREZ-FRANCO: Most years, Prince says bird casualties hover somewhere between 8,000 and 10,000 birds. Last year, it was closer to 12,000. She and her group have pushed McCormick Place officials to install bird-safe film for years. And this summer, they started. They plan to have the building fully covered in time for fall migration. She hopes it's a sign of good things to come.
PRINCE: I think McCormick Place is going to be a great example that we've significantly reduced bird death and injury there.
RAMIREZ-FRANCO: So now city officials, scientists and birders will wait for the next bird migration, when temperatures fall. They'll be making a new count, checking to see if the birds avoid the newly speckled McCormick Place windows as they fly to their destination.
For NPR News, I'm Juanpablo Ramirez-Franco in Chicago.
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