We'd had a very warm fall until Wednesday of this week. Temperature dropped 30 degrees. Birds had been enjoying the warm weather and then the sudden change had

We'd had a very warm fall until Wednesday of this week. Temperature dropped 30 degrees. Birds had been enjoying the warm weather and then the sudden change had them all migrating at once. They ran into a rainstorm which made migration very difficult (this is called fallout). So now you've got tons of birds struggling to migrate and aiui flying at lower altitude because of the rain McCormick (the building in question) is a very large building immediately off the lake with lots of glass windows. There may be some additional mitigations to be made but it's a bad confluence of events. It doesn't happen even once a decade. This is an important migration corridor, there's even a nice bird sanctuary within site of McCormick. If you're ever there for a convention the area surrounding the convention center is very nice. Northerly Island is becoming one of the nicest parks in Chicago, and is a wonderful walk from the convention center.