Minneapolis (Learfield News Service) - Birds are flying into the Minnesota Vikings new stadium at an alarming rate and it's all because of the glass facade designed to keep grass growing inside.

The stadium sits in a migratory bird flight path. Birds apparently see their reflections in the glass, or they see trees and blue sky reflected off the glass and then fly right into the stadium. The belief is the stadium is killing at least 500 birds a year. At that pace, US Bank Stadium would be Minnesota's deadliest building for birds. The question is what to do. The group in charge of the stadium says it might cost $60-million to replace the glass. Another option is to coat the glass with a substance that limits the reflection.