Birders across the country are up in arms about the Minnesota Vikings’ new stadium, which is likely to be a death trap for migratory birds that can’t see glass and fly into it. The stadium design includes 200,000 square feet of glass, and the Minnesota Sports Facilities Authority (MSFA) has said they won’t spend the extra $1.1 million to use bird-safe glass. But what exactly is bird safe glass? And if not having it is such a big problem, how can you keep birds from flying into your windows at home? You have questions, we have answers. Why do birds fly into glass? Birds can’t see glass. Instead, they see whatever happens to be reflected in its mirror-like surface. Often, this is open sky or trees, which, if you’re a bird, are appealing (and perfectly safe) things to fly towards. It’s estimated that between one hundred million and one billion birds die every year in collisions with manmade structures—one of the biggest killers of migratory birds. What is...