I found this forgotten photo in my archives from several years ago of what appears to be the outline of an Eastern Screech-Owl that crashed into our glass door, despite the main door being closed right behind it, on a July night. This was all that was left and it presumably flew off, hopefully OK. The wing position makes it look like the owl saw that it was about to fly into an object and slowed down before impact, thankfully. Hundreds of millions or perhaps billions of birds die as glass strikes every year in the U.S. It doesn’t have to be a window and it can still happen despite having an object immediately behind the glass. Covering glass or making it nearly entirely non-reflective are the best options.