Too many times I've heard an ominous "thunk" as one more hapless bird flies into my sliding door. Decals to repel birds don't work. This one made a particularly loud noise and its heart was still beating as I picked it up to bring it into the warm house where I prepared a little bed for it in a colander. I placed it outside in the sun, but alas, it was mortally injured. Such a pretty victim. Here are some suggestions to prevent the strikes: http://www.birdwatchersdigest.com/bwdsite/learn/top10/windowstrikes.php