I actually saw one fly into the glass door one evening (!!!!) and was afraid/hoping I might have to rescue him. I've saved a few birds who have flown into the glass door or windows, though some hit too hard and were too far gone. He sort of ended up on the porch rail, and after he sat there a bit, he flew up into a tree. I walked after to watch him, and he just kept bobbing his head and looking at me.
I like to think of them as my own little live squeaky toys, glad they allow me in their presence as they are growing up.