A robin comes tapping at our window fairly regularly. It's trying to tell the other robin to go away, but of course there is no other robin. It's just a reflection in the glass. That silly robin can't figure it out and it keeps tapping and tapping. I remember the first time I saw a mirror. I ran around to the other side to look for the other parrot, but I realized my mistake right away. I'm no dumb robin. We parrots are very quick learners.