That Blasted Bird!

We have a young robin that thinks he has to defend his turf from another bird in the window of my office. While it's cute to watch, he is the messiest bird I've ever known! While he's busy making faces at the "Other" bird, he's pooping on the limestone sill. Do you suppose he's scaring himself, or is this just the nature of the bird?

I hope he gets the idea soon that the reflection is no threat, and gets on with his life!