My wife told me about this spectacle, which she saw yesterday. Today around the same time (presumably the light is right to create the reflection) we watched this Spotted Towhee do battle with his own image in a plate glass window for about ten minutes before we chased him away. He stared from close range, attacked with his bill, and flew up attacking with his talons. For a view of the attacker through the window, see http://www.pbase.com/image/133940424 .