For almost 2 weeks now, a male cardinal has been launching himself at the top corner of my dining room window. He usually starts around 7am and goes on for about an hour. He'll sometimes do it in the afternoon as well. I know the conventional wisdom is that he sees his reflection and is being territorial, but that can't be the case here. The window is almost completely shielded by a holly bush, and he launches himself from a good foot and a half below the particular window pane he strikes - it's always at the same place, and he couldn't possibly see his reflection from there. Even if he could, he'd have a better and closer reflection to attack. I've put silhouettes of owls, covered some of the panes with black paper, put out a feeder - nothing makes any difference. I don't worry any more about him hurting himself - I just want him to stop. Any advice would be appreciated. It would be difficult for me to do anything on the outside of the window but I'd hire someone if necessary. I have video. Thank you.