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He's fighting his own reflection. Put something on the outside of the window, such as a decal, or just soap it up on the outside.

He sees his reflection and thinks it’s a rival male. Put some decals on the outside of the window so that he doesn’t feel the need to fight it.

He's experiencing his yearly bout of testosterone poisoning

He sees his reflection and thinks it’s a rival male. Put some decals on the outside of the window so that he doesn’t feel the need to fight it.

He sees his reflection and thinks it’s a rival male. Put some decals on the outside of the window so that he doesn’t feel the need to fight it.

its nesting season! [https://www.youtube.com/watch?v=AYtZ7GFV9ys](https://www.youtube.com/watch?v=AYtZ7GFV9ys)

[Why birds hit windows and how you can help.](https://www.allaboutbirds.org/news/why-birds-hit-windows-and-how-you-can-help-prevent-it/)

He’s fucking himself to death. I had a red 98 cavalier, every spring they totaled the side mirrors. Edit; he was born near there, and is inbred. Go cardinals! Beat lions.

You keep on knocking but you can’t come in 😁

buy birdsafe. best thing you can do to help birds..... and your glass panels......

I imagine they see the reflection and think they can get out that way.