What about stringing some fishing line in a way to block them from getting close to the window? It seems to work for seagulls and is invisible from a distance.

We used to have a male cardinal that would attack our driver's side window and mirror. I guess it mistook its reflection for a rival.

I hung some old CDs and it scared off blue jays.

Go outside and look at the window - do you see a reflection?

For mine it was trees - they were trying to get at the trees.

Fishing line bad. Fishing line bad.

They are back. I can see two males, one attacking the windows on both sides of the house. I was cleaning the bedrooms and one was bashing my sons room, I banged on the window and he flew into a large orange tree near the house. I went outside and I saw, what looks like a possible nest on top of the tree. he was attacking the window while I stood there. I shooed him away and he stayed in the orange tree.

I came back into the house and the other one was attacking my office window, on the other side of the house.

Its crazy, wakes us all up at sun rise and it continues all day long.

Yes, our windows have some sort of reflecting glass and I think they see themself in the reflection. ...crazy!

On another note, they are beautiful, fully colored.

Jane

I was going to tell you about the nest. Female cardinal was the hitter of the window that was near the nest. A different window was and is the long-time target of male;

We had this problem years ago. They would come and knock on our bedroom window in the morning. They also drilled a hole in our soffit. Bird-X gel finally worked to get rid of them, but that stuff is messy to get off the ledge.

Bring in a local cat by setting out cat food?