We have a male cardinal that keeps seeing itself in the windows and thinks it's another cardinal. As they are very territorial it keeps attacking it's reflection and it's driving me potty. So the woman at the bird store in Orangeville suggested I put up newspaper on the outside of the windows for a couple of weeks to see if that stops him. You have to put it on the outside as he can still see his reflection if you put it on the inside. I'll let you know how we get on.
Not sure if you can see these, but we also bought some stickers for the large window as the birds are forever flying into them. Again you have to put them on the outside of the window.