Last year - I think - there was a male cardinal who, for a week or more, kept bonking into the window. He saw his reflection and thought it was another bird; he wanted to protect his territory, so he fought this stubborn intruder. Finally we were able to scare him away. Now his mate is doing the exact same thing! It drives us nuts and I think she's going to hurt herself, too. We've had smaller, less tough birds die from just one collision with the window; for instance, about a week ago the 8-year-old found a dead ovenbird right below the glass. Has anyone had this problem? With the male cardinal we had to climb up on the roof and tape deer netting across the roof window before he would stop. Anybody have any other ideas??