This is a common question we receive from Seabrook Island Birder (SIB) members! Have you ever seen this behavior at your home?
We have a female cardinal that continues to try and get into the house. Generally 3-4 times a day she flies up the window sometimes she perched on the sill looking in. This has been going on for over four months.Christine Dennis
For starters, rest assured the bird is not trying to get into the house. During the breeding season, birds aggressively attempt to drive off intruders of the same species. This is an instinctive behavior and not something the bird can control. What you are experiencing is a bird that sees its reflection in your window and instinctively attempting to drive the intruder away. The process follows a pattern. First the bird sees its reflection. Thinking it is an intruder, it displays a warning posture. Needless to say, the reflection responds with the same threat. This quickly accelerates to a full out attack. This is not something the bird can understand or learn not to do.
The solution is to change the reflectivity of the surface the bird is attacking. This is easier said than done! There are several things you can try, none of them visually appealing. Some people have had success with strips if different color paper taped on the inside of the window to break up the image. Completely covering the reflective surface on the outside works, but it also blocks the window. Installing screens will break up the reflection and soften the blow if the bird does hit the window. Finally, some people tie moving objects, pie tins, ribbons, etc., around the area to create movement that scares the bird away.
All that said, the bird will not hurt itself, will not break or damage the window, and will stop eventually when the breeding season ends.Bob Mercer, SIB’s “Resident Naturalist”
Thanks to dlinnehan, we found this video on YouTube which provides great footage of both male and female North Cardinals attacking their own reflection.