Expert: Roger Lederer - 6/15/2008

Question
Dear Roger,
My husband and I have been wondering about the very unusual behavior of some birds around our house. We think it's mostly cardinals doing it, but not sure they're the only ones. We don't think it's a single bird because it occurs at several different windows locations.

The birds actually throw themselves against a window--as many as 6 or more times within a couple of minutes--and do this off-and-on throughout the day, beginning at sunrise. It doesn't matter if the window blinds are open or closed. We've lived in our northern Indiana house for 22 years and have never seen anything like this. The poor birds are knocking themselves silly, and we can't imagine why. They aren't dying, but it's not for lack of trying! Have you ever heard of such bizarre behavior? On another wild bird site, someone from California reported on the same behavior from a sparrow. Is there such a thing as Mad Bird Disease? Thanks for your help.

Answer
This is actually very common behavior. Cardinals and many other birds are territorial and when they establish territories in the
spring they become aggressive and chase off intruders. Unfortunately, they don't distinguish between their own reflection in a window (or car mirror) and try to chase that off. The solution to the problem is to eliminate the reflection. Misting the outside of the window with a very weak detergent or soda solution will eliminate the reflection but will also impair visibility for you. Awnings, eave extensions, and window screens will eliminate all reflection and stop the collision problem. Hanging ornaments such as wind chimes, wind socks, and potted plants also help. The behavior will stop when nesting begins.