Expert: Roger Lederer - 2/4/2009

Question
QUESTION: A male cardinal has been attacking my home for a few weeks.  From about sunrise to sunset he flies into my windows.  He will spend most of his time flying into my dining room window, which is his favorite.  He'll perch himself on my holly bush just outside the window, look inside for a few minutes, and then fly into the window hitting it with his feet.

If I go to another room, he will fly to a bush near the window of that room and attack that window in the same way.  He will also follow my husband from room to room, attacking the windows in the same way.

He doesn't appear to be bullying any of the other birds though.  I've even seen him sharing the feeders with several other birds.

I've tried hanging things in my window but they all seem ineffective.  The only thing that appears to work at all is pulling down the shade, but even that doesn't work very well.

I know my neighbor also had a male cardinal attacking his bay window for about a year.


ANSWER: This is 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 often 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.

---------- FOLLOW-UP ----------

QUESTION: Thank you so much for your quick response!  I'm still curious why the bird follows my husband and me from room to room though.  

I mean, if the bird is following his reflection why wouldn't he just attack whichever window is closest to where he is, as opposed to flying to the window of whichever room we are in?  It doesn't seem like the window shade would affect his reflection outside.  

Also, if this odd behavior usually stops during nesting, why did the cardinal continue attacking my neighbor's window for about an entire year, not just the spring season?

Answer
If he sees reflection AND movement (yours), he assumes it's another bird and he follows it. As far as your neighbor's bird, sometimes Cardinals establish winter territories as well and thus will do this most of the year. Again, eliminate the reflection and he will cease.