"BRW" wrote in message
...

Female cardinals have a tendency to sit in a tree right outside one
of my windows and to gently fly into the window - repeatedly often
until I put my hand by the window - which scares them off.

I've got several bird feeders out on my property and am not annoyed by
these characters at all, but am very curious.

Does anyone have a good explanation for why they're doing this?

They may be seeing their reflection in the glass and trying to run off
the "intruder". Something to dull the reflection (like dulling spray) or
hanging something in front of the glass might help.