Bipolar Bird

[sm4him]

Funny, I had a sparrow about a week ago doing the exact same thing. I've seen them do it before a time or two, maybe three, before they give up. But I'd never seen one spend as long as this little sparrow doing.
Same as you described; it would fly right up into the mirror and flap away for a few seconds, land on the edge of the window and keep attacking the mirror; then suddenly fly off, either down to the ground near the car, or over to a branch of a nearby bush. It would sit for a minute then come right back at the mirror.
I was in my car (different car) about to leave for work when I noticed it. Didn't have my camera with me, and I was so close to it that I figured as soon as I tried to sneak out of the car to go GET the camera it would take off. I watched it for about five minutes before I left for work, as far as I know it was still giving that mirror what-for.

Glad you got pics of your cardinal doing that!

Apparently not too unusual. When I showed these to my wife she remembered years ago we had one of those gazing ball (mirror surface) yard ornaments and a cardinal showed up one day and spent an afternoon repeatedly flying at.

Joe

Birds DO tend to fly at anything reflective, and as Designer mentioned, it's often because they think another bird is encroaching on their territory. But it's a little unusual (though certainly not unheard of) for them to continue for that long. I've never seen it myself, but have heard stories of birds literally knocking themselves out or wearing themselves out to the point where they can't fly for a while, because they spent so long fighting with their reflection in something.