I've had that happen. He is attacking his reflection. You can cover the window or buy some spray frost to prevent him from seeing himself. Probably after chick season is finished he may not act so crazy.

Its springtime and he probably sees his reflection as a challenger to his turf. Try covering the window with something. Once he can no longer see himself, he should stop. Hopefully, he won't start fighting with another window. They do that with car mirrors too.

I lost track of how many times DH washed the living room window at his sisters one year...same story. Robin. It just would not give up, and could apparently get enough of a reflection even with the drapes closed it would not leave that E facing window alone.

Another year it was my elderly neighbors bathroom window. The robin would sit on the fence in the side yard and attack (itself) over and over. We even tried talking to the bird, it wouldn't listen.

There have been springs where DH had to put a bag over the side mirror on his truck when he parked it in the driveway. Not robins, but smaller birds beating (and pooping) on the mirror ;0)

Since the reflection is on the outside anything that is done needs to be done on the outside. Pulling drapes etc. can only make the reflection stronger.

A couple years in a row we had a Robin leaving blood smears on the window it fought so hard, or maybe it was two birds. I did have to tape up something to stop the reflection.

At our house it has often been a male Cardinal doing the same thing.

I had a cardinal attacking himself in the side view mirror of my car. He beat himself bloody. I had to put a lunch bag over the mirror whenever I came in the driveway.

Years ago our "knockingbird" was a titmouse. As the years went by our windows became dusty enough that the reflection no longer caused a bird reaction. We washed the windows before selling the house ... I wonder if the bird came back? lol.

I had a deranged woodpecker who was attacking my brand new Marvin aluminum clad windows. I know there is not rotted wood under them as there is BRICK. He did it for a couple of weeks and left.

You have to cover the outside of the glass, not the inside. Covering the inside doesn't affect the reflection that the bird sees.

This happened to my neighbor. She had her DD's beanie baby animals lined up on the windowsill to deter the birds.

some people have success by putting an image of a hawk in the window.

We have a female cardinal attacking the garage windows and the mirrors on the cars parked outside for several days this week.

I have a mirror standing up next to the foundation to reflect light onto some plants. Lots of shade from trees, etc. on that end of the house. Had to remove the mirror this fall because the wild turkeys passing thru the yard were fixated with it. Crazy birds.

Went down to a park on the river, and a cardinal set in on the driver side mirror. To Illustrate--

I went out to the car in the carport this morning for a doctor appointment and OMG, there was bird poop all over the car, lots of it. Didn’t have time then, but went right to the car wash after. Must have been revenge for putting paper on the aforementioned house window!

Good picture, Matthias.