She see her reflection and thinks it is another female in her territory so she is trying to chase her away. Birds do not know it is their own reflection. You could try to put something up to stop the reflection. I had a Robin do this at the garage window a couple of years ago it went at it all day for a couple of weeks.

That is very, very sad..... A new pair will come. Be strong. Ann

catherine........I just posted a similar question. I have a female cardinal that keeps knocking on my window. I find it very curious that this is happening in the Fall. In the past, I've tried scaring them (just by yelling at them), closing the drapes, turning on a light in front of the window. You could try a vinyl stick-on hawk figure, but I fear he might just go to another window. Hopefully, he (or she) will just go away soon. I've never had titmice do this........just cardinals.

We have been blessed to have bluebirds nest in our bluebird house for several seasons now. When I noticed the male and female tending to the box this spring, I took a photo of the nest which showed 5 perfect bluebird eggs (4/29). Two - three days later we noticed that the pair was no longer tending to the nest. The male began to charge at his image in our windows all day every day. The female could be seen at the suet feeder from time to time but not at the bluebird house. A closer check of the house revealed a clump of pinestraw protruding from the entry and so I checked the nest. It appeared that the eggs had been stolen (by raccoons?) and only a small piece of shell was left. The birds were no longer tending to the nest and so I cleaned it out and the pole was greased with cayenne pepper to deter raccoons. Another few days went by and I noticed that the pair was tending to the box again. I waited a few more days and took a photo on 5/10 of the new nest which showed 4 white eggs in it. Ever since then the female bluebird has been diligent in tending the nest, but the male rarely goes to it. I checked the box again today 6/7 and the eggs have not yet hatched. It seems that the hatching is overdue. Are these indeed bluebird eggs? I will avoid removing anything from the nest but I'm just curious about might be going on here. Any advice? The photo from 5/10 is attached.