Is it bad for a bird to hit your window?

Yes, it is bad for a bird to hit your window. If it is going at a fast enough rate of speed, it could break its neck, which would kill it. Alternatively, if you are living in a skyscraper and the bird hits your window, it could knock it out and then it would fall to its death. But many times it just shakes its head and flies off. It would depend upon the bird and the window. But no, it's not a good thing when a bird and window intersect.