He’d get very upset. Especially when the lamp was on. He’d attack the window, trying to get through to kill it. They are the most territorial bird I’ve seen.
He got angrier fast and it was appearing like he could hurt himself, so I moved it to a room he might not know about.
I had one that attacked the bird it saw in the mirror film on a window, it tapped at the glass for days. I finally peeled the film off and it quit, thinking likely that it had scared the other bird off.