Earlier this week, Max, Stella, and Calypso were on the shower curtain rod after my shower. I had my back turned so I'm not entirely sure what happened, but at the same time Max screamed and flew to the counter and Calypso fell to the ground (softly -- he has all of his flight feathers) inside the shower. Then, about 20 of Max's feathers fell to the ground.
I'm guessing that either Calypso or Stella jumped Max; I'm just not sure why Max didn't fly away in time. (My money's on Stella since Calypso and Max generally get along; I'm just not sure why he fell to the ground during the altercation if he wasn't involved.) No serious damage was done, but Max has a couple of head feathers that will no longer lay straight. We joke that she looks like a short-eared owl, with that feather sticking up, so I've been calling her my short-eared timneh. And now I'm taking even more precautions with my showering to make sure nothing like this can happen again.
This is why I was very hesitant to bring Brian in to our home, and why we are extremely cautious with him so that no accidents can happen. When it's these guys who are about the same size, it's a cautionary tale; with Brian it could have been a tragedy.