Enderdragon with no AI kills mobs

I was working on my zoo when i spawned an enderdragon with no AI. Im sure it had no AI because it wasnt moving. Then I heard the Wither in its cage next to the enderdragon get hurt. I assumed he was shooting wither skulls at the Iron Golems but while i was working on the cage for the Giant, I saw the snow golems all crowded up in the corner of their cage. I went in the cage to split them up but when I did, they got thrown around the cage. I went in survival to see what was happening and same thing happened to me. As soon as i used kill @e to kill the enderdragon, it stopped. Please help me with this. It will make my server happy Thanks.