We've had Rex for 9 years, we got him as an adult and have no information on his history. He had become fairly tame and well behaved. Then a week ago we got a 4-week old baby cockatiel, Rex was very curious but still well-behaved. He even seemed happier with more whistling and sitting on my kids' heads, normally he would only sit on my head. Then he started to get protective around the baby and would hiss and peck. Now he has gone full Alfred Hitchcock. When we let him out of his cage he'll check out the baby for a few minutes then go crazy bloodlust attack mode, flying in the face of anyone nearby and biting hard. Is he going to have to stay locked up forever? I guess I'll try trimming him next, then at least we would only have to worry about our toes. Any clues about what to do.