What are some ways to train your Quaker parrot to not screech when you leave the room?

All parrots are flock animals, and when they call out if you leave the room, what they are doing is called a contact call. To teach a bird that loud calling is unacceptable, you need to first of all, NEVER respond to inappropriate noises. Any time you react to loud noises, either verbally, or by coming back in the room immediately, you are teaching your bird that this loud call is a good way to get your attention. What you need to do is teach your bird that quieter alternatives will work. I have found the best contact call to teach parrots is a whistle. Immediately upon leaving the room, BEFORE your bird screams, whistle to him. Call out periodically with a whistle or other quieter, acceptable noise, while you are out of the room and he is not yelling. Praise your animal whenever he is being quiet. It can take months to fix this issue, but it can be done if you are persistent and consistent with your actions.