Behaviour Modification is all fine & good. I believe most of us grey owners are able to, as you would say "train" them using it. But my amazonn has a stubborn streak in her, a very good memory, and not one to get distracted when she sets her mind to it! I know that her biting IS just a stage, she knows NOT to bite, she KNOWS what the word NO or Stop Biting means. I know this because all other times, she will stop her biting if told to do so, or not bite when we tell her No bites. It is bedtime where she tests me, she is young and prefers to let you know that she is still trying her boundaries, this too shall pass.