

I need advice on plucking feathers.
Good evening, this my first time posting on this forum. I was wondering how can I get my cockatiel to stop plucking his feathers. He is missing feathers on his chest and under/on his wings. Also one of his wings feathers is shorter then the other but it never use to be like that. I know it can be due to boredom but he does have toys. He is about 20+ years old. This is my grandparents bird.