Is he preening that area or are feathers coming out in places he can't reach?
What is his diet?
Does he have visible bald spots?
When was the last time you took him to an avian vet?
Welcome to the forum.
More info and a picture would help. How old is the burd. What food do you give?
To post a quick picture, click go advanced under text box. Click paperclip choose picture, tgen on far right hit upload, then close thst window, abd post