Chlorine bleach is not a good chemical for bleaching fur or feathers, and especially not feathers, as it will literally dissolve the fibers. I know this from experience!
Try a hair color remover like those made by Clairol or Loreal and peroxide, which is what hair stylist use. My sister is a pro with over 30 years experience & she gave me some commercial color remover one time, which worked very well. She's also the person who told me not to use chlorine bleach as it seriously damages hair (or feathers).