I need more information: type of bird, age of onset, diet offered and diet eaten, and interactions with family, just to start.

Feather picking has a differential list of over fifty diagnosis. These can range from a deadly viral disease called Psittacine Beak and Feather Disease (which can start as feather picking of the tail) to malnutrition (diet eaten is sometimes very different from diet offered) to intestinal parasites (cockatiels and giardia combination can cause a severe pruritis-itching) to cloacal polps (hemorrhoids for birds) to yeast infections of the cloaca (the cloaca is like the rectum of a mammal). Many times lab testing will be required to determine the cause. And without a cause, it is impossible to provide a treatment.

One more complication: The longer it goes on, the less chance of regrowth. If the bird or disease continues to damage the feather follicles, the follicles will not be able to produce normal feathers.

I am always amazed that people will ask their pet shop owner/worker for medical advice. Many owner/workers know next to nothing about the animals they sell. Even in the area of husbandry, which I believe they should know, they give bad advice.

I have seen fish "burned" with salt treatments recommended by fish store people (know your fish), hamsters with prolapsed eyes and hugh skin lacerations because they were kept with other hamsters (hamsters are solitary creatures - they do not tolerate other hamsters except for a 12 hour breeding period and as youngsters) and birds almost dead from mite treatments when mites are RARE (rare, rare, rare, rare!!!) in pet birds.

Or how about tortoises on lettuce diets that take one to five years to die from calcium deficiencies, or iguanas that suffer third degree burns from their hot rocks, or snakes ripped open and eaten ALIVE by the live, unmonitored rat.

I could go on for hours. I guess the bottom line is that you get what you pay for.