Many of the birds that we care for have been emotionally damaged at the hands of humans. A major symptom of their distress is feather destructive behavior (FDB). FDB is never seen in wild birds, and rarely seen in birds that were parent raised. It is the birds who were taken from the nest and raised by humans that generally experience FDB. Cockatoos, African Grey Parrots, and Eclectus Parrots are all prone to this behavior issue. (It is important to note that even birds who have wonderful, loving homes can be affected by this disorder).
At Best Friends Parrot Garden, we spend a lot of time working on FDB behaviors. And we have had a lot of success using behavior modification techniques. We do not utilize collars and rarely have to resort to pharmaceutical intervention. But it is a long process that requires many different techniques. One of the primary components is to teach birds that they are indeed birds, and not humans. Helping them to make connections with other parrots has been highly successful. Here is a picture of Charlie, the Moluccan Cockatoo (a self-mutilator) and O, a DuCorps Cockatoo who pulls his feathers out with his feet. They have been spending time preening each other. When they are interacting with others, they are not obsessively preening themselves. It is a tiny step towards recovery from FDB.
Feathered Angels 
I would love to hear/read some of their other ways that they are working with this; do you have a link? This behavior is also very common with Scarlet Macaws and Scarlet hybrids and is very frustrating for many who own these birds. I used to believe it was dietary, then I thought it was environmental, now, I think it’s a combination of issues.
Here is a link to my own article on Feather Destruction. Sadly FDB can show up in any species living in captivity. While we dont know exactly the cause, you will notice that it is not seen in wild. So while there is no definite answer yet…we can safely assume that somehow we have failed these Angels in captivity. Rather it is dietary, environmental or mental this just further proves that captivity is harder on some of them.
Deborah