About 6 months ago a friend bought my son a cockatoo for his birthday. The bird is a rescue animal, who's previous owner was very abusive to him. We've overcome the fear issues he's had and he's a very pleasant bird. However, he has one "renegade" tailfeather that grows in sideways (I'm guessing from prior abuse). He attempts to trim it or pluck it (not in front of us, but when he's alone) and ends up trimming off ALL of his tailfeathers. My understanding is that they take several months to regrow. Is there any way to get him to stop doing this? Or it just something he's going to do and he's always going to be without full tailfeathers? Thanks for any help you can provide!!