If preening, sounds normal to me. Also remember that several exaggerated preening motions are actually courtship displays....so a drake will appear to preen more.
Clint
Sure he is picking and not preening? Ducks have 2 complete body molts and one wing molt per year, buy stakes and ducks usually do not molt at the same time so with several birds, someone will probably be molting at any point in time.
Clint