I doubt this would work for ducks, but it worked for my dog...... He wouldn't leave his injured, bandaged paw alone, untill I put wasabi on it!!!!!! ;-)
Alas, too bad about the anti-feather picking spray now working. Didn't consider the waterproof factor -- maybe that can be someone's "get rich" invention -- waterproof anti-picking spray for waterfowl that won't harm their natural oil coat.