Update: Hensaver covered the featherless areas- but feather loss started occurring on shoulders, sides, under wings, etc. I still wasn't sure if it was her feather picking herself or the ducks really doing it. Noticed that she was getting worse and now missing feathers on the back of her neck right about the hensaver too. Got confirmation yesterday when I looked at the group as they were free ranging in the backyard (which they have been every day even when it was cold and when it was raining!) and I saw the 2 ducks had Maple and were going at her feathers- both of them just chewing away at her and she was just taking it. All the other hens were at the other end of the yard dust bathing.
So she is going to be a house chicken until her feathers grown back (it is supposed to get very cold) and we can build a separate duck pen. Frustrated because I thought that when they were free ranging, they would all be content.
Still mad at my ducks. They don't bother my other hens.