Missing feathers on neck and around eye

[DuckLadyRo]

I have two Drake Mallard's, they are brothers, Max and Shadow. Recently Shadow has been attempting to meet with Max. Sometimes it looks quite violent. Recently I have noticed feather loss around maxes neck and his eyes. I'm wondering if the feather loss has to do with the molestation he is receiving on a daily basis, or if it could be mites. I had a run with mites one time before on both ducks and was able to get it under control. It looks kind of similar to that, but this time it's only on Max. Any help is greatly appreciated!

 

[DuckLadyRo]

It's only one eye, and I did just notice Shadows neck is missing a little bit too.. mites or defensive wounds!? Here is a picture of Max.