Any of those would kill and eat a duck. Without a picture of the one with the hole in it, I couldnl't tell you if it looked like a mink attack or not. We don't see mink often either, but have lost chickens to them.
Sorry - I wasn't clear. I was referring to the one that was "killed without getting eaten".
From what I understand from the first post, however, the OP hadn't seen their ducks in about a week. A 1-2 pound animal could polish off a duck in that amount of time.
Possibly a mink. They will sometimes just leave a couple of little bite marks. In my experience, it's been under the wing or on the neck. I've also had them eat the back of the head of my chickens.