Above is a short video of the merganser scratching.
I spent a dark drizzly morning in February at Honeymoon Island. I walked up to the north end of the trail, out to the beach and saw a small flock of red breasted mergansers floating by. These were all females although some of them could have been immature males that don’t have their dark colors in yet. They seemed pretty relaxed and all of them were busy preening and scratching. These ducks only visit for the winter and are probably home up north by now.