I watched this Duck in the water as well as walking on land. Unlike the body position of Mallard and Black Duck when walking, this bird walked with it's body raised in a 3/4 upright position. The closest species I can find on line is the domestic variety called the Khaki Campbell Duck.
It resembled no wild species of which I'm aware, approached humans eagerly and closely. This behaviour indicated a domestic species to me.
Khaki Campbell was the first thing that sprang to mind when I saw the photo. A bit lighter in colour than usual but it could be crossed with a Pekin.
Eric, you have much greater knowledge of domestic ducks than I do. I learned of 'Khaki Campbell Duck' only after Googling 'domestic ducks with upright stance'.
Sadly, not the first I've heard of released birds. I had 3 (2 Khaki Campbells and a mutt drake), quite a few years ago, that I rescued off a marsh with the help of a friend's black lab. Someone had released them and they were starving. Never saw a duck that was so skinny.
The duck at Rockwood isn't skinny and will chase you around like a puppy.
That one is lucky. Mine were on a marsh that didn't get humans visiting to feed the ducks.
Just to clarify, yes I am aware that people often feed the ducks in these areas unsuitable foods. I simply meant that the birds I rescued had absolutely no access to any food source and lacked the skills to forage wild.