Another domestic breed known as the Black East Indies Duck. I've seen them around before. They're pretty cheap to buy (around $100 per pair) so it's not unusual do have escapees from people who either don't know how to take care of them or lose interest. Here's a few pics online:
Cool! Thanks! There must be a lot of escapees of several varieties running around. Some years ago I had a run-in with a Reeve's Pheasant that had been let loose (as a nuisance) by a "safari park" operation near us. After a bout of hand-to-beak combat it spent the night in an old rabbit cage. I let it go the next day and haven't seen it since. I suspect the local mountain lion had it for dinner.