Friday January 4 at Greenway Park near the corner of Wharncliffe and Riverside in London, I saw an immature male Northern Pintail among 1000 or so Mallards, Black Ducks and Common Mergansers. Because of it's intermediate plumage, I had wondered if it was a Pintail x Mallard hybrid, but more knowledgeable people than I assessed it otherwise. I would have posted sooner, but wanted to clarify the ID.
Not sure if it's still there-- it was quite tame and allowed me to observe it at length from the path.
stuart