I was at a meeting on Monday near Mavis Rd. and the QEW in Mississauga. This happens to be not far away from Arkendo Park in Oakville where two or three Harlequin Ducks have been seen regularly since Luc Fazio reported them on November 4th.
So after my meeting adjourned, I dropped by Arkedo Park, and in the company of some fellow onlookers I got some fine views of the adult male and lesser quality views of one of the "female" type birds. I put the female in quotes because of a recent article I read in Birding magazine that leads me to believe that first year male Harlequin Ducks might retain a female-like appearance into November. Still, I'll go along with the diagnosis that the bird was a female.
I have only ever seen Harlequin Ducks on large bodies of water, and although I have no complaints about that, I do sometimes wish I could see them in the swiftly flowing rivers and streams where they breed. Broadly speaking there are two populations of Harlequin Duck; a west coast population and an east coast population that breeds in Labrador. Presumably the ones that appear on the Great Lakes in fall and winter are of the eastern population.