I live in Toronto and bike along a beautiful river. Last week there was a lone black duck of a sort I had never seen. It was solid black except for a bright white apron and I think some white on its head. I looked through a lot of ducks listed on the internet and could not figure out anything even close. It was std duck size - about the size of a woodduck or teal. This week it is gone and I cannot stare at it any more. It’s a longshot, but I thought I would enquire about what it might be.
Most likely a Muscovy Duck. Domestic breeds often are black with variable amounts of white on the head and/or body. (Some individuals may be almost pure black and others pure white).
Some images:
http://www.compsoc.man.ac.uk/~cheesyrobman/gallery/Scenic/Muscovy_duck
http://www.zinnysworld.com/Water%20Birds/duck,%20muscovy%20-%20P020320-047m.jpg
Maybe a merganser, or a hooded merganser?
Buffleheads are very small; the OP said his duck was average duck size. And Toronto would be a bit outside their range.
Without meaning to insult the OP’s ability to recognize a duck, is there any possibility that it was actually a coot (another photo).
Woodducks and teal ARE small, smaller than mallards anyway, and MUCH smaller than Muscovy.
I think Colibri hit it. Any chance you can take a pic an post it?
We have Muscovy in our neighborhood, they’re as big as a turkey. The OP said they are gone now. Buffleheads range from Alaska to the Great Lakes, that would include the Toronto area.
It sounds like a blue swede, or Blue Swedish duck, to me. It’s a domesticated duck, so if that’s what you saw it would really stand out and look unusual in the wild.
Why do the people who start these threads never seem to come back to them?
Give it time. People cannot always be on the SDMB while they work and sleep. Although, some can…
Some of us are on even in the middle of a hurricane.
Auntie Em!!! Auntie Em!!! :eek:
Yes, Muscovies are large, and that’s one aspect of the OP’s description that doesn’t match. (Also, if he saw it well, it would be likely he would mention bare red skin on the face if it were a Muscovy.) The OP says it was “standard” duck size, which to me means about the size of a Mallard. However, he then goes on to say it was about the size of a teal or Wood Duck, both of which are smaller than a Mallard.
The OP didn’t say “they” are gone now. He said “it” is gone - there was only one individual, which makes it possible it was just one unusually colored bird.
If the OP is giving an accurate description - solid black with a “bright white apron” and some white on the head - then it isn’t any duck species native to North America.* In fact, it doesn’t match any wild species of duck anywhere in the world (I just checked the Handbook of Birds of the World, which illustrates all species). This means it is either a domestic breed of some kind (and Blue Swede, I think, would be another possibility besides Muscovy, though it would be larger than a teal or wood duck), or else the OP’s description is not accurate. In the latter case, all we can do is guess as to what it might have been.
*The closest would be Hooded Merganser, I think, if one ignored the chestnut the sides. However, I think the OP would have mentioned the crest if this had been the case. An immature male King Eider would be a remote possibility, as this would be extremely rare at this location and season.
So no one thinks my picture of the female Bufflehead is even CLOSE to what the OP described??? I don’t know, it seems VERY close to the OP description to me.
OP:
“It was solid black except for a bright white apron and I think some white on its head.”
“about the size of a woodduck or teal”
Now, look at this picture of a female Bufflehead:
http://www.ronausting.com/bufflehe.htm
A female Bufflehead is not really “black,” it’s more of a gray-brown. The lighting on that photo is bad. Also, they don’t often show that degree of whiteness on the breast, as is shown in this photo - usually the breast is somewhat grayish.
Really, until the OP comes back and gives an opinion on the different options, or offers a more detailed description, there’s no way to be sure of the ID.
Sorry if I’m a bit snarky, I haven’t slept in awhile and the eye of the storm is passing though Tampa right now. I need to get some sleep, but Frances just won’t let me be.
The Muscovies in my neighborhood are really funny, they’re like neighborhood pets. They strut around going from door to door, they have their daily route for handouts. Then they waddle slowly across the road, at the busiest time of the afternoon, as if to arrogantly tell the commuters to slow down when passing through THEIR neighborhood. 
I interpreted the word “apron” in the OP to refer to the breast only, not the whole belly. The blue swede looks to me like the most likely candidate by far.