This dark male Mallard-like duck was at Horseshoe Lake North (farm pond north of Horseshoe Reservoir) in northeast Loveland on 16 Nov 2014. All images are digiscoped and edited, except for last two flight shots.

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The plumage characteristics exhibited on this male don't fit neatly into either Mexican or Mottled, so Mallard hybrid may be the correct identity (although I think that Mexican is the closest match). If hybrid, then the other parentage would be Mexican, Mottled or American Black. Any opinions?

Update (19 Nov 2014): I have heard from two experts that Mallard genes are evident in the black rump (visible in one of the flight shots), and the slightly raised central tail feathers. I think the best label for this bird is Mallard (Mexican intergrade), although in reality this appears to be mostly Anas diaszi with some genetic influence from Anas platyrhynchos, probably several generations ago.