an answer from the 'net

A couple of years (well, apparently 4 years) ago, Booker and I came across an unusual duck and I speculated on these pages that it was a bird in eclipse plumage, or perhaps a hybrid. A number of folks commented and offered informed opinions or guesses as to what exactly we had, but no definitive answer was forthcoming.

Recently, flipping through some outdoor wish book or another, I became aware that Greenhead Gear™ is making a "hybrid  black duck decoy".

Looks just about the same to me:

Once again, the internet answers all questions (a Google Image Search for "hybrid black duck" further suggests that the bird we got was indeed just that).