Again, lots of white is often involved, including all-white breeds like the popular Pekin Duck. Body size can often be a clue toward domesticity. The bottom line to this article is that you can expect to find some ducks out there as well as other birds, too that just do not look like anything in your books. Hybrids between these species, including backcrosses are often reported, but only F1 hybrids can be used to test this prediction. There is little controversy about this idea because it is a predictor of hybrids in many species.
It can be hard to tell sometimes if a duck is a mutant or has domestic duck genes.
In general, watch for symmetrical abnormalities, patches of color or lack of color. Third rule of thumb: Call ducks are tiny, teal-sized things that have smaller bills and more rounded heads than normal ducks. Thus, when the first nest of a presumptive Cinnamon Teal female was found in North Dakota, three young from this nest that were hatched and raised in captivity proved to be Cinnamon x Blue-wing hybrids. This means that Redhead chicks raised by Canvasbacks will be imprinted on Canvasbacks and inclined to mate with them. Then, differences between species pairs that produce hybrids can be used to predict their sire the father species.