We have a bunch of ducklings that are the result of uncontrolled breeding. The possible fathers are a black Swedish and a Blue Swedish. There are nine possible mothers: 5 black Swedish, 4 hybrid layers, and 1 buff. We'll be narrowing down the number of ducklings and want to focus on the Swedish going forward. But, the vast majority of these ducklings look like black Swedish. Some are clearly mutts and some are all white. Some are blue. Those are easy to separate out. But that leaves a lot of ducklings that look like black Swedish, except perhaps for their bills.
So, the question is: is it possible to tell the difference between a true Swedish duck and a mixed breed with dominant black coloring that just looks Swedish?
If I understand the genetics, I think we are safe with ducklings that look like blues - if it looks like a blue Swedish, it probably is. Is that right? It is the blacks that pose a bigger problem.