I have seen Muscovy crosses that look like these, but damned if I can remember what they were crossed with...
'Theoretically this level of creeping Orwellian dynamics should ramp up our awareness, but what happens instead is that each alert becomes less and less effective because we're incredibly stupid.' - Jerry Holkins
Dave Holderread also did research on alleles and their affect on duck color (it's in Storey's Guide to Raising Ducks, and I can't find the study online). I have Cascade ducks from Holderread that are sex-linked; basically if I breed a drake with another breed, the ducks will be sexed at birth by bill color.
I think Oregon State did a study as well, but I just got off from work and my brain is mushing. I'll check when I've decompressed (today I hate my job), because I usually nerd out on this stuff.
We are all related
Justin Rhodes 45 minute video tour of wheaton labs basecamp