Yes, white is what they call a incompletely dominant color. A homozygous white will be completely white (yellow down) from hatch w/ no traces of black. A heterozygous white will have yellow down & the black cap which typically molts out at the 12/14 week molt. A pied bird, what I call a color + white, is technically, genetically speaking, a white with haphazard color. I try to speak in layman's terms so I use the term pied for anything that has some color and some white. I am not a genetics expert by any means.
As far as the bill, yes they can change some, how drastically I do not know as I have never paid that much attention to it. Sometimes, birds with hormonal issues/imbalances are reported to have drastic bill changes in the Mallard Derivative breeds. Whether that applies to Muscovy I do not know. It typically is an elderly female issue with the MDs, however.
So Folks - I guess this "could" be Spentie. I have to find out more. It's a start. I will keep you posted to more findings!
"Spentie" and Angel were seen across the Canal yesterday.
I was busy so could not take a photo.
They are the same size. It just seems tooooo coincidental.