any white on a cayuga duck is a disqualification in showing
No it is not. In drakes especially, the tip will have olive color. In the APA Standard of Perfection, this is acceptable.
28 days
it depends on the type of duck egg you have. i had a cayuga duck, it was incubated at 99 - 99.5 degrees for approximately 28 days.
The Black Swedish duck would match that description, as would the Cayuga.
Only the females will accept Cayuga ducklings, and if she has ducklings of her own, and the ducklings that you have aren't part of her family, she will most likely just peck them away from her and her babies.
A male duck is called a drake.
Initially they are black in color, but progressively lighten to white by the end of the season
they are used for egg and meat production as well as an ornamental bird
For showmanship, it's a disqualification for a Cayuga duck to have white on any of the plumage. Cayuga ducks are supposed to be all black and be iridescent beetle green when in the correct lighting, though it's not uncommon for females to have white on their chest.
They will be fertile. They are the same species, just different breeds.
Most likely.
The only duck I can think of is a cayuga. but it isn't that often that they get a green pigment in their feet.