Brooding question.

[bizzycard]

So I have two female ducks. They started laying eggs about 2 weeks ago maybe not quite. One female has been laying on the eggs at night and not during the day. Now that same female has started laying on them full time. Could they still be viable? There is 16-17 eggs in the nest.
Also how long after ducks mate, can the eggs typically fertilized? When do they stop being fertile ?

 

[huntersquail]

She may have been guarding the nest at night, but not incubating them. The eggs can stay viable for a while. 12-16ish days, but longer would push it. The longest I have ever heard of eggs staying fertile after mating is one month. But, mine would stop before the second week.