Well, I don't think my husband is going to go for feeding all these birds if they're not feeding us - or only feeding us a couple of months of the year. I can't seem to find the Holderread book that convinced us that ducks were a viable option, but I believe the claim made there was that with 14 hours of light, ducks will lay for as long as 18 months before needing a break. That seems excessive, but we were hoping for three-seasons of the year anyway.
I know that lights do affect ducks, since a friend who had a heat lamp in the barn for her chickens couldn't figure out why her ducks always laid all winter, then abruptly stopped at the end of March. Turned out that was when the chickens' heat lamp got turned off. Apparently it was providing enough light to the ducks, too, to keep them laying.
The one duck that molted in early June isn't the most fit duck. She was being over-mated, plucked, and very stressed out. We added another, more willing, female to the flock and everyone seems pretty happy now.
The others started molting after the days began shortening, and since days are still getting shorter, I figured it was just a light thing.
