Ducks lay one egg a day. If you say, “My duck laid two eggs in one day!” you’ll probably get funny looks. It takes 24-26 hours for a duck’s body to create a fully-formed egg. Some would say it’s physically impossible for a duck to lay two eggs in one day.
But they’d be wrong. The boundaries of possible are not always where logic would have them to be.
Can a duck really lay two eggs in one day?
Surprisingly, yes, ducks occasionally lay two eggs in a day.
It’s rare, but it does happen and it’s completely normal.
This paper from the Alberta Poultry Research Centre mentions the possibility of a hen laying two eggs a day: http://www.spottedcowpress.ca/chapters/02FemaleAnatomy.pdf
Even more rare, but not unheard of, is a duck laying three eggs in one day.
Don’t automatically jump to that conclusion, though—it’s possible the extra egg was laid the previous day, and you either missed it or it was laid in the afternoon or evening. It might also be possible that a duck you think is a male is actually a female.
A duck that is laying her first ever eggs is most likely to lay two eggs in one day, due to her hormones being out of whack. Most commonly, one or both of the eggs will be soft-shelled, since ducks rarely have the resources to manufacture two shells in one day. Occasionally, both eggs will have normal shells.
Note: Be sure your ducks have access to free-choice oyster shell or another calcium supplement. Also be sure they have plentiful access to an appropriate layer feed—laying two eggs a day is hard on their bodies!
Young ducks, in general, are most likely to lay two eggs in one day. Breeds that are heavy layers (Cherry Valley Pekins, White Layers, and Khaki Campbells, for example) are also most prone to it.
Sometimes this will be a one-time occurrence and the duck will have a normal laying routine thereon.
Other times, the duck will lay two eggs a day for several days.
Either way, these extra eggs usually don’t last long. Soon enough, the duck’s hormones will balance out and she will start laying normally, one egg a day.
Very rarely, a duck will continue laying two hard-shelled eggs a day for long periods of time. If you have one of these “wonder ducks,” as long as she is healthy, don’t worry about her. Enjoy the extra eggs for as long as she’ll give them to you!