Fortunately, I had one Khaki Campbell duck who still had that instinct and she has passed it on to at least one of her daughters. This is not the original duck, but one of the offspring, who hid under the steel building and sat on her eggs for at least 28 days. I knew she was there, but her nest is not visible at all, so I also don't know what her hatch rate was. Usually, for ducks it is 100%. Every egg they lay hatches.
Khaki Campbell ducks do not have much meat on their breasts so they cannot cover a lot of eggs. They make their nests quite deep and round and put the eggs all around the nest so that they touch, but none overlap. They visit the nest as they are laying their eggs and turn the already laid eggs at least once a day. When they feel they have adequate eggs, they begin to brood.
Today Mamma Duck was out with her ten little ones bright and early. Most likely they hatched over a two to three day period and she remianed on the nest until she was sure there were no more. The babies can peep inside the shell and talk to their mothers to let them know to hang on for the slow ones. But, the ravens were already watching and on patrol, too. Last year they had breakfast daily. 80 ducklings were hatched by 7 ducks all together in one shelter. They hung around together afterwards too, but with that number of ducklings, it was difficult to fend off prey. The ravens swooped down, picked one up and kept on flying. So, I locked up Mamma Duck and her ten little ducks. It must feel like jail to her I am sure, but she is safe and the babies are too. The ravens are so smart. They know that she is not accessible to them now and they will wait for the moment a baby escapes. Hopefully that won't happen. I picked some grass for Mamma Duck and gave the babies a tray of water. Mamma Duck cannot have much water to bathe at this stage because the babies can drown in deeper water. For a few weeks she will have to make do with what she gets and once in a couple of days I will give her a bucket of water for a few minutes so she can clean her eyes and sinuses (necessary for ducks) and remove the water so the babies do not drown.
Thanks for your diligence Mamma Duck. It is a gift from the Creator, this hatching business and I am blessed to give you care while you care for your babies. I am.