I've been keeping four duck eggs under a lamp in the house, turning them over several times a day, and waiting. I found them in the nest after Mama Duck took her ducklings out of it. Mother ducks and chickens know when their babies need to leave the nest to find food. Sometimes a few get left behind. I've hatched chicks this way before, but never ducks. The last two times I've tried to hatch left over duck eggs was a failure. So glad to have this little one. It's been five hours since hatching and little duckling has already jumped out of the box onto the floor, giving me a coronary. I put him (?) in a small rabbit cage with a top to keep him in, and cats/dogs out. One other egg has a little crack in it. Perhaps another duckling is knocking on the door?