We have chickens and ducks. Our ducks hatched a brood of 5 ducklings this spring. She continued to lay a few eggs in a nest we found hidden behind a shed. We put them in our incubator but only one egg looked to be growing when we checked. At the same time one of our hens was determined to sit on her eggs. I collect them every day but she still would not give up. So we put the one duck egg under her and let her alone. To our surprise she did indeed hatch the duckling. They are doing great and she is very good mama to her adopted baby. I wonder if they will stay that way. I guess we will see.