Spring is the season for a mallard or muscovy duck who is at least 7 months old to lay her eggs. Plenty of straw and what looks like the top of a dog house with room for her to go in and out is a good place for her to lay her eggs and raise them. One thing about muscovy ducks is that they will mother other types of ducks if the mother doesn't want them. They will use there feathers to line the nest.