Part of the reason for this is that they get more exercise browsing in the pasture. Whole or cracked corn is always appreciated by ducks and geese and they will eat it readily. This is not a balanced diet, however, and is too high in fat and low in protein to be healthy alone. Naturally, most waterfowl appreciate stale bread and other baked goods, but, again, these should not be fed in large quantities but only as treats. You do not need a male bird to get eggs from chickens, but with ducks and geese, you are more likely to get eggs if you have a few boys running with the flock.
Trios are usually successful as breeding groups, one drake or gander with two ducks or two geese.
If you want ducklings and goslings you must have male birds. Always be careful introducing new ducks to a flock. Ducks are very territorial and will attack a stranger and kill it if possible. If you bring in a new male or female to set up a breeding group, introduce them gradually, with a barrier between, until everyone is acquainted. Otherwise you may find the new arrival dead the next morning.