How many males and females should I have?
For ducks it depends on the space they have and the flock size. If you have 10 or less, you can have pairs.
Over this, you need to provide plenty of room or reduce the number of males. Unless you have a large pen with plenty of hiding areas,
the ratio should be one male for every three to five females if your flock is over 25 or 30.
The problem with too many males is they will become very aggressive sexually and will harm some of the weaker females.
Geese can be kept as pairs with far fewer problems. In a large commercial operation, however, you would have one gander for every 2.5 to 3.5 females.