I think having at least one drake is a good idea! For one it adds a special sound to your flock quacking ducks; the drake’s voice is quite adorable! Second, the males(of some breeds or feather color) add a bit of color to your flock. The third thing, and something I had encountered is that if one of your birds is taken by an illness or a predator, the ducks can lay fertilized eggs almost up to three weeks after. So even if the drake is taken, the eggs are probably still fertilized. You can incubate the resultant eggs and not have to order ducks through the mail.