Best time to mate ducks

[Bluegray87]

I have 2 khakis, a drake approximately 5 months old and a duck around 16 weeks old. I want to mate them when they are ready so need to know when this is and what signs to loom out for, reason being I also have a drake Harlequin that I don't want getting involved

 

[Pyxis]

If your welsh harlequin drake is in with them, he's definitely going to mate with the female KC. If you don't want that to happen, make the two KCs their own pen. That way, only the drake you want will have access to her.

There's not really a 'time' or age to put ducks together to breed. They're not like mammals, where they mate one time and they're done. They mate constantly so all the eggs are fertilized. They will do so several times a day. So the only way to ensure that the father of the ducklings you hatch is the KC drake and not the other drake is to make sure only the KC drake has access to the hen, by way of putting them in a separate pen.

You'll want to put a few other female ducks in with them too so that the one female doesn't get overmated, since it's best that each drake has three to four females. If you only want to hatch her eggs specifically, you could mark her vent with food coloring or lipstick, which will color her eggs when she lays them and you'll know which are hers.