I noticed their beaks are different colors. I looked this up and that is apparently how you determine the sex of the ducks. The lighter peach colored beaks are the females. We have two females and three males. It really did not matter to us what sex they were since they are just bug-eaters.
|Beak colors indicate sex|
(This will be after I modify the tarp over the pen. It was nicely waterproof, but also collected a lot of rain, sagging down and damaging the chicken-wire cover to the cage. Since it has been quite some time since we had any significant rainfall, I had not thought of this possibility.)