This is one of my adult hen Mandarin ducks. Notice how grey the bill is, @Mantisquailman .
That pinkish coloring in the corners is the most they'll ever get.
I would say based off just the first pic the one on the far right could be a hen, but in the second pic they definitely all look like drakes.
The reddish bill is how to tell drakes at this stage so any that are pinky on the whole bill are drakes. A little in the corners does show up on some...