Please help me sex my ducks!

[FairygodmotherINC]

Hello I hatched my 4 ducks out around end of March all 4 different breeds of duck. However I am having a HUGE issue seeing them as who's a drake and who's a hen.
My muscovey duck (Petrie) I'm almost sure is a drake. Petrie has begin mounting the black/white magpie (Spike) and the tan/white (ducky) over the past 2 weeks very aggressively. He hasn't caught the white one (Sara) yet lol.
I've attached photos of all the ducks so maybe someone can help me correctly sex my flocking quackers!
Thanks in advance!

 

[sourland]

The Muscovy is a drake, and at this point in time the others appear to be hens.

 

[Eris_]

Easiest way to tell is the voice will eventually change, and at this stage I believe the difference will be drastically noticeable. Your females will be much louder, while the males will have a softer voice. Visually, though, it’s hard to tell, especially for what I assume to be the Pekin (white one) considering males and females don’t seem to have any common differences, small or not

 

[FairygodmotherINC]

The muscovey Petrie is also a escape artist as he inevitably busts the gate to the quack shack down every night at bedtime to make his ever so famous escape for himself and the other 3 ducks.
He is just SO BIG that he literally climbs the wire or material on the gate and literally flaps his wings to rock it and work it back and forth until it either.
1. Pops open
2. Falls over enough for the escape
Or his new trick
3. Busts completely off the hinges and breaks.
Just so him and it's other 3 Partners in crime Can sleep right on our back porch. Which we have told him a thousand times we hate him on the back porch with his friends. But he don't care apparently! And in the morning's if we're not up by 6:30 am for their breakfast, he will literally picks at the back door it's like someone's knocking causing all four of our dogs to bark nonstop until we get up.
He is definitely a character!