Sexing khaki Campbell's-drake or duck?

[dailyduck]

So we had purchased two khaki Campbell ducklings from rural king back in May of 2015. They were actually an older group so they were already almost a month old so they are around 5 months old now and I can't sex them. Neither of them had any sign of a drakes curly tail feather which should have developed by now but the beans of their beaks are way darker than the rest of their bill and their heads seem a darker brown than the rest of their body. One of the is particularly aggressive and has the darkest bean to bill ratio. The aggressive campells bill is a yellowish green and the other Campbell's bill has stayed a slate grey/blue. He also has a darker bean on his bill but I'm not sure how reliable that is to sex Campbell's (I read a forum saying that's one way to tell) they are around the same size but the more aggressive one is a little bigger and full.

Here are some pictures of the more aggressive Campbell that I suspect is a drake:

As you can see there are no signs of drake feathers but the bean is darker along with his head.

Here are some pictures of the other Campbell that I think to be a duck:

Also no signs of drake feathers.

And I know voice sexing is the easiest to do but I actually have a really hard time with that

 

[duckmommy64]

Hi dailyduck and welcome to BYC.

By looking at your pictures you have 2 boys. (drakes)

My Drake looks just like the one in the pool with the pretty runner.

If they still peep or sound raspy (like a frog) they are boys.

 

[needlessjunk]

Voice sexing isn't hard when you know what to listen for. Check out this link http://www.majesticwaterfowl.org/artquacks.htm

 

[JadeComputerGal]

I'm thinking one duck and one drake, but you should know for sure within the next month even if the voice sexing seems uncertain. Campbells are one of the most prolific layers of all the domestic ducks, and they'll typically start laying by the time they're 6 months old.

 

[SandiDonn]

Voice sexing isn't hard when you know what to listen for. Check out this link http://www.majesticwaterfowl.org/artquacks.htm

These sound mature. Can you voice sex these? I think I can but hubby wants another opinion
https://soundcloud.com/user-413193342/ducklings/s-nIXRS

 

[PaulX]

These sound mature. Can you voice sex these? I think I can but hubby wants another opinion
https://soundcloud.com/user-413193342/ducklings/s-nIXRS

Yours are indeed juvenile but OP's are mature.
I already voted in your post, btw, easy if you know what you're listening for.

 

[SandiDonn]

Thank you. Poll is unanimous.

 

[ElleCeci]

I am thinking two drakes, but perhaps you already know that. Curious what they look like now.

 

[Baylee_baby_]

Voice sexing isn't hard when you know what to listen for. Check out this link http://www.majesticwaterfowl.org/artquacks.htm

Boys almost sound like hogs haha