Any 'Sex' guesses for my pekings and rouens?

[chicks & ducks]

According to the 'quacking' theory I have 1 female peking, 2 male pekings and 2 female rouens. The rouens look slightly different though so I'm still hoping one may turn out to be male.

 

[hennyjenn]

My daughter, who is only 7, swears she can tell the difference between our rouens (about 7 weeks old). She claims their chest feathers are different and their bills. The male's bill is greener, and the female's blackish down the center line and orange on the outside. Who knows? She definitely spends more time with them than I do!

 

[SugarDuck]

Our Pekins look to be about the same age as yours (8wks). We have two females and two males. The males are definitely aggressive towards our other ducks or chickens. They are also much taller than the females. All of the birds we have are pretty young though. They are funny though. While we brooded them we would let them out during the day and then collect them at night and put them back up. They got to where they would wait on us to come get them at night and then run from us. I don't know anything about the Rouens though. I definitely believe in the quacking for females and I can see the tail feathers have more of a curve upwards on the males.

 

[Chris09]

On the Pekings I think I see 2 males and a Female.. ( the ones with a curled feather in the tale are males)...

On the Rouens it is had to tell by the pictures but it looks like 2 hens.
Males - Bill Greenish Yellow, without any other shade, except black bean at tip
Female - Bill Brownish Orange, with dark Blue blotch on upper part and Black Bean.

(Bean = The little "ball" at the tip of the upper bill)

Chris