Please help! My Ducks are bleeding on their wings!

[Miss Lydia]

i only have two and they have a big pen all day and a duck house at night I am pretty sure the one with blood on its back hind feathers is a female and the loud one is a male he spends alot of his time loud quacking and she is a very quiet one today is the first time I have seen blood

Loud quacking sounds more like a female drake have a raspy voice they don't have a loud quack.
http://www.majesticwaterfowl.org/artquacks.htm