Also, about ducks and chickens fighting... for the first two years, after the ducks got out of their teenage stage where they'd try to bully the chickens to see if they could get away with it -and they could except for one barred rock who puts up with no crap - there hasn't been any fighting.
And then we got some production reds, and they are aggressive as anything, and when they learned half the flock wasn't going to put up with them and fought back they tried to go after the ducks.
Opie - the drake - does not tolerate anyone attacking his girls, and he beat every single one of them into submission, and now whenever a red-colored chicken goes up to his girls (even if it's a red sex link or buckeye who are both peaceful) he chases them away.
If you have a drake he will keep his girls safe from any aggressive chickens - from my experience. I don't know if the same is true for every drake. We have two protective roosters, for example, and then one rooster who just stands there like a brick while everything is going to hell. So same could be true for drakes.
We have 5 girls and he's never tried to mate with a hen. I don't think he likes the chickens anyway. He's a bit picky about who he mates. He would never mate with our pekin because she was a white duck even though she kept getting into position.
If you have a dog, be careful. Some dogs go after ducks... and some ducks go after dogs.
Our Opie always viciously attacks our 50 pound dog who is terrified of him and won't leave the deck if he's outside the fence.
And lastly... keep a window open. If you have a loud, continuous quacking at any time (not pitched like the teenage duck that goes quack QUACK QUUUACCCK, but similar to honking, look outside. That's usually a warning call that there's danger or a predator, or they're being attacked (sometimes by a chicken). Sometimes they're just nervous, but best to be on the safe side. If you ever see ducks running away from the chickens then there was likely a fight. Ducks remember. They hate my sister because she used to chase them two years ago, and whenever they see her they get up and leave.