I drove to Monroe today and bought three new runner ducks. I tried to get one male and two females but they aren't quite old enough so that its obvious to tell the difference. As male ducks mature they get a few curled feathers on the top of their tail. Since I wasn't prepared to vent sex them there at the feed store we had to rely on their voices to tell the males from the females. As the feed store employee explained to me, female ducks make a nice clear quack sound while male ducks sound like they have a smokers cough when they quack. I took his word for it and there was a definite difference in the voices of the two smaller ducks (I think female) and the larger duck (I think male). However, I will try to get them vent sexed some time in the next week to make sure I've got the right makeup for our duck trio. It won't be so bad if I end up with three females. I just won't get fertile eggs. It will be bad if I end up with two males as they will spend all of their time fighting over the lone female.