We have had 3 ducks for a year. 2 males one female. We got 6 female ducks that we had penned up near our pond and just now let them loose. The 2 males have ganged up on one of the new female ducks keeping her head under water, not trying to mount her. One of the males in particular send to pick on then more and he appears to be the dominant male. It really looks like they are trying to drown her. They actually did that to our other khaki (also one of the new females) and now we can't find her. I don't know what to think. Can anyone help?