We recently got a drake from some friends of ours. We put him in with our three female ducks and things seemed to be working out ok. But in the last couple of weeks he has become very aggressive towards one of our females. He won't let her get near him which usually means all of them. We figured he was just letting her know the pecking order, but it's getting worse and she is starting to look haggard. What should we do or should we just let them figure it out.