It's been almost 6 months since i've introduced a pair of young female ducks to my mature drake-hen couple. 6 months later, the hen still occasionally chargse at them, and the drake has plucked both of the back of theiir necks clean of feathers, and keeps them isolated a good distance away, wether inside or outside their run. Is there anything I can do to help these ducks merge together into a single flock? I don't know why, but I expected it to happen naturally. Does it ever?