We have some runners that are a couple months old, still have a little fuzz on them. I had separated areas of my property by brooders(my chicks) and as the chickens get older they get their area opened to free range and have the chance to mingle with the other brooders. My runners were just always in my front yard, mostly so I can watch them and didn't want them in the backyard really just in case they noticed the lake 100 ft away(neighbors would kill me ). Lately the runners have taken to doing "rounds". They go, sample the food and water then come back to theirs to chase off the poor birds from their food they already displaced from their own . The ones that are penned the ducks go over and as dh puts it "gives them a talking to" and seemingly walking away shaking their heads . He gets a kick out of these ducks and admitted he wishes he caved in a long time ago about having them. He calls them the " duck mafia" and they run this "neighborhood"