Our 2 ducks think they are chickens. They did not even meet them until they were 6 weeks old and that was when we first put them in the big run. There was no fighting or pecking, and they have been in there for about a month. They hardly even quack, they just do little pips like the chickens. Also, they are glued to our roosters side,and he protects them like they are his ladies. He gets all mad and puffed up if I pick one up. I do agree that you should get another on, because our two do stick together in the run.