It depends on personalities, size, past interactions, stress levels, competition, space they are confined to etc.....and what is fine today may not be tomorrow. We had a nasty mallard drake, Mojo, who had the swagger of Lenny Kraviitz but the insecurity of Conrad Black... was completely fearless, he went after one of the Toulouse geese relentlessly, if I grabbed him, even if I grabbed him by the neck, he'd just look at me defiantly like "you want a piece of me ?" Another drake, Buff Orpington [ his full name] [picture Noam Chomsky], with a double PHD in theology and physics, bonded with that goose, protected her and buddied around with her all the time and when he was with the ducks, would check in with her regularly and actively protected her from the other drake, ...he loved her , I mean really LOOOVED her, became rough with her and tried to mate with her while pulling feathers out of the back of her neck. Our other new arrival Toulouse goose and gander couple bonded with the goose and she spent most of her time with them after a short while, but also continued to buddy around with her drake friend. The new goose and gander were not tolerant of the ducks and pecked at them if confined to the same space or passing in close quarters or at the food dishes. the moral of this story...both ducks and geese can be mean to their own kind and to others. They are cute but at some level are not nice animals.. they can, like chickens, kill each other depending on the factors I mentioned above. Unfortunately, they will "kick someone when they are down" for whatever reason they may pick on an individual until they fall in status, after that the behaviour will gather momentum until that duck or goose is dead. So , your question is about confinement, and all may be well except for the fact that it can always change and, confinement is itself one of the factors that will encourage bad behaviour. They have their pecking order, and when they are outside, that works out fine because the picked-on animal can get away, it's just a social thing, no permanent harm done.... but with confinement,there's no getting away and bad behaviour will gain momentum until someone is hurt or worse, because there;s nothing to stop them.
