We have three male mallards who have all been raised together since birth, about 5 months ago - Blofeld, Le Chiffre, and Scaramanga. They live in a coop and run together, and mornings and weekends they get to hang out in the pond in our backyard. Le Chiffre has always been a little "pissy", running after Blofeld every now and then with his mouth open, but nothing ever came of it. Scaramanga always was kind of mellow. The three of them have been very used to wandering around the yard together foraging, and swimming together in the pond. Two mornings ago, they were hanging out together for their morning pond swim, and wandered back to the coop together when I put them away. A few hours later, checking up on them via web cam (yes, we have a 24 hour live feed...), Le Chiffre and Scaramanga were repeatedly chasing Blofeld around the run. Smashing him from both sides, grabbing him by the head and forcing his head down, biting the back of his neck and tearing out feathers! And Scaramanga was clearly the ring leader. When I got home, I separated out Scaramanga into a large dog crate, but kept them all visible to each other. Le Chiffre stopped attacking Blofeld at that point. I won't say they are now nuzzling again as when they were babies, but at least Le Chiffre will let Blofeld within a foot of him now. Le Chiffre and Scaramanga clearly want to hang together (Le Chiffre and Scaramanga slept on opposite sides of a wire barrier from each other last night, and Blofeld hung two feet back from the both of them). Trying briefly to reunite them this morning, Scaramanga was clearly in a mood to chase Blofeld away, so separated again they have been. So, here's my question. Is this a phase that will pass? It came on very suddenly! Or are we doomed to have to get rid of one of the ducks? And if so, do we get rid of the aggressive one? (Scaramanga) Or do we get rid of the submissive one? (Blofeld) In the short term, we're going to add another coop and run, and have the two runs facing each other with a wire barrier inbetween, so in the future we have a way of separating them during any temporary hostilities. But right now we can't even let all three run in the yard and use the pond at the same time!