Why are my ducks suddenly picking on one of my other ducks?

[Yorkshiregal]

I have four male ducks. 2 Pekin 1 khaki Campbell and a Rouen. I’ve had them for over year I got them as babies. They all seem to get on but I’ve realised this past couple of weeks they have pushed out the Rouen. They don’t let him swim or eat? They chase him off whenever he gets close and tries to join in. He looks totally depressed!!! They live and sleep in the coop and run with my 9 hens and one rooster. I always thought the Rouen was the leader of the gang so I’m not sure he got too big for his boots at one time??? Do I need to find him a new home or will this get better?

 

[Isaac 0]

Its spring time so hormones are running high in most places, Could you separate the male that's getting picked on before any more damage is done for now? You may have to re-home either the male that is getting picked on or the ones who are inflicting the damage, your choice. That many males with chickens/hens usually doesn't go well, especially since they don''t have any other females, male ducks can inflict serious damage to a chicken if they mate with one, they have very different anatomy.

 

[Yorkshiregal]

I’ve had them all living together since I got them. They aren’t attacking the Rouen just chasing him off. I know they are very boisterous with each other. I’m going to have to monitor the coop and keep an eye out for over rapey behaviors.
I’m waiting to get 3 females so I can put one of the boys with them. They would have their own place. The Rouen is hanging out with the hens. He seems pretty fed up.