My runners act like the morality police whenever Bean tries to mate with Romy.
I think it's some kind of territorial-social heirarchy dynamic. I am still figuring it out. While I have read some of what I consider simplified explanations, my own observations lead me to think that social structure is complicated and nuanced.
Background for us: Runners were raised from day-olds. Added two rescue buffs, Romy and Michele. They quickly became part of the flock, though as bff's they stuck together. Michele died, Romy was distraught. Adopted a trio, drake and two ducks, Bean, Hazel and Carmella.
Much more difficult to integrate. Einz spent three weeks screaming. But after a few weeks (this was late fall), we settled down into one flock. Then it was Valentine's Day, and the hormones were rising. Bean started hopping on his girls, then Romy (who was ecstatic - she likes boys). Then occasionally a couple of the runners. A few weeks later, the runners began doing to Bean what your KCs are doing to the roo, but only when he was on Romy. Romy got tired of being the mattress for a wrestling match, and began running away from Bean, who then got fixated on jumping on Romy, which stirred up the whole flock.
Right now I have two flocks. Bean and his girls, and Romy and the Runners.
Sometimes, in the large 1800 square foot garden, we can happily coexist, even with Bean and Romy having an encounter or two. But then sometimes a runner will yell at Bean, who immediately seeks out Romy and hops on top of her.