If you want to keep separate chicken flocks, you may end up with one flock on one side of the farm and another flock on the other side. Or in the same barn, but separated by a wall. In this case, the chickens (most notably the roosters) will hear each other day in and day out, but not see one another. Will this be stressful for the chickens? I can imagine that a rooster that constantly hears another rooster will start thinking "oh, get off my land or come and challenge me already!", while a rooster that hears hens will go "why won't you come to me when I'm crowing for you? Get over here, you need my protection and wonderful semen!" I guess hens would be more laid-back, but I don't find it a stretch that even they might find it disturbing. When I ponder chicken psychology questions, I tend to think "what would it be like for wild chickens?" And I assume that wild chickens would often hear chickens from other flocks that they can't see, living in thick vegetation and all. However, maybe it's an unnatural situation to hear it day in and day out? Thoughts, comments and experiences, my friends?