10 hens for each roo with common breeds.
15-18 hens for each roo with Med breeds and banties.
8-10 hens per roo for heavies.
These are the suggested numbers. YMMV, of course.
Dominance is their thing. They dont like strangers, be it bird or human, especially when the hens are around. They will attack strangers, un-provoked, for this reason. Fighting is part of their make-up. Some call it aggression and want to see it, and the male, done away with. Shame, that.
They strut and parade around, fearless in their domain.
They crow, issuing challenge to all comers and announcing their presence. This also serves to marshall the flock.
They crow whenever they feel like it. They dont need a sunrise or a windmill in the background to do it.
They guard the flock, alerting them to danger.
They also alert them to choice food, when found.
Males mate a lot. It's the other thing they do. Dont be alarmed by it, but do keep enough hens for him. He will wear out the hapless hens that are too few.