Not that often really.With cockerels - a few things to know
- Often times, cockerels raised just with flock mates, get bigger faster than pullets, and with no older birds to thump some manners into them, they become bullies, both human and chicken aggressive.
Even if you have cockerels in with elders to teach the youngsters manners, you can still end up with aggressive/human aggressive cockerels/roosters.
With, or without elders doesn't seem to make a huge difference.