Just wondering what age roos become ...umm... active? And, what age they become reliably fertile? Mine are 12-14 weeks and I noticed some muddy marks on some of my pullets backs, and it's most noticable on the white/light colored pullets. Could I have an active roo ( I know I have a few young cockerals) but none crowing and none I have seen doing/trying to do the "deed". Could someone else just be stepping on her making it look like she is being covered? Would they even be attempting to mate yet?