I have a 4 mo old EE cockerel (only roo we have) starting to grab the hens at the nape of the neck. Haven't seen him try to climb on top of them yet. Is this just him working up to mating? Interestingly, seems like he's only tried it on the 2 hens who are lowest on the pecking order. At what age can I expect him to reliably be fertilizing the eggs?