I saw this behavior in mine yesterday. The red cinnamon (should be sex linked?) 14 week old jumped on top of the hen who has been laying for over a year, grabbed and held onto her comb and was really going at it. Red has no signs of being a roo, no feathering or crowing. Could she be a different breed? I posted pictures of her at about 8 weeks and everyone said female, but that behavior was really startling. Poor Jewel. After Jewel shook her off, they went at it so I'm thinking dominance. Dominance fits in with other actions--Jewel won't let the young birds up onto the roost at night. I have to go in and remove her, let the others in and then let her go in last. Jewel also keeps them away from treats and goes at them at other times for no apparent reason. (Side note, granddaughter had to do a report on bullying and this made for a good conversation about finding your place in the world/assertive behavior v bullying).