this is my first time raising chickens & I have five buff orps.s hens five white leg horn hens & three white leg horn cockrels they are 14 weeks old . and I let them free range in my back yard all day & then in the late after noon I put them in thier run and of corst they go in there hen house when it gets dark . I put them in there runand all of a sudden two of the cockrels started biting some of the hens real hard behind the neck . is this how they catch them when they go to mate them it did not seem like he tried to mate them he just bit them real hard. is this normal . I plan on culling to of the rooters I just didn't think they would sart trying to mate them when they were this young . any answers would be appreciate.