I have a Barred Plymouth Rock - about 20 weeks old - who has been trying to mount several of the other hens frequently for the last 3 weeks or so. But s/he has never crowed and doesn't look a lot different from the other hens except for being a bit larger/ taller. S/he also has a sort of silvery feathers around the eyes, but nothing else really noticeable yet. When will Iknow if s/he is a rooster, or just a dominant hen?