Don't worry about the little hen amongst the larger birds- with chickens, it's less to do with the size of the bird and more to do with the sass of the bird. RIRs aside, my highest pecking order hens have usually been some of the smaller ones. The absolute meanest hen I ever had was a bantam silkie; she was 4 ounces of feathers and eight ounces of wildcat. She wouldn't tolerate any other bird not making way for her and, if she was in the nest, I'd best wait for her to get off before checking for eggs. She'd bite, clamp down like a pit bull and shake and twist her head like she was looking to take a wedge of flesh off me.