While watering some plants, I was surprised to see our 1.5 year old hen (Sophie) knock down one of our 5 month old hens. She proceeded to sort of lay on top of younger hen and looked like she was going for the throat. The younger hen was not low in the pecking order as I understood it, so it seemed very odd. I sort of wondered if she was acting like a rooster, since we don't have one. I tossed some water on them to break up the fight. Bossy Sophie came up with some feathers in her beak. She then proceeded to take a few threatening steps at a second 5 month old hen, who immediately took off in another direction. Can anyone explain what I witnessed?