Some hens, upon reaching sexual maturity, will no longer run from the attentions of an eager roo but will just stop and squat when he sidles up to her. This is an indicator that the hen has reached her sexual maturity and should soon be laying eggs. Some hens will do this if a human places a hand on their back....squat and sit real still until the hand is removed.
It means they are getting ready to lay. It is their way of being submissive to the rooster. If no rooster then the human becomes the rooster. They will drop spread their wings out a bit and stick their hind end up. If you rub them they will fluff up and do a shake.
