Ok, so all of the sudden my rooster has started chasing off one of my hens. They are about a year old and have grown up together along with my six other chickens, but she is the only one he suddenly won't let near the flock. What is up with that? What would make a rooster suddenly turn on one of his hens? It reminds me of the behavior between my two roos; I eventually butchered one of them but the one wouldn't let the other near.