Horse society is also built around a strict hierarchy. The leader of the herd, contrary to popular belief, is not the stallion, but the eldest and strongest mare. This horse is called the "alpha mare." The alpha mare is the queen: she is in charge of where the herd will go to find food and water, and discipline the younger herd members. She detects predtors and storms, and guides her horses to safety. In other words, the job of the alpha mare is to look out for the well-being of the entire herd. (from Monty Roberts)