When danger or perceived danger is encountered, it is the lead mare that will make the decision either to flee or stop and keep the threat under surveillance. If the danger is up front, the stallion will trot quickly from his position in the rear and move past the lead mare to investigate. If it is merely another wild stallion approaching to challenge for supremacy, the mares will pay little attention and might begin grazing as the two males square off. If, however, the danger involves riders on horseback, the lead mare will focus on them for a moment, body trembling in anticipation of flight, ears up, eyes focused, nostrils flared. If the riders continue their approach, even though up to a half a mile or more away, she will spin, and with the band trailing behind her, disappear over the nearest ridge in a cloud of dust.
Flight also remains the wild horse's best defense against predators.
Although predators don't pose a serious threat to many wild bands, they are a definite factor in the survival scenario for others. In places like the North Dakota Badlands, coyotes that do not have the size and strength to attack and kill a grown horse, nevertheless keep watch at the fringes of the herd, awaiting the birth of a weakened foal or seeking to bring down an aged or injured horse whose infirmities have rendered it defenseless. In the remote and rugged Cerbat Mountains of Northern Arizona, however, the mountain lion reigns as the king of predators and is a serious threat to a herd that has made its home there for more than 125 years. An abundance of mountain lions during that time period was blamed. Man also poses a threat to wild horses.