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.
Being chased by trail riders is a peril for the wild bands in Theodore Roosevelt National Park. Foals have died from the stress of being chased. In other areas, man's presence is curtailing the roaming bands' range, posing as much danger as any natural predator. Nowhere has it been felt more dramatically than in the barrier islands off coastal Virginia and North Carolina, where bands that are believed to be the descendants of shipwrecked horses being brought to the new world by the Spanish make their home. Even the herd's dominant stallion was a victim.