A Mustang is a free-roaming feral horse of the North American west. It first descended from horses brought to the Americas by the Spanish.

In 1971, the United States Congress recognized Mustangs as “living symbols of the historic and pioneer spirit of the West, which continue to contribute to the diversity of life forms within the Nation and enrich the lives of the American people.” Today, Mustang herds vary in the degree to which they can be traced to original Iberian horses. Some contain a greater genetic mixture of ranch stock and more recent breed releases, others are relatively unchanged from the original Iberian stock, most strongly represented in the most isolated populations.

Mustangs are often referred to as wild horses but, since all free-roaming horses in America descended from horses that were originally domesticated, the more correct term is feral horses. Today, the only true wild horse is the Przewalski's Horse, native to Mongolia.

Prehistoric North-American Horses

Horses lived in North America in prehistoric times, but died out at the end of the last ice age around 10-12,000 years ago, possibly due to climate change or the impact of newly-arrived human hunters. Horses returned to the Americas by the Conquistadors, beginning when Columbus imported horses from Spain to the West Indies on his second voyage in 1493. They returned to the mainland with Cortez in 1519.

Origin of Mustangs

The first Mustangs descended from Iberian horses brought to Mexico and Florida. Most of these horses were of Andalusian, Arabian and Barb ancestry. Some of these horses escaped or were stolen by Native Americans, and rapidly spread throughout western North America.

Native Americans quickly adopted the horse as a primary means of transportation. Interestingly, in light of the horse's prehistoric existence in the Americas, many Indian myths and stories about the arrival of horses claimed that "the grass remembered" them. Horses replaced the dog as a travois puller and greatly improved success in battles, trade, and hunts, particularly buffalo hunts. Many tribes bred their horses carefully to improve them for their purposes.

Among the most capable horse-breeding people of North America were the Comanche, the Shoshoni, and the Nez Perce. The latter in particular became master horse breeders, and developed one of the first truly American breeds: the Appaloosa. Most other tribes did not practice extensive amounts of selective breeding, though they sought out desirable horses through capture, trade and theft; plus quickly traded away or otherwise eliminated those with undesirable traits.

Mustangs in the 19th century

Starting in the colonial era and continuing with the westward expansion of the 1800s, horses belonging to explorers, traders and settlers that escaped or were purposely released joined the gene pool of Spanish-descended herds. It was also common practice for western ranchers to release their horses to locate forage for themselves in the winter and then recapture them, as well as any additional mustangs, in the spring. Some ranchers also attempted to "improve" wild herds by shooting the dominant stallions and replacing them with pedigreed animals.

In some modern mustang herds there is still clear influence of other domesticated horses being added to feral herds. Some herds show clear influence of Thoroughbred or other light racehorse-type stallions being turned into the wild herds, a process that also led in part to the creation of the American Quarter Horse. Others show the addition of heavy draft horse breeding, where farm horses were turned into wild herds in the wake of the Dawes Act, in a misguided attempt to create workhorses and force Indian people to become farmers. Other, more isolated herds, retain a strong influence of original Spanish stock.

Mustangs Today

By 1900 North America had an estimated two million free-roaming horses. Since 1900, the mustang population has been reduced drastically. Mustangs were viewed as a resource that could be captured and used or sold (especially for military use) or slaughtered for food, especially pet food. The controversial practice of mustanging was dramatized in the John Huston film The Misfits, and the abuses linked to certain capture methods, including hunting from airplanes and poisoning, led to the first federal wild free-roaming horse protection law in 1959. Protection was increased further by the Wild Free-Roaming Horse and Burro Act of 1971.

The Bureau of Land Management is tasked with protecting, managing, and controlling wild horses and burros under the authority of the 1971 Wild Free-Roaming Horses and Burros Act to ensure that healthy herds thrive on healthy rangelands and as multiple-use mission under the 1976 Federal Land Policy and Management Act.

Today, free-roaming horses have disappeared from 6 states and, according to the Bureau of Land Management (BLM), their remaining population is fewer than 25,000, with more than half of them in Nevada, with other significant populations in Montana, and Oregon. A few hundred free-roaming horses survive in Alberta and British Columbia.

The Bureau of Land Management controls the mustang population through a capture program, intended to control competition with cattle. Most horses that are captured are offered for "adoption" to individuals willing to pay a small fee to cover paperwork and a few basic costs. In order to prevent the later sale of mustangs as horse meat, adopted mustangs are still protected under the Act, and cannot be sold in the first year except when certain very specific criteria are met. However, there usually is a much larger pool of captured horses than of prospective adoptive owners, which in part gave rise to the controversial "Burns rider."

In January 2005, a controversial amendment known as the "Burns rider" was attached to an appropriations bill in the Congress and modified this program to allow the sale (with the result usually being slaughter) of captured horses that are "more than 10 years of age" or have been "offered unsuccessfully for adoption at least 3 times." Due to the controversy provoked by this rider, there is also a considerable political movement to have it repealed and the original language restored.