Across the globe, there are small populations of wild horses that roam free, ridden by no one. Among the most famous of these are the mustangs of the American West. But mustangs, like many other "wild" populations, are actually descended from escaped domesticated horses. The only truly wild horses live in Asia: The Przewalski horses of Mongolia have never been domesticated by anyone.

Today, all wild horses need human help to survive. As people made more and more demands on the land for livestock and human use, their numbers dwindled. Consider the case of the mustangs. The mustang population dropped from about two million in 1900 to just 17,300 in 1971. That year the U.S. Congress passed a law protecting mustangs, which stated, "Congress finds and declares that wild free-roaming horses and burros are living symbols of the historic and pioneer spirit of the West." About 30,000 mustangs remain on public land today.

Mustangs.

Klein & Hubert/Bios/Peter Arnold, Inc.

Mustangs

Horses have roamed free in the American West since the Spanish brought these animals to North America in the 1500s. For years, wild mustangs were rounded up and used for anything from rodeos to dog food, until a 1971 law made it illegal to kill or capture them. Most Americans strongly favor protecting mustangs, but some worry that they harm native plants and animals and drain conservation resources, and cattle ranchers complain about sharing land with horses. Mustangs today have few natural predators so their populations rise quickly if left unchecked. Since 2000, the U.S. Bureau of Land Management has been reducing the number of mustangs on public lands, but the question of how many horses to remove remains controversial.

Adopt a Mustang

The U.S. Bureau of Land Management controls the number of wild mustangs by regularly capturing a specific number and offering them for adoption. Many remain in corrals for years without finding homes.

The Last Wild Horses

Mustangs and wild ponies from Assateague, Virginia, or Sable Island, off Novia Scotia, Canada, capture our imagination--but the only truly wild horses alive today are the Przewalski horses of Mongolia. They nearly became extinct in the 1960s, when the last free-roaming wild horses in Mongolia died. Fortunately, captive populations remained in zoos, although at one point, that population dwindled to no more than 15 horses. But these animals were bred successfully, and since 1992, many have been released into the wild. By 2005, the number of Przewalski horses reached 1,500, with 248 living in the wild in Mongolia.