East Pryor Mountain (elevation 8,822 ft) dominates the horizon. In the foreground is Yellowtail Reservoir, in the Big Horn River Canyon. Pompeys Pillar is about 60 miles to the right (north-northeast) of this photo.
Close-up of the East Pryor Mountain.
The foothills of the Pryors in a rosy winter sunrise.
On the south slopes of East Pryor Mountain roams a herd of 159 (as of March 2002), wild horses. Dozens of herds, actually—mature stallions with their mares and colts, and young ones hanging out with their peers, all following spring greenup from the foothills to the high ridges and meadows, or retreating from winter's winds into the deep draws of the badlands along the Bighorn River. It is of course impossible to say whether any of those mustangs are descendants of the horses taken from Nathaniel Pryor back in July of 1806.1
The Crows—if that's who took them—could not have had any reason to keep them separate from the rest of their horses. Besides, the animals Pryor was responsible for had been bought cheap by the Corps' captains from Shoshone, Nez Perce, and lower Columbia River Indians.
In any case, DNA evidence indicates that, like all the other feral horses in the Western United States, the Pryor Mountain horses are descendants of Spanish Barbs, or "Barbery horses" bred by the Berbers of North Africa.2 brought to the Americas as early as 1493. Sometime after the beginning of the 18th century, Plains Indians acquired Spanish horses through trade, or by culling them out of stray herds.
The fenced, 38,000-acre Pryor Mountain Wild Horse Range, established in 1968, was the first of three federal "special status areas" for feral horses.3 The other two ranges, designated in the Wild Free-roaming Horses and Burros Act of 1971, are located on the Nellis Air Force Base in Nevada and near Grand Junction, Colorado. All three are administered by the U.S. Department of the Interior's Bureau of Land Management. In addition, the BLM oversees 209 other "herd management areas" that cover about 35 million acres of public land in Arizona, California, Colorado, Idaho, Montana, Nevada, Oregon and Utah, and, as of 11 June 2014 contained an estimated 40,815 feral horses and 8,394 burros.4
To maintain healthy ranges, which in many places are shared with cattle, the BLM makes some wild horses available for adoption every year, so there are now privately owned herds in many other states. Also, historic herds of a somewhat smaller breed of wild horses totaling about 150 animals have survived for perhaps 300 years on Assateague Island, off the coasts of Virginia and Maryland.
Wild horses are mentioned twice in the journals of Lewis and Clark. On July 5, 1806, having recently crossed the "east fork of Clark's river" at today's Missoula, Montana, Lewis noted: "there are many wild horses on Clarkes river. About the place we passed it we saw some of them at a distance. There are said to be many of them about the head of the yellowstone river." And in the monumental "Estimate of Eastern Indians," which included several mountain tribes, there were "La Playes," a wandering people whose country, from the heads of the Arkansas and Red Rivers eastward to "the gulph of Mexico," was said to abound in wild horses.5
1. The scientific name for the domestic horse is Equus caballus, The name of the genus, equus, is Latin for "horse"; the specific epithet, caballus also means "horse." The noun mustang came from the Spanish mestengo, meaning "stray" animal.
2. See "Jefferson's War," footnote 2. The population figure for feral horses includes wild burros. National Audubon Society Field Guide to North American Mammals, revised edition (New York: Knopf, 1996), 810–813.
3. There are 640 acres in a square mile, so the Pryor Mountain Wild Horse Range officially encompasses 59.375 square miles.
4. "Wild Horse and Burro Quick Facts," http://www.blm.gov/wo/st/en/prog/whbprogram/history_and_facts/quick_fact... (retrieved 11 June 2014).
5. Moulton, ed., Journals, 3:438.