Share This Article

“From the accounts of all the Indians, I have seen, it is probable there may be a species of Antilope near the head waters of R. River.”

Those words, penned for the eyes of President Thomas Jefferson, were written by Peter Custis, the official naturalist attached to Jefferson’s Red River Expedition, the president’s follow-up to Meriwether Lewis and William Clark’s Corps of Discovery Expedition into the Louisiana Purchase. When Custis conveyed to Jefferson accounts from the Indians and their guides about the mysteries that lay farther up this river of the South, he was writing at a portentous time in the early exploration of the West. His brief mention of “Antilope” also captured a critical moment in time in the long history of one of the true marvels of the American Great Plains, the pronghorn antelope.

The year was 1806, and Custis was with a party of scientists, soldiers and guides that a Spanish army had just turned back from the edge of the southern Plains. In almost a final, dying gasp of its North American empire, Spain had risen to the occasion to keep the Americans out of the Southwest. Naturalist Custis was taking one last wistful look upriver before returning to civilization. On his mind was this rumored African-like creature that roamed the horizontal yellow prairies just beyond his reach as an Enlightenment Age scientist.

When Americans did finally make it to the Great Plains at the turn of the 19th century, we called these fabled animals antelope for good reason, as in size, form and speed they resembled no other wildlife quite so much as the antelopes and gazelles of Africa. But pronghorns, it turned out, were not true antelope. The Antilocapridae (“antelope-goats”) emerged roughly 25 million years ago as a distinctly American family of animals. They probably evolved from an ancient line that produced both pronghorns and deer, though there are modern biologists who argue that their closest living relatives are in the family Giraffidae—the giraffes, whose legs do resemble those of pronghorns. But Antilocapra americana, our present-day pronghorn, is the sole surviving representative of the Antilocapridae family.

The pronghorn is one of only a handful of Great Plains species that managed to survive the epic extinction some 10,000 years ago that ended the Pleistocene

In 1997 University of Idaho zoologist John Byers, after studying pronghorn behavior on western Montana’s National Bison Range, offered up a provocative argument explaining much about an animal that since Jefferson’s time has seemed almost “alien,” even to admirers. A grasslands creature shaped by the open country niche it occupied, the pronghorn never experienced any selective pressure to jump obstacles, which ultimately became a maladaptation to the modern world that has played a central role in pronghorn history across the past 150 years. The pronghorn is one of only a handful of Great Plains species that managed to survive the epic extinction some 10,000 years ago that ended the Pleistocene. What if, as Byers would have it, much about the behavior of the modern pronghorn has little to do with present circumstances? What if most of its physical characteristics and behaviors are adaptations to a lost world that winked out 100,000 years ago, leaving the pronghorn to live out its existence among us, reacting to a world of “ghosts”?

The primary predators of pronghorns for the past 10 millennia have been wolves and coyotes, neither of which can run over 45 mph. Pronghorns, the Ferraris of the natural world, have broad nostrils and a huge windpipe to deliver turbocharged oxygen to their outsized lungs and heart. The 120-pound males can top 55 mph, and the slighter females can reach 70 mph. That’s as fast as a cheetah. Pronghorns, like horses, adapted gigantic eyes to detect predators at great distances. But why? Why so much protective excess?

Pronghorn behavior features other oddities. Like Thomson’s gazelles and other African ungulates pursued by big cats, pronghorns have a powerful inclination toward a form of grouping known as the selfish herd. The lower-ranking, less dominant animals get pushed to the outer margins, where, were they on the African veld, they would face greater danger from predators.

The fascinating question, then, is whether the whole suite of pronghorn behaviors is connected to the lost world of the Pleistocene Great Plains, which featured such formidable predators as short-faced bears, an ever-shifting lineup of wolf and coyote packs, steppe lions, particularly swift and leggy hunting hyenas and two species of large, long-legged American “false” cheetahs. These fearsome American predators, long since vanished from the continent, are the creatures that “overbuilt” pronghorns for the modern world.

Like most wild ungulates then or now, pronghorns follow a routine that varies considerably with the seasons. At the conclusion of the September rut, the exhausted bucks, which would have been prime targets for ancient predators, disguise themselves in a form of mimicry, shedding the outer sheaths of their horns and joining the female herds. Since the Pleistocene, winter has been a time of migration for northern pronghorns. A few years ago, with a friend who lives in Jackson Hole, I photographed the storied Sublette pronghorn herd, which summers in Grand Teton National Park but still migrates some 200 miles south, to near Green River, Wyo., in winter. This inclination to migrate was adaptive in the wild but, coupled with their inability to jump obstacles, would produce tragic results in the 19th and 20th centuries.

In the spring, young pronghorn bucks form bachelor bands, sparring and practicing moves they will later use in earnest. Around age 3 males split off on their own for much of the spring and summer, during which time they set up territories, whose perimeters they scent mark and use to cloister a harem of females during the rut. Bucks fight over females, to the death in 15 percent of the encounters. Reproductive success is the prime directive. Some bucks win the lottery, while others sporadically mate or never sire offspring.

Female pronghorns reach sexual maturity at around 16 months and are capable of giving birth every spring for the rest of their lives. During the September rut females regularly break away from their cloistered harems, joining those of other bucks and/or inviting males to compete for them. Apparently they are setting up contests to find the bucks that demonstrate genetic fitness by running faster and longer than their rivals. Thus is the pronghorn’s ancient acceleration maintained even in the absence of predatory hyenas or cheetahs.

After a long gestation period, averaging some 252 days, females give birth, usually not to single offspring but to litters, typically twins. Twinning is likely a response to predation, another adaptation to that distant past with three or four different predators. Today it means that coyotes, the principal remaining predators of pronghorn fawns, are able to cull 50 to 80 percent of an annual fawn crop without appreciably affecting a pronghorn population that no longer suffers from adult predation.

As cud-chewing ruminants capable of processing forbs and shrubs, pronghorns demonstrate yet another adaptation to the ancient savanna ecology of the West. Bison and pronghorns cropped the same range, producing mutually beneficial results. Bison, which cropped the grasses while ignoring the often-toxic species like locoweed, rabbitbrush and sagebrush, encouraged the growth of forbs and shrubs in their wake. Coming along after the bison and browsing on flowering plants and shrubs, pronghorns shifted the advantage back to the grasses. Both preferred freshly burned areas.

Pronghorns increased into the millions—40 million according to naturalist Ernest Thompson Seton, 15 to 25 million according to more recent estimates. On the Great Plains, where their ranges overlapped most precisely, pronghorn and bison populations were comparable in number. We’ve long thought of the historic-era Great Plains as the great bison belt. In truth it was just as much the great pronghorn savanna. Bison were able to graze mid-height grasses, and when the climate was favorable and times flush on the Plains, overflow bison populations did pool westward but more often went eastward, to the Mississippi and beyond. Pronghorns, by contrast, are animals of the shortgrass plains and desert grasslands. They don’t appear to have advanced eastward beyond about the 97th meridian in Texas and Mexico and the 93rd meridian (into Iowa and Minnesota) farther north, but they ranged westward all the way to Baja California and eastern Oregon and Washington. Adapted to tundra climates, bison survived winters better on the Canadian plains. But pronghorns were able to colonize the desert grasslands, much farther south than bison ever ventured. Pronghorns drink about 3–4 quarts of water a day during hot weather, which limited their numbers in the Great Basin and desert Southwest.

‘The antelope is most remarkable for its fleetness: not bounding like the deer, but skimming over the ground as though upon skates’

As with their evolutionary behavior, we have only recently come to understand something about the role pronghorns played in the Indian world. Abundant and widespread, they long attracted the attention of Indian hunters. Archaeologists have unearthed butchered pronghorn remains at Clovis and Folsom sites. But it required 15–20 pronghorns to equal the caloric possibilities of a single giant bison, and as pronghorn flesh was so lean, the animal commonly ranked well down the list of commonly pursued prey. Nonetheless archaic hunter-gatherers and even historic-era Indian hunters killed them in large numbers. Ancient pronghorn corrals, such as the Bridger antelope trap site in southwestern Wyoming, evince one such method, in which Indians enclosed local herds in rock and sage corrals, pushed them to run in circles until exhausted and then clubbed them to death. Historical references also describe how horse-mounted Plains Indians engaged in a kind of “surround,” again with the goal of getting a pronghorn band to run in circles until bow-wielding hunters could ride down the spent and stumbling animals. Lewis and Clark watched the Shoshones try this for three hours with no result but sweat-drenched horses. In the late 19th century, when pronghorns gathered by the thousands in winter, some tribes used rifles from horseback. “The antelope crowd together in their fright,” Richard Irving Dodge observed of such hunts, “and present a mark not easy to miss.”

While hunters could tan leather from pronghorn skins, most considered the hides inferior to those of bison or deer. There were exceptions. When Dr. John Sibley, Jefferson’s Indian agent in Orleans Territory, held a council for southern Plains Indians in Natchitoches in 1807, among the assembled tribes were the Comanches, a soon-famous Plains people with a band known as the Kwahadis (“Antelope”). “They dress the skins of the Antelope most beautifully,” Sibley recalled, “and Colour [sic] them of every shade from light Pink to Black of which they make their own and Husbands’ Clothing, the edges Pinked and scalloped resembling lace.…You would take them for fine Black Velvet.”

About the time Custis, Jefferson’s naturalist on the Red River, was writing the president of the rumored Western “Antilope,” Charles Willson Peale was in Philadelphia unpacking and preparing to mount Meriwether Lewis’ collected specimen from the fall of 1804. The Lewis and Clark party had seen their first pronghorns on September 5 of that year, not far from present-day Niobrara, Neb., during the same two-week stretch in which they crossed that magical boundary from woodland to prairie and first encountered (and began collecting) a whole suite of Great Plains animals: bison, prairie dogs, coyotes, mule deer, magpies, etc.

The pronghorn’s turn came on September 14 when William Clark, fruitlessly searching for a rumored volcano, shot what he described (rife with the explorers’ usual misspellings) as “a Buck Goat of this Countrey, about the height of the Grown Deer…verry actively made…his Norstral large, his eyes like a Sheep—he is more like the Antilope or Gazella of Africa than any other Species of Goat.” A few days later, finding “Antelopes…in every direction feeding on the hills and plains” but discovering them to be “extreemly shye and watchfull,” Meriwether Lewis penned a classic line about pronghorns. Hoping to collect a female for science, Lewis could only watch as the harem of seven he was stalking whirled away and vanished. Within minutes he spotted them some 3 miles distant. “I had this day an opportunity of witnessing the agility and superior fleetness of this anamal, which was to me really astonishing,” he wrote in his journal. “When I beheld the rapidity of their flight along the ridge before me, it appeared reather the rappid flight of birds than the motion of quadrupeds.”

It fell to George Ord, a naturalist who worked up many of the Lewis and Clark specimens, to publish a scientific description and propose a Linnaean binomial for the pronghorn in 1815. To his credit Ord recognized that despite their similarities to African antelopes and gazelles, pronghorns were unrelated to any existing family of animals then known. Antilocapridae, the family name he devised, and Antilocapra, the genus Ord fashioned for a creature combining the traits of both antelopes and goats, have stood ever since.

In 1820 U.S. Army Major Stephen Long led a scientific party, including painter-illustrators Samuel Seymour and Titian Ramsay Peale, up the Platte River westward across the central Plains to the Rockies before returning eastward across the southern Plains. From his own animal drawings and a landscape sketch by Seymour, Peale rendered an oil painting that served as the American public’s introduction to what pronghorns looked like in the wild.

In 1843 naturalist/painter John James Audubon—with The Birds of America under his belt—was on the Missouri River researching Western species toward a guide to North American quadrupeds. Audubon noted Pronghorns “often die from the severity of the winter weather” and “are caught in pens in the manner of Buffaloes and are dispatched with clubs” by Indian women.

One of the 19th century’s best-selling books about the West was trader/naturalist Josiah Gregg’s Commerce of the Prairies, first published in 1844. In it Gregg made the following contemporary observations about the pronghorn:

That species of gazelle known as the antelope is very numerous upon the high plains.…The antelope is most remarkable for its fleetness: not bounding like the deer, but skimming over the ground as though upon skates.…The flesh of the antelope is, like that of the goat, rather coarse and but little esteemed: Consequently, no great efforts are made to take them. Being as wild as fleet, the hunting of them is very difficult.

The commercial market hunt of wildlife in the West had been underway in earnest since at least the 1820s, but for almost three-quarters of a century it left pronghorns largely unaffected. Unlucky animals fell prey to hungry emigrants along the pioneer trails, foreign hunters on safari in the American Serengeti, or game hunters providing food to railroad crews on the Great Plains or miners in California. But not until bison numbers began to drop did pronghorns finally draw attention in the slaughter of Great Plains animals for profit.

By the 1880s—with more than 5,000 professional hunters operating out West and Plains Indians both invested in the market hunt and hunting for subsistence on their new reservations—only two primary charismatic animals remained on the Great Plains in significant numbers: wild horses and pronghorns. Mustangers would round up the horses, selling them for use in various European wars or, by the 1920s, to the American pet industry as a source of dog food.

The pronghorns were hit on multiple fronts. Homesteaders in western Kansas and Nebraska steadily tore up pronghorn habitat. Ranchers overstocked the Plains with cattle and sheep that undermined the vegetation on which pronghorns depended. The new barbed-wire fences went straight to the pronghorns’ evolutionary weakness. Pronghorns could get through loose or downed fences, but tight fences bounded them in, preventing the herds from migrating and from escaping winter blizzards. The historically bad winters of the 1880s devastated pronghorn populations. In the winter of 1882 homesteaders in the Texas Panhandle discovered and killed 1,500 pronghorns trapped against a fence.
And then there was the market hunt. With everything else gone and a deathly silence descending across the Great Plains, market hunters finally turned their rifles on pronghorns. In places like the Black Hills hunters managed to slaughter the winter concentrations of pronghorns in two or three seasons. Plains hunters desperate to keep in business sold pronghorn meat to butchers for 2 or 3 cents a pound.

Naturalist George Bird Grinnell alerted conservationist and future president Theodore Roosevelt to the impact of market hunting, but by the time Roosevelt became president in 1901, only about 13,000 pronghorns roamed the West. Naturalist Vernon Bailey, of the Bureau of Biological Survey, crossed the Texas Panhandle by train in 1899 and counted just 32 pronghorns. Rescuing them from almost certain extinction required pronghorn stocking in Yellowstone, on the national wildlife refuges Roosevelt created, and eventually on a scattering of state parks and national monuments on the Great Plains. Between 1925 and 1945 state and provincial game departments regularly captured pronghorns to recover the animals in places where they had disappeared.

Today the North American pronghorn population hovers at around 700,000 animals, half of them in Wyoming, with another 1,200 in Mexico. A series of highway overpasses now allow some of them, including the Sublette herd, to continue their winter migrations.

For a few years in the 1880s and ’90s the two ancient Americans, pronghorns and mustangs, held out almost alone on the vastness of once-teeming American prairies. In April 1884 a cowboy named George Wolfforth, rounding up strays for the Kidwell Ranch in west Texas’ Yellow House Canyon, rode his horse up over the rim of the canyon about where present-day Lubbock stands. The scene that unfolded seared into his memory. “As far as we could see,” he wrote, “there were antelope and mustangs grazing in the waving sea of grass,” the whole tableau “rendered misty and unreal by the mirage that hovered over the plains.”

They were almost the sole surviving Pleistocene megafauna of the Great Plains. Many of their compatriots had died out in that mystifying extinction 10,000 years before, and almost all the rest had suffered extinction or extirpation across the previous 30 years. But even this moment was brief, a romantic flickering to hold in one’s mind. Wolfforth was right—that last vision really was a mirage. WW

New Mexico historian Dan Flores has won National Cowboy & Western Heritage Museum Wrangler Awards for his Wild West articles on bison and coyotes. This article garnered him a 2016 Spur Award finalist slot in nonfiction from Western Writers of America. Flores’ book The Natural West: Environmental History in the Great Plains and Rocky Mountains is recommended for further reading, along with American Pronghorn: Social Adaptations & the Ghosts of Predators Past, by John Byers; Prairie Ghost: Pronghorn and Human Interaction in Early America, by Richard McCabe, Bart O’Gara and Henry Reeves; and Antelope Country: Pronghorns, the Last Americans, by Valerius Geist.