The Rise and Fall of Pronghorn

I was driving home from a hike in Yellowstone and had just passed through its north gate. I turned down a side road that passes some of the commercial buildings and vehicles needed to run a national park. A movement to my left caught my eye and I spotted this pronghorn mom and her two young. 

I immediately pulled over and used my car as a blind to enjoy this uncommon sighting. Pronghorn hide their youngsters—these two were only days old—to keep bobcats, wolves, bears, golden eagles, and coyotes from taking a tender fawn. A pronghorn usually gives birth to two fawns and the youngsters see their mothers only every three to four hours when the mothers return to nurse, groom, and lead them to water.

This mother had her young in a sagebrush and grass meadow enclosed by roads bustling with cars, trucks, and campers motoring to and from Yellowstone. She could be using a strategy biologists call human shielding, keeping her young safe in an area that predators avoid because of heavy human presence. 

As I watched the fawns feed and frolic, I was struck by their eyes, so gentle, so inviting, and so large. Set on the sides of the head, they provide a wide field of vision, enabling pronghorns to catch sight of a predator approaching from almost any direction.

Superb vision is just one of the adaptations this species made while evolving over the last twenty million years in North America. Compared to its body size, a pronghorn’s windpipe, lungs, and heart are oversized and enable the animal to draw in and use lots of air. Each leg has two cushioned toes that act as shock absorbers. Add to this their light bone structure, and you’ve got a body built to sprint at forty-five to fifty miles per hour—much faster than any predator they’ll face today. But such speed was a lifesaver long ago when these fawns’ ancestors had to outrun a now-extinct American cheetah.

Though pronghorn outlasted that cheetah, they have not fared so well with humans. When Euro-Americans arrived in the West, pronghorn were about as abundant as bison—thirty-five million grazed the countryside, according to Yellowstone Resources and Issues. Now, only about one million survive in the US, Canada, and Mexico, according to the IUCN Red List. 

The decline in Yellowstone began in 1871 when homesteaders laid claim to the Gardiner Basin, adjacent to the area that would soon become Yellowstone National Park. Within thirty years, much of the vegetation that pronghorn need to survive—sagebrush, rabbitbrush, and wildflowers—had been ripped out by industrious settlers determined to plow, plant, and harvest crops they could survive on. While the settlers grew non-native plants such as alfalfa and oats, most pronghorn went elsewhere in search of native plants. Those that remained were shot by hunters or killed by ranchers who saw them as stealing food from the mouthes of their cattle. By the early 1900s, even the National Park Service was in on the action, culling—killing—pronghorn because park management feared overgrazing.

But by the 1930s, the prospects for pronghorn improved when Congress, according to historian Aubrey Haines, authorized the purchase of 7,600 acres of land in Gardiner Basin to expand Yellowstone’s northern boundary and provide more winter range for pronghorn. Great concept, but there was no federal money given for buying. After a game preservation company in New York donated $14,000 (equivalent to about $200,000 today), the park began acquiring. Ranchers—who were suffering agriculturally from a drought and strapped financially by the Great Depression—took the money and left. But their non-native vegetation did not uproot and leave with them. Even today, the remains of plantings by those early settlers reduce the amount of nutritious native vegetation available to this mother and fawns in Gardiner Basin. 

Those years of ranching and hunting and culling reduced Yellowstone’s pronghorn herd from roughly 1,000 animals to 500 or so today. With such a small number remaining, the National Park Service warns that pronghorn are a species of special concern in Yellowstone that could be wiped out by disease or a severe winter.

Even without a natural disaster, One of these two fawns will likely be lost to predators or disease before reaching its first birthday. The survivor will grow up feeling the crunch from development north of the park. Fences enclosing private land, for example, in increasingly populated Paradise Valley can block access to vital winter grazing when Yellowstone is covered in snow or ice.

But for now, these two have much to learn, a lot of Yellowstone to explore, and a mother who cleans, feeds, and protects them.

Thanks for reading! I write, speak, and photograph to protect wildlife and wild lands. My bestselling In the Temple of Wolves; its sequel, Deep into Yellowstone; and its prequel, The Wilds of Aging are available signed. My books are also available on Amazon unsigned or as eBook or audiobook.