Where Have All The Pronghorn Gone?

An exquisite ecotype and one that’s often overlooked dominates landscapes in Greater Yellowstone: the sagebrush-bunchgrass steppe. From a speeding automobile it may appear as a featureless expanse of gray brush, but a closer look reveals many hidden ecological gems. In Jackson Hole there are at least four species/subspecies of sagebrush and several herbaceous species of Artemesia, along with grasses and wildflowers.

I have a deep admiration for this community type and the adaptations of the plants that live here. But what strikes me most is the haven it provides for so many animals, from Greater Sage Grouse to wintering mule deer and moose, for rodents and badgers and weasels, and for the beleaguered pronghorn.

Readers may know about the 2022-23 winter wildlife die-off in western Wyoming that more than decimated mule deer and pronghorn. (To “decimate” is to reduce by a factor of 10.) If it were only that much.

This past winter, the sagebrush sea between the Wyoming and Wind River ranges was covered with deeper-than-average snow, in what is called an inverted snowpack (less accumulation up high, more on the lower elevation winter ranges), leading to a combination of deadly factors that whacked mule deer and pronghorn herds in late winter. Factors included a severe lack of access to food buried under crust-layered snow; fences that pronghorns couldn’t crawl under, also due to the snow; the usual high-speed traffic on highways; and a contagious bacterial infection that caused pneumonia to spread in the weakened herd.

Result: the Path of the Pronghorn—the only officially designated wildlife migration route in the region—between the upper Green River and Grand Teton National Park, was all but empty this spring.

As many as 500 pronghorn once made the trek over the divide between the Green and Gros Ventre Rivers to reach summer range in Grand Teton National Park. In recent years, 300 has been a more typical number, as residential development, fences, roadways and energy extraction has increased in the upper Green River basin, thus squeezing habitat for pronghorn, mule deer and sage grouse. Still, 300 or so is quite a few pronghorn.

Until 2023, a spectacular springtime event has occurred each May, and on a few occasions I have been lucky enough to catch groups of pronghorn walking their well-worn trails through the Gros Ventre foothills and onto the national park’s sagebrush flats. This year, instead of hundreds of pronghorn, wildlife biologists have counted about 25. In the Red Hills north of the Gros Ventre River, I walked part of the Path of the Pronghorn in May, looking for tracks. None.

Wyoming Game and Fish and national park biologists continue to try to find more individuals, with overflights and on-ground surveys, in hopes that some of the pronghorn that usually summer in the park might still be hidden among the folds of sagebrush hills upstream, or possibly still on the east side of the divide with the Green River.

All of the pronghorn with radio collars died this winter. We don’t know how many of the few surviving does are pregnant, and how many offspring might make the trek back to the Green River this fall. Will these few animals comprise the last generation that remembers what their ancestors knew—the Path of the Pronghorn?

I drove through Grand Teton National Park recently to attend an evening event at Jackson Lake Lodge, sponsored by the Wyoming Migration Initiative. I felt like a true tourist, enthralled by the beauty of the low sun and storm clouds around the mountains. I rarely go into the park during the summer these days, as most trailheads are overflowing with vehicles and trails are crowded with people. But on that magical evening I was reminded of the reasons why so many love Grand Teton National Park.

Crepuscular light rays shone through the clouds to illuminate deep mountain canyons and sage-green flats. Wildflowers brought splashes of sunflower yellow, gilia scarlet, larkspur blue and sulfur-flower white to the scene. I was late for the meeting because of all the photos I took along the way.

As I headed home around 9 p.m., the light was even more sublime. The last sunlight ignited vertical faces and crags while lightning did the same to the dark clouds drifting off to the east. The low light brought out colors in the sagebrush from electric blue-green to gentle gray, along with the hues of rabbitbrush, bitterbrush, snowberry and other shrubs, each with its unique signature of color.

Scanning the array of greens, I was filled with joy and wonder, yet it never escaped me that something was missing. Where were the pronghorn? They should have fawns by now, and both adults and offspring would have glowed with deeply saturated golds and tans and whites. The land, in all its splendor, looked empty without them.

North of the Gros Ventre River crossing, as I slowed for the airport intersection (where people often seem to wait at the stop sign until you are almost there, then pull out in front of you), I saw a flash of movement not far off the roadside. Two pronghorn does nibbled on bitterbrush, their noses nearly touching, as if each sought reassurance that she was not the only one left. I whooped and waved (with window rolled up). Their coats were pale and seemed a bit shaggy compared to the usual healthy buckskin tan I would have expected, and I couldn’t help thinking it was because of the harsh winter they had endured.

But: they had made it. With their tails toward the road, I couldn’t assess whether either might be carrying a fawn, and with my need to pay attention to driving, it was impossible to tell if there might be a fawn hiding in the tall grass around them. But it gave me some hope that the Path of the Pronghorn would not be forgotten by future generations. It gave me hope that this creature, so adapted to, and emblematic of, the vast sagebrush steppe that is home, would not fade away.