The herd of pronghorn near Pinedale have gained much attention in recent years

By Rob Breeding

We’re a mobile species. Humans have been so since well before we developed the technology to put us anywhere on the continent in a matter of hours, or anywhere on the planet in a day.

During the fall I migrate the 10 or so miles to my favorite chukar spot two or three times a week. Elsewhere, The Bucket, a spot on the Shoshone River where the professor and I like to exercise the local trout population, is about 25 miles from home. If it isn’t hunting season then that’s where you’ll find me.

My favorite Mearns’ quail spot in Arizona is nearly 1,500 miles away. That’s an annual migration for me, a trek timed to coincide with a number of favorable environmental conditions — such as the timing of winter break, as well as family obligations for the holidays.

I don’t consider my migrations epic. The Arizona trip gets special dispensation only when I’m manic enough to drive it straight through. But any migration propelled by a modern internal combustion engine has a ways to go to qualify as epic.

Last week I had a chance to listen to Matt Kauffman, the director of the Wyoming Migration Initiative, talk about some of the epic journeys big game have just recently set off on this spring. The herd of pronghorn near Pinedale have gained much attention in recent years for the annual trip those animals take to summer range near Jackson Hole. The animals travel up to 170 miles, there and back again, in the longest known pronghorn migration.

The trip is especially tricky. Pronghorn are notorious for their bafflement in the face of human erected barriers on the plains. Fences freak them out. Fences on the side of highways can be death traps.

In Wyoming there’s also energy development to contend with. The Jonah Field south of Pinedale is one of the largest onshore natural gas discoveries in the country. Aerial photos of this sagebrush plain show that Jonah is studded with drilling pads. The field sits right in the middle of the migration corridor.

Pronghorn migrate both through, and around, the gas fields. Then, as the corridor narrows down as it hits the mountains, pronghorn have to navigate the suburban development around growing Pinedale.

The pronghorn continue to wind through this increasingly complicated maze of obstacles. Development proponents will point to the many animals choosing to move right through the fields as evidence the disturbance isn’t harming wildlife. Kauffman, however, said data gathered from radio-collared animals in the herd indicates it’s more complicated than what those photos of happy pronghorn suggest.

The pronghorn and mule deer in the southwest part of Wyoming travel from the sagebrush basins to the mountain meadows around Jackson to take advantage of nutritious summer vegetation. It’s there where the animals build the fat reserves that will last them through winter. It’s not as if the animals wake up one spring morning, however, and make a bee line for Jackson Hole.

Instead, the animals follow a meandering path, pausing along the way as they follow the green up leading to the summer range. Kauffman calls it “Riding the Green Wave.”

So the animals may still use those corridors through the Jonah Field or suburban Pinedale, but they use them differently. Instead of following the meandering pattern of green up, they hurry through developments, stressed by the presence of trucks, drilling rigs and neighborhood dogs.

The pronghorn still make it back and forth, but the added stress of having to hurry no doubt means the animals aren’t quite as fit as they once were at journey’s end. What we haven’t learned yet is just what is the limit for these long distance travelers.

Sadly, that limit may announce itself by way of the rather bleak sight of a sagebrush plain that no longer supports migrating pronghorn.

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