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Small but cherished, the Grand Teton herd faces a growing number of man-made obstacles—including more than 100 fences (this one near Pinedale, WY) thrown up along the migration route that it has followed for millennia. (Wendy Shattil & Bob Rozinski)

End of the Road?

Development threatens to block the ancient migration of a herd of pronghorn antelopes in western Wyoming. Without new protections, conservationists say, the speedy animals are running out of time.

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The chase began just after dawn. In a curious predator-prey role reversal, the pronghorn antelope pursued a coyote across a knoll. The doe could have run down her quarry in seconds, but she was not trying to catch the coyote, only shoo it away. After a half mile, she stopped and headed back to resume her vigil over two light brown fawns in this southeastern corner of Wyoming's Grand Teton National Park. When last seen, the coyote was high-tailing it up a treeless draw.

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Joel Berger, a biologist with the Wildlife Conservation Society, had brought me to this perch on Blacktail Butte to observe the pronghorns. The doe, Berger said, had just performed a classic feint, steering the coyote away from the short grass daybed where her fawns had been playing a deadly game of hide-and-seek with predators in the days since their mid-June birth.

Pronghorns evolved in the harsh, high-plains habitat of North America tens of millions of years ago alongside swift predators like saber-toothed cats and dire wolves. They are not related to true antelopes of the Old World, but like those species pronghorns are specialized for speed. They are arguably the world's fastest living land animals. Although a cheetah could beat it in a hundred-yard dash, the pronghorn has greater stamina and would probably prevail in the 400-meter and one-mile races, the latter of which it would run in about a minute. Pronghorns can spot movement three miles away, and a startled pronghorn herd confuses predators by darting in unison at 50 miles an hour like a skittish school of fish. Pronghorns survive harsh winters on the barest intake of sage leaves they paw from the snow. But for this sentinel herd of pronghorns, the greatest threat to its survival is a rapidly changing West.

If this doe's fawns survive the summer, they will follow their mother and a few hundred other pronghorns on the longest terrestrial migration in the lower 48 states. By early fall, the herd will leave Grand Teton National Park, fording rivers and climbing steep ridges to reach its winter range at least 120 miles away, south of Pinedale. If the fawns endure the windblown, minus-20-degree Wyoming winter, they will make their way back to the national park in the spring.

This extraordinary migration is getting more difficult with each passing year, due to land development that is placing obstacles in the animals' way and a natural gas boom that is carving up their critical winter range.

Berger and his wife, Kim, who is also a wildlife biologist, have been working to preserve what's left of this herd's long, narrow migratory route. In 2003, the biologists proposed the nation's first National Migration Corridor—a trail that would be protected from further harm by federal restrictions on development and industry. The trail would also benefit the mule deer, moose and other mammals that have traveled the same high-mountain highway for millennia. More than 90 percent of the proposed corridor is federal property, the Bergers point out, and the plan requires mainly that the trail suffer no further deterioration. "We're not asking for a corridor 20 miles wide," says Joel. "We're asking for something long and narrow." It's 90 miles by one mile, to be exact.

Pronghorns are not in trouble everywhere in Wyoming. In fact, there are probably as many of the animals in the state—about a half million—as there are people. Most pronghorns live in eastern Wyoming, where they roam shorter distances across landscapes not yet so prized. But the herd of 200 or so animals that migrates in and out of Grand Teton National Park treads across what has become some of the most valuable real estate in the West. Berger argues that without a protected corridor, the herd will die off, an outcome that he says should be unacceptable.

From our ridge-top perch, Berger and I spy bison, elk, a great blue heron and another doe with two fawns (pronghorns almost always give birth to twins). As the coyote-chasing doe returns, her fawns pop their heads out of the grass to greet her. Berger estimates they are about 3 days old. The twins take turns nursing, then the threesome ranges over a quarter mile of terrain, alternately feeding, gamboling and lying down to rest. Several times a minute, the mom pricks her ears and scans for coyotes and other threats.

In this part of the park, the Bergers have documented that 90 percent of fawns die, mostly from coyote attacks. The fawns must also weather late spring snowstorms, sub-freezing nights, bears, cougars, bobcats, golden eagles, wolves, badgers, disease, river crossings, roaring SUVs and other perils. If they dodge these bullets, not to mention the actual ones fired at them outside the park during the autumn hunting season, they will migrate before the snows blanket their birthplace.

Then comes the hard part.

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