Growth crimping wildlife corridor

PINEDALE, Wyo. — The sophisticated motion sensors that line a one-mile stretch of highway in western Wyoming seem out of place. There are no pricey jewels, no rare artifacts, just desolate landscape.

The equipment is here because every fall and spring, 300 to 450 pronghorn antelope cross the bustling two-lane on their journey between the snowcapped mountains in Grand Teton National Park and the expansive, sagebrush-covered mesas and hills of southwestern Wyoming.

The journey extends about 160 miles; of all the mammals in the Western Hemisphere, only the Arctic caribou migrate farther. And every year the pronghorns' trek gets a little tougher: more homes, more fences, busier highways.

If growth continues unchecked, some biologists fear the migration routes may be cut off.

The nearly $900,000 detection system is one of the measures wildlife managers have taken to help thousands of pronghorns and deer make the increasingly dangerous trek between summer and winter stomping grounds in western Wyoming. And local authorities say they're mindful of the animals when deciding whether to allow development projects.

Supporters of the herds propose a more unified approach to protect the pronghorns, which have used this route for some 6,000 years — the first federally protected wildlife migration corridor.

"It's truly unique, and quite frankly, special in a nation of 350 million people that we have migration at this distance," said Joel Berger, a senior scientist with the New York-based Wildlife Conservation Society who studies the herd.

Along their migration route, the pronghorns come across three "bottlenecks," or areas where their path narrows because of the terrain. The narrowest is about the length of a soccer field. The speedy pronghorns prefer wide open spaces.

"They just run through it when they get there, probably because it's so narrow," Berger said. "It's kind of like a gantlet."

All the bottlenecks have private homes that squeeze the path but are not dense enough to sever the migration route, according to Berger.

A booming energy industry has brought more people to the area, including Sublette County, which encompasses about half the pronghorn migration route and a number of deer migration paths.

The county, bigger than Rhode Island but with only about 7,300 residents, issued a record number of building permits last year and created about 1,000 new residential lots in the past few years.