For roughly 6,000 years, Wyoming pronghorn have migrated seasonally between the mountains of Grand Teton National Park and the warmer plains of the Upper Green River Basin. The roughly 100-mile journey is among the longest land migrations of North American mammals. But biologists worry that roadways and new energy and housing development threaten to fragment the route and disturb wintering grounds ("Perilous Passages," HCN, 12/26/2011 ).
Now, one deadly threat to the migration has been overcome. To keep the 300-head Teton pronghorn herd, plus mule deer and elk, out of traffic, the state built six underpasses, two overpasses and fencing along a 13-mile stretch of Highway 191 in 2012. During the past year, cameras at the crossings have recorded roughly 23,000 animal crossings. Scientists hope this marks a successful step toward preserving the pronghorn migration and protecting other large game.