Yellowstone ecosystem may lose key migrant

A mammal that embarks on the longest remaining overland migration in the continental United States could vanish from the ecosystem that includes Yellowstone and Grand Teton National Parks, according to a study by the Wildlife Conservation Society (WCS) and National Park Service. No, it's not the bison, the grizzly bear, or even the wolf, but the pronghorn antelope, which travels more than 400 miles between fawning grounds and wintering areas. Second only to caribou in the Arctic for long distance migration in the Western Hemisphere, this isolated population and its ancient migration route could disappear because of continued development and human disturbance outside the parks according to the study, which appears in the latest issue of the journal Biology Letters.

The study says that pronghorn have used the existing migration route in and out of the Yellowstone ecosystem for at least 6,000 years. Animals travel up to 30 miles a day, clambering over 8,500-foot mountain passes, and moving through bottlenecks now barely wider than a football field due to recent residential development. Increased petroleum extraction could further impact the migration route. Six of eight antelope migration corridors in and out of the Yellowstone ecosystem have already been lost.

“It's amazing that this marathon migration persists in a nation of almost 300 million people,” said WCS researcher Joel Berger, the study's lead author. “At the same time, the migration is in real trouble, and needs immediate recognition and protection”

According to Berger and his co-authors, Steve Cain and Kim Murray Berger, safeguarding the migration route would be relatively easy, since the antelope population has used the same corridor for so long, unlike other overland migrants, such as caribou, which often change routes from year to year.

While pronghorn are abundant in many areas of the American West, Berger says there are both biological and historical reasons to preserving this particular population, which numbers around 200-300 animals.

“The protection of this migration corridor is more than symbolic,” He added, “An entire population from a national park could be eliminated, leaving a conspicuous gap in the ecology and function of native predator-prey interactions.”