Where The Deer & The Antelope Drown - Pronghorn Migration Faces Flooding, Deep Snowpack - NYT

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An antelope migration drama is unfolding on the plains of northern Montana. One of the longest overland migrations in North America takes place each spring in north-central Montana and southern Saskatchewan and Alberta. In the spring, tens of thousands of antelope travel as far as 260 miles from their wintering ground in central Montana to their fawning grounds in northern Montana and Canada.

Most long-distance land migrations around the world have ceased or are imperiled because of habitat destruction and barriers, so understanding those that remain is a priority for wildlife researchers. The World Wildlife Fund and other groups have collared 102 of the peripatetic antelope in Montana for study. Extreme weather this year and the possibility of more of the same in coming years, possibly related to climate change, has raised concerns about the viability of this migration. In May, more than 16 inches of rain fell in a small town near the river in one month. It was an all-time statewide record, and even exceeded what often falls in an average year.

More antelope than usual moved south this year because of record snow. Instead of traveling in broad groups, they move single file. ”You’ll have hundreds if not thousands of animals strung out for miles in single file,” said Dennis Jorgensen, a wildlife biologist with the World Wildlife Fund in Zortman, Mont. “What that does is tromp down the snow. It’s like bike racing where someone takes the lead for a while, and then drops back and allows someone else to lead.”

That tactic didn’t work this year. Punishing snows as deep as 10 feet and cold temperatures killed thousands of the animals; as much as 70 percent of a herd of more than 40,000 animals was wiped out. Some also gathered on Burlington Northern train tracks to escape the drifts, and 700 or 800 were mowed down by freight trains. Carcasses of the dun-colored animals with the distinctive white markings and black horns, have been found across the prairie.

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http://green.blogs.nytimes.com/2011/06/09/for-weary-antelope-a-perilous-swim/