Hoofing it long distances

Which mammal embarks on the longest remaining overland migration in the continental United States?

The pronghorn antelope (Antilocapra americana)), which travels more than 400 miles between fawning grounds in Yellowstone and wintering areas. Second only to caribou in the Arctic for long distance migration in the Western Hemisphere, this isolated population (of 200 to 300 animals) and its ancient migration route could disappear because of continued development and human disturbance outside the parks according to a study which appears in Biology Letters.

See Berger, Cain & Berger (2006) "Connecting the dots: an invariant migration corridor links the Holocene to the present" Biology Letters [link]

Numerous species undergo impressive movements, but due to massive changes in land use, long distance migration in terrestrial vertebrates has become a highly fragile ecological phenomenon. Uncertainty about the locations of past migrations and the importance of current corridors hampers conservation planning. Using archeological data from historic kill sites and modern methods to track migration, we document an invariant, 150km (one-way) migration corridor used for at least 6000 years by North America's sole extant endemic ungulate. Pronghorn (Antilocapra americana) from the Greater Yellowstone Ecosystem, like other long distant migrants including Serengeti wildebeest (Connochaetes taurinus) and Arctic caribou (Rangifer tarandus), move nearly 50kmd-1, but in contrast to these other species, rely on an invariant corridor averaging only 2km wide. Because an entire population accesses a national park (Grand Teton) by passage through bottlenecks as narrow as 121m, any blockage to movement will result in extirpation. Based on animation of real data coupled with the loss of six historic routes, alternative pathways throughout the 60000km2 Yellowstone ecosystem are no longer available. Our findings have implications for developing strategies to protect long distance land migrations in Africa, Asia and North America and to prevent the disappearance of ecological phenomena that have operated for millennia.

[tags: mammal | yellowstone | conservation ]