America’s great mammals have nowhere to go. New houses, farms, energy plants and pipelines are hemming in bison, antelope and elk, cutting off migration routes that the animals have been using for at least the past 5800 years.
Virtually every large migrating North American animal outside Alaska lives in the Yellowstone Park ecosystem. But Joel Berger, senior scientist with the Wildlife Conservation Society, has found that bison now cannot migrate at all, while over three-quarters of the routes used by pronghorn antelope and over half used by elk have been lost or truncated.
Pronghorn make on average a 430-kilometre round…
