Study shows bison tend their pastures

MAMMOTH HOT SPRINGS, Wyo. (KIFI/KIDK)-A 10-year study of bison migration and grazing in Yellowstone National Park confirm the animals shape vegetation cycles and enhance growth throughout the summer months.

Using NASA satellites scientists learned that areas grazed intensely by large groups of bison greened-up earlier, more intensely, and for longer durations each year.

Biologists from the National Park Service, U.S. Geological Suvey, and the Universities of Montana and Wyoming participated in the study.

The research also found thyat bison migrations follow spring green-up, but their intense grazing lets them fall behind the wave of spring.

"Whereas migratory mule deer closely choreograph their movements so they are in synchronization with the flush of fresh green grass as it moves up the mountain, bison movements are not so constrained. They make their own fresh grass by grazing intensely in large aggregations," said Dr. Chris Geremia, lead author of the study and senior bison biologist at Yellowstone National Park. That finding sets bison apart from other North American ungulates.

The Yellowstone bison population is one of the only free-ranging populations in North America. Animals migrate more than 60 miles in the park.