"BILLINGS, Mont. -- Yellowstone National Park's iconic bison herds are suffering their worst winter in several years with almost 400 of the animals being held for possible slaughter — and a much-heralded initiative to expand where they can roam on the verge of failure.

Forty-seven more bison were captured at the Montana border on Thursday. Yellowstone workers and state livestock agents were trying to halt the animals' exodus from the snow-packed park to lower elevations.

Bison periodically attempt to migrate out of the park in search of food, but many end up in government-operated corrals under a controversial program meant to guard against the spread of the disease brucellosis to livestock."

Matthew Brown reports for the Associated Press February 4, 2011. [2]