The endangered American bison in Yellowstone National Park

From Correspondent Don Knapp

WEST YELLOWSTONE, Montana (CNN) -- The U.S. Department of the Interior is wrestling with how to protect the endangered American bison in Yellowstone National Park without threatening cattle herds near the park with brucellosis, a disease that causes cows to abort their calves.

Bison, once abundant in Yellowstone and throughout the West, were hunted nearly to extinction by the turn of the 20th century. Only 23 animals in the Yellowstone herd survived. But through conservation, and transplants of animals from other herds, the bison population in Yellowstone rose to more than 3,500 by 1996.

Then came that winter's killing snows, a natural process that Park Service officials believed would cull the herd. But the bison, driven by hunger to find food, followed paths out of the park on roads groomed for recreational snowmobilers.

Once the federally protected animals were outside the park, gunmen hired by the state of Montana mowed them down under an agreement with the Park Service to protect nearby cattle herds from brucellosis.

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CNN's Don Knapp reports on the problem and the various solutions the Department of Interior is considering. WARNING: This report contains graphic pictures.
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The Park Service also corralled many of the bison leaving the park, returning the healthy ones to the herd and shipping those infected with brucellosis to a slaughterhouse.

However, video of the shootings and news of the slaughterhouse shipments enraged conservationists and others across the United States. So now, the Interior Department is holding public hearings to gauge the response to seven different plans under consideration to control Yellowstone's bison herd.

"I think the real difficulty here is that we don't have technology at the present time to simply flip a switch and eradicate brucellosis," says Wayne Brewster of the National Park Service.

Plans being considered range from the current practice of capture, testing and slaughter to public hunting to aggressive medical attempts to control the disease. There is also discussion of buying up private lands adjacent to the park to let migrating herds graze safely there.

Winter snow normally culls the bison herd

Native American groups are proposing that the bison be moved to tribal lands to supplement herds there.

The Interior Department is expected to take several months to finalize a bison management plan. Activists say they hope something is done before winter snows again tempt the bison to roam out of the park.