Yellowstone Bison A Risk To Cattle, Report Concludes

Diseased bison in Yellowstone National Park pose a small but real risk of infecting Montana cattle herds, according to a study released Thursday by the National Academy of Sciences.

The state of Montana has cited the possibility of bison infecting cattle with the disease brucellosis as the rationale for shooting bison that wander out of the park.

Last winter nearly 1,100 bison that roamed outside the park’s borders were shot in Montana or shipped to slaughter in an effort to eliminate any chance the disease would spread to domestic cattle.

Sen. Conrad Burns, R-Mont., was quick to praise the draft report by the National Research Council, principal operating arm of the academy.

“This report confirms much of what we’ve been saying for years,” Burns said.

A critic of bison management policies, biologist D.J. Schubert of the Fund for Animals, said the report appears to be biased in favor of the cattle industry.

“They’ve basically bought into the assumption that somehow cattle are more important than these wild bison, and that’s tragic,” Schubert told a reporter.

Brucellosis, believed to be wide-spread among Yellowstone bison and elk, can cause cattle to abort calves and also can cause undulant fever in humans.

The draft study released Thursday calls for an aggressive management plan with bison quarantine zones around the park and a concerted effort to develop an effective vaccine to control or eradicate the disease in the park’s elk and bison herds.

“The risk of bison or elk transmitting brucellosis to cattle is very small” because ranchers in the region are vigilant about vaccinating their cattle and monitoring the disease, said Norman Cheville, the study’s principal investigator and chairman of the Department of Veterinary Pathology at Iowa State University.

However, if the disease were passed to cattle the results could be catastrophic, Cheville said in a conference call with reporters.

“The danger is very high that it would get into the cattle population, smoulder quietly and then spread to the cattle populations in other states,” Cheville said.

No effort to eliminate brucellosis in the Yellowstone bison herds will be successful unless the disease is eradicated in the elk herd as well, and the effort will require the testing and slaughtering of infected bison, elk and cattle, the report says.

Burns said the report reaffirms cattlemen’s fears that their herds are at risk and that aggressive management is needed.

A state wildlife official said Montana supports both the notion of quarantines and of vaccinating Yellowstone herds to control or eradicate brucellosis.

“The first order of business is to make sure that we’re controlling the circumstances that lead to preventing transmission,” said John Mundinger, bison specialist with the Montana Department of Fish, Wildlife and Parks.