published on July 11, 2024 in Front Page News

THE BUFFALO WAR: The Disease

Bison outside Yellowstone National Park

Though bison are well-suited for the harsh climate of Yellowstone National Park, the winters from 1995 to 1997 were particularly severe in the high country, forcing bison to leave the park in search of food. They found milder conditions and convenient grazing on several U.S. Forest Service allotments that were used by area cattle ranching families in the summer.

In 1995, the Yellowstone bison herd was designated by the Montana state legislature as a species in need of disease management, as some bison carry brucellosis.

The Montana state legislature then designated the Deparment of Livestock (DOL) to be the lead agency for the bison/brucellosis disease management outside of Yellowstone. It was the DOL's responsibility to work with other state and federal agencies either to force the bison leaving Yellowstone National Park back within park boundaries or to capture and test for brucellosis those bison that could not be moved back into the park. The DOL's role in bison management has been problematic for environmental groups who believe that wildlife officials, not a livestock agency, should be managing bison.

Brucellosis

USDA film, 1954

Ranchers are nervous about mingling between cattle and bison because of brucellosis, which can decrease milk production and animal weight, cause spontaneous abortion of the animal's first fetus and cause infertility. For nearly 60 years and at a cost of billions of dollars, the livestock industry across the United States has waged a war to eliminate brucellosis from its herds. In 1952, the U.S. Department of Agriculture (USDA) estimated that annual losses due to this disease were more than $400 million. To prevent an epidemic of the disease, federal and state agriculture officials have eliminated infected herds.

Brucellosis can also infect human beings, causing persistent, intermittent flu-like symptoms known as undulant fever. Transmission occurs through direct contact between a person's open cuts and birthing fluids or animal tissue. Veterinarians, butchers and farmers have been those most commonly affected, though the incidence of brucellosis in humans is extremely rare.

Brucellosis was first identified in domestic cattle in the United States in 1910. In 1917, it was first identified in Yellowstone bison.

The USDA, responding to livestock and public health concerns, began an effort to control and eradicate brucellosis in 1934 by developing vaccines and depopulating entire herds when several animals tested positive for the bacterium. Currently, all but Florida and South Dakota are brucellosis-free, and these last two states are poised to eradicate the disease.

After more than 30 years and $30 million, and the sacrifice of many cattle, Montana achieved brucellosis-free status in 1985. That same year, state and federal agencies began eliminating some Yellowstone bison that migrated out of park boundaries. Since the winter of 1991-92, Native Americans from reservations such as northern Cheyenne, Crow, and Fort Peck have sometimes assisted in harvesting and using the bison carcasses. Other bison carcasses have been distributed to nonprofit charitable organizations and food banks.

A scientific dispute

Trapped bison

Yellowstone's bison herd carries an uncontrolled pocket of the disease. However, detractors of the slaughter believe there are flaws in the bison management:

Bison migrate out of the park to graze in the winter and spring, whereas cattle are not placed on the allotments until June, after most bison have gone back over the park border. However, there is disagreement about how long the Brucella bacteria can survive in the environment. As a precaution, cattle and bison are kept from interacting for at least 45 days.
Transmission occurs mainly through direct contact with birthing matter, but state and federal officials have included hundreds of male bison in their slaughter, contending that males still present a risk.
Methods of testing for brucellosis are hardly foolproof. Among those bison who field-tested positive for brucellosis and were killed between 1996 and 1999, 80 percent later tested negative for the disease in more reliable lab tests.
Thousands of elk in the region also carry the disease, but are not managed similarly.
There has been no documented case of brucellosis transmission in the wild between cattle and bison. Known transmission has only occurred in the lab.

Today, some tribes and Native groups are trying to reintroduce bison onto their reservations. They are also working to take in unwanted bison from Yellowstone instead of having these animals sent to slaughter. So far, these requests have been denied by government officials.

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