Travel Reference
In-Depth Information
THE BRUCELLOSIS PROBLEM
Yellowstone is the only place in the continental United States where bison have exis-
ted since prehistoric times. Current policy mandates that the animals stay within the
park's unfenced boundaries, and how best to enforce this is a matter of constant de-
bate.
The park's management of the bison has changed throughout the years, just as
bison numbers have fluctuated. Prior to 1967, park authorities would trap and re-
duce the herd to keep it manageable. After 1967, however, the guiding philosophy
changed, and the bison were managed by nature alone. By 1996 the number of bison
in the park grew to 3,500. The size of the herd, coupled with winters that brought
significant snowfall, led many of the bison to migrate out of the park in order to find
better grazing and calving grounds. The problem of brucellosis played out on the na-
tional stage.
Brucellosis is a bacterial infection present in the bison and elk in the Greater Yel-
lowstone area. The disease can cause spontaneous abortions, infertility, and lowered
milk production in the infected animal, but the Yellowstone elk and bison popula-
tions seem relatively unscathed by the disease, despite the number of animals infec-
ted. The same tolerance of the disease is not common among cattle, however. The
overwhelming fear is that bison exiting Yellowstone could infect neighboring cattle;
this would be gravely detrimental to Montana, Wyoming, and Idaho beef production.
Brucellosis cannot be treated in cattle and can be passed on to humans in the form of
undulant fever. The government created a fairly simple inoculation program to erad-
icate the disease in cattle as early as 1934, but brucellosis has never been eliminated
from wildlife.
Starting in the 1980s, when more than 50 percent of the park's bison tested pos-
itive for the disease, the park's approach was to control the borders with hazing to
limit the number of bison that left the park. When hazing was unsuccessful, the bison
were shot. The winter of 1996-1997 brought record cold and snow, and bison left the
park in large numbers to forage for food; 1,079 bison were shot and another 1,300
starved to death inside the park's boundaries. This incident magnified the problem of
maintaining a healthy herd while preventing the spread of brucellosis.
The National Park Service, the U.S. Department of Agriculture, and Montana,
Wyoming, and Idaho are working together to see how brucellosis can be eliminated
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