In the Lamar and Madison valleys of Yellowstone National Park, one-ton bison bulls plow snow caves. Their massive, woolly heads dig to reach grass that will sustain them till green up comes to this high country months from now. Half-ton cows and calves spend their winter days in the same routine. Their movement is determined by Mother Nature. They go where they can eat grass.
Meanwhile, last week park managers and Montana livestock officials announced separate policy positions that basically will continue the status quo on bison management.
After a decade of studying the potential for using “biobullets” to remotely vaccinate bison in the park against brucellosis, the Yellowstone leaders concluded that approach would be a waste of taxpayer money and may also change the natural behavior of bison.
Meeting in Helena, the Montana Board of Livestock voted against expanding the area of public land adjoining Yellowstone where bison will be allowed to remain without being hazed back into the park or sent to slaughter.
On the same day, the Montana Department of Livestock announced that it was delaying a bison brucellosis vaccination program it had planned to start this winter until it updates an environmental assessment. The state veterinarian had planned to vaccinate bison by hand when they are captured near West Yellowstone.
Bison management may be Yellowstone’s most complicated resource issue among many, many policy controversies in America’s beloved park.
A National Park Service list of reasons supporting the decision against biobullets gives a glimpse of that complexity:
Lack of an effective vaccine (for example, 10 to 15 percent reduction in infection); short duration of immune protection; cannot vaccinate females in second half of pregnancy.
Limitations of current vaccine delivery technologies.
Effects of bison nutrition, condition and pregnancy/lactation that lessen protective immune responses from vaccination.
Potential adverse consequences (for example, injuries; changes in behavior) to wildlife and visitor experience from capture and remote vaccination.
Chronic infection in elk would almost certainly re-infect bison.
So the uneasy truce in the bison war continues. State and federal agencies work year round to keep park bison separated from cattle with much of the work happening in winter. The state of Montana and some Indian tribes hunt bison outside the park. Hand vaccination of captured bison will continue on the north side, but relatively few animals will be vaccinated in a population now at a historic high of about 4,600.
No Montana cattle have been infected with brucellosis from bison. In fact, no transmission of brucellosis from bison to cattle in the wild has ever been documented. (Elk have been linked to cattle infections.)
The Yellowstone bison herd is healthy. After two decades of sending roaming bison to slaughter and intermittent bison hunts, there are more bison in the park than ever. Exposure to brucellosis has not caused the wild herd to shrink.
As of last week, state and tribal hunters had taken 76 bison this winter in the West Yellowstone area and four in the Gardiner area, according to a Yellowstone spokesman. The numbers reflect the fact that few bison have migrated out the park’s north boundary so far and that more have moved out the west side.
The weather is a wild card in bison management. If big snowstorms bury the bison winter range, or the snow becomes encrusted with ice that keeps bison from their food, more will migrate and fewer will return at green up.