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University Researchers Suggest Solution To Yellowstone National Park's Bison Problem


Is there a more cost-effective way to manage Yellowstone National Park's bison and brucellosis? Kurt Reanshek photo.

It's been relatively quiet so far this winter on the front lines of the battle over Yellowstone National Park's bison and their migratory desires.

That's not to diminish the problem. After all, last winter roughly one-third of the park's bison were killed over concerns that they might spread brucellosis to livestock, mostly in Montana. While various groups continue to search for a long-standing solution to this dilemma, some researchers at the University of California, Santa Cruz, believe they have the most cost-effective answer.

"There are more cost-effective management solutions than the current approach, which has been highly controversial," says Marm Kilpatrick, assistant professor of ecology and evolutionary biology at the university and lead author of the study released today.

The alternatives suggested by the study, such as buying grazing rights from cattle ranchers in a few areas around the park or testing all cattle within a special zone around the park, are not new ideas. But Mr. Kilpatrick said his group's quantitative risk assessment highlights the substantial benefits of these strategies, as well as their consequences.

Working with Colin Gillin of the Oregon Department of Fish and Wildlife and Peter Daszak of the Consortium for Conservation Medicine in New York, Mr. Kilpatrick developed a quantitative risk assessment model for the transmission of brucellosis from bison to cattle in the Yellowstone area. Brucellosis is a bacterial disease that causes weight loss, spontaneous abortion, and reduced milk production in cattle. It is considered a major threat to the cattle industry, which has achieved "brucellosis-free" status in most states after an intensive effort by the U.S. Department of Agriculture.

It's widely held that the Yellowstone bison herd probably became infected from cattle that grazed in the park a century ago. Now, cattle ranchers want to keep the bison confined to the park. During severe winters, however, when heavy snow or ice covers Yellowstone's grasslands, many bison move outside the park's boundaries to graze at lower elevations.

To keep bison away from areas where cattle graze, state and federal agencies try to herd the bison back into the park by "hazing" them with helicopters, horses, and snowmobiles. When that fails, the bison may be shot or rounded up, sometimes tested, and shipped to slaughterhouses.

But Mr. Kilpatrick and his coauthors found that the risk of brucellosis transmission to livestock is very low in most years and is periodically high only in certain localized areas.

"There are just a few areas where cattle graze around the park. Compensating ranchers for the grazing rights for those areas would be much more cost-effective than the current management plan," Mr. Kilpatrick said.

Another proposal has been to consider the greater Yellowstone area of Montana as a separate zone from the rest of the state in terms of brucellosis infection status and to provide yearly testing of all cattle within that zone. The cost would be just a fraction of the amount spent by government agencies on the current management strategy, which was estimated in 2000 to be about $2.5 million per year, the researchers said. Similarly, compensating ranchers for the value of all the cattle that graze on public and private lands around the park (assuming they would sell their rights), would cost about half the current yearly amount.

"To me, the most interesting result of the study was that in a number of years, the model predicts there will be no risk of transmission at all," Mr. Kilpatrick said. "Even with the bison population at 7,000--the largest population size in our simulations--there was zero risk 10 to 15 percent of the time, because even when some bison leave the park, they don't always give birth and leave infected birthing materials."

To transmit brucellosis to cattle, an infected bison would have to enter an area where cattle graze and abort or give birth, leaving infected tissue on the ground, and cattle would then have to contact the infected material while the bacteria in it were still alive.

Mr. Kilpatrick noted that so far there have been no documented cases of brucellosis transmission from unconfined bison to cattle, although transmission from elk to cattle has occurred several times around feed grounds. Blood tests show that about half the Yellowstone bison herd has antibodies indicating exposure to the brucellosis bacteria, but it's much harder to determine if an animal is actually infected, he said.

Vaccination efforts are currently under way to reduce the prevalence of brucellosis in the bison herd. Eliminating the disease entirely would be very difficult without rounding up all the bison and vaccinating every animal for several years in a row, according to the researchers.

Even in the absence of brucellosis, however, management challenges would remain, he said. Without periodic culling, the Yellowstone bison population will continue to grow and could reach 7,000 by 2012. As the population grows, more bison will tend to leave the park, and the massive animals are not particularly respectful of fences and property lines.

"Bison used to roam the plains in the millions, and they will try to do so again as their population grows," said coauthor Peter Daszak. "Ultimately, our society will have to decide whether to let bison roam freely or continue shooting them. It's a tough challenge, but hopefully our analysis provides a way forward for alternative approaches."

There are other bison herds on public and private lands in the United States, but the Yellowstone herd is the only one that has remained free-ranging and unconfined. A record number of Yellowstone bison--about 1,600--were killed last winter. With the herd now reduced to about 3,000 animals, a repeat of that is unlikely this year, Mr. Kilpatrick said.

Funding for the study, which is scheduled for publication in the February issue of the British Ecological Society's Journal of Applied Ecology and is being published online today, was provided by the Wilburforce Foundation, the National Fish and Wildlife Foundation, the National Science Foundation, and the V. Kann Rasmussen Foundation.


I went on my first ski patrol ever with Buffalo Field Campaign on Saturday. I didn't see any bison on the western edge of the park out by Duck Creek. It was quite an education to see how close the trap was to the boundary of the park (and in the north, the trap is actually INSIDE the park). The snow isn't particularly deep for this time of year, and last year was such a cruel year.

Today, a couple of my friends from BFC are staying with my family in Bozeman; they are attending the Board of Livestock meetings, where tomorrow brucellosis is on the agenda. They don't have particularly high hopes for the meeting; news recently is that a management zone around Yellowstone is getting push back from some stockgrowers groups and an increasing number of state vets.

We have known for a long time that even if you aren't an ideologue like me who wants to see bison roam free all the way back into their historic range that there are pragmatic solutions for people who want something in between. Brucellosis need not be a bugaboo for ranchers; what is the bugaboo are outdated APHIS rules that penalize them unfairly for a relatively harmless disease that is easy to contain. Fences could be built in the few areas where cattle are. Year round tolerance is possible in the many areas where cattle are not. Negotiations could be made on a rancher by rancher basis (several wouldn't mind seeing bison on their property), and bison could be managed as are other wildlife.

Now, of course, once the boundary shifts, people like me are certainly what the stockgrowers worry about - people who will continue to push the boundaries and challenge a way of life that uses cows as a commodity to use over the land. But, frankly, they worry too much - there aren't a lot of people like me. They'd be better off cutting people like me off from the majority of people around here who think that their stance is extremely unreasonable. However, when you control the levers of power, as the stockgrowers do in Montana despite their lack of similar influence on the overall economy of our states, there's not much incentive to change. Cost isn't the issue; power over the land is. Therefore, the outrageous cost is worth it to those who hold the power and see the price as a way of maintaining their power and their own bizarre notions of what the land should allow.

Jim Macdonald
Buffalo Allies of Bozeman
The Magic of Yellowstone
Yellowstone Newspaper
Jim's Eclectic World

The war on elk and brucellosis in Montana has just started.

Elk were just killed near Gardiner.

This is an important and unprecedented development and a rather stupid move when it comes to building public support. Let's see these so called elk groups like Friends of the Northern Yellowstone Elk Herd speak up against this; no doubt, they will be silent because they only care about killing wolves, not protecting elk. But, let's see.

Jim Macdonald
The Magic of Yellowstone
Yellowstone Newspaper
Jim's Eclectic World

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