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Paying ranchers to let bison roam in areas typically used for cattle grazing — rather than killing the giant animals — could reduce the risk that the bison will transmit a bacterial disease to cows, ecologists say.

Some 1,600 Yellowstone National Park bison were killed last winter to control the spread of brucellosis, a disease that causes miscarriages, weight loss and reduced milk production in cattle that inhale infected bison afterbirth or aborted fetuses. Brucellosis was widespread in cows in the 1800s, but cattle in most states are now free of the disease. No cases of bison-to-cattle transmission of brucellosis outside of captivity have ever been documented, according to the National Park Service, but they are periodically slaughtered as a precaution.

Yellowstone's 4,000 bison typically stay in the park's higher elevations, but they sometimes graze at lower levels near cattle-grazing areas in the Montana section of the park if heavy snow or ice makes food scarce. (The park spans three states: Wyoming, Montana and Idaho.) Limited numbers are allowed to roam in those areas as part of the Interagency Bison Management Plan devised by government agencies including the National Park Service, U.S. Department of Agriculture, Montana Department of Livestock and the state's Fish Wildlife & Parks department. If too many bison leave the park and are found to have antibodies to brucellosis, they're killed.

But mathematical modeling shows that even as the bison population grows, the chances are low that the animals will migrate and give birth to infected offspring in areas that cattle graze in, zoologist Marm Kilpatrick reports in today's Journal of Applied Ecology. Compensating ranchers for the use of their land and allowing more bison to roam there, then, would cost less than killing the animals, he writes. "If you could work out something with those ranches, you could let a lot more of those bison roam without increasing the risk," Kilpatrick, an assistant professor of population biology at the University of California, Santa Cruz, told the Associated Press.

The other option is reclassifying the brucellosis infection-status of the area surrounding Yellowstone so that if bison were to transmit disease to cattle, "the cost of testing all the animals and the economic loss will be relatively small" for ranchers, Kilpatrick tells ScientificAmerican.com.

In 1902, hunting had reduced Yellowstone's bison population to just 23. Preservation efforts restored the population, and there are now about 150,000 bison in public and private U.S. herds, 4,000 of them in Yellowstone, the Park Service says. Still, the majestic bison is beloved by conservationists who consider it a symbol of the American West.

"The risk of disease transmission from bison or elk — the two wild hosts to cattle — is not uniform" across the park's 2 million acres, Glenn Plumb, Yellowstone's chief of aquatic and wildlife management, tells us. "Estimating the risk of transmission in a spatial context will be helpful to understanding where to prioritize risk management."

A DOI veterinarian, Jack Rhyan, told the AP that the study's modeling looked accurate, but that buying grazing rights wasn’t necessarily the best alternative to killing the bison. "It's a temporary way to take the heat off of the problem," Rhyan told the newswire, "but that just allows the problem to get that much bigger."

Third paragraph updated on Jan. 13 at 2:15 p.m. to add geographical clarity.

Image of bison by U.S. Department of Agriculture via WikiMedia Commons

4 Comments

1. 1. ghettoplainsman 11:53 PM 1/12/09

   The buffalo have suffered so much yet the last wild herd left in the Yellowstone area are being blamed and killed for a cattle disease that came with ranchers' European cattle and the conquest of the West. Buffalo are not relics of the past; they are living, breathing survivors of a catastrophic violence that has turned the Great Plains --- the Garden of Eden that once was America's prairies and plains-- into a beaten, struggling, overgrazed deathzone, America publicly prides itself on concepts of fairness and decency, yet until we as a nation move past our pathological violence against the Earth, each other, and ourselves, we will never evolve, and in fact likely find that same death and misery ultimately catching up to us too in the end. By healing the Earth, we can heal ourselves, and that is our our crucible and sacrament in the new millennium, embodied in our stricken Great Plains like no other.
   
   Jarid Manos
   
   Author/Ghetto Plainsman www.ghettoplainsman.com
   
   Founder/CEO
   Great Plains Restoration Council www.gprc.org
   
   twitter.com/ghettoplainsman

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2. 2. Twosox in reply to ghettoplainsman 02:28 AM 1/13/09

   Amen for your comment! I have no idea how ANY American will win against the cattle lobby, who can afford high buck congressman and reps. The WILD life will never win in ANY state when in competition with cattle and sheep! Look at the wild horse round ups, constant, reducing herds to non-sustainable lows, knowing those targeted herds can not recover with numbers so low. It is a sad day in this country. Somehow we have forgotten who our true Mother really is, and that is Mother Earth. She will only take the killing so long.....and hopefully she will wipe the Planet clean, being as we continue to remain so ignorant about it. Peace!

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3. 3. Buffaloed 03:43 PM 1/13/09

   Paying ranchers for tolerance of anything has never worked. Just look at the "tolerance" that ranchers have for wolves even while Defenders of Wildlife compensates them for livestock losses.
   
   In my opinion ranchers should not be compensated for anything that happens on public lands to their livestock. Better yet, end public lands grazing and much of these "conflicts" will dissolve.

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4. 4. mtrancher 10:31 PM 1/25/09

   How tolerant should ranchers be of wolves that repeatedly kill their livestock, horses and dogs specially bred to protect sheep from coyotes when the "compensation" you mention is inadequate and presently too large for the Defenders Of Wildlife to provide?
   
   And, yes, brucellosis did come from Europe but so did smallpox but what logic says to leave a small reservoir of infection to perpetuate the plague? We wouldn't do it with any other disease! The appearance of the disease in cattle herds seems to come from elk that have mingled with cattle or shared their calving grounds. The reason bison haven't spread theirs to cattle probably is because they haven't been allowed to mingle in this manner.
   
   And speaking of a struggling, beaten, over-grazed deathzone, that pretty well describes the range condition of much of the park with its 70+ years of too many elk & bison. The National Forest grazed by wildlife and sheep or cattle is pristine compared to Yellowstone Park! Any rancher would be expelled from his forest permit if he grazed it just one year like the park is grazed every year. It's getting better now that the wolves are killing most of the elk calves every year and changing the herds' behavior (i.e. keeping them up on the foothills away from the stream bottoms).
   
   Management of the Park has to consider some big problems that can't just be left to "nature" because like it or not, the Park is not and cannot be all "nature" in today's world. Brucellosis in the Park and wolves outside the park are two of those problems that will require the park service and many of you to accept some modern solutions.

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