A major study released Wednesday now says elk – not bison - are the primary source of new brucellosis infections in Greater Yellowstone Area cattle.
That’s a significant change in thinking from 20 years ago when the scientific community blamed bison for most of the area’s brucellosis transmission cases.
The new conclusion is from the National Academies of Sciences.
Washington State University’s Terry McElwain chairs the committee that conducted the study and wrote the report.
"Brucellosis control efforts will need to sharply focus on approaches that reduce transmission from elk to cattle and domestic bison,” McElwain said.
But the Greater Yellowstone Area is a complicated place. It’s home to more than 125,000 elk and 5,500 bison that are descendants of the area’s original bison herds. Their habitat is managed by federal, state and tribal agencies.
The Academies’ new report is the first update on brucellosis in the GYA since 1998.
Terry McElwain says a lot has changed in those 19 years.
“There have been a number of cases, 27 total, of brucellosis that have spilled over into domestic cattle and domestic bison since 1998. It’s a very significant increase and is a cause for alarm,” McElwain said.
Brucellosis is a disease that influences the politics, policies and economies of areas in Wyoming, Montana and Idaho that surround Yellowstone National Park.
Agriculture is Montana’s biggest economy. Cattle infected with brucellosis can abort their calves or have lower milk production. If the disease is detected, big cattle herds can be quarantined - meaning they can’t be sold until after extensive and expensive testing.
The National Academies committee offered several recommendations to control the spread of brucellosis, including improved coordination and cooperation among area stakeholders. That’s a tall order - those stakeholders include groups with competing economic interests.
Among the Academies’ recommendations sure to stir some controversy include this one.
“Reducing elk group sizes and/or density may decrease elk seroprevalence over time and potentially decrease the risk of elk transmission. So, population control alone may help address the population to some extent,” McElwain said.
Doing that would almost certainly lead to outcries from hunters who want big elk herds, and outfitters and other businesses in three states who rely on elk hunters for their livelihoods.
Another tool highlighted in the report is the potential to close supplemental elk feedgrounds.
“There is a self-sustaining reservoir of brucellosis in elk without feedground contact,” McElwain said. “However, the weight of evidence suggests reduced use, or incremental closure of feedgrounds could reduce the overall prevalence of brucellosis in elk on a broad population basis and could benefit elk health in the long term.”
Bison advocate Stephany Seay would like to see the elimination of elk feedgrounds, but she thinks there an even better solution.
“Remove the cows remove the problem,” Seay said.
Seay is with the bison advocacy group Buffalo Field Campaign.
“The fact that they didn’t even look at a vaccination for cattle, that’s not ok. That should be one of the main things they’re looking at," Seay said. “Cattle are the most manageable element. Either get vaccinations for them, switch to steers or get them out of this ecosystem.”
But South Dakota State Veterinarian and Brucellosis committee member Dustin Oedekoven says while that would reduce interaction between wildlife and cattle, the problem is more complicated than that.
“Of course, it is a multi-use area surrounding the park," Odekoven said. "The other thing is, population reduction in any of those species, free ranging elk, bison or cattle in the area would help reduce the risk of transmission of the disease, but I think the solution to the problem really has to be more comprehensive than that.”
Calls to eliminate cows from the Greater Yellowstone Area would also certainly lead to outcries from ranchers.
The Academies’ report is non-binding, but is likely to garner plenty of attention from the people and agencies that manage elk, bison and cattle in the region. It was sponsored by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service.