Study: Focus Should be on Elk in Yellowstone Infection Fight

Report says agencies should consider reducing the elk population through hunting, contraception and other methods

By Dillon Tabish

BOZEMAN — Wildlife managers around Yellowstone National Park should focus more on elk than bison in their efforts to prevent the transmission of an infection that causes cattle to abort their offspring, a new study recommends.

The report, released Wednesday by the National Academies of Sciences, Engineering and Medicine, says agencies should consider reducing the elk population through hunting, contraception and other methods. It also recommends gradually reducing the use of supplemental winter feed grounds in Wyoming to avoid the creation of large concentrations of elk where brucellosis could spread.

However, the study acknowledges the feed grounds could also offer managers an easy way to test and kill female elk that have been exposed to brucellosis and to administer a contraceptive to those that do not test positive.

Brucellosis has been eradicated from the U.S. with the exception of areas of Idaho, Montana and Wyoming. It is spread through contact with aborted fetuses and birthing tissues and fluids.

Elk have transmitted the disease, but there has never been a documented case of bison transmitting the disease to cattle in the wild.

Current management efforts are focused on bison, in part to reduce the population in Yellowstone and because cattle producers fear bison will infect their herds as they graze near the park. Cattle that graze in the area are subject to additional testing requirements.

“However, until tools become available that would simultaneously allow for an eradication program in elk, additional aggressive control measures in bison seem unwarranted,” the study says.

Glenn Hockett of the Gallatin Wildlife Association in Bozeman and Stephany Seay of the Buffalo Field Campaign were concerned because the report puts the focus on managing wildlife.

Seay said the simplest solution is not to allow cattle to graze in the Greater Yellowstone Area.

The report says further studies are needed to monitor elk migration patterns, how the disease spreads in elk and bison, and what management efforts produce results.

The effort could benefit from improved vaccines, contraceptives and rapid field tests for exposure to brucellosis.

The report acknowledges that addressing the issue is difficult because it involves numerous agencies and an interconnected ecosystem.

Eradicating brucellosis might be an ideal long-term goal, but it’s not a feasible short-term goal for scientific, social, political and economic reasons, the study said.

The National Academies of Sciences, Engineering and Medicine are private, nonprofit institutions that provide independent, objective analysis and advice related to science, technology and medicine.