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Know the West

Latest: Elk, not bison, are spreading disease near Yellowstone

Agencies have historically culled bison to prevent the spread of brucellosis to cattle.


Since Wyoming first established its feedgrounds in 1912, thousands of elk have munched taxpayer-funded rations every winter. Conservationists have long warned that the crowding could spread brucellosis, which causes miscarriages. However, since state and federal agencies have long assumed that bison, not elk, transmit the disease to livestock, they’ve focused their attention on the bison, restricting their winter migration out of Yellowstone National Park and culling hundreds each year (“The killing fields,” HCN, 2/6/06).

In May, research by the U.S. Geological Survey and its partners found that elk — not bison — are the most likely source of brucellosis outbreaks in cattle around the Greater Yellowstone Ecosystem. DNA analysis revealed that strains found in feedground elk were much more widespread than the strain found in bison. “We found no direct links (of transmission) from bison to livestock,” Pauline Kamath, USGS ecologist and lead author, told the Billings Gazette. The findings could eventually transform national game management policies.