Published November 1, 2005 | November 2005 issue
Yellowstone National Park reported in September that an estimated 4,900 bison live in the park, about 700 more than last year and the highest level recorded. The bison boom raised alarms for the Montana Farm Bureau Federation and the state Stockgrowers Association, both of which favor more aggressive control of the herd as a means of eradicating brucellosis.
A federation official said that wandering bison pose a disease risk to Montana cattle. During the winter, bison in search of forage often wander out of the park, where they can come in contact with cattle. Some bison in the park have brucellosis, a disease ranchers fear because it can cause cows to abort.
The National Park Service has been criticized for not culling the herd. But a park spokeswoman said that the growing herd has had no measurable effect on the land, and wildlife advocates have long argued that there hasn't been a documented case of brucellosis transmission from bison to cattle in the wild.