Horseback riders and helicopters ran the animals from West Yellowstone to their summer range in the interior of the park. A group of about 70 bison will be hazed in small groups east along the Madison River corridor, as they vacate that location some of the nearly 300 bison currently on Horse Butte will be hazed toward Baker's Hole.

It is part of the Interagency Bison Management Plan. The goal is to conserve a wild bison population and protect Montana's brucellosis-free status.

Advocates rallied against what they are calling the largest slaughter since the 1800's. And they're blaming Governor Brian Schweitzer and Yellowstone Superintendent Suzanne Lewis.

Members of the Buffalo Field Campaign say that over 1,600 bison have been killed over the past winter due to irresponsible management. They consider the state's latest bison management plan to be an over reaction to last year's brucellosis outbreak.

The group also believes the state should end a 1999 land lease deal with the Church Universal & Triumphant, saying the deal spends millions of taxpayer dollars only to continue to harm and slaughter the bison.

In response to the advocacy group, the governor's office released this statement. "The State of Montana remains committed to working with the land owners, livestock interests, wildlife and conservation groups, and the federal agencies that bear responsibility for bison management.”

As we move forward to better manage bison, the State of Montana will continue to work with bison management partners to seek and support vaccine research that provides better protection against brucellosis, work with other willing landowners on creative grazing and management agreements, and utilize fair-chase hunting to manage bison in a manner similar to other large wildlife species."