Yellowstone National Park officials said at a meeting in Nevada last week that their wild bison population is larger than ever, with over 5,000 animals in the herd. This could be a challenge for the park, which is charged with controlling the numbers that migrate into Montana. The park met with a group of federal and state agencies to discuss updates to their Interagency Bison Management Plan (IBMP).
Each winter, harsh conditions push bison herds into lower elevations, and many leave the park. Ranchers worry that incoming bison will infect their cattle with brucellosis, a disease that causes pregnant females to miscarry. The state of Montana once sued the park to stop the migration. Biologists say, this year, they may have to remove as many as 900 bison from outside the park.
Under the agencies’ current plan, hunters can kill bison outside the park from November until March. Others will be captured and sent to slaughter. Park biologist Rick Wallen says hunting is the cleanest of these management options, but it comes with challenges.
“There is a very limited area for wild bison to migrate to,” Wallen said. “We have huge demand by hunters to come to the area outside the park and harvest animals. So what we’ve observed since we endorsed hunting is that hunting cannot remove enough animals to manage population abundance.”
Wallen says that if hunting were the park’s only tool, the bison population would increase to an unsustainable level. The animals wouldn’t have enough food to survive.
Wallen adds that another option managers have been exploring is to allow disease free bison to be transferred to tribal lands in Montana.
“Most, if not all, tribal nations across the country find wild bison as spiritually and culturally viable, and would like to be part of a solution that does reduce the number of animals that get put in trailers and shipped to slaughter plants,” Wallen said.
One thing that's certain, Wallen says, is that the park has to limit where the bison are allowed to roam as long as bison and livestock compete for habitat.