Yellowstone National Park has proposed a culling of around 1000 wild bison this winter.

Bison grazing in Yellowstone National Park.

Bison grazing in Yellowstone National Park. Image by Tony Hisgett / CC BY 2.0

Officials say they need to manage the animals’ migration into Montana, where bison can spread disease to livestock. The proposal is part of a controversial agreement between Montana and the federal government that requires the park to prevent the spread of brucellosis from bison to livestock. With numbers reaching 5000 bison in the park this summer, park officials believe a harsh winter could drive many of the animals into Montana.

Yellowstone’s bison population has been one of the most successful in the country, and, in spite of aggressive attempts to control bison numbers, the animals have reached near-record numbers. This year’s proposal targets females and calves in order to stymie the population’s reproduction rate. Alternative plans to relocate bison have been minimally successful, with strong opposition coming from ranchers worried about the spread of disease. Read more: