Bison have started to migrate out of Yellowstone National Park and into southwestern Montana where they could be the target of hunters attempting to reduce the herds’ population size by up to 900.

Yellowstone spokeswoman Morgan Warthin told the Associated Press the bison have moved into the Gardiner basin as part of their yearly migration. Outside the confines of the park, Yellowstone states, they may be captured and taken to slaughter at the Stephen’s Creek Facility.

The hunt is part of a policy to regulate the population of bison in Yellowstone…