For the second time this winter, someone broke into a holding pen for Yellowstone National Park bison and allowed the animals to escape.
Park officials said the Stephens Creek pen was broken into sometime Wednesday night or early Thursday morning.
Most of the 73 wild bison stayed in the immediate area and eventually returned to the pen via the fence openings they had escaped through.
Bison captured as they leave the park during their winter migrations are slaughtered or held in quarantine for possible relocation at a later date. This year’s capture began Feb. 16, and as of Monday, 96 bison were being held at Stephens Creek.
Fifty-two bison escaped in a similar incident last month. They were later found in the Mammoth Hot Springs area, but the Park Service did not plan to recapture the bison unless they returned to the holding facility on their own.
No charges have been filed in connection with the January escape.
Montana has limited tolerance for natural bison migrations from the park due to fears about spread of brucellosis, a disease that can cause pregnant cattle to miscarry. Brucellosis is also carried by free-roaming elk in the region.
Park Superintendent Dan Wenk said whoever broke into the holding pen was threatening the success of the quarantine program and ensuring more bison would be sent to slaughter instead of being released on tribal lands.
Federal and state agencies responsible for managing bison that migrate out of the park plan to cull 600 to 900 animals this winter through hunting and slaughter.
Tribal and public hunters had killed 91 Yellowstone bison as of Feb. 2.
About 4,800 bison live in the park.