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Send an alert. Missing - dozens of bison. Last seen together, two holding pens at Yellowstone National Park. Authorities say the animals escaped when someone used bolt cutters to open up a fence. As Yellowstone Public Radio's Nate Hegyi reports, the park wants to find out who's responsible.
NATE HEGYI, BYLINE: It's a windy and unseasonably warm winter day in Yellowstone National Park in Montana. Spokesperson Morgan Warthin is standing in the middle of a massive empty valley.
MORGAN WARTHIN: Yellowstone is, like, so big. Where do you begin to look?
HEGYI: She's searching for any of the 52 bison that were set free in mid-January. That's when the National Park Service discovered their holding pens had been broken into. Now the bison are scattered across an area larger than Delaware, and officials have launched a criminal investigation to find out what happened.
RICK WALLEN: I didn't believe it when I was first told.
HEGYI: That's park bison biologist Rick Wallen. He says finding these animals won't be easy because there are literally thousands of bison in Yellowstone. And the only thing that sets the escaped animals apart is a tiny ear tag, which can be hard to spot from long distances.
WARTHIN: Bison, in the wintertime, are incredibly furry animals. And so the fur, being so thick, covers up those tags. So it makes it very difficult to find the tag.
HEGYI: Before the bison went missing, Yellowstone Park officials hoped to send them to a nearby Indian reservation in Montana. It was part of an effort to help the animals avoid what's become an annual and controversial slaughter of bison from Yellowstone. See, over the past decade, the park - under court order - has sent hundreds of bison to be killed almost every year because nearby ranchers fear the animals could infect their cattle with a disease called brucellosis. It can cause pregnant cows to abort their young. However, there's never been a confirmed case of bison passing on brucellosis to cattle in the wild. Biologist Rick Wallen says the fear is exaggerated. But ranching is also big business in Big Sky Country.
So the park service hoped they could save some bison otherwise headed to slaughter by first quarantining them and then creating a new herd on the Fort Peck Indian Reservation. The animals lived in the holding pens for more than a year while the park service worked with Montana and the USDA to get the pens approved as a quarantine. Then, Warthin says, someone cut the fence.
WARTHIN: A lot of hard work was put into testing these animals. And all that work, all that effort is gone.
HEGYI: Now the question is who allowed these animals to escape. Rick Wallen says he suspects animal rights activists could be involved.
WALLEN: Folks that hate seeing wild bison contained in fenced facilities.
HEGYI: Folks like Chris Hurley, a coordinator with the Buffalo Field Campaign. Hurley's got a bison patch on his jacket with e pluribus unum written underneath. He says his group had nothing to do with the animals' escape.
CHRIS HURLEY: Something like that from the campaign would be kind of detrimental to anything we're trying to achieve.
HEGYI: That being said, he's kind of happy someone cut the animals loose. Hurley says all Yellowstone bison should roam free.
HURLEY: Once they're inside of that facility, they're never going to be wild animals again. After years of domestication and being fed and being watered just to be shipped to end up on lands behind a fence somewhere is just insulting to this, which is our national mammal.
HEGYI: Park officials say they've spotted some of the missing bison more than five miles away from the holding pens. But they won't round them up like cattle because it's too far away. Instead, they hope the bison return on their own. For NPR News, I'm Nate Hegyi in Mammoth Hot Springs, Wyo.
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