Winter brings a special beauty to Yellowstone National Park. But it also brings hard times for Yellowstone's wildlife.
Animals such as elk and bison have to dig through snow to find food. Many of the burly bison migrate out of the mountains to greener pastures near the edge of the park. But they do so at their peril.
Although they have no way of knowing it, once bison cross the park's boundary lines and step out of Yellowstone, they are subject to capture and death. That's because of an agreement between federal agencies and the state of Montana to keep bison away from cattle outside the park. Many of the park's 4,200 bison carry a disease called brucellosis. In cattle, it can cause cows to abort their calves.
Frank Riegler, a rancher near Yellowstone, says, "You can't have livestock and buffalo. I mean, you just can't do it."
Livestock represent a multi-million dollar industry in Montana, with powerful influence. So, when bison cross the park's boundary, they are hazed back — by horse, snowmobiles, even by helicopters. If that does not work, the bison are herded into pens. Those that test positive for the disease are shipped to slaughterhouses. Sometimes they do not even make it to the pens. They are simply shot on the spot.
About 3,000 Yellowstone bison have been killed over the past decade. Critics call it a senseless and random slaughter.
"There has never been a single recorded case of bison transmitting brucellosis to cattle in the wild," says Tony Jewett, senior director of the National Parks Conservation Association. He also points out that, even though the only threat, however remote, is from pregnant female bison (the disease is passed through birthing fluids), half of the 244 animals killed last year were bison males and calves. Rick Wallen, a wildlife biologist at the park, says the risk from those animals is "virtually non-existent."
The Montana Department of Livestock, however, says low risk is not the same as no risk. State veterinarian Tom Linfield says, "What we're doing, anyway, appears to be working…from the Montana perspective, in keeping the separation between cattle and bison."
Ironically, brucellosis was originally introduced into the park by cattle.
Both state and federal officials would someday like to eliminate the disease in the park. There is, however, no effective vaccine and no effective way to deliver one to Yellowstone's bison or, for that matter elk, which also carry the disease.
In fact elk, not bison, are blamed for brucellosis that has shown up this year in cattle herds in Wyoming. But there is no similar program for capturing and killing elk that stray out of Yellowstone. Jewett says that is because elk have "a constituency that supports them, which is a hunting constituency."
Wildlife biologist Wallen says, "The killing of bison is something that we don't like to see. But there's no tolerance for those animals beyond the park boundaries."
A dozen bison have already paid with their lives for wandering out of the park this winter. For Yellowstone's bison, another killing season has begun.