BILLINGS, Mont. - Hunters killed more wild bison migrating from Yellowstone National Park this season than they have in decades, with the numbers driven by strong participation from American Indians who harvest the animals under longstanding treaty rights.
Roughly 250 bison have been killed since last fall after leaving Yellowstone for low-elevation winter range in Montana.
Combined with a mild winter, that means there's unlikely to be a repeat this year of the massive slaughters that have killed thousands of bison in the last two decades in the name of disease control.
Fewer bison leave the park when the weather is mild, and wildlife officials said the largest harvest since 1989 is relieving some of the pressures posed by a burgeoning population. The park had more than 4,200 animals at the season's start.
Still, hunting carries its own challenges, beyond criticism from animal-rights advocates.
After scores of gut piles from harvested bison recently were found outside the park's northern boundary near the town of Gardiner, wildlife officials said they removed 8,000 pounds of bison waste and one carcass. That was done out of worry the remains could attract hungry grizzly bears now emerging from their winter dens, posing a safety risk to nearby residents.
In recent years, government agencies that oversee Yellowstone bison have moved away from the practice of capturing them for slaughter or hazing them back into the park as soon as they cross the Montana boundary.
As a result, bison have access to tens of thousands of acres of historic grazing areas - and hunters have more chance to shoot them.
"This season has been really, really busy," said Keith Lawrence, wildlife division director for Idaho's Nez Perce Tribe.
Since 2006, members of the Nez Perce have traveled to Montana to hunt bison under a 1855 treaty that recognized the Yellowstone area as a traditional tribal hunting ground.
For Lawrence, that's much preferred to shipping bison to slaughter, which the tribe argues violates its rights by removing animals that hunters otherwise could harvest.
"We would like to see the population at a level where there's an annual migration," he said, adding that the tribe "is not interested in seeing a gross movement of animals" to slaughter.
Hunting is not allowed inside the park, so Yellowstone administrators rely on the killing of animals that migrate into Montana to keep the population in check. Park biologists recommended removing 450 bison this season.