BILLINGS, Mont. (AP) -- 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, the 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 past 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 travelled to Montana to hunt bison under a 1855 government 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.
A limited slaughter still is possible, park spokesman Dan Hottle said, and the U.S. Department of Agriculture is seeking up to 63 bison this year for use in an experimental animal contraception program.
Several other tribes with treaty rights also participated in this year's hunt, including the Confederated Tribes of the Umatilla Indian Reservation
The Umatilla police chief, Tim Addleman, said seven Umatilla hunting parties took 48 bison after traveling from their reservation in Oregon to the Yellowstone area, a distance of almost 700 miles. Each hunting party included a tribal wildlife officer and at least four people in addition to the hunter.
The large crew is necessary to carry out the laborious task of butchering animals that can weigh up to 2,000 pounds.
The tribes combined took an estimated 211 bison. State-licensed hunters took 37 during a three-month season that ended Feb. 15.
Many bison carry the disease brucellosis. If transmitted to cattle, it can cause pregnant animals to prematurely abort their calves.
Despite recent changes in federal policy that eased trade sanctions against states with brucellosis-infected cattle, Montana's livestock industry and its supporters are pushing to restore restrictions that would keep bison in the park.
That includes so-called "zero tolerance" bison legislation pending before the Montana Legislature and a state lawsuit that would reverse the state's decision to allow the animals to roam largely free in the 75,000-acre Gardiner Basin.
The state is fighting the lawsuit, and Montana Fish, Wildlife and Parks has come out against the zero tolerance measure.
Wildlife officials say the proposal harkens back to the late 1980s, when the state actively encouraged hunters to kill every bison that crossed the Montana line.
That resulted in a record 489 bison killed in 1989. It also trigged an international outcry that led to the cancellation of bison hunting until it resumed on 2005.
The hunts since then have been more closely regulated.
"Our goal was to as much as possible manage the population level through hunting as opposed to other means," said Pat Flowers, the Yellowstone region supervisor for Montana Fish, Wildlife and Parks. "If we can have a more consistent removal out of the park, we can get the population back down near the target of 3,000 to 3,500 bison."
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