HELENA, Mont. (AP) — The annual hazing of bison into Yellowstone National Park is underway, prompting a wildlife organization's latest attempt to block the use of a helicopter to drive back the animals that crossed the park's boundary over the winter.
The Alliance for the Wild Rockies filed its request for an emergency injunction Monday with the 9th U.S. Circuit Court of Appeals, saying low-altitude helicopter hazing harasses and displaces federally protected grizzly bears in the area.
Bison migrate from the park to lower elevations in Montana in the winter, but a federal-state agreement requires their return to the park in the spring to make way for cattle to graze. Montana officials led by the state Department of Livestock have hazed bison from public and private land in southwestern Montana since 2000.
This year's hazing operation began last week, said agency spokesman Steve Merritt.
"We have been moving bison pretty much every day," he said.
Total numbers were not immediately available, but Merritt said the operation moved 200 bison on Monday, 55 Tuesday and there were 250 bison remaining for Wednesday.
A large number of the animals are still on Horse Butte just west of the park near Hebgen Lake, said Yellowstone spokesman Al Nash.
There are regulations that must be followed in using helicopters to haze the animals, "but nothing prohibits it," Nash said.
The helicopter flights are authorized and paid for by the state Department of Livestock in coordination with state and federal agencies that oversee the Interagency Bison Management Plan that governs bison movements around Yellowstone.
The Alliance for the Wild Rockies filed a lawsuit in 2011 seeking to block the practice, saying the hazing flights can drive bears from their habitat.
Last year, U.S. District Judge Charles Lovell granted a temporary restraining order blocking helicopter hazing for a brief period in May 2012, but he ruled against the alliance's lawsuit in March.
In his order, Lovell cited conclusions by the U.S. Fish and Wildlife Service and the National Park Service that the operations headed by the Interagency Bison Management Group aren't likely to hurt threatened grizzlies. The bison management group also makes efforts to avoid hazing in areas where there are grizzlies, Lovell wrote.
The alliance appealed Lovell's decision to the 9th Circuit in March, and filed its emergency injunction request Monday to stop the current operation.
"There is significant documentation of grizzly bear presence in the area where helicopter hazing operations have commenced. There is also a significant body of scientific evidence indicating that helicopters cause grizzly bears to panic and flee from preferred habitat," attorney Rebecca Smith wrote in the request.
The federal appeals court has not taken immediate action on the request.
It is unclear how long the hazing operation will last this year, Merritt said. But he disputed the argument that the flights hurt grizzlies.
"We've used the helicopter for a number of years and it doesn't seem to have that much impact on the bears," he said.
AP writer Matthew Brown contributed to this report from Billings.