BILLINGS, Mont. — Federal wildlife officials on Monday listed 20 parcels of public lands in 10 states that could be suitable for bison from Yellowstone National Park, but said it would be years before any relocations of the animals.
The sites eyed for potential future herds include areas as diverse as Arizona's Grand Canyon National Park, an Iowa wildlife refuge and a North Dakota national historic site.
They were identified in a long-awaited Department of Interior report that looked at using Yellowstone's bison herds to further the restoration of a species that once ranged most of the continent.
Tens of millions of bison occupied North America before overhunting nearly drove them extinct by the late 19th century.
Yellowstone was one of the last holdouts for the animals in the wild. It had roughly 4,600 bison at last count. During their winter migrations, the animals periodically spill into neighboring Montana, triggering large-scale, government-sponsored bison slaughters to prevent the spread of the animal disease brucellosis.
Capturing the animals and shipping them to other public lands would ease those population pressures.
A pilot bison relocation program in Montana has struggled for years against opposition from ranchers. They worry both about the disease and the possibility of bison competing with cattle for grazing space.
Several dozen Yellowstone bison have been moved onto American Indian reservations in the state after the animals were held in quarantine for years to make sure they were disease-free.
Efforts to relocate another group of about 145 bison that went through the quarantine have stalled. Montana Fish, Wildlife and Parks officials in June said they were considering new requests to take the animals from tribes, private conservation groups and the state of Utah.
If the park service were to revive the quarantine program and make it permanent, federal officials said it could be five years to a decade before more animals were relocated.
"If we were to do this, where would you place these bison? This report gives us a head-start on that question," said Jorge Silva-Banuelos, a U.S. Interior Department official.
Some of the 20 sites listed Monday already have bison. However, most bison outside Yellowstone are bison-cattle hybrids that lack the pure genetics of the park's herds.
Yellowstone's chief scientist, Dave Hallac, said planning for a bison quarantine program is expected to begin in late summer or early fall. Public input will be part of that process.
"Within a five-year-period there may be the possibility of moving some brucellosis-free bison," Hallac said.
Conservation groups that have pushed for alternatives to Yellowstone bison slaughters welcomed Monday's report. But Defenders of Wildlife said it fell short of a clear plan of action, and the National Wildlife Federation said it did not include enough collaboration with American Indian tribes.
Silva-Banuelos responded that the Interior Department had helped with the prior relocation of bison to the tribes of Montana's Fort Peck and Fort Belknap reservations. He said Monday's report would be a "foundation for future collaboration and consultation" with tribes.
Then-Interior Secretary Ken Salazar first issued a directive for his agency to come up with a relocation plan for Yellowstone bison in May 2012.
The states and locations identified Monday as potentially suitable for relocated bison were:
• Arizona: Grand Canyon National Park
• Colorado: Baca National Wildlife Refuge, Great Sand Dunes National Park and Preserve
• Iowa: Neal Smith National Wildlife Refuge
• Kansas: Tallgrass Prairie National Preserve
• Montana: Charles M. Russell National Wildlife Refuge, National Bison Range
• Nebraska: Agate Fossil Beds National Monument, Fort Niobrara National Wildlife Refuge, Scotts Bluff National Monument, Valentine National Wildlife Refuge
• North Dakota: Knife River Indian Villages National Historic Site, Sullys Hill National Game Preserve, Theodore Roosevelt National Park
• Oklahoma: Chickasaw National Recreation Area, Wichita Mountains National Wildlife Refuge
• South Dakota: Badlands National Park, Wind Cave National Park
• Utah: Book Cliffs, Henry Mountains