BILLINGS, Mont. - A group of Yellowstone National Park bison is due to finally arrive at a permanent home on a northeastern Montana American Indian reservation on Thursday, almost a decade after they were captured and spared from slaughter.

About 100 of the 138 animals were loaded onto trucks late Wednesday to travel overnight to the Fort Peck Indian Reservation, home to the Assiniboine and Sioux tribes.

All of the bison were set to make the trip Wednesday, but one of the trucks broke down. The remaining bison will begin their journey Thursday.

The small herd will help tribal members regain a connection to an animal which helped shape their ancestors' nomadic existence, tribal officials said.

Bison, also known as buffalo, still play a central role in many ceremonies for Plains Indian tribes.

The Yellowstone animals will be "welcomed with prayers," said Tom Escarcega, one of a group of Assiniboine and Sioux tribal leaders who planned to escort the animals to Fort Peck.

"It starts to bring back our ceremonies that we kind of forgot," Escarcega said. "In our culture, we treat the buffalo as a people, and we're the two-legged nation. They deserve respect."

Escarcega said a bull bison from the group that could not be transported because it was uncooperative had to be killed. The meat was to be distributed to tribal members.

Yellowstone's bison are highly prized for their pure genes. Yet thousands have been killed during their winter migrations under a government-sponsored program meant to protect livestock outside the park from the disease brucellosis, which many bison carry.

The bison for the tribes were culled from Yellowstone's wild herds in 2005 and 2006 under an experimental program designed to start new populations elsewhere.

They are being shipped at night because they will be calmer and easier to move, said Tom Palmer with Montana Fish, Wildlife and Parks. The wildlife advocacy group Defenders of Wildlife is covering the shipping costs, Palmer said.

On the reservation, the bison will be kept in a 140-acre pen for a 10-day adjustment period, Fort Peck Fish and Game Director Robert Magnan said. Then they'll be released onto a 13,000-acre pasture north of Poplar which already holds about 48 Yellowstone bison transferred to the tribes two years ago.

Earlier attempts to relocate the animals failed, in part because of opposition from livestock interests. They had been held since 2010 on CNN founder Ted Turner's ranch near Bozeman. As compensation for caring for the animals, Turner gets to keep 75 percent of their offspring, or 179 bison.

Most of those offspring will be kept in Montana for the foreseeable future as part of a conservation herd, Turner Enterprises General Manager Mark Kossler said. Some of the bulls will be used for breeding to improve the genetics in other Turner-owned bison herds scattered over 15 ranches across the Western U.S., Kossler said.

"It's worked out well for the bison," Kossler said. "They've been preserved instead of going to slaughter, and they're going to be used for conservation."

The experimental program under which the original animals were captured as they attempted to migrate outside the park has since ended.

However, Yellowstone administrators have proposed reviving the program in hopes of establishing the park as a source of bison to start new herds across the U.S.

Closer to the park, wildlife officials on Wednesday released a proposal requested by Gov. Steve Bullock which would allow bison to roam year-round in some parts of Montana if the park population drops below 3,500 animals.

If adopted, it would break a longstanding impasse over where and when bison should be allowed to roam in areas of Montana bordering Yellowstone.

Bullock intervened after state livestock and wildlife officials could not agree on a solution.

At populations exceeding 3,500 animals, bison still would be subject to slaughter, increased hunting and hazing back into the park.

Yellowstone had about 4,900 bison at last count.