An initiative to repopulate bison in the West finally kicked off this week. A herd of 64 animals were transported from Yellowstone National Park to Fort Peck Reservation in Montana Monday night, the Associated Press reports.

Montana Gov. Brian Schweitzer told the Associated Press that state and tribal officials approved the transfer Friday. The bison arrived at the reservation without any public announcements because officials wanted to avoid a courtroom battle — landowners and property rights groups who opposed the transfer say bison could spread disease and compete with cattle for grazing grounds. Schweitzer sees the transfer as a major step in restoring bison populations across the West.

“This is where we’re going to establish the beachhead of genetically pure bison that will be available as their numbers grow to go to other reservations and other public lands all across the West,” Schweitzer told the Associated Press.

Extensive hunting during the 19th century wiped out many bison herds that once roamed North America. The bison found in Yellowstone are said to belong to one of the world’s last remaining pure bison gene pools. Many of today’s bison are bred with cattle. Opponents to the transfer say the bison could spread brucellosis, a disease that can cause female animals to abort their young. The bison were tested extensively during the winter to make sure they were free of the disease, according to the Associated Press.

State Sen. Rick Ripley, a plaintiff in the landowners’ lawsuit, said the unannounced transfer was in defiance of a law that required officials to come up with a statewide bison management plan prior to moving the animals.

“They just seem to think they are above the law,” Ripley told the Associated Press. “They’re going to have a lot of problems with damage to private property that they could have addressed prior to translocation.”

Fort Peck Fish and Game Director Robert Magnan said the buffalo will remain in a fenced compound on the reservation. And half of these buffalo might be making a second trip later this year to the Fort Belknap Indian Reservation in central Montana.