BADLANDS NATIONAL PARK, S.D. — Buffalo stroll undisturbed, pausing occasionally to wallow in the grass and caked dirt, while prairie dogs yip intermittently as they dive into their holes and pop out again to survey the landscape.
This northern stretch of the park, known as Sage Creek Wilderness, is what the Northern Great Plains used to look like.
Several miles away, in the park’s 133,000-acre South Unit, located on the Pine Ridge Indian Reservation, the scene is more barren. The Army forced more than 800 Oglala Sioux families to leave their homes here in 1942 so that part of the reservation could be turned into a bombing range. The land has partly recovered, but the bison have yet to return.
That could soon change. The Oglala Sioux and National Park Service are drafting legislation to create the first tribal national park — giving the tribe the right to manage and operate the lands — in an effort to bring buffalo back to the grasslands where they roamed long before human settlement.
These steps would reshape only a portion of the Great Plains, a landscape that has been transformed by cornfields, highways, and big box stores. But for the Oglala Sioux, the wildlife that has defined their tribe and the region’s ranchers, it is a chance to reclaim an area that served as a crucible for the nation’s economic and political expansion in the 1800s.
Ruth Brown, an Oglala Sioux tribal council member who is helping draft the legislation for the new park, said in an interview: ‘‘Our buffalo are going to be coming back to our country.’’
The group envisions a herd of more than 1,000 animals to ensure that it has sufficient genetic diversity.
Tens of millions of bison used to range freely in North America before they were almost wiped out in the late 1800s. The American Bison Society disbanded in 1935 with the understanding it had saved the species by placing 20,000 animals in conservation herds; there are now an additional 400,000 or so being raised in the United States and Canada for meat production.
But those numbers are not enough for the buffalo to reclaim their traditional role in the ecosystem, especially because even those conservation herds amount to what buffalo herder Duane Lammers calls ‘‘islands,’’ in circumscribed areas.
Free-roaming bison provide habitat for grassland birds and other animals by grazing intermittently, leaving the grass at different heights. Cattle ranching, by contrast, leaves the grass at a more uniform level.
The Wildlife Conservation Society relaunched the American Bison Society in 2005, and a coalition of tribes, environmentalists, and ranchers have been working to bring them back to areas where there is enough available land.
‘‘We’re in a sort of a renaissance, where conservation groups are realizing it needs to happen on a larger scale,’’ said Dennis Jorgensen, a biologist and Northern Great Plains program officer for the World Wildlife Fund.
The Badlands — where sediment deposits have been eroded by wind and water during millions of years — is an ideal setting for buffalo to make a comeback. The region is less suitable for agricultural development than other parts of the Great Plains.
But even though it makes sense from an ecological and economic perspective, reintroducing buffalo poses a political challenge because some Oglala Sioux own cattle-grazing permits in the area, including on the reservation. On June 11, the tribal council voted to phase out all cattle leases on the South Unit by Oct. 31, 2015.