On the wide open plains of the Fort Peck Indian Reservation, Robert Magnan leaned out the window of his pickup, set his rifle against the door frame and then “pop!" — a bull bison tumbled dead in its tracks.

Magnan and a co-worker shot two more bison, also known as buffalo, and quickly field dressed the animals before carting them off for processing into burgers and steaks for distribution to members of the Fort Peck Assiniboine and Sioux Tribes in northern Montana.

As lawmakers in Washington D.C. plod toward resolution of the record-long government shutdown that interrupted food aid for tens of millions of people, tribal leaders on rural, impoverished reservations across the Great Plains have been culling their cherished bison herds to help fill the gap.

About one-third of Fort Peck's Assiniboine and Sioux tribal members depend on monthly benefit checks to get by, said Chairman Floyd Azure. That's about triple the rate for the U.S. as a whole. For November they received only partial payments after President Donald Trump’s administration choked off funds to the Supplemental Nutrition Assistance Program (SNAP) as it sought political leverage during the shutdown.

Fort Peck officials say they anticipated this moment years ago, when they were bolstering their herd with animals transferred from Yellowstone National Park over the objections of local cattle ranchers worried about animal disease.

The tribal government in October authorized killing 30 bison — equal to about 12,000 pounts of meat. Half had been shot by Tuesday and the potential deal to end the shutdown comes too late for the rest: With Montana among states that dispersed only partial SNAP payments, Azure said Fort Peck will keep handing out buffalo meat for the time being.

Tribes including the Blackfeet, the Lower Brule Sioux, the Cheyenne River Sioux and the Crow have done the same in response to Washington's dysfunction: killing bison from herds they restored over recent decades after the animals were hunted to near extinction in the late 1800s.

Fort Peck tribal members Miki Astogo and Dillon Jackson-Fisher, who are unemployed, said they have been borrowing food from Jackson-Fisher's mother in recent weeks after the SNAP payments didn't come through, but she has a full household. On Sunday they got a partial payment — about $198 instead of the usual $206 for the month, Astogo said, so they walked four miles into town to pick up a box of assorted food that included two pounds of bison.

Native American communities elsewhere in the U.S. also tapped into natural resources to make up for the lost federal aid. Members of the Mi’Kmaq Nation in northern Maine stocked their food bank with trout from their fish hatchery and locally-hunted moose meat. In southeastern Oklahoma, the Comanche Nation has been accepting deer meat, and in the southwestern part of the state the Choctaw Nation set up three meat processing facilities.

Another U.S. Department of Agriculture program that provides food to income-eligible Native American households, the Food Distribution Program in Indian Reservations, has continued through the shutdown.

Buffalo for centuries played a central role for plains tribes, providing meat for food and hides for clothing and shelter. Assiniboine historian Dennis Smith says bison were “the staff of life” for his ancestors.

That came to abrupt end when white “hide hunters” arrived in 1879 in the Upper Missouri River basin around Fort Peck, which had some of the last vestiges of herds that once numbered in the millions of animals. By 1883 the animals were virtually exterminated, according to Smith, a retired history professor at the University of Nebraska-Omaha.

With no way to feed themselves and the government denying them food, the buffalo's demise heralded a period of starvation for the Assiniboine, he said. Many other plains tribes suffered similar hardships.

AP Video by Matthew Brown