Bison were once a wellspring of sustenance and spiritual strength for the Sioux and other Plains Indians. Today, tribes across the country are working to return herds to their lands. This is far more than an effort to simply re-establish a keystone species and improve habitats for other grassland wildlife. To bring back bison is to regain a primary source of healthy natural food amid the modern epidemic of obesity and diabetes afflicting Native Americans, re-invigorate cultural traditions and provide new economic opportunities. A lot of people out West, including Native Americans, prefer the old word for these animals: buffalo (not to be confused with true buffalo, which live in Asia and Africa.) By any name, Bison bison are the largest native grazers in the Western Hemisphere, with adult males, or bulls, standing six feet at the shoulder and weighing one ton or more. They were once North America's most abundant big mammal, one that came to characterize the size and fertility of this continent. In numbers almost beyond reckoning--perhaps 20 million or more--they ranged through eastern woodlands and into northern boreal forests, as well as across thousands of miles of prairies. Then, in an eyeblink, they were taken away. By 1889, only a few hundred had survived the whites' campaign of slaughter. More than a century later, in 1992, representatives from various native groups formed the South Dakota-based InterTribal Bison Cooperative (ITBC) to promote buffalo restoration on Indian lands. The organization now has 57 tribal members in 19 states. Between them, they oversee close to 18,000 buffalo. Four hundred of those live on the Fort Belknap reservation of the Assiniboine and Gros Ventre tribes in north-central Montana. Considering that 800,000 bison hides were shipped from nearby Fort Benton in the year 1876 alone, 400 animals doesn't seem like many. But it's a start, and that number just jumped to 402. "There's a real new-looking little guy," says Mike Fox, a Gros Ventre, former fish and wildlife director for the reservation and interim executive director of the ITBC. He's pointing to the second new calf we've seen this morning up on Snake Butte. Three massive bulls stride together along the rimrock. Bands of females and subadults pattern the broad valley beyond. And the prairie sweeps largely unbroken from there all the way to the snowy Bears Paw Mountains on the west and Little Rockies on the south. It is a vision of what was, and what could be once more. The Fort Belknap herd was started in 1974 with 35 bison. Defenders of Wildlife and other non-profit groups provided funds to add more over the years and purchased supplemental feed during times of drought. Meanwhile, the portion of the 645,500-acre reservation made available for buffalo increased from 1,900 acres to 15,000. Knowing that bison and prairie dogs have a long history of mutually beneficial co-existence, tribal authorities granted prairie dogs on the pastures protection from shooting and poisoning, a rare reprieve out West. That was followed by reintroduction of the endangered predator that depends almost exclusively on these animals: black-footed ferrets. Ecologically, the bison throngs of yesteryear added up to a force like wind or wildfire. Their grazing, trampling, dust wallowing and constant movement altered and renewed habitats decade after decade, creating niches for all kinds of creatures. Predators and scavengers large and small followed in the herds' wake. Pronghorns and prairie grouse favored the herbs and grass sprouts that appeared after buffalo had mowed down the taller growth in passing. An estimated six billion prairie dogs--along with black-footed ferrets, cottontail rabbits, amphibians and other animals living in or around the rodents' underground metropolises--were also tied to a bison-dominated community. The cows that followed in the wake of the bison's near-demise are, by contrast, an uneasy fit with prairie flora and fauna. They tend to wander much less than bison and will graze sites until native plants give way to weedy invaders. Since cattle need more water than bison do, they are particularly hard on streams and streamside vegetation--to the detriment of nesting birds, native fish and a host of other wildlife. Cattle are also less hardy than bison, and require more day-to-day attention--including feed grain and protection from predators--by a livestock owner. The many advantages of raising bison must be weighed against the fact that the herds require tall, stout fences to hold them in. These fences are expensive, and even the strongest won't always hold a big bull with wanderlust. Managers also need to make the herd profitable to overcome resistance from those who think the land should be grazed by cattle. Much as tribal members value ancient traditions, many have adopted ranching traditions as well. This is the 21st century, and it seems that bison are going to have to pay their way into it. Bison-raising experienced a flurry of commercial popularity during the 1970s and 1980s, when people could readily sell breeding stock to others chasing the next big thing. What was missing was a steady demand from consumers, and the market soon flattened out. "People are used to fatty beef," Fox explains. "They also don't know how to cook buffalo. It has to be roasted slowly at a lower temperature than beef. The meat dries out quickly because it's so lean." The buffalo market has picked up a bit lately, driven by the growing ranks of Americans who want their red meat to be organic and low on lard. At 2 percent fat, compared to an average of 12 percent for beef, buffalo fit the bill. Their flesh and excrement aren't laden with residues of antibiotics and growth hormones either, and they can't give you mad cow disease. Around the northeastern Montana towns of Wolf Point and Poplar sprawls the Fort Peck reservation of the Assiniboine and Sioux tribes. At 2.1 million acres, it is roughly the size of Yellowstone National Park and currently holds around 170 buffalo. Some came from Fort Belknap in a move sponsored by Defenders, which also supplied Belknap buffalo to Montana's Blackfeet reservation just east of Glacier Park. As at Fort Belknap, the challenge at Fort Peck has been to expand the range available to the herd. Here again, this involves competing for pastureland with cattle ranchers. Farmers raising wheat and other grains also claim a large share of the reservation. Yet practically everyone in the community recognizes an ancient kinship with the shaggy beasts, which once provided staple foods, hides for tipis and bedding, bones for tools and skulls for sacred rituals. When the modern herd first arrived at Fort Peck in 2001, tribal elders were on hand to sing the old songs of welcome. The tribes have since started a Buffalo Run in which young people race in relays 27 miles from the pasture back to town. Buffalo roasts and buffalo pemmican are served at an annual cultural camp for youth and their families, where the entertainment includes rides on horse-drawn buffalo hides. "I ranch cattle myself," says Robbie Magnan, director of the tribal fish and wildlife department. "But the way things are set up, cattle only benefit individual families, whereas buffalo benefit the whole tribe. We contribute the meat from five [bison] every year to our diabetic diet program [which emphasizes lean protein over processed food.] More buffalo meat goes to a food program for our elders. We'd like to develop two herds. One would be a traditional herd that roams without much interference from us. Whatever surplus we harvest would be used for cultural purposes like our Sun Dance ceremony. The second group would be our business herd, producing animals we can sell. We have 5,000 fenced acres of range now. Our Tribal Council's land committee is meeting very soon to decide whether or not we can add more." That afternoon, Magnan takes me to see a different sort of habitat acquisition on the reservation--1,800 acres of marsh in the floodplain of Big Muddy Creek. The area is slated to be set aside as a tribal wildlife refuge, chiefly for waterfowl, shorebirds and rare species such as Baird's sparrow, white-faced ibis and the only Franklin's gulls known to nest in the region. Over time, Magnan hopes, the tribe may protect several thousand adjoining acres in this wetland complex, which continues north toward the federal wildlife refuge of Medicine Lake. The following day, Magnan has more good news: the council just voted to enlarge the bison range by 3,300 acres. That ought to make the burrowing owls happy as well. According to the tribe's bison manager, Bruce Bauer, these birds were scarce on the reservation before the buffalo returned. Sage grouse, another declining species, also occur on the current pasture. So do mule deer, Bauer has found; the largest ones on the reservation live side-by-side with the buffalo. Bauer goes on to introduce me to Straight Horn, a five-year-old female bison with a yearling calf; Half Horn; and Skimpy, a thin-necked juvenile. Beside them are Number 21, "who's so friendly and so nosy," he says, and Number 96, "the lead cow. When she goes, they all go. This is a matriarchy. One reason Indian people respect buffalo so much is that they are very family-oriented. They're smart too." While they would avoid a strange vehicle, these animals know Bauer's truck and even come over to rub against it. "When I feel like taking a break from work, I just go sit with the buffalo," he says. "They have a lot to teach us. Sometimes, I make offerings to thank them." There are centuries-old rings of tipi stones on the hilltops we pass and three brand-new calves at the edge of a coulee. Across the way are the McDonald Breaks, the countryside that will be added to their home as soon as it can be fenced. Farther west, 10 swift foxes provided by the Montana Department of Fish, Wildlife and Parks will be introduced to the reservation this year to help promote recovery of this cat-size predator of the open plains. The Crow tribe has 1,500 to 2,000 bison on its huge reservation between Billings, Montana, and Sheridan, Wyoming. The Cheyenne River Sioux of central South Dakota oversee 1,200 to 1,500. Other tribes manage smaller numbers elsewhere in the region. All told, tribal reservations now have more bison than all federal parks and refuges. But these reservations aren't nature preserves--they are homelands where native people make their living. Gradually, however, they are becoming true homelands for buffalo and for more of the other animals in the great circle of life. I can almost feel the past and future merging here beneath the boundless prairie sky.