Once nearly extinct, bison are now climate heroes
Indigenous tribes are leading the effort to bring back the bison — a victory not only for the sake of biodiversity, but for the entire ecosystem they nurture
By Jess McHugh
July 13, 2022 at 12:25 p.m. EDT
A herd of bison graze the prairie lands at the Wichita Mountains Wildlife Refuge in Oklahoma. (Photo by Mariah Tyler)
A herd of bison graze the prairie lands at the Wichita Mountains Wildlife Refuge in Oklahoma. (Mariah Tyler)
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Miles of prairie stretched out across the Wichita Mountains Wildlife Refuge in southern Oklahoma, acre after acre of brush, grasses and hearty vegetation creeping toward the low-range granite mountains rising in the distance. Like in much of Oklahoma, the road is flat here, but the speed limit remains 30 mph. That’s because of the bison.
They appeared seemingly out of nowhere: dozens of massive animals lumbering up the shoulder of the road to cross to the fresh vegetation on the other side. The herd moved slowly, their soft, bovine eyes barely registering the stopped cars awaiting their passage. They quickly set to work mowing down the fresh springtime grass.
The bison’s quiet munching does more than nourish their bodies — it’s one of many things they do to nurture their entire ecosystem, one that is increasingly under threat from climate change. Grazing bison shaving down acres of vegetation leave more than dung behind: Their aggressive chewing spurs growth of nutritious new plant shoots, and their natural behaviors — the microhabitats they create by rolling in the ground, the many birds that forged symbiotic relationships with them — trickle down the food chain. Once bordering on extinction, bison now serve as a great provider for their ecosystems, standing as an example of the ways in which animal conservation and ecological protection can work in tandem.
“Buffalo is the original climate regulator,” said Troy Heinert, a member of the Sicangu Lakota (Rosebud Sioux) tribe and executive director of the InterTribal Buffalo Council, a coalition working to restore the animal on tribal lands. “Just by how they use the grass, how they graze, how their hoofs are designed, the way they move. They did this job for us when we allowed them to be buffalo.”
Tribes are leading the effort to bring back the bison, Heinert says, which in turn allows for the return of other native grasses, animals and insects — all of which will “help fight this changing climate.”
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Bison, called buffalo by some Indigenous peoples, are mammoth creatures. Weighing up to 2,000 pounds, they are the largest land mammal in North America. Their giant horned heads balance on hulking sloped shoulders. This massive upper body sits on spindly goat-like legs, lending them an otherworldly quality — more Minotaur than moose. Despite their size, they have a gracefulness to them.
Two centuries ago, bison dominated much of the continent from Canada to Mexico, when tens of millions roamed North America. They were so numerous that the pounding of their hoofs beating across the land sounded like rolling thunder. For the many tribes of the plains region — the Lakota, the Shoshone, the Arapaho, to name a few — buffalo was a sacred animal that nourished their people and played an important ceremonial role. For European colonizers, the bison were both a commodity and a weapon. Americans massacred them by the thousands, selling their pelts and organizing vast sport hunts. As the United States pushed West in the 1800s, bison became a pawn in their quest to wrest Indigenous tribes off their ancestral homes. By killing as many bison as possible (in one case, the U.S. government provided ammunition to private hunters to illegally trespass on tribal land to kill buffalo), they attempted to starve tribes out. By the turn-of-the-20th century, millions of bison had been killed. In 1900, fewer than 1,000 — of an estimated 30 to 60 million — remained, many in zoos.
President Theodore Roosevelt ordered federal bison herds to be put into place (some, such as Custer State Park, were ironically sourced from tribal herds). The bison observed in the Wichita Mountains are descended from 15 animals commandeered from the Bronx Zoo in 1907 and brought to Oklahoma via train car. In the intervening century, federal, tribal and private herds have brought the species back from the brink of extinction. The estimated number of bison nationwide — while far from the millions — now hovers in the low hundreds of thousands.
Two bison follow the herd through tall prairie grass. (Mariah Tyler)
Indigenous peoples have been integral to this effort from the start, both by managing herds and by introducing legislation to protect and expand bison territory. In the past few decades, tribal herd numbers have soared: The InterTribal Buffalo Council, which began as a modest coalition of fewer than 10 tribes in the early 1990s, will soon count 76 tribes across 20 states from New York to Hawaii among its members, managing a total of more than 20,000 animals across 32 million acres.
The return of the bison is a victory not only for the sake of biodiversity but for the entire ecosystem in which they live. As a keystone species, the bison sustain their environment from the top down.
“They move through, graze everything down. It’s a type of disturbance — like fire would be,” said Dan McDonald, lead wildlife biologist at the Wichita Mountains Wildlife Refuge. “The fresh green [draws] other animals that would feed on it: elk and deer and whatever other type of grazers that would consume some of that new forage.”
The herd in Oklahoma is approximately 625 animals, but when large herds move synchronously across the land, they create what scientists have dubbed a “green wave.” The bison’s vigorous grazing stimulates plant growth, creating a flood of new vegetation that follows in the bison's wake to be "surfed” by animals large and small. Green waves can be so dramatic that some — such as the one created by Yellowstone’s bison herd — can be seen from space.
While bison produce methane much like cattle, their grazing patterns and the fact that they are wild animals that usually roam hundreds, if not thousands, of acres means that bison are generally far less destructive to the environment (and produce both more and leaner meat) than domesticated cows.
Reintroducing bison as a food source has been essential within tribal herds. Indigenous peoples have the highest rate of diabetes of any ethnic group in the United States, in part because many reservations are located in “food deserts,” where access to supermarkets — and to healthy food in particular — is hugely limited. That problem was exacerbated during the coronavirus pandemic, when supply chains nationwide crumbled. Thanks to their local herds, some tribes have put lean buffalo meat into school lunches, and the Rosebud Sioux tribe was able to feed residents struggling with homelessness using the first buffalo harvested from their Wolakota herd.
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At the same time, holistic herd management techniques spearheaded by tribes operate on this principle: Bison are wildlife — not livestock. These animals require lots of land to maintain ecological balance and not to overgraze.
The southern plains are especially vulnerable to climate change, where periods of extreme drought and flooding have cropped up more frequently in recent years. There is example after example of how the bison serve a crucial role in their imperiled environment: Their hoofs push seeds deep into the ground and aerate the soil. Small birds often fly around bison’s ankles because their heavy footfall kicks up insects that the birds can feed on. The brown-headed cowbird often rides on the back of bison, plucking parasites off its skin. Even bison’s dung — which contains high levels of nitrogen, a vital nutrient for plant growth — fertilizes the soil as they graze.
Their “wallows” — huge depressions created by bison’s rolling on the ground — can serve as microhabitats for other animals. After strong rains, those wallows fill with water and welcome insects, frogs and other amphibians, according to McDonald. In one poignant example of a once nearly extinct animal supporting a threatened species, bison’s wallows serve as an ideal habitat for bird’s-foot violets, the preferred food source for the larva of regal fritillary, a rare butterfly.
A prairie dog perches on a small dirt mound and looks toward rock formations in the distance. (Mariah Tyler)
Bison suffer from the effects of climate change, too. Warming temperatures have caused bison to shrink, according to several recent studies. That’s because climate change acts on the grasses they eat, reducing the protein content. One study found that for every 1 degree Celsius the temperature warmed, male bison weighed on average 20 pounds less. (The climate is expected to warm by nearly 3 degrees Celsius by 2050.)
There are other challenges too. The Indian Buffalo Management Act — a piece of legislation that would guarantee steady resources for tribal herd management — has stalled in the Senate after passing the House of Representatives. Heinert says proponents of the bill have been able to assuage concerns and is optimistic about the bill eventually becoming law. Meanwhile, it’s an ongoing process for herd managers to negotiate with ranchers to convince them that there’s enough land for cattle and bison alike.
Still, many experts in the bison world are hopeful for the future. The ongoing restoration of this animal is a rare success story in nature conservancy. To go from a few-hundred bison to several- hundred-thousand nationwide in little more than a century is astounding. This triumph has in turn brought about the resurgence of local flora and fauna in the regions in which bison are found, including native grasses and rare insects.
Buffalo — much like bald eagles or wild mustangs — are one of those potent symbols of American culture that contain multitudes of meaning. The stories told about them are endless, though some stories are truer than others. For tribes, they were a giver of life, a cherished member of the community. For colonizers, they were a trophy, then a commodity and a geopolitical tool. Much like the tribes that lived along buffalo’s migration patterns and are now instrumental in these conservation efforts, bison eventually became “outcasts in their own homeland.”
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Looking toward the future of bison in our changing climate requires looking back, because restoring bison is not just about saving the animals — it’s about making efforts to return their environments to a time when the ecosystem regulated itself. A time when bison were not a symbol, but a part of a richly biodiverse landscape.
“As we look to the future, any assistance or effort that tribes are making to restore buffalo back to their lands is going to be beneficial for everybody, because it is a climate-smart, holistic idea of the relationship with nature,” said Heinert.
“If we continue to view buffalo as a commodity, we’re not going to reach that ultimate goal of restoring and healing our lands.”
