America's only true bison herd needs more room to roam. Will they find it in Montana?

by Heidi Ridgley


“They’ve just rebelled,” breaks the garbled voice over the radio, barely audible amid the deafening tha tha tha tha chugging of the cherry-red helicopter cresting over the treetops.

Its pilot and a handful of Montana government officials on horseback are marshalling hundreds of wild bison back into Yellowstone National Park in an annual drive called hazing. In the steady march over barely green sedges and bluebunch wheatgrass that began six hours ago at sunrise, two mothers with a calf apiece have had enough bullying and bolt.

Watching the chaos from a nearby truck with Rick Wallen, the park’s bison biologist, and field tech Amanda Bramblett, I don’t catch sight of the two one-ton insurgents when they break. I am too preoccupied watching all the days-old, rust-colored calves desperately trying to nurse under their mothers as they are prodded along.

It’s hard to envision today, but American bison once blanketed much of North America, rivaling the greatest mammal migrations on Earth—at 20 million to 30 million strong. In great herds they thundered across thousands of miles of prairie, stretching from the eastern woodlands and the northern boreal forests to the desert Southwest. In less than a century, they almost blinked out, overexploited by white settlers on the Great Plains for food, hides and finally industrial leather for fledgling factories in the East. Killing bison also had the added “allure” of destroying the bison-dependent plains Indians or, at the very least, it served to tame the tribes’ wandering ways and settle them onto reservations.

By the mid 1880s only a few hundred plains bison survived, scattered in five private, captive herds and one remaining wild herd in Yellowstone. And, unlike America’s other hoofed animals—deer, elk, pronghorn, bighorn—their numbers haven’t recovered in the wild. “When it comes to conservation of wildlife, bison have been left behind,” says Jonathan Proctor, Defenders’ Rocky Mountain region representative.

About 500,000 bison exist today—but almost all contain cattle genes because of hybridization by ranchers in the late 1800s. Most are raised as livestock behind fences and only 20,000 or so are managed for conservation. Of these, only the Yellowstone population exceeds 1,000 individuals, and even they have not been allowed to roam freely except within the park. “Basically, bison are treated as prisoners on their own land,” says Proctor.

The bison hoofin’ it in front of me today are the great exception—and the best hope for the future. The only herd thought to be free of cattle genes, Yellowstone’s bison—some 3,500 strong—are the descendents of 24 saved from poachers by rangers in the park’s early years. And they wander at will—when they stay within park boundaries. “Outside the park, even in the vast public lands of Gallatin National Forest, they are allowed only a tiny portion and only during winter,” says Proctor.

For some Yellowstone bison, their annual journey begins with autumn’s first snowfall in the park’s higher elevations. Others may hold out until December or leave in spring in search of calving and feeding grounds. Not all migrate outside the park. But for those that do, their return date is set in stone: May 15, before summer cattle-grazing season starts. The bison here on Horse Butte Peninsula, just west of the park’s boundary, must cross an imaginary line by then, no matter if their mainstay spring grasses have grown tall enough to entice—and even though cattle no longer graze these grounds. Some years bison find they’ve arrived before there’s enough to eat. “You can push bison to an acceptable area but that doesn’t mean they won’t accordion back out if it’s barely spring there yet,” says Wallen. “No one likes to gather and push them like this. It’s not natural. But we try to do it in a sensitive manner by letting young calves or laboring females fall behind to let the little ones grow for a day or two. And we let the more recalcitrant individuals fall out of the group, too, and come back later to see if they’ll fall in line.”

But other agencies involved in the annual hazing operation—namely, the Montana Department of Livestock—are not necessarily as light-handed and injuries and deaths occur regularly, 
says Proctor.

Montana regulations mandate that bison move back into the park in May to protect cattle from brucellosis, a contagious disease transmitted to bison and elk from Old World cattle early last century. Yellowstone’s bison and elk now carry the bug, which causes miscarriages. Since ranchers and agriculture officials long ago eradicated brucellosis from Northern Rockies domestic cattle, they resist bison grazing outside the park. Ranchers worry that comingling the species could cause the loss of their cattle’s “brucellosis-free” certification, which allows their beef to be sold outside the state without costly and time-consuming quarantines. “Given this, we would much rather participate in a controlled moving situation than watch bison be removed from the system all together,” Wallen says. He means slaughtered, which is what happened to more than 1,600 bison in 2008, when they left the park in search of food—the largest wild bison massacre since the 1800s. “Without long-term policy changes to give bison more tolerance outside the park, such slaughters will happen again,” says Proctor.

Yellowstone alone provides sustenance for only about 5,000 bison, primarily because in winter, with heavy snowfalls, there isn’t enough grazing land available. During particularly harsh winters when the population exceeds 3,000 animals and food is scarce, as happened in 2008, agents are authorized to capture and ship to slaughter all bison leaving the park. “For the only wild herd to survive, change is desperately needed,” says Proctor.

Over the last four years, researchers have captured and quarantined—instead of killed—some Yellowstone bison each year as part of a test to see if bison can remain brucellosis-free. Today about 63 disease-free, plains bison—sans cattle genes—live in isolation just north of the park and could be relocated to establish new herds for the benefit of wild bison conservation. At least two Indian reservations in Montana have shown interest, and Defenders is working with the Assiniboine and Sioux tribes of Fort Peck Reservation and the Assiniboine and Gros Ventre tribes of Fort Belknap Reservation to convince Montana wildlife officials to move forward with bison relocation.

With support from Defenders, Fort Peck also expanded their bison reserve and constructed a 16-mile, wildlife-friendly fence—which keeps bison in while allowing elk and deer to jump over and pronghorn to go under—around 5,000 acres of prime bison habitat. The fenced area includes upland prairie and bottomlands along the Poplar River, once a migration corridor for herds moving south to winter in eastern Montana.

“Working with the tribes, we are hoping to help restore part of their cultural heritage,” says Proctor. “At the same time, they are helping all of us by restoring wild bison to a small part of the West. It may only be 5,000 acres for now, but it’s a step toward a better future.”

Tolerance for bison migration outside park bounds is also growing. In April, Montana officials finalized a deal among eight state, federal and tribal agencies to allow bison to roam north of the park into the 75,000-acre Gardiner Basin during winter months. And last winter, when hundreds of bison began leaving the park in search of food, Montana Gov. Brian Schweitzer issued an executive order prohibiting the shipment of Yellowstone bison through Montana, effectively stopping them from being shipped to slaughterhouses in 2011. “This just may be the beginning of a real and desperately needed change,” says Proctor. “We don’t slaughter bear or elk simply for crossing the park boundary, so we shouldn’t slaughter bison for doing the same thing. The difference between managing animals as wildlife and keeping animals in a zoo is giving them room to roam and survive on their own.”

As the herd we are watching today moves closer, Bramblett starts the truck and backs up, giving the bison more space to pass. “This is good,” says Wallen when he sees the helicopter pilot back off instead of chasing the two mothers. Wallen’s jurisdiction exists only inside the park. Here he is relegated to observer. “They don’t need to do this in one fell swoop. It should be done to ensure the survival of the animals.”

Turns out it will be almost a clean sweep for the day. Officials had hoped to herd about 200 and, according to the tracking telemetry, all targeted bison were on the move. The only bison that wasn’t was one that recently had a breech birth. “That cow,” Bramblett sighs, “I watched her for awhile getting ready to quit a few days ago. Every five minutes, she’d put her head down. I thought, ‘she’ll be deceased by morning,’ and now I hear they are seeing a bear on her.”

As enormous protein sources for predators and scavengers—including grizzlies, wolves, coyotes and foxes—bison are a vital thread in the diverse greater Yellowstone ecosystem, especially in April and May when many bison die after the stress of winter. Others become prey after they are weakened from infections by abscessed teeth or wounds incurred while fighting over mates. “Bulls fight ferociously during breeding season in August,” Wallen says. “One horn with a massive male behind it pokes another’s side or a lung, and it will fester and become infected. If the infection doesn’t kill it, a predator like a wolf has a powerful ability to sniff out the weakness.”

On my way home the next day, I spot another bison whose luck ran out this winter. A big bull that had crashed through a frozen pond and drowned has floated up with the spring melt, bloated and bulging. There are no scavengers on him yet, but soon his body, too, 
will complete its natural cycle.

Behind him, come the spring calves. Now safely within the park’s bounds, some of the bison mothers—so distressed yesterday during the hazing—sit contently with their legs tucked. A few stand munching grass. Each keeps an eye on her own calf, which never frolics too far from her flank. When one calf halts, like a relay race, another one or two start up, in what looks to me like happy bursts of energy. It’s impossible to know if any of these several dozen are the same two that struggled to nurse as they were shunted along the day before, or if they will survive next year’s haze. But today at least, for these newborns, all appears well in their world.

Heidi Ridgley is the editor of Defenders.

Defender to the Core

A Q&A with a Defenders expert: Jonathan Proctor



Q: Why should we care about bison?

A: Bison are a keystone species. This means their presence—or absence—alters the ecosystem. Migrating, grazing bison once created habitat for prairie dogs, grassland birds and even many plant species. They carried seeds, created mini-wetlands by wallowing and their carcasses provided an incredible amount of meat for other animals in the food chain. But today, wild bison herds are far too small and their range is far too limited to play any real ecological role. They are, in fact, “ecologically extinct.” We need to help wild bison rebound for the health of grassland ecosystems.

Q: Today a half million or more bison live in North America. Isn’t that a lot already?

A: It’s true that bison have made an incredible comeback since the 1800s when humans wiped out all but a couple hundred. But bison once numbered in the tens of millions in vast wild, migrating herds. About 96 percent of today’s bison are raised as captive livestock for food. Fewer than 25,000 are managed as wildlife, and almost all of these are in very small, fenced herds. At only 3,500 or so, the Yellowstone herd is the largest. This is not nearly enough to restore the role of wild bison in the environment. In Montana alone, there are more than 2.5 million head of cattle.

Q: What's next for Defenders and bison?

A: Defenders is working to reform Yellowstone bison management so that one day this important bison population will have more room to roam outside of Yellowstone National Park and be treated as wildlife, not hazed and slaughtered. We are also working to relocate some of these genetically important bison to new areas to help prevent their slaughter and to restore additional wild bison herds. We are working with the Fort Peck and Fort Belknap Indian reservations in Montana—the first landowners who have stepped forward to help save Yellowstone bison—to convince Montana officials to transfer some of these bison. Finally, we are working with Montana officials and other conservation partners to begin unique projects with private landowners around Yellowstone to coexist with wild, migrating bison as they leave the park.

Only select articles from Defenders are available online. To receive 4 issues annually of the full award-winning magazine, become a member of Defenders of Wildlife

More Articles From This Issue

Living Green

Coral Conundrum

Worth Defending

Bowhead whale

Too Hot to Trot

Western states move forward with hunting plans

A Defenders Roundup

Leaders of the pack; Polar bear protections upheld

Turtles in Trouble

Trawling for shrimp kills sea turtles

Wild Matters: Relocation Redux and More

Relocation redux; Fast and furious fungus; To spot an ocelot

Politicking Instead of Protecting Wildlife

Defenders leads the fight to defeat House bill attacking ESA

Join Today

With engaging stories and spectacular photography, Defenders of Wildlife's magazine provides readers with a behind-the-scenes look at what biologists and conservationists are doing to protect imperiled wild animals and plants.

Get the Magazine