Bison Management

Duration:

2 minutes, 6 seconds

The protection and recovery of bison in Yellowstone is one of the great triumphs of American conservation. This video explains why Yellowstone bison are managed.

 

The National Park Service (NPS) has sole authority to manage bison within Yellowstone National Park’s boundaries. However, unlike other migratory wildlife, bison are managed differently due to Montana’s limited tolerance for their presence outside the park. To address this, the NPS coordinates with other federal agencies, the state of Montana, and American Indian Tribes under the Interagency Bison Management Plan (IBMP), which was established in 2000 and signed by the secretaries of Agriculture and Interior and the governor of Montana.

In 2024, the NPS developed a new bison management plan, formalized through a Final Environmental Impact Statement and Record of Decision under the National Environmental Policy Act. This update responds to new scientific information, changing circumstances, and recent litigation. The 2024 plan outlines how the NPS will manage bison within the park and sets conditions for supporting partners' efforts outside the park, while maintaining the primary goals of the IBMP. To achieve these shared goals, the NPS will continue collaborating with federal, state, and American Indian Tribe partners under the existing IBMP framework to coordinate the plan's implementation.

 

 

Our Goals

We preserve a sustainable population of 3,500-6,000 wild, migratory bison.

Yellowstone’s bison are the closest resemblance left today of the vast herds that once roamed the continent. Bison act as ecosystem engineers fundamentally designing grassland ecosystems, and they hold significant cultural importance to people, with a connection spanning thousands of years.

We coordinate with federal, state, and Tribal partners to manage the bison population.

Yellowstone bison must be managed because the population is growing exponentially and there is limited winter range for bison within the park. Like other wildlife, bison migrate out of the park to find food in winter, but unlike other wildlife, there is limited tolerance for them outside the park. Yellowstone works with its partners to control numbers, limit bison migrating out of the park, and help Tribes restore Yellowstone bison to their livelihoods.

We develop the best available science to preserve our national mammal.

Making decisions about bison population management requires contemporary research on population viability, habitat use, and the effects that bison have on grasslands to ensure a sustainable bison population and habitat.

 

Conserving Yellowstone Bison

Archaeological evidence shows that bison have inhabited the Greater Yellowstone Area for over 10,000 years. By 1902, however, only 23 bison remained in the park—representing the last wild bison in North America. Throughout the 1900s, dedicated conservation efforts helped Yellowstone's bison population recover, making it one of the most significant conservation successes for bison worldwide. As the population rebounded, bison began migrating out of the park and into Montana, leading to one of the most complex wildlife management challenges of our time.

 

Duration:

34 minutes, 49 seconds

Bison Program Coordinator Chris Geremia talks about the past, present, and future of bison management in Yellowstone National Park.

Learn More

 

NPS Bison Management Plan

Multiple federal, state, and Tribal entities are involved in managing bison and hold different opinions on how bison should be managed. These opinions are intensified by each entity’s varying authority over bison management, which depends on the specific lands where the bison are located—whether within Yellowstone, on adjacent U.S. Forest Service lands, or on private lands in Montana.Yellowstone’s new Bison Management Plan aims to secure a sustainable future for our national mammal by updating our tools for population control, setting a target population range, and establishing strategies for managing brucellosis within the bison population. The 2024 plan outlines three methods to control bison numbers: the Bison Conservation Transfer Program (BCTP), the Tribal Food Transfer Program (TFTP), and regulated Tribal harvests and state hunts.

 

Bison in holding pens to prepare for transfer to Fort Peck Indian Reservation.

Bison Conservation Transfer Program (BCTP)

The 2024 plan prioritizes the BCTP to capture, identify, and transfer brucellosis-free bison to Tribes. As bison migrate north out of the park, some are captured at Yellowstone’s bison facility and enter the program. The goal is to add 100-300 animals annually, though this may vary if fewer bison migrate or if the park population falls below 3,000. About 30–40% of captured bison qualify, as eligible animals must test negative for brucellosis and be under three years of age.

Once accepted into the program, bison go through multiple testing phases. The first phase is conducted at Yellowstone quarantine facilities or on private land leased by the Animal and Plant Health Inspection Service (APHIS) near the park’s northern boundary. This phase, which takes about 300 days for males and 2.5 years for females, ends with certification as brucellosis-free by APHIS and Montana animal health officials. The bison are then moved to the Assiniboine and Sioux Tribes of the Fort Peck Indian Reservation, where they undergo one additional year of testing in an assurance facility. Afterward, the Fort Peck Tribes transfer some bison to the InterTribal Buffalo Council, which distributes them to other Tribes across North America.

Listen to the story of the first live bison transfer in 2019 to the Fort Peck Indian Reservation located in northeastern Montana (this episode was created before the expansion of the park’s bison facility and the reduction of timelines for male bison in the BCTP):

 

• Home On The Range

  
  

  Bison have lived on the Yellowstone landscape for millennia, but the history of bison conservation has been fraught with challenges. In 2019, federal, state, and tribal partners came together to make history: charting a new path for this American icon and assuring a place for wild bison on the broader landscape. Music: Walking Together by L-Ray Music Hail and Sleet by Harpo Marks Touches by Max Brodie Seek My Fortune by L-Ray Music

  Credit / Author:

  NPS / Jennifer Jerrett

  Date created:

  04/22/2020

  Audio Transcript

  (Sounds of Stephens Creek Facility fade up)

  Stephens Creek Worker: “OK. We’re ready for the first one”

  Narrator: It’s not yet dawn when someone gives the signal. Dark figures in puffy jackets are up on a scaffold. They move into place against the pale sky. It’s quiet. Weirdly quiet for the number of people here and what’s about to happen. Everyone braces. It’s like there’s this giant, collective inhale.

  (sounds of pulleys)

  Narrator: At the Stephens Creek facility inside Yellowstone National Park, the staff works a system of ropes and pulleys.

  (sounds of gate opening)

  Narrator: A corral gate opens. And then a single bison rushes through a curved passage toward what’s called the “squeeze chute.”

  (sounds of gate closing)

  Narrator: The gate closes behind.

  (sounds of squeeze chute)

  Narrator: Inside the squeeze chute, mechanical walls close in on the animal’s flanks.

  (sounds of scientists logging the animal’s I.D. number)

  Narrator: His ID number is quickly logged.

  (sounds of chute door opening)

  Narrator: Then the chute opens. And this 3-year-old bison—a wild, American plains bison—escapes down a constricted alley in the only direction he can…

  (sounds of bison running past and into the trailer)

  Narrator: …and into a livestock trailer.

  (sounds of loading fade)

  Narrator: Many winters, hundreds of Yellowstone bison are loaded on trailers—trailers just like this one—to be slaughtered. They’re shipped to slaughter facilities to reduce the number of bison migrating outside the park and into the State of Montana. Because in the state of Montana, there is limited tolerance for wild bison on the landscape.

  (sounds of truck starting)

  Narrator: But these bison are not being shipped to slaughter.

  (music, then sounds of truck driving away)

  Narrator: These bison are going to a wide prairie on the Fort Peck Indian Reservation.

  (music with sounds of truck fading out)

  Narrator: Today on Telemetry, we’re talking about the rehoming of wild bison from Yellowstone National Park to the Assiniboine and Sioux Tribes of the Fort Peck Indian Reservation. That rehoming is part of a program called “Quarantine.” The program is one of the only alternatives to shipping wild bison to slaughter. And it’s history in the making.

  (music fades out, field sounds fade up: Chris Geremia talking about the biting flies at Stephens Creek )

  Chris Geremia: Let’s go down to the facility.

  Narrator: Doctor Chris Geremia is a wildlife biologist at Yellowstone National Park. He manages Yellowstone’s bison program.

  Chris Geremia: Just be careful, sometimes there are rattlesnakes.

  Narrator: Chris and I are walking around the Stephens Creek facility. It’s midsummer. Weeks before any bison will go to Fort Peck. The ground is threadbare: dead grass and dirt. The flies are pretty bad today. Stephens Creek is the epicenter of bison conservation. Bison are migratory and the states surrounding Yellowstone National Park treat bison differently than other migratory wildlife. And after a court-mediated settlement, Stephens Creek was built in the late 1990s to manage bison migrating out of the park. Today, Stephens Creek is where migrating bison are captured and either shipped to slaughter or held until they can be transferred outside of the park as part of quarantine.

  Narrator: Chris says the story of quarantine is a story of success. It’s the result of decades of collaboration between a legion of federal, state, and Tribal stakeholders.

  Chris Geremia: There’s so many people that want us to find another solution to sending bison to slaughter. They want us to find a way to get live bison out. We’re really just trying to show people how you can do it. That we can move live bison out of Yellowstone. We can reconnect Tribes and bison, and hopefully, in the fullness of time, reconnect bison with public lands.

  Narrator: But like most stories of bison conservation, Chris says it’s also shot through with complexity and compromise.

  Chris Geremia: You know, I kind of see it as you're standing in Hayden Valley—which is a huge valley in the middle of the park. And you’re waist-deep in snow. And bison conservation is like postholing across that valley. You just don’t go anywhere quickly and it’s an awful lot of hard work. Chris Geremia: Let’s go to the original sorting pen, which we call the bullpen

  (sounds of walking up metal stairs)

  Narrator: We climb up onto the scaffold that overlooks the facility. This is my first time up here and I’ll be honest. The view is a little...unsettling. I’m used to seeing wild bison out in the big, green valleys of the park. Rivers and trout streams running through.

  Narrator: But here, I see 55 male bison. Inside an ordinary pen. (music)

  Narrator: And I’m thinking: how did we get here?

  (music fades under)

  Rick Wallen: One hundred or more years ago many wildlife species -- most wildlife species -- were harvested to sustain the pioneering way of people exploring the west.

  Narrator: That’s Rick Wallen back in 2014. Rick used to lead Yellowstone’s bison program before retiring in 2018.

  Rick Wallen: And elk, deer, pronghorn, all the large animals were of very low abundance after we colonized western United States.

  Narrator: But with bison, the situation was even more troubling. It’s estimated that somewhere between 30 and 70 million bison roamed this land before European colonization. As settlers moved west, the extermination of the American bison began. Many saw bison as both a marketable commodity and a means to suppress the Tribes—Tribes who revered and depended on bison. And so within just a few decades, the bison were all but annihilated.

  (music fades)

  Rick Wallen: In fact, at the turn of the last century the only known wild bison were in Yellowstone National Park. There were only a couple of dozen.

  Narrator: From tens of millions to a couple of dozen; A couple of dozen animals hunkered down deep in the interior of Yellowstone National Park. The only wild, free-ranging bison in the area remaining from the original great herds. It’s hard to grasp: such willful decimation. But national debate over that near-extinction of the American bison would go on to inspire one of the country’s first conservation achievements.

  Rick Wallen: It was phenomenal that our forefathers had the insight to preserve Yellowstone National Park and I think they did it partly because they saw what was happening to wild bison across the country and partly to preserve the unique landscape and geological features of the landscape. So this is it. This is the location that preserved wild bison into eternity.

  Narrator: In addition to the couple of dozen animals in Yellowstone, there were an estimated 300 or so bison that survived in privately-owned herds across North America. In fact, a few animals from those private herds were brought to Yellowstone to start a breeding program. And after decades of protection and restoration efforts, the number of bison in Yellowstone grew from a couple of dozen animals to a few thousand.

  (music) Rick Wallen: That's a very successful program. With all of that success comes the propensity for them to wander and roam and now they want to roam well beyond the preserve we've set up here as Yellowstone National Park.

  Narrator: And roaming beyond the boundaries of Yellowstone National Park has led to one of the most complex cross-boundary wildlife issues of our time.

  (music) Narrator: Three states surround Yellowstone National Park—Idaho, Wyoming, and Montana. Very few bison migrate outside the park into areas of Idaho and Wyoming. Most of the bison that migrate outside Yellowstone wander into the State of Montana where there’s limited tolerance for bison.

  Rick Wallen: Bison are big. They scare people. They break things. Encountering a buffalo at 70 mph isn't very comforting sight.

  Narrator: But there are also fears that bison could transmit a disease called brucellosis to cattle. Brucellosis is a bacterial disease that can cause miscarriages in animals like bison, elk, and domestic cattle. Domestic cattle introduced the disease to wildlife before the 1930s. Now wildlife in the Greater Yellowstone Area—including elk and bison—can give it back to cattle.

  Rick Wallen: The concern about brucellosis is that if wildlife—let me back up—In the agriculture industry once an animal tests positive it has to be removed from the herd. So it's an economic loss for the rancher.

  Rick Wallen: The concern really is that the livestock industry has worked really hard for many decades to eliminate the disease in livestock. So their concern is legitimate. They've worked hard, cleaned up their industry, and they'd like to see this additional threat eliminated.

  Narrator: In an effort to try to eliminate or at least mitigate conflicts between humans and bison in the State of Montana, the State and the federal government reached a court-mediated settlement on how to manage Yellowstone bison. The idea was to limit the number of bison in Yellowstone and reduce the risk of bison migrating out of the park and transmitting brucellosis to cattle.

  Rick Wallen: So in order to prevent dispersal beyond our established conservation area, there are years where the agencies need to get together and develop a management strategy to cull bison. Narrator: Until Quarantine, there were really only two main options for culling—or removing—bison: Hunting outside park boundaries or shipping animals to slaughter. Hunting only removes a limited number of animals. So shipping to slaughter has been the primary method of culling wild bison. Narrator: But here’s one of the tricky things about managing bison when it comes to brucellosis. It’s elk, not bison, that have re-infected domestic cattle. Elk have reinfected cattle almost 30 times over the last several decades. And elk are not managed the same way as bison. Elk are not shipped to slaughter. In fact, elk roam free outside the boundaries of the park, where they frequently come into contact with cattle.

  Narrator: Because of this, many experts argue that the risk of brucellosis transmission between bison and cattle is not a scientifically credible reason for the differential treatment of bison compared to elk. Narrator: So until there is more support for wild bison living outside of Yellowstone National Park, hundreds of Yellowstone bison will continue to be culled in many years. Some bison are removed through hunting outside the park, some undergo quarantine, and some are sent to slaughter, Rick Wallen: So that is a very controversial side of bison management. Many people don't like to see the animals sent to slaughter. The National Park Service would prefer not to send the animals to slaughter. But it is a mitigation measure to allow us to have the acceptance for bison outside the park that we do have.

  (Sounds of Stephens Creek fade up)

  Narrator: I’m back at the Stephens Creek facility with Chris Geremia. We’re still looking out over the facility. At the 55 male bison inside their ordinary pen. At the 55 bison who are about to complete part of the quarantine process.

  Chris Geremia: So quarantine is a three step process and probably the biggest challenge to quarantine is trying to figure out where and how we do these three phases.

  Narrator: Chris is talking about the protocols for males. The steps for quarantine are different for males and females. But for males, the process goes like this: Phase One is a screening phase during which all animals in the group have to test negative for brucellosis during two consecutive months, which takes about 200 days. Animals that pass Phase One move on to Phase Two. In Phase Two, they must test negative two more times over the course of one year. And Phase Three is what’s called “assurance testing;” it’s kind of a fail-safe. Phase Three includes two more tests over another year. So for males, that means 200 days, plus one year, plus one year.

  Chris Geremia: So when we originally built this pen, the thought was that only that first phase would happen in Yellowstone. Because we’ve never documented an animal having brucellosis after those first 200 days—that screening phase—we thought that would be sufficient. And Fort Peck would be the place where they’d undergo that Phase Two Quarantine and Phase Three Assurance Testing. We didn’t think they’d be here that long. We thought they’d be here for 200 days.

  Narrator: The Tribes thought that way too. They built their facility with managing the full quarantine process in mind.

  Chris Geremia: The facilities up at Fort Peck are much more capable of handling large numbers of animals than what we have here. It has all of the infrastructure, it has all of the land, and it’s much larger than any of the structures within Yellowstone National Park. It’s a great place to do quarantine. And on top of it all of the costs associated with caring for and feeding animals would not be incurred by the Federal government.

  Narrator: But disease-management protocols dictate that it’s only after an animal passes Phase Two that a state veterinarian can certify it as brucellosis-free. And according to Montana state law, only brucellosis-free animals can be transported outside the designated surveillance area for brucellosis, which surrounds Yellowstone.

  Chris Geremia: So we were stuck at this impasse. So I think we got to the point where maybe it makes sense to try and reach the common ground we all have and start getting operational quarantine started.

  Narrator: And for now, that means Phases One and Two happen inside the designated surveillance area for brucellosis which surroundsYellowstone National Park and only Phase Three happens at Ft. Peck.

  Chris Geremia: And something we’ve had to learn now is can these bison actually live in an old weed field?

  (sounds of truck)

  Narrator: I spend the later part of the day on a flatbed truck with Chris and a couple of the Stephens Creek wranglers.

  Narrator: They fill the truck with bales of hay. Then, Chris drives around the pen in a wide arc.

  (sounds of truck driving and feeding)

  Narrator: The wranglers flake bales off the back of the truck. The bison file in behind to feed. They follow the contour of hay in plodding steps. Almost two years of this.

  (sounds of truck driving and feeding fade out, field sounds fade up)

  Chris Geremia: It keeps you up at night at times. Never at any point in my life would I envision that I would be trying to help come up with strategies for wildlife conservation that just don’t feel like wildlife conservation because it’s very complex. But I would definitely do it again in a heartbeat.

  Chris Geremia: You know seeing these animals with those trailers heading north to Ft. Peck, I think that makes all the rest worthwhile. It’s gonna be a good day.

  (Sounds of trailers driving into Fort Peck, Rick Wallen saying “how’s that for some space!”) Narrator: On August 19 2019, seven trailers full of bison pull in to the quarantine facility at the Ft. Peck Indian Reservation. The Fort Peck reservation lies beyond a stretch of northern Montana called the Hi-Line. I’ve heard people describe it as “God’s Country,” and now I see why. Rolling hills of late-summer grass and wheat draw an endless line under a wash of blue. These bison traveled 500 miles to get here. They’re the first of that larger group of bison to be transferred to the Tribes: 55 in all.

  (sounds of preparing for animal release)

  Narrator: The trailers line up side-by-side.

  (sounds of preparing for animal release)

  Narrator: Workers unlock the trailers.

  (sounds of doors opening)

  Narrator: Then, one by one, they open the doors.

  (sounds of bison running out of trailers and out into the pasture)

  Narrator: Nineteen wild bison barrel out of the trailers and into the prairie beyond. The start of a new fate for Yellowstone bison captured at Stephens Creek.

  (sounds of wind blowing in the grass, Fort Peck Tribes welcome song) Chairman Azure: The bison that we just released out here is an awesome event.

  Narrator: That’s Floyd Azure, chairman of the Fort Peck Tribes.

  Chairman Azure: It’s a feeling I can’t express. I mean it's something that—I don’t know—I think you have to be Native American to understand what it is.

  (sounds of wind blowing in grass)

  Narrator: Chairman Azure is looking out past the fences. Past the fences at the group of bison that are noses to the ground, nibbling on bites of grass.

  Chairman Azure: That’s beautiful. I mean, you don’t see anything more beautiful than that. And my ancestors seen that every day and they realized what they had. And now I understand. That’s why they were very protective of the bison. It was their everyday survival and that’s what I feel today—just that, I understand.

  Narrator: Bison hold great value—cultural and spiritual value—for many Tribes. And Yellowstone bison are special because they’re seen as some of the only genetically-pure descendants of the ancestral herds that once roamed across North America. Many Tribes view the treatment of bison as a grave injustice and see the restoration of bison as a source of healing.

  Chairman Azure: I want to get back to where we were back then. Where we took care of ourselves. Where we didn’t have to depend on any government or anybody. We took care of each other. We took care of nature to make sure that we had food for the next day.

  (sounds of wind blowing in grass)

  Chairman Azure: We’ve had a lot of ups and downs since then, we had to prove ourselves numerous times. And finally I think we got it across that we can do this and we will do this.

  Narrator: Chairman Azure says that trust has been an issue among the inter-agency partners that manage quarantine, and that sometimes the Tribes have felt left out of the decision-making process.

  Chairman Azure: It’s the stereotypical picture of the Native American that we can’t do anything. No we can. I mean, it’s just like anybody else: you get the right people in place you get the right attitude it gets done.

  Narrator: And Chariman Azure says the Ft. Peck Tribes have the right attitude and the right people.

  Robbie Magnan: Today was a very historical day, I feel

  Narrator: Robbie Magnan is the director of the Ft. Peck Tribes Fish and Wildlife Department. He runs the buffalo program for the Tribes.

  Robbie Magnan: Personally I feel that we accomplished something finally. We wanted to see these animals come out alive. Our whole goal is to get buffalo restored to other places in the United States.

  Narrator: Once bison complete their last phase of quarantine at Fort Peck, they can be released on the reservation or go to other Tribes and organizations that want to establish conservation herds. In fact, the Ft. Peck Tribes have already transferred some of their earlier quarantine graduates to the Bronx Zoo and some to the Wind River Reservation in Wyoming. And the Fort Peck Tribes are actively exploring more possibilities like these with the InterTribal Buffalo Council—a coalition of 69 federally-recognized Tribes committed to restoring buffalo to Indian Country. Robbie Magnan says it’s time for Tribes to reconnect with the buffalo.

  Robbie Magnan: Buffalo have always been part of Native Americans’ economy. We left the buffalo they didn’t leave us. We need to get back to the buffalo and learn from them again. To keep watching these guys keep learning from these guys is my only hope right now.

  Narrator: Hope. Chairman Azure says that’s the overriding feeling here today. Hope for a future with bison. Hope for a future with more collaboration.

  Chairman Azure: I hope we don’t have any more fights over this. I hope that we can work together on more projects than this.

  Chairman Azure: Working together solves problems. No one is any different than anybody else. God created us all equal. The problems can be solved by working together not by separating each other.

  (sound of wind in grass cross-fades with crickets)

  Narrator: That night, Chris and the rest of the group from Yellowstone’s bison management office make camp outside the fenced pasture. The sky turns orange, then starry, and the crickets start to sing. Rick Wallen is there, too. He’s come to help and, not for nothing, to see the years of work before retirement bear out.

  Rick Wallen: Well, you know, Yellowstone Bison for many decades have had a frightful ending when they leave the national park. The conservation of Yellowstone bison should never be about, you know, fright. They’re not a pest on the landscape.

  (music) Rick Wallen: Yellowstone bison are a cultural resource and a legacy type of a species. They’re a noble, native, wildlife species on the landscape and deserve some sort of an honorable ending. And for these animals that want to migrate out of the national park they find that there’s no place for them to go. We spent a decade trying to find a place for them to go and that place right now is a trailer trip to Ft. Peck Indian Reservation. And the Tribes here at Ft. Peck honor them—more than most of the world.

  (music)

  Rick Wallen: So until we can find more space for wild bison in the Greater Yellowstone area, this becomes an alternative to a death trap and a shipment to slaughter and we’re happy. We’re happy to see them find tall grass and beautiful sunsets on the prairie, where their ancestors lived by the millions. May they long live a happy life.

  Narrator: The next morning, we make the trip back to Yellowstone. Back to Stephens Creek. Back to get ready for two more transfers of bison. In thirty-six hours we’ve driven a thousand miles. And there are two thousand more to go.

  (sounds of crickets and music fade out) (Sounds of walking at Stephens Creek fade up)

  Chris Geremia: Last night when we were up at Ft. Peck, you asked me, you know, what was I thinking about seeing those first bison get released up at Ft. Peck. You know today, we’re back at Stephens Creek; here we are again (starts to laugh) at Stephens Creek. Ten years ago I never would have thought that Quarantine was a possibility. And you know, it was a compromise. Everybody had to give something to reach that goal. And each partner has to do exactly what they need to do for this to be successful. You know, we need to trust each other. We can only go as far as we can go together.

  Chris Geremia: My goal with these 55 bison is to show people how to do quarantine. So we need other people to learn from what we just showed is possible. And take up doing quarantine. I think what we need to say is that we opened the door, but we also need to pass the torch on doing quarantine. And these 55 bison, they’ll be teachers to us all.

  Narrator: Chris and I get in his car. He sticks the key in the ignition then takes it out. In the silence we can hear sounds of staff working at Stephens Creek. It’s only a few months until winter when culling could begin, but also the next opportunity to bring new animals into quarantine. Through the dusty windshield we can see the pen holding rest of the bison that will go to Ft. Peck. Chris looks out past the fences, past the bison, past the line of cottonwoods that marks the park boundary in the distance. It’s been a long road. But I think Chris is the kind of guy who’s OK with playing the long game.

  Chris Geremia: I’ve spent a lot of time with bison in this park and I’ve seen some of the most amazing things whether it’s the natural behavior of bison or watching a young kid go out to watch bison carrying his little bison stuffed animal just so excited to see Yellowstone bison and I’ve seen some of the hardest things that I’ve had to do which is to send these animals to slaughter and I just see a place for quarantine. It can reconnect Tribes with bison it can help protect the genome of bison and it has the potential to reconnect bison with public lands.

  (Sounds of truck starting and old fan belt squealing, then background dialogue: Tell me about your truck. It’s a 1997 Tacoma. How many miles? 271,000. (laughing) Maybe it’s time to replace the fanbelt…)

  (music)

  Narrator: As Chris and I drive back to his office, we pass under the Roosevelt Arch. It’s is a 50-foot stone arch with the inscription “For the benefit and enjoyment of the people.” That’s a phrase from the 1872 legislation that established Yellowstone National Park. “For the benefit and enjoyment of the people.” And not just some of the people. All of the people. Just that one phrase. It holds so much. How simple things might have been if Yellowstone had been established solely with the preservation of nature in mind. But it wasn’t. And that tension—that balance—between managing for our ecological values, our cultural values, and our political values is what makes our decisions so hard...and so worthwhile. Make no mistake. We have tough choices ahead. But even Theodore Roosevelt knew that nothing worth having comes easy.

  (music fades out)

 

Yellowstone bison released at Fort Peck Indian Reservation in 2019.

Tribal Food Transfer Program (TFTP)

Yellowstone transfers bison to Tribes, who then process them for their meat and hides at Tribal meat-processing facilities. This program supports Tribal food sovereignty and provides bison meat to Tribal members who may not have access to harvest opportunities outside the park.

Tribal Harvests & State Hunts

Currently, eight American Indian Tribes exercise their treaty rights to harvest bison outside Yellowstone, with each Tribe managing its own harvests. We support Tribal efforts to expand harvests outside the park, enhancing access to traditional food and cultural resources. The state of Montana also manages a smaller public hunt. Together, the harvests and hunt help manage bison populations effectively, especially under favorable weather conditions.

 

A bison group on the move in Lamar Valley at sunrise.

Target Population Range & Adaptive Management

Managing wildlife populations to a static number isn’t realistic or suitable for bison, as their migration patterns fluctuate with the weather, causing the number of bison exiting the park to vary significantly each year. For this reason, the Bison Management Plan sets a flexible target population range of 3,500 to 6,000 animals.

Each year’s management strategy is adjusted to the current bison population and migration numbers, with specific guidelines provided to IBMP partners and Tribes each fall to help ensure that removals do not harm the population’s health. The management tools applied each year depend on the following population thresholds:

• Above 5,200: We rely primarily on Tribal harvests and state hunts to manage numbers. If harvests and hunts are unable to reduce numbers, we commit to decreasing the population by removing additional animals through the TFTP. We prioritize the removal of brucellosis-infected bison, which stabilizes or decreases brucellosis prevalence over time.
• Below 5,200: We only place bison in the BCTP and utilize the TFTP to remove brucellosis-positive bison that are identified in selecting animals for the program.
• Near 3,000: We protect the population inside the park and encourage partners to reduce hunting outside the park.

 

Studying Yellowstone Bison

Each summer, bison managers conduct aerial counts of the bison population using fixed-wing aircraft. We integrate these counts with survival rates of radio-collared bison and ground surveys of male-to-female and female-to-calf ratios to estimate the population status. We then use population modeling techniques to provide management recommendations to our partners for implementing hunts in winter.

Genetic Monitoring

Bison in the park are a metapopulation or a single population with two distinct breeding groups. During the July and August breeding season, we collect genetic samples from bison using biopsy dart projectiles. From these samples, we determine gene frequencies and track genetic diversity to help ensure that we are sustaining the population.

 

Duration:

1 minute, 12 seconds

A Yellowstone field crew collects bison DNA samples during the rut.

 

Rangeland Monitoring & Grazing Experiments

Bison use only about 40% of the grazeable acreage in the park, but in some areas, like Lamar Valley, they graze intensively. We use small grazing exclosures throughout the high-grazing areas of the park to evaluate consumption patterns and impacts on soil health, plant productivity, and nutrient cycling. We monitor long-term exclosures to see how plant communities are changing with and without bison.

To view more bison research in Yellowstone, visit Science Publications and Reports.

 

Questions & Answers

 

NPS Bison Management Plan

Why does the 2024 Bison Management Plan identify a bison population of 3,500 as a lower limit?

Genetic evaluations indicate a minimum population of 3,500 (post-calving) will likely protect existing genetic diversity.

What will the NPS do if the bison population drops below 3,000 in late winter?

The NPS will take action to protect the bison population if numbers drop below 3,000 animals in late winter. The NPS will cease placing bison in the BCTP and communicate and coordinate with other partners to reduce lethal removals outside the park. If needed, the NPS may capture bison and hold them until spring to protect the population.

Why does the plan identify a bison population of 6,000 as an upper limit?

The upper limit of 6,000 (post-calving) is determined by the size of wintering areas outside the park, as defined by Montana.

What will the NPS do if the bison population exceeds 6,000?

The population may exceed 6,000 animals due to a series of mild winters with little migration. When that happens, the NPS will remove enough animals to reduce the population to below 5,200 animals (post-calving). That may occur incrementally, or in a single winter depending on the number of animals migrating out of the park.

Can the NPS make the other agencies manage for 3,500-6,000 bison?

No. The NPS will provide an annual removal recommendation to IBMP partners and American Indian Tribes each fall and further coordinate through winter to assist their decisions on implementing hunts, captures, or other lethal removals outside YNP. The number of bison removed each year will depend on the magnitude of the migration, with more animals removed when more animals migrate. The NPS will take precautions to help ensure the bison population remains within a range of about 3,500-6,000 animals.

Why is the NPS managing for more bison than identified in the original IBMP?

The original IBMP proposed a population target of 3,000 at the end of winter or 3,600-3,700 (post-calving), and subsequent scientific studies indicate that larger numbers benefit the ecosystem and visitor experience and can be effectively managed.

How are bison captured for the Bison Conservation Transfer Program (BCTP)?

Bison are captured near the north boundary of Yellowstone as they migrate out of the park. Fences guide them into enclosures, so they wander in on their own or are sometimes guided in by riders on horseback.

Are animals abused at Yellowstone's bison facility?

No. The safety of people and animals is our top priority. The Humane Society has evaluated the operation twice, and each time we've adopted their recommendations. During 2020, we received expert training and worked to improve low-stress handling of bison during handling and processing. Two old photos are often used to falsely depict our handling practices. One shows a bison being held with a nose ring during brucellosis testing, a practice we haven’t used in many years (we now have a hydraulic chute that holds the animals relatively still during testing). The second shows a bison being carried by a front-end loader: a photo that was taken outside the park, most likely after a bison was shot by a hunter or hit by a car. Adult bison can be very large and heavy and often times require heavy equipment to move carcasses from vehicle accident scenes.

What is the capacity of the BCTP?

The NPS and APHIS have the capacity to hold 200-300 animals in the quarantine facilities in and near the park. This holding capacity supports entering 100-300 animals into the program most years. Annual variations in migrations may not allow the NPS to operate the BCTP at full capacity in some years.

How many bison have been moved to American Indian Tribes through the BCTP?

Since 2019, over 400 bison have been transferred to 26 other Tribes across 12 states, which has been the largest transfer of Yellowstone bison among Native American Tribes in history. Numbers of bison moved to the Fort Peck Tribes for assurance testing include:
2019: 93 bison
2020: 11 bison
2021: 50 bison
2022: 28 bison
2023: 116 bison
2024: 116 bison (No additional transfers are planned for the remainder of 2024.)

Does the NPS want to expand the BCTP?

The NPS is committed to increasing the number of bison given to Tribes and expand Tribal involvement under Secretarial Order 3410. The new management plan commits the NPS to work with Tribes and state and federal agencies to find reasonable and acceptable ways to expand the program.

How many Tribes harvest bison outside the park?

Currently, eight tribes exercise treaty rights to harvest bison on unclaimed lands outside the park, including Blackfeet Nation, Confederated Salish and Kootenai Tribes, Confederated Tribes of the Umatilla Reservation, Crow Tribes, Nez Perce Tribes, Northern Arapaho Tribes, Shoshone-Bannock Tribes, and Yakama Nation.

Why can't harvest alone control the bison population?

Bison harvest has been ineffective at limiting bison numbers unless winter is very severe with big migrations out of the park. The area where bison can be hunted is very small, and bison often respond to concentrated hunting pressure along the park boundary by returning to the security of the national park where hunting is prohibited.

Why doesn't Yellowstone allow hunting in the park?

Federal law (National Park Protection Act, 1894) prohibits hunting in Yellowstone. Because of this prohibition, Yellowstone offers some of the best wildlife viewing opportunities in the world. This prohibition also supports our goal to manage the park so that human activities have as little effect on natural processes as possible. Allowing hunting in Yellowstone would drastically affect the behavior of animals and change the experience for people who come to watch them.

Will the NPS continue to ship bison to slaughter?

Yes. The 2024 Bison Management Plan will shift away from transferring bison to Tribes who would then sacrifice them for their meat and hides at meat processing facilities through a Tribal Food Transfer Program (TFTP). Instead, it prioritizes the BCTP, which requires testing enough animals each year to fill the program. Brucellosis-positive animals identified through testing will continue to be given to Tribes through the TFTP. When the population is above the assurance threshold of 5,200 animals, more bison may be captured and tested to help control numbers. In such cases, the NPS will prioritize brucellosis-positive bison for the TFTP and adjust the number of bison for the TFTP down based on the number harvested outside the park.

How are bison killed for the Tribal Food Transfer Program (TFTP)?

As part of the Tribal Food Transfer Program, Tribal Nations receive the bison from the NPS in the park bison facility, and the Tribes transfer them to meat processing facilities on trucks and trailers.

What happens to the meat of bison killed for the TFTP?

Tribal Nations distribute the bison meat and hides to their members.

Does Yellowstone profit from shipments of bison?

No. We receive no payment for bison given to Tribes.

Does culling put the bison population at risk?

No. Yellowstone’s bison population has grown steadily over the last 50+ years: from 500 animals in 1970 to nearly 5,000 in 2023. Each year, the bison population in the park increases by 10%-17%. Along with elk, bison are the most numerous large mammals in Yellowstone, and periodic culling will not alter that fact. The sizes of most wild ungulate populations in North America are limited by hunting and/or captures and removals.

 

Interagency Bison Management Plan (IBMP)

Who manages Yellowstone bison?

Five federal/state agencies and three Tribal entities make decisions about Yellowstone bison in a cooperative effort called the Interagency Bison Management Plan (IBMP). These include the Animal and Plant Health Inspection Service, the Confederated Salish and Kootenai Tribes, the InterTribal Buffalo Council, Montana Department of Livestock, Montana Fish, Wildlife and Parks, the National Park Service (Yellowstone National Park), the Nez Perce Tribe, and the U.S. Forest Service (Custer-Gallatin National Forest).

How does the IBMP work?

The IBMP set a principal purpose of conserving a wild, migratory bison population and reducing the risk of brucellosis transmission from bison to cattle. None of the entities released their authority for managing bison through the IBMP. For example, the NPS retains its authority to manage bison in the park, the State retains its authority to manage wildlife in Montana, the USFS retains its authority to provide habitat for wildlife, APHIS retains its authority to regulate diseases that impact livestock, and Tribes retain their authority to exercise treaty hunts on unclaimed land. The IBMP serves as a forum for the entities to reach agreements on bison management as they move across different jurisdictions and to inform one another of the management actions they intend to take each year.

Where are bison allowed to roam outside the park?

Bison are allowed to migrate from Yellowstone during winter and spring into relatively small management (tolerance) areas in Montana adjacent to the northern and western boundaries of the park. Given existing political and social constraints, however, it’s unlikely these management areas will be increased if bison numbers continue to increase, and there remains a possibility that management areas outside the park may decrease, which may require the NPS to take additional management measures.

Where do bison management actions take place?

Bison are only managed when they are migrating out of the park. The NPS operates a bison facility near the northern park boundary where bison are captured, tested for disease, entered in the BCTP, or held and released back into the park. State hunts and Tribal harvests occur in tolerance areas defined by Montana outside of the Yellowstone boundary.

Why do states treat bison differently than other wildlife when they leave the park?

Bison are not allowed to move freely outside Yellowstone due to fears they might transmit brucellosis to cattle and out of concerns about competition with cattle for grass, human safety, and property damage. Elk are also infected with brucellosis, but their movements outside the park are not restricted. State governments control the management of wildlife outside Yellowstone (unless a species is federally listed as threatened or endangered).

Why doesn't Yellowstone force surrounding states to change their policies?

Outside Yellowstone, states manage wildlife, and Yellowstone cannot force them to tolerate more migrating bison.

Why doesn't Yellowstone ignore or withdraw from the IBMP?

Yellowstone isn't big enough to manage a migratory species like bison on its own. Bison conservation is a shared responsibility that crosses many political boundaries. Withdrawing from the IBMP would make it more difficult to collaborate with the land management agencies and Tribes that share an interest in what happens to bison when they leave the park.

 

Bison Stats

How many bison were removed from the population in winter 2023/2024?

Approximately 61 bison were removed from the population during winter 2023/2024, including 5 bison placed in the BCTP, 15 bison captured by the NPS and transferred to Tribes through the TFTP, and 41 bison harvested by state hunters or Tribal members.

What is planned for the bison population in winter 2024/2025?

The NPS will count the population in August 2024 and recommend a removal objective to the IBMP partners in fall based on the 2024 Bison Management Plan.

Is Yellowstone's bison population healthy?

Yes. Yellowstone’s bison population has grown steadily over the last 50+ years: from 500 animals in 1970 to nearly 5,000 in 2023. Yellowstone bison represent a unique source of genetic diversity.

Aren't bison protected as our national mammal?

No: that designation did not provide any special protection to bison. Read more about the National Bison Legacy Act.

 

Brucellosis

What is brucellosis?

• Brucellosis is a bacterial disease that can induce abortions or stillbirths in infected animals but does not kill them. For ranchers, brucellosis has an economic impact because it affects the reproductive rate and marketability of their animals.
• Up to 60% of Yellowstone bison test positive for exposure to brucellosis (depending on age and sex).
• Brucellosis has been eradicated in cattle herds across most of the United States. Bison and elk in the Greater Yellowstone Ecosystem persist as one of the last reservoirs of infection.
• Brucellosis was introduced to Yellowstone bison and elk by domestic cattle in the early 1900s.

Is brucellosis really a threat?

Yes. People both understate and overstate the risk of brucellosis transmission. Transmission of brucellosis from bison to livestock is possible because in late winter, bison migrate to low elevation areas outside the park where livestock are concentrated. At this time, bison are late in their pregnancy: the most probable time for infected animals to abort fetuses that might be found by other animals. The fact that there's never been a documented transmission of brucellosis from Yellowstone bison to cattle does not mean it couldn't happen. Rather, it’s a testament to the diligent management efforts put forth by the state of Montana and the National Park Service to prevent commingling of bison and cattle during the time period when transmission is most likely.

Do other animals carry brucellosis?

Yes. Over the last two decades, more than 20 livestock operators in the three states surrounding Yellowstone discovered brucellosis in their animals. In each case, wild elk transmitted the disease.

Why don't local ranchers vaccinate their livestock?

They do, but there is no vaccine that is 100% effective at reducing abortions due to brucellosis or eliminating the potential of infection from wildlife.

Why can't bison that test negative for brucellosis be allowed to live?

The NPS initiated the Bison Conservation Transfer Program to identify bison that don't have brucellosis and transfer them to new areas as an alternative to sending them to slaughter. Continued coordination with APHIS will result in transferring about 100 animals per year to Tribes as an alternative to slaughter.

Why can't bison be vaccinated against brucellosis?

• Vaccinating wild bison against brucellosis with existing vaccines would not substantially suppress the disease and could have unintended, adverse effects on the bison population in Yellowstone.
• There is no easily distributed, highly effective vaccine: current vaccines would only create a 10% to 15% reduction in infection, and immune protection is short-lived.
• Even if we reduced the prevalence of brucellosis in bison, they could be re-infected by elk.
• For more details, read the final Environmental Impact Statement that evaluated the potential of remote vaccination of bison.

 

More Information

 

 

Bison Management News