A record cull of Yellowstone bison intensifies debate into how to best manage them

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America’s Bison were once close to extinction.

Now, there are nearly 6,000 bison in Yellowstone National Park.

But sometimes they migrate out of the park.

"Bison are a huge animal and being diseased and habituated to people ... you don’t want them around," Druska Kinkie says.

Yellowstone Bison carry brucellosis, a disease the cattle industry doesn’t want.

"It really is a day-to-day balancing act, and we are doing everything possible to not leave anyone behind, to listen to all of the different stakeholders with bison," wildlife biologist Chris Geremia says.

Today, On Point: Managing Yellowstone's iconic bison.

Rick Wallen, former Bison Biologist at Yellowstone National Park. He worked with bison at Yellowstone for 17 years and retired in October 2018. Co-editor of Yellowstone Bison: Conserving an American Icon in Modern Society.

Martin Zaluski, Montana State veterinarian with the Montana Department of Livestock.

Druska Kinkie, cattle rancher in Paradise Valley, Montana. She operates a third-generation commercial cattle ranch about 30 miles north of Yellowstone National Park.

Robert Magnan, director of Fort Peck Tribes Fish and Game Department.

Kola Shippentower-Thompson, member of the Confederated tribes of the Umatilla Indian Reservation in eastern Oregon and she participated in the bison hunt this year.

MEGHNA CHAKRABARTI: The American bison is a symbol of a country that was, in the past, open and free. 30 to 60 million bison may have roamed North America before the mid-1800s. Then came the rapid westward expansion of American settlers. That brought commercial hunting and mass slaughter of the animals. More painfully, the United States Army sought to starve native tribes into submission. The lives of Native Americans were intimately intertwined with the bison. The army sought to exterminate the bison from the Great Plains.

In 1867, one Army colonel is said to have ordered his troops, quote, 'Kill every buffalo you can. Every buffalo dead is an Indian gone.' So by the late 1800s, those 60 million bison had been reduced to just a couple hundred animals. But since then, restoration efforts and the creation of the National Park Service have led to the rebounding of the American bison, particularly in Yellowstone National Park, where the iconic bison herd there was recently numbered at 6,000 strong. And park visitors are in awe when they see the animal, such as in this video from a couple caught in the road in the middle of a bison herd.

VIDEO [Tape]: Oh, my gosh. Oh, my God, I'm scared. This is the way to do this. Oh, my gosh. He just liked his tongue. This is a once in a lifetime.

CHAKRABARTI: So, yes, the bison inspire awe. But they also seem to inspire stupidity in human beings. There's always that story of a park visitor who gets too close. Like in this video caught by a bystander, which played on national news a lot.

NEWS BRIEF [Tape]: This tourist at Yellowstone National Park thought it would be a good idea to taunt the massive beast. You can hear the bison grunting. The guy escaped serious injury because it was the bison who made the decision to walk away.

CHAKRABARTI: Lucky guy. And people, just don't do that. If it's human versus bison, the bison is going to win. But the bison themselves are not so lucky when they roam out of Yellowstone's park boundaries. They are following their ancient migratory patterns, but now once they do, they cross into a world of competing interests. Ranchers, environmentalists, state and federal stakeholders, all competing for the resources the land has to offer.

So some of those out of bounds bison are hunted. Others quarantined, approximately 1,500 animals this past winter. So how to balance stakeholder interests and the bison's preservation? That is a pressing question for Yellowstone National Park. How to best manage Yellowstone's iconic bison herd. Well, Rick Wallen joins us today. For 17 years, he was Yellowstone's lead bison biologist. ... Rick, welcome to you on Point.

RICK WALLEN: Thank you very much.

CHAKRABARTI: So I'm going to, first of all, put to rest the most controversial question in today's hour. Is it bison or buffalo, Rick?

WALLEN: Well, we in the Park Service call them bison, but many people across the country still refer to them as buffalo, especially American Indian partners.

CHAKRABARTI: Okay. Is there a proper one? I mean, how should I refer to them through the rest of the hour?

WALLEN: You know, I've always told people to refer to them as you wish. And I think it's more cultural than anything. Bison is the scientific name, and science geeks just sort of stick to those genus and species names all the time.

CHAKRABARTI: But as you pointed, native peoples call them buffalo. So acknowledging that, I'm just going to stick with the scientific one for now. So the bison, first of all, what made you want to dedicate your professional life to studying and observing North American bison?

WALLEN: You know, that's a really good question, and I haven't thought about that in quite a long time. But early in my career, it was just one of the duties among many. And as I spent more and more time in the field, you know, following them around and realizing that they needed help, because they had been persecuted to such small numbers. And the Park Service had a mission to restore bison, to really return to the ecology that they represented on the landscape. It motivated me to apply for the job at Yellowstone, and I was lucky to be hired.

CHAKRABARTI: Well, what is the ecology then that the bison represented? Tell me more about that.

WALLEN: Well, bison represent the grazing influence on the landscape. And the grazing influence actually impacts the plant community as well. Bison rub on trees, prevent the trees from filling in, you know, large forests. They preserve prairie ecosystems. And bison can actually sort of stimulate grass production in the open grasslands by grazing them intensively, recycling the nutrients and making it more efficient for the nitrogen cycle to function and fertilize all the grasslands out on the landscape.

Bison represent the grazing influence on the landscape.

Rick Wallen

CHAKRABARTI: So this was their sort of key role in the Great Plains ecology. Before that mass slaughter took place in the in the middle of the 19th century.

WALLEN: Precisely. And having millions of animals moving across, you know, Central North America allowed the grasslands to be thriving and productive. And the only other kind of influence that has that kind of magnitude is large fires on the landscape.

CHAKRABARTI: So both of which are now controlled, right? The bison and the fires. ... So we talked about in the introduction, I described really just the murderous effectiveness with which both Western settlement expansion and the United States Army reduced bison numbers from, you know, maybe 60 million down to, I think around 500 or so animals. I mean, it's a shockingly small number. What has it taken to bring the numbers back up? They're never going to be back in the millions. But how many bison are there nationwide now?

WALLEN: So nationwide there are roughly a half a million bison. But of those half a million bison, there's only about, you know, 10,000 or 15,000 that are in wildlife preserves. And then among those small numbers, there's really only a couple of locations, I'm trying to think. Three locations where they free roam on the landscape, where they really can exhibit, you know, the ecology that they did thousands of years ago.

CHAKRABARTI: So the ones that aren't on preserves, those are bison that are privately owned and ranched, presumably.

WALLEN: That's correct. And it has quite a big industry. And many of the ranchers in the bison industry do it from a very ecological perspective with little hands-on type of management. So they're trying to preserve the ecology as best they can. But what they don't have is like an equal sex ratio of the population. Males tend to create a few more problems if you have a lot of them, especially if you have 50% of them. And they don't have predators on the landscape to sort of help bison follow that survival of the fittest that nature directs most of the time.

CHAKRABARTI: So then that's one of the things that makes the Yellowstone's herd, really keep using this word, iconic? Because they're living a life as close to the life the bison used to live before the mid mid-19th century.

WALLEN: That's correct. And that's what Yellowstone argues often. That there's so limited locations where we could actually preserve that kind of situation. We have to go to great lengths to do it as best we can.

CHAKRABARTI: Yeah, just as a little aside. So, I mean, obviously, Yellowstone is a gem in the National Park Service system. And I got to visit it several years ago and saw the bison. And they are truly magnificent animals. Right? They're gorgeous. They're big. They're powerful. Do you ever ask yourself why any person, and this happens every year, would be dumb enough to, like, get close or, you know, try to even taunt the bison? Because I think it just happens with sad frequency in the park.

WALLEN: You know, I think it's naivete, primarily. Because, you know, people don't know enough about wildlife. And they would do it to bears, if the bears would let them. But bison actually let them get very, very close before they exhibit some sort of reaction that people might regret. And over time, you know, a dozen or so people have very much regretted getting too close to them.

CHAKRABARTI: I see it as a form of natural selection in action.

WALLEN: Absolutely.

CHAKRABARTI: Okay. So tell me a little bit about what it took to get the number of bison that are in Yellowstone, or considered Yellowstone's herd, to the numbers that it was until earlier this year?

WALLEN: Well, you know, that really was an evolution of thought. And in the turn of the last century, in around 1900, when the population was down to just a couple of dozen animals throughout Yellowstone, it was thought that we needed to implement ranching type techniques. We needed to bring the animals in from somewhere else, put them in a facility where we could protect them from the predators, feed them during the wintertime.

And so the early Park Service folks did that aggressively and the population grew quickly. And then the evolution of thought sort of drove to, well, maybe we don't need to feed them as much. So my predecessors quit feeding them. Pretty soon they quit growing the hay to feed them. And before we knew it in the 1960s, there was this change in policy to just let the evolutionary processes play out and see, you know, only the survival of the fittest would, you know, survive.

And then they would be stronger, and they would learn to use the landscape the way their ancestors had. And so because bison are fit well for this landscape, they reproduce well, they defend themselves against predators very well. They've grown to large numbers. And in the early 1980s, they had expanded their use of the park to pretty much all around the park, even going to the park borders.

Because bison are fit well for this landscape, they reproduce well, they defend themselves against predators very well.

Rick Wallen

CHAKRABARTI: A record number of animals ... were removed from Yellowstone's iconic bison herd. So, Rick, can you tell us a little bit about what happened? I mean, there was a really harsh winter over Yellowstone that put a lot of snow on the ground. And then what did the animals do in response to that?

WALLEN: Animals tend to move around across the landscape every fall, just, you know, exploring the area, finding out what each of the grassland areas look like. And they'll move to the park boundary even well before the snowpack accumulates. But as the snow gets deeper and deeper, you know, every animal has a mind of their own and they begin to, you know, slowly and methodically migrate to where they think they can, you know, find the most resources to get through the rest of the winter. And as the winter unfolds and the snow gets deeper and deeper and deeper, they cannot move.

You know, enough of it out of the way to find, you know, grass at the bottom of the snow pack. And they'll seek locations where they can. And sometimes they'll go higher elevation and look for windswept ridges and places where the wind blows the snow out of the way. And it doesn't accumulate so much. Sometimes they walk down valley knowing that at lower elevations, snow accumulates less. And there is a point in time where the grasslands transition from within the national park to outside the national park. And I think that we started seeing animals move to the park boundary as early as the middle of November this year.

CHAKRABARTI: Wow. And so eventually, a lot of them, crossed the boundary, what into Montana's Paradise Valley, is that right?

WALLEN: That's correct. They go to the park boundary and beyond in two locations, and they follow the Yellowstone River Valley out into the Paradise Valley area. And then they also follow the Madison River Valley west towards West Yellowstone and the Hebron Basin. So there's two sort of egress locations that they migrate towards.

CHAKRABARTI: Okay. Now of course the park boundaries are meaningful only to human beings, right? Not animals. So the bison have no idea where they're going, or what they're doing, where they're crossing into. But once they do that, though, there's, as we said at the beginning of the show, this whole host of different stakeholders that suddenly become involved.

And sort of the mass movement of Yellowstone's bison led to what officials say was, you know, a difficult situation. Where they had no choice but to approve the lengthy culling of the herd, some ... nearly or approximately 1,500 animals either hunted or quarantined. Can you briefly explain why?

WALLEN: So Yellowstone has a philosophy of preservation of the ecology. And let the system play out and let animals live and die based on the decisions that they make. And outside the national park, commerce sort of drives businesses that are agriculturally related. And livestock industry has a concern about animals that carry a bacterial disease called brucellosis that affects the reproductive system.

So bison have been infected sometime in history by cattle that brought this brucellosis infection to North America. And now maintains the disease within the population and has really evolved to sort of deal with it, if you will.

It affects a small number of animals. They go through a period of a couple of years, get through the infection. You know, I call it they're cured from the infection. But basically, they don't exhibit those signs of abortion and shedding of bacteria. And given enough time you won't even be detectable in an animal that's recovered from the disease. For livestock men, that operates a business, he can't afford to lose calves and lose production. Whereas in a wildlife population, it's just a part of the natural mortality that occurs.

CHAKRABARTI: Yeah, it is sort of one of those things that gives you pause regarding human beings' impact on ecosystems. To hear you say that it's cattle that were brought to the continent that first spread the brucellosis and to the bison. And now the concern is the bison spreading brucellosis back to the cattle. I should note that the elk have it, too, and we'll talk about that in a minute. But one of the things that happened, as I mentioned, is that some 1,500 animals were approved for a quarantine. Some of them were sent to property owned by native tribes.

Others were hunted. Now, eight indigenous groups do have longstanding treaty rights to hunt bison when the animals wander out of the park boundaries. Kola Shippentower-Thompson is a member of the Confederated Tribes of the Umatilla Indian Reservation in eastern Oregon. Now, this was her sixth year going to the bison hunt at Yellowstone's boundaries. She brought home 13 bison this year and she shares her take with her entire community. And for her, the hunt is about tradition, about spiritual connection, and about basic survival.

KOLA SHIPPENTOWER-THOMPSON: One buffalo could mean the existence of a family for an entire year. We're talking warmth, we're talking food. We're talking other tools that they might need. We're talking about ceremonial rites. We have things within these animals that we need. And buffalo isn't the only animal that we have. We have several other animals that we hunt, but one buffalo could mean the world. And it means not having to rely on government assistance.

It means not having to rely on any outside resources to take care of our families. It's relying on the most pure resource that we have, which is from this land, essentially. That we were given rights to by the creator. And fulfilling that journey with that animal of their promise that they made to the indigenous people, which is, I'm going to take care of you. So we're very mindful about when we make contact with these animals and after they're down there, we also pay respects to them as well.

CHAKRABARTI: Now, just a reminder, historically, again, the bison were so intertwined with the lives of indigenous tribes in North America that, as I mentioned earlier, the United States Army, in trying to eradicate the land of tribal members, tried to do so by exterminating the bison. So when Kola talks about the connection that her families have to the bison, there's a deep and historical one there.

Now, in addition to hunting the bison who wander out of the park, some are captured and put into quarantine and eventually they end up on tribal lands in Montana and beyond. Robert Magnan is director of Fort Peck Tribe's Fish and Game Department, and he's charged with overseeing the bison transfer program. He receives the bison, keeps them in quarantine, and when they are proven to be disease free, they are added to the bison herd at the Fort Peck Reservation. And he says the program has reconnected his people with their past.

ROBERT MAGNAN: My grandchildren and my children get to enjoy what my ancestors enjoyed and what I, my family and my grandparents missed out. I never got to grow up around Buffalo and learn more stories. I'm very fortunate now that my children and my grandchildren can share the same stories that my great grandparents did.

CHAKRABARTI: So, Rick Wallen, let me ask you, I mean, these hunting rights for tribal members have been in place for some time. I mean, is this year just kind of an anomalous one because of how far the bison had to move to search for food? Or is there something sort of more fundamental about the management approach outside the park that concerns you?

WALLEN: Inside the park, there's no hunting allowed because of the nature of the preserve. And so the hunting community has to wait until animals migrate to lower elevation winter ranges in order to have that opportunity to harvest animals. So from year to year, the reason bison migrate is really driven by population abundance or really a combination of population abundance and winter severity. And the last couple of winters have been relatively mild or extremely mild compared to this past one. And last winter, you know, for example, I think the hunters only harvested about 50 animals. So that's sort of the range of variation you would expect over time for the hunters to have access to 50 vs. 1,000, like what happened this year.

CHAKRABARTI: And so, therefore, hunting is not the concern here, is that what you're saying?

WALLEN: Hunting's not necessarily a bad thing for how you manage population abundance. Bison reproduce so well that if we gave them the opportunity to just reproduce and recolonize areas of the country, it would be pretty rapid. Because about a 15% growth increment occurs each year. And for example, in a population of 6,000 animals, that's, you know, 1,500 animals. So we took out this past year one increment of growth.

Bison reproduce so well that if we gave them the opportunity to just reproduce and recolonize areas of the country, it would be pretty rapid.

Rick Wallen

CHAKRABARTI: Okay, well, so I read this quotation from Cam Sholly, who's Yellowstone's superintendent. It was in The New York Times, and Cam said that ... bison management is probably the single most challenging wildlife issue in Yellowstone. The bison is the only species we constrain to a boundary. Can you explain what he might mean by that?

WALLEN: Well, the Yellowstone mission is to preserve ecosystem processes. And in the last 125 years, we've restored bison to about as far as we could go. In Yellowstone National Park, they explore around virtually all of the park except for the high elevation areas. And so we've accomplished our mission to restore bison to the capacity that Yellowstone has to preserve them.

And the only way to take bison conservation any further is to look for partners that have some sort of managed management jurisdiction beyond the park boundary. Park superintendent really can't do anything outside the park in the state of Montana. That's another jurisdiction. And for the last 25 years, there's been this interagency sort of management strategy put in place due to a court negotiation.

And the state has a different role. Their role is to find out, you know, how they want to manage the population when animals leave the national park and how far out are they willing to manage Yellowstone bison when they leave the national park?

CHAKRABARTI: Right. So just to underscore what you said, when the bison leave the park boundaries, it's the state of Montana that has the management authority over them.

WALLEN: So the state has the management authority over the animals. The public land managers, like the National Forest Service or the Bureau of Land Management, really manage habitat for those animals. And all the private landowners that live within and mingled among all of that public land, as well.

CHAKRABARTI: We also spoke with Martin Zaluski, the Montana state veterinarian with the Montana Department of Livestock. And it is his job to manage for that disease we talked about, brucellosis. To date, all the known transmissions of brucellosis to cattle in Montana can be traced back to elk, not bison. So if elk are the problem, why is there so much emphasis on bison management? Well, Martin Zaluski told us it's not so simple, because he is required by statute in the state of Montana to manage the bison.

MARTIN ZALUSKI: No similar authority exists for elk. And so I am a public servant and I have to meet, or I have to execute the authority that I've been charged with. However, to say that we don't do anything with elk was also a misnomer. We work very closely with Montana Department of Fish, Wildlife and Parks.

We've worked with ranchers to provide erect barriers between their hay piles, so elk can't get into those. And then create a co-mingling, or a kind of a concentration point for elk. There is a full-time paid employee whose primary focus is to haze elk away from cattle properties. There are kill permits that are offered to landowners in areas that are particularly highest risk.

CHAKRABARTI: So again, that's Martin Zaluski, the Montana state veterinarian. He was describing there, they do things to help control elk intermingling with cattle there. But do you know the story about why there's no statutory requirement to manage the elk the way that there is the bison?

WALLEN: You know, I don't have a very good answer for that because it doesn't make sense to a lot of people. I've always felt like there's a bit of bias against wild bison. People are afraid of the things that they could do if you gave them free roam to move farther and on a larger landscape. So it's going to take a while for people to learn how to live with bison. Because we haven't had to for 200 years.

So that's a role that the state could implement, is besides the aggressive, prevent co-mingling. There could be an opportunity there to have an education effort to teach people how to live and co-mingle with wild bison if they really wanted to.

CHAKRABARTI: I understand, though, that there are very low tolerances for cases of brucellosis in cattle herds. I mean, please correct me if I'm wrong, but if there's one case of brucellosis in the herd, does the whole herd have to be quarantined?

WALLEN: That's correct. And so what they do, is if you can detect it early enough in the infection of the herd, you can clean the herd, if you will, by testing frequently and removing the individuals that test positive for the disease. And it's a difficult disease to detect. Because there can be a positive reactor in the herd, but doesn't have a high enough antibody count within the system to be detectable on the blood test.

So, you have to do repeat tests over the course of about a year to make sure that you've gotten all the animals removed from the population. So, you know, there is an impact to the cattlemen if there's an infection within their population, those cows.

CHAKRABARTI: The question of how to best manage the bison has taken on renewed urgency this year. Now, as we noted earlier, for ranchers, particularly in Montana, the concern is the possibility of bison spreading the disease brucellosis to cattle. However, of Montana's roughly 2 million head of cattle, exactly zero cases of brucellosis could be traced back to Yellowstone Bison. It's mostly coming from the elk, but nevertheless the risk to a cattle herd of getting infected by brucellosis is so potentially economically consequential to ranchers that that means a lot of them are not so enthralled by the bison.

DRUSKA KINKIE: My name is Druska Kinkie. We have a commercial cow calf operation. We live in Paradise Valley ... we're about 30 miles north of Yellowstone National Park.

CHAKRABARTI: Druska lives in what's called a designated surveillance zone, which means there are heightened controls on her cattle because of her proximity to the brucellosis in Yellowstone's bison and elk.

KINKIE: Historically, like back in 2007, 2008, the rules said you had to destroy your entire herd for even just one positive animal. That has changed. And what they do now is they put you in quarantine. And so the minute you come back with a positive, you know, it's this massive, you can't do anything. You can't move any animals. So you can't ship things. If it's time to ship your calves, you can't do that. If it's time to turn out, I don't think you can do that either. The quarantines are really difficult, very difficult to come out of.

CHAKRABARTI: Now, over the last decade, she's seen three or four positive transmissions of brucellosis in her community. The transmissions now, as we mentioned, have solely been from the elk, which are not managed as the bison are. But nevertheless, she says, there is no way bison should get more land to roam because she believes it would make the problem worse.

KINKIE: We are long past the times when bison could be free ranging in the state of Montana. There's too many people. There's too many obstacles. It's just too much futuristic. You know where we are that ... you can't go back. You can't go back and put them on the landscape now. Because they'd be in trouble all the time. So the time that we have right now says that we have bison in Yellowstone National Park. They have a certain amount of geography that they can utilize in the winter when they migrate out of the park, and that needs to be enough.

CHAKRABARTI: Druska's son works with her on the ranch, and in time he'll take over the business. But she says ranching is so hard now in many ways, and the constant battle over bison is just another thing. And for her, it's almost the last straw. So she worries about leaving the ranch for her son.

KINKIE: I actually feel bad. That this is what we have for him, because there are so many things wrong with this area that make it hard to ranch. And, you know, I wish that we were leaving him a ranch that didn't have the Yellowstone River running by it that can wreak havoc. That we weren't so close to the park where we have the diseased elk and the bison. I wish that it was more of what a ranch used to be, because I really feel bad as a parent that this is the ranch we're leaving him.

CHAKRABARTI: That's Druska Kinkie. She runs a third-generation cattle calf ranch with her husband in Paradise Valley, Montana. Now, Rick, you heard Druska say there that there's just no way to let the bison roam free in Montana. I know some people are calling for that, but not that many. I mean, what do you think even of the idea of that being a potential management strategy?

WALLEN: Well, I'm supportive of giving bison some room to roam on the landscape in Montana, because what we see at this point in time is the tribes really want to have an opportunity to harvest animals, and outside the park is the right place to do that. And there is a lot of public land in Montana. So I can understand Druska's concern.

I'm supportive of giving bison some room to roam on the landscape in Montana.

Rick Wallen

And if there's only one really, truly wild population of bison in the country that has the opportunity to, you know, exhibit the same ecological role that historically and prehistoric bison exhibited, we should consider coming up with creative ways to preserving something like that and allowing it to play out in as large a landscape as possible.

And, you know, I heard Druska say that there's more issues that make ranching hard than just bison and brucellosis. And so maybe there is a way that, you know, we can slowly work towards solving some of the conflicts that occur. I used to live in that same zone, you know, before I retired.

And there are a lot of people in that zone that really enjoy having wild bison in the wintertime, you know, roaming nearby where their properties are and has learned to live with them and are willing to do the things they have to do to live with wild bison. So I look back at early in my career when we were going through similar kinds of cultural conflict, if you will, with allowing grizzly bears to expand population abundance as a way to preserve that species and its ecology.

And I don't see that it's significantly different. And I think in, you know, 100 years from now, you know, we'll look back and read the history books and say, wow, if you know, those guys have come a long ways and learning how to live with wild bison on the landscape. And I think ranchers could learn to do it, too. And there could be a new role for conservation organizations to assist ranchers in developing the infrastructure that they would need to preserve and protect their interests from contact with wildlife.

CHAKRABARTI: So I was intrigued to hear you say this reminds you of lessons learned early in your career regarding the grizzly. Can you tell me more about that? What were the conflicts then and sort of how were they resolved?

WALLEN: Well, grizzly bears were an endangered species. There were very few animals there. Really the primary conflict with grizzly bears was recreation. And campers. And bears would get into campgrounds and steal people's food and scare people. And then they become habituated to the garbage cans behind all of the lodges, and not just in the park, but throughout the system. And, you know, we learned to go after those particular conflicts, the key conflict locations.

We made major trash dumps and more bear proofed. We told lodges you got to do a different way of managing your garbage. We didn't just go throw them out into the ravine on the back forty, like our grandparents did, and consequently bear populations grew up. We killed a few of the animals that did the wrong things and the animals that did the right things learn to hide in places that there is less conflict with humans.

And I think that's how bison would learn to use the landscape, is given the appropriate sort of conflict management strategies. The animals that learn the right things to do will protect, and the animals that learn the wrong things to do will just harvest them, you know, and get them out of the system so they don't teach their offspring to do more wrong things.

CHAKRABARTI: I wonder if there are tools available to sort of assist that process. I mean, first of all, it seems like one of the big tools is also bringing elk under management regarding brucellosis. But as we heard earlier from the Montana State vet, they do some things to try — I don't know how effective it is, but to try to separate elk from cattle on public lands outside of Yellowstone. Would any of those things be effective for bison? I mean, I heard him say earlier, like they try to haze the elk maybe from the air fencing even. Would any of those things work for bison?

WALLEN: All of those things would work well for bison, every single one of them. And it's been tried in the past. And we learned how to do that when bison were first allowed to move outside the national park. We did a lot of hazing to, you know, keep them away from conflict areas. We probably went a little overboard by pushing them too far back to the park. And I think we missed an opportunity in the early 2000's when bison were trying to do the same thing that they're doing now in Paradise Valley. They used to do in the Hibbing Basin, an explore out.

And we put so much heavy-handed management pressure on them to move them back into the park that they learned from all of that, and they started going to a different location. And now they're going to the north and the northern part of the park has accumulated huge numbers of animals. And they're doing the exact same thing they did in the early 1980s through the mid 1990s, up in the north end of the park. So, it would be nice if we could have a sort of in-between kind of management strategy where we allowed them a little chance to use public land and instead of hazing them strictly all the way back to the park, just raise them to suitable public land where they could hang out.

CHAKRABARTI: You had mentioned earlier about the deep conservation philosophy regarding the bison that Yellowstone adopted in the 1960s to truly let them live wild with almost no human intervention, which is why the park stopped feeding them. But I wonder, in years like this one, where we can see the winter snowpack may actually force the bison to move in larger numbers outside the park. Is it even possible to consider maybe for those select years, feeding them in places that would prevent as many bison from leaving park boundaries?

WALLEN: That's a good question. That's really debated amongst theorists. And I think that feeding animals is something that should be an absolute last resort. And the reason they say that is because they remember that kind of stuff. And they'll look at the place they were fed as just another source that they could go to find food. And over time, biologists have tended to shy away from feeding wildlife because it doesn't really solve the problem. We're better off trying to help them find another place that they could forage on their own than we are to just give them the welfare, if you will.

CHAKRABARTI: Okay. So there's another potential part of the puzzle here that I want to ask you about briefly, because brucellosis being the concern that we're highlighting in this conversation, there is a vaccine, brucellosis vaccine for bison. But when we talk to Martin Zaluski, he's the Montana state veterinarian with the Montana Department of Livestock. He said there also needs to be a vaccine for elk, so one for elk and one for bison if they're really going to eradicate the disease.

ZALUSKI: I would like to see efforts to develop a vaccine for elk that's effective that would have to be developed, co-developed with also an effective delivery mechanism. You can't be running wild elk through a shoot. So you'd have to have either some type of an airdropped vaccine, like they do for rabies, for the oral rabies prevention program on the East Coast. Or we would have some type of bait stations or other things. So both of those technologies have to be developed in concert.

CHAKRABARTI: Now, I also understand that cattle can be immunized against brucellosis. Is that right?

WALLEN: That is correct. Brucellosis is a difficult disease to vaccinate against because the bacteria hides in the sort of center of the cell where there's a lot of hiding locations. So. I think Dr. Zaluski, you know, has a good idea from his perspective. But the challenge has always been that brucellosis is a hard thing to research because of regulatory features. There has been, in places like Russia, weapons of war developed with the brucella bacteria.

And the brucella that we see in the wild animals of Greater Yellowstone are the same genus as the brucella ... but they're not nearly as virulent. So there are sort of restrictions against the kind of research that could develop those vaccines. And I think that maybe it's possible to develop one that you could simply implement and vaccinate cattle. We can't do that kind of research right now in a very economical manner because of those restrictions.

WALLEN: ... Brucella abortus, which is the bacteria that the bison and elk exhibit is such a poor weapon of war that it seems foolish to have to have those kinds of restrictions for that type of research.

CHAKRABARTI: Well, Rick, we only have about a minute left, and I'm wondering if you could leave us with the last thought about how you see this chapter in the story of the North American bison. In terms of like the questions around managing the bison herds now? I mean, how do you see it vis-a-vis the long history of these animals on our continent?

WALLEN: You know, I think bison are moving in the right trajectory. The Park Service has restored. Yellowstone Basin to truly contribute to the ecology that they would have contributed across North America for centuries. And I think they have enough of a following of, you know, conservation interests across America, really across the world, because of that influence. That slowly and incrementally continues to look at all the little conflicts that occur along the way. And I think that the winter of 2023 is simply a stimulus to regenerate the kind of conversation that requires, you know, creative thinking to solve all of those problems because we brought up a few this year.