For the third year in a row, grizzly bears have seen record mortalities in the Greater Yellowstone Ecosystem.
So far this year, the latest federal numbers show 81 bears have died — the majority at the hands of humans. Environmentalists are sounding alarms, saying this is evidence the bears need more federal protections, while a federal research team says this is par for the course.
“Naturally, larger populations tend to have higher numbers of mortality,” said Matthew Gould, the biologist who leads the Interagency Grizzly Bear Study Team, which puts out these numbers.
He added, “Although we've seen record counts of mortality over the last couple years, we're also [seeing] estimated record abundance for this population the last few years.”
Several conservation groups, however, expressed concerns over the record 81 mortalities, compared to the 74 documented last year, which was also a modern record.
“With this many deaths occurring year after year, it’s obvious that we still have a long way to go before we can say we are doing a good job of properly coexisting with grizzly bears,” Kristin Combs, executive director for Wyoming Wildlife Advocates, said in a joint statement with other nonprofits.
Wildlife managers killed 25 grizzlies because they were attacking cattle. Twelve were killed for getting too used to human food or getting too close to people. Another 11 got hit by cars. Two drowned in a canal.
Of the natural causes, nine were killed by other bears. Two bears were removed from the ecosystem and taken to a zoo.
Sixteen deaths are still under investigation.
Conservationists said it’s the wrong time for the Trump administration to attempt to let states manage the species, which is currently listed as “threatened” under the Endangered Species Act. The administration released a proposal to do just this last summer. Once the proposal is finalized, the administration plans to remove all federal protections for the bears.
“Record high grizzly deaths show bears need more protection, not less, as they continue expanding their range and attempt to reoccupy the places they once freely roamed,” Adam Rissien, rewilding manager with WildEarth Guardians, said in the joint statement.
But Gould, the federal bear biologist, tells another story. A transcript of his interview with Wyoming Public Radio is below.
Editor’s Note: This interview has been edited for clarity and brevity.
Hanna Merzbach: Why do deaths continue to climb?
Matthew Gould: One thing that's important to consider is not only how many mortalities there are, but also the size of the population. Naturally, larger populations tend to have higher numbers of mortality. Although we've seen record counts of mortality over the last couple years, we're also [seeing] estimated record abundance for this population the last few years [also considering birth rates]. The frequency of mortalities can sometimes be misleading, and that's why we try to look at the rate of mortality.
HM: Do you have that mortality rate on hand?
MG: For the GYE [Greater Yellowstone Ecosystem], the mortality rate varies by the age class of the bears. Our adult females and males have survival rates of 94, 95%, so that's a mortality rate of, say, 5 to 6%. Where we see most of the mortality in the system is in what we call dependent age classes. For our yearlings, we see about a 65% survival rate from year to year, and then our cubs are roughly 50% from year to year.
HM: What you're saying is: We're seeing this record number of grizzly bear deaths when you look at the raw numbers this year, but it sounds like that mortality rate is staying pretty steady across the years because that population is also growing slightly at the same time?
MG: Exactly. We look at population growth rates. That's the percent change in population from one year to the next, and we could still see positive population growth. This past year was about 2.8% growth from 2024 to 2025. Granted, population growth has been slowing down over the last few decades, and that's because the population is starting to occupy and fill all of the ecological and socially suitable habitat in the ecosystem. There's greater competition for food.
What we see most commonly in our ecosystem is adult male bears killing cubs and yearlings so that they can breed with the female, because there may have been a chance that they weren't the father of those offspring. Those lower cub and yearling survival rates is what we've seen cause the slowing in population growth over the last couple decades.
HM: I do want to get into some of the human causes of deaths this past year. Cattle conflicts were the number one reason, then grizzlies getting too used to human food, and also vehicle strikes. There were 11 recorded so far this year. What kinds of places is this happening in?
MG: What typically is involved with some of these is our higher traffic or higher traveled roads, so the North Fork of the Shoshone [River], the highway into [Grand Teton National Park], or U.S. Highway 191 that goes from Bozeman down to West Yellowstone. They're occurring at night when bears are more active, and people have a harder time seeing. Bears might be attracted to roads, whether it's because of ungulates [i.e. cattle, sheep or deer] that have been struck and killed, or if there's been trucks that have tipped over and an attractant has been spilled.
HM: What happens if population numbers continue to level off as grizzlies continue to expand their territory to where ranches, roads, campsites are? I'm just wondering if there's a future where the mortality rates rise so much that it impacts population numbers. Are we getting to that point?
MG: There's always a chance that something impacts it, but ‘impacts’ has different meanings. For example, we could increase mortality rates and the population growth could be stable, meaning the number of bears we lose one year is equal to the number of bears we gain that year. In the near future, I would not be surprised if we have zero population growth or slightly negative growth for a few years, followed by a couple of years of positive population growth. That's what we've started to see this population do.
HM: So we're not expecting any steep drop-off in overall population numbers?
MG: No. I think what's also important is the reason why we know this population so well is because it's so well studied. The Interagency Grizzly Bear Study Team, which is what I'm the team lead of, is a scientific team of eight state, federal and tribal agencies. We meet every year and we look at the numbers, and we discuss the health of the population. If we did start to see that population decline, we would be able to look at it, and we'd be able to monitor and assess potential reasons, if that is increased human-caused mortalities, or if that's natural effects that we've started to document already.
HM: You're doing this work against the backdrop of what could be some changes for how grizzly bears are managed. To catch listeners up, the Trump administration is pushing policies that could give states more management flexibility when it comes to grizzlies. They're currently listed as ‘threatened’ under the endangered species list in the lower 48 states. This could be a step towards taking them off that list, so taking away federal protections eventually.
You've said in previous interviews your job is really focused on the data, the science, not the politics. I am wondering though, however, what this could mean for population numbers and recovery going forward.
MG: Under a delisted scenario, we still would continue our long-term monitoring. An important document that folks may not know about is called the Greater Yellowstone Ecosystem Conservation Strategy. That document lists exactly what would happen in terms of habitat monitoring, population monitoring, conflict reduction, information education outreach. That provides a detailed plan as to what the state and federal partners would do with grizzly bears if they were delisted.
HM: To wrap up, every year I feel like we see the same headline about record grizzly bear mortalities. But it sounds like you think that's hiding part of the story, which is: What actually matters is mortality rates, not those raw numbers. What do you think the headline should be right now as we look at this year's numbers?
MG: That's giving me a lot of power. I think from a science perspective, we don't necessarily have to take away record mortality, but we could also add to it that we see record abundance and continued population growth for this population.
I think that shows how robust and resilient it is. That's because of all of the science that has helped document the issues [of] why grizzly bears were doing poorly in the 1980s, [and] the management agencies that took that science and implemented conflict reduction techniques [that have] allowed the population to grow to where we are.
Our research, for a number of years now, has been that it's a demographically recovered population. Where we're at now and the issues we're facing now stem from the fact that we were able to conserve and grow the population of grizzly bears in the Greater Yellowstone Ecosystem, to where now, we have new challenges that we're facing and we're trying to solve.
For more on grizzly bears, check out our series Living with Grizzlies. It follows people who get up close to grizzly bears as the debate rages on about whether they should remain protected under the Endangered Species Act.
