Montana, Alberta scientists say delisting plans put grizzlies at risk of extinction

Conservation geneticist Fred Allendorf said the USFWS Conservation Strategy goals for the Greater Yellowstone and Northern Continental Divide grizzly bear populations aren’t enough to prevent inbreeding, which can diminish survival. (Laura Lundquist/Missoula Current)

From a scientific perspective, U.S. grizzly bear populations are still endangered and more needs to be done before they can be delisted.

That was the message of five scientists from Montana and Alberta who came together Friday at the University of Montana to explain how experience and evidence from various biological specialties do not support the U.S. Fish and Wildlife Service’s push to delist at least two regional grizzly bear populations.

The Flathead-Lolo-Bitterroot Citizen Task Force organized the panel to publicize the science that it wants the Interagency Grizzly Bear Committee to prioritize when it meets next month. That information includes the genetic dangers of small isolated populations, the loss of habitat, modeling migration routes, and how road density and human habitation threaten the species.

“The question arises, ‘Why should you believe them?’ ” said grizzly bear advocate Michael Bader. “Well, in addition to their cumulative knowledge, experience and career achievements, they are independent of the government chain of command. They were not paid to do this. They are doing this because they believe strongly about this.”

Conservation geneticist Fred Allendorf said the USFWS Conservation Strategy goals for the Greater Yellowstone and Northern Continental Divide grizzly bear populations aren’t enough to prevent inbreeding, which can diminish survival. 

Animals in small populations end up having to breed with one another and successive offspring develop problems that make survival a more significant challenge. Over generations, more problems can show up in more of the population, and the resulting “inbreeding depression” causes health and reproductive problems, and the population shrinks in a deadly feedback loop.

Some might think that a population of 700 to 800 bears isn’t small, but the catch is that not every bear reproduces. So the breeding population, called the “effective population,” is always smaller than the total population. 

The Conservation Strategy for the Greater Yellowstone grizzlies sets a goal of maintaining a population of 500 bears. But Allendorf calculated that the effective population in that case would be only 280 bears, about half of what is needed for the population to persist over the long term.

“In the long term, the Yellowstone population is viable only if we can reconnect it genetically to other grizzly bear populations,” Allendorf said.

The longer a small population is isolated, the more genetic problems it can develop, and the quicker it can die out. 

That’s a problem for grizzly bears that have already been in small, isolated populations for decades, said U.S. Geological Survey ecologist David Mattson. 

Settlers had almost wiped out grizzly bears by 1910, so small populations have already been isolated for about a century. And Allendorf said it takes about 100 years for the effects of inbreeding to start to appear.

Genetically, the Yellowstone population looks different than the other two Montana populations. But bears in the Northern Continental Divide population aren’t different from those in the Selkirks and Cabinet-Yaak. 

So by legal definition, they aren’t distinct and can’t be delisted individually, Allendorf said. All three northern populations must be healthy enough to be delisted together.

That might not be possible anytime soon, Mattson said, because bear habitat is not doing well.

In the greater Yellowstone, climate change and pine beetles have wiped out more than 80% of the whitebark pine, which bears used as a food source. In the meantime, lake trout and other non-natives have pushed out the cutthroat trout that bears once ate. 

So grizzly bears are turning more toward meat sources, such as livestock or hunters’ carcasses, and that leads them out into areas and situations that get them in trouble.

The hunt for food, not a burgeoning population, explains part of the grizzly bear expansion into areas around Yellowstone National Park, Mattson said. So the population probably isn’t thriving as much as agency managers have said.

Grizzly bears have already been in small, isolated populations for decades, said U.S. Geological Survey ecologist David Mattson, and that increases their risk of extinction. (Laura Lundquist/Missoula Current)

“During (1998 to 2018), the distribution increased substantially,” Mattson said. “But that increase in distribution far outstripped even the most optimistic estimate of population growth. So, increases in shear numbers of bears cannot explain that rapid increase in distribution.”

Conditions could be worse for bears in the Northern Continental Divide where the wildfire regime has changed rapidly. While it’s good to let wildfires burn in wilderness areas, the burned areas take about 20 years to regenerate to the point where bears have enough to eat again, Mattson said. So that can push bears into other areas that are less safe for them.

In the Blackfoot Challenge area, people have made changes that diminished human-bear conflict. But after the wildfires of 2017, bears moved down and conflicts were “off the charts,” he said.

The way to offset all the habitat loss is to identify and use habitat outside the core areas, Mattson said.

“We can draw a line around all that potential and this is what we get: We’ve achieved connectivity; we could support thousands of bears; we could achieve meaningful recovery. It’s possible – it’s just a matter of how we do that in more practical terms,” Mattson said.

As it stands now, protecting enough connectivity is also going to take time, said Bozeman bear researcher Lance Craighead. 

Craighead has used models to identify the good habitat outside those core areas in the hope that bears would use those areas to move around. The biggest barrier, aside from subdivisions, are highways such as Interstate 90 and I-15. That’s where wildlife crossings are needed.

Otherwise, the challenge is a lot of the good habitat along those migration routes is on private land. So more landowner tolerance is needed, especially in those areas, Craighead said.

“The recovery plan needs to be updated,” Craighead said. “People complain about ‘You’re moving the goal posts.’ This is not a football game. It’s real-time science in a changing landscape in a changing climate with changing human and wildlife populations. And we need to have a flexible and changing recovery plan.” 

Alberta scientist Brian Horejsi said the USFWS needs to make sure U.S. populations are truly recovered before delisting instead of assuming that they can fall back on Canadian populations if something goes wrong. 

Because Canada doesn’t have laws similar to those in the U.S., such as the Endangered Species Act or the National Roadless Rule, timber companies can road and log in much of the bear’s habitat in Alberta and British Columbia. Road density exceeds what science has shown bears can tolerate so Canadian grizzly populations are threatened, Horejsi.

Task Force advisor Jake Kreilick said the task force has been drafting a citizens’ alternative to the upcoming Lolo-Bitterroot Forest Plan revision, which will reflect the science discussed during the panel.

“Despite the rosy picture painted by the federal and state agencies, the survival of the grizzly is tenuous,” Kreilick said. “Mortalities have increased dramatically over the past two years, ongoing threats to its habitat, numerous disruptions of its food sources and of course the looming impact of climate change all point a future of not more bears but less bears.”

Contact reporter Laura Lundquist at lundquist@missoulacurrent.com.