Only about 35 miles separate Yellowstone’s relatively small, isolated grizzly bear population from the expansive contiguous population of Montanan, Canadian and Alaskan grizzlies that numbers in the tens of thousands.
Bridging the gap, and diversifying the Greater Yellowstone Ecosystem bruins’ gene pool, has been a longstanding goal, a centerpiece of the debate over bear management and thus far, a vexingly elusive accomplishment.
Yet, grizzly researchers expressed hope last month that population “connectivity” may soon be within reach, despite also reporting at the same meeting in Cody that Yellowstone region bears have stopped expanding their range.
“I’m optimistic,” Interagency Grizzly Bear Study Team leader Frank van Manen told WyoFile. “The reality is we are really close.”
Why, after a half-century without any interpopulation exchange, and in the face of a stagnating range, would connectivity happen now?
Biologists have assembled something of a Yellowstone-region grizzly family tree by capturing, extracting blood from and mapping the genes of more than 1,000 bears over the decades. The project has yet to produce firm evidence that even one animal has trekked south and mingled its genes with the locals.
But at least one grizzly has gone in the opposite direction.
In 2021, a 5-year-old male was caught and killed for preying on cattle near Montana’s Little Snowy Mountains, far to the east of the grizzly population swelling into the plains from the Glacier National Park-anchored Northern Continental Divide Ecosystem. Surprisingly, the itinerant bear came from somewhere else. From the grizzly family tree, van Manen and other biologists deduced that the boar moseyed 110 miles from the Greater Yellowstone Ecosystem’s Beartooth Mountains, where it was likely born and raised.
“It’s in the wrong direction, but it shows the potential of connectivity,” van Manen said. True connectivity, from a wildlife biology perspective, requires an influx of fresh genetics into the more isolated population — in this case the Yellowstone Ecosystem bears — meaning a bear trekking north doesn’t check the box. But, the opportunity is “there, if we just had a bear do the opposite. And there’s no reason to think that would not be possible, right?”
Biologically, yes. But 21st century grizzlies inhabit a human-dominated landscape in which politics, policy and the behaviors of people arguably have as much influence over connectivity as biology.
Montana’s grizzly bear management plan “basically says we are going to allow for connectivity,” said Cecily Costello, a research biologist with Montana Fish, Wildlife and Parks.
But can the bears avoid deadly conflicts as they head south? The prospect of conflict is much lower in the ecosystem cores than in the intervening landscapes. Some 84% of the Northern Continental Divide Ecosystem’s grizzly recovery zone is public land, and the figure is a whopping 98% within the Greater Yellowstone Ecosystem. But only 54% of the connectivity area is publicly managed ground, according to data Costello presented at the Cody meeting.
Conservation groups are mounting efforts to create more bear-friendly landscapes in the connectivity areas, but that’s a long-term and costly endeavor. It might take 20 years of hard work, guessed Gary Burnett, a managing director for the Missoula-based Heart of the Rockies Institute.
“From a connectivity perspective, we think there are two things in particular you need to have,” Burnett said. One, he said, is an “open landscape” — achieved through means like conservation easements. The other component is diminishing the harmful “attractants” that come with humanity, be they agricultural or residential.
Some causes of grizzly mortality are easier to eliminate.
Former U.S. Fish and Wildlife Service grizzly bear recovery coordinator Chris Servheen believes Montana’s management plan doesn’t do enough to safeguard grizzlies in the connectivity areas. He’s also optimistic that a Montana grizzly will successfully disperse south — it’s likely to occur within “three or four years” — but worries state management could jeopardize the chances of such a movement occuring.
“Every year we see bears further and further out and closer and closer together,” Servheen said, “but that’s happening while they’re listed [under the Endangered Species Act] and that’s happening without any hunting in that connectivity area.”
Factoring in hunting, Servheen said, the three- or four-year estimate for a successful disperser “would be completely out the window.”
“In my mind, hunting would put connectivity at grave risk,” he said. “I really object to the tone of intolerance that exists in many of these state plans. They look at grizzly bears as a competing interest with everything else.”
Montana officials, he said, are talking out of both sides of their mouths by prioritizing connectivity while simultaneously saying they would allow hunting in linkage habitat.
The Fish and Wildlife Service is weighing whether to attempt a third go at delisting grizzlies — a process Wyoming is suing over to move it along.
Ahead of the federal agency’s analysis, the states of Wyoming, Montana and Idaho forged a pact that outlined the parameters of grizzly bear hunting — potentially with few restrictions along the ecosystem’s periphery — and other aspects of management. That agreement called for a 13% reduction in the grizzly population within a monitoring area where bear numbers are counted. There would likely be even heavier hunting and no firm requirements to maintain grizzlies at all outside that zone. Roughly 40% of occupied grizzly range is outside of the monitoring area.
Just passing through
If hunting were layered atop other conflicts already constraining the grizzly range, bears would have an even tougher time establishing and persisting in the most people-packed connectivity areas of west-central Montana.
Connectivity, however, does not require persistent habitation.
“That’s sometimes misinterpreted by some people: That you need occupation,” van Manen said. “You don’t. You don’t need resident bears to connect genetically.”
A single dispersing male that successfully makes the trek south and spreads his genes would do the trick, he said.
Costello shared preliminary findings at the Cody meeting from research investigating potential Yellowstone-to-Glacier region grizzly bear corridors. U.S. Geological Survey ecologist Sarah Sells, University of Montana biologist Paul Lukacs and Montana Fish, Wildlife and Parks employees Lori Roberts and Milan Vinks collaborated on the study.
There are several primary linkage paths, according to maps Costello presented and discussed with WyoFile. The two most direct routes shoot more or less straight northwest to southeast. The easternmost corridor skirts Helena and Bozeman, Montana by way of the Big Belt, Bridger and Gallatin mountain ranges, while another direct linkage route runs from the Boulder and Highland mountains down the Tobacco Roots and into the Madison Range.
“We have observations of bears in all of the mountain ranges I just mentioned except for the Tobacco Roots and the Bridgers,” Costello said. “So they’re halfway there.”
The modeling predicted grizzly bear use of linkage areas based on several habitat qualities, but foremost was the greenness of the landscape. Mountains, forests and riparian areas rank higher, whereas sagebrush steppe and high plains environments rank lower.
Another component tracked the “forest edge,” Costello said, which is a particular productive part of the landscape that grizzly bears prefer.
The model also factored in the habitat preferences of real-world Northern Continental Divide Ecosystem grizzlies.
“The way that we ran the analysis is we simulated each bear’s model on the landscape,” Costello said.
Similarly, the model accounted for habitat qualities that grizzlies tend to avoid: roads and housing. The likelihood of conflict nearer to humans is another important factor for predicting where grizzly bears can persist in the currently grizzly-less void.
Even without connectivity, van Manen said, the Yellowstone ecosystem population is on good ground genetically. “With the current population size,” he said, “that concern is decades away — and probably more than decades.”
In the absence of a successful grizzly bear dispersal south, wildlife managers have pledged to force the issue. The tri-state pact commits the states to translocating “at least two” bears from outside the Greater Yellowstone into the region by 2025 unless migration is detected in the interim.
That’s not an ideal outcome, in Servheen’s view: “Allowing this to happen naturally is really important,” he said.
Moving bears from one ecosystem to another is dependent on “political whims” and agency administrators. Having that fallback option also deprioritizes good planning, he said.
“The end result is really poor conservation and poor management,” Servheen said. “I don’t think driving them around is a good solution.”
If a grizzly bear does bridge the 35-mile gap it will have to cross interstate highways, settled valleys and other human obstacles. Those barriers, van Manen said, inhibit the already sluggish expansion of a species that biologically has a slow “life history strategy.
“They live longer, and can afford for that process to take a longer time,” he said.
Even so, due to decades of conservation and range expansion, connectivity might have already occurred. There is a time delay in crunching data and completing parentage analyses from grizzly bear bloodwork, van Manen said. The bear that showed up in the Snowy Mountains, for example, was sampled in 2021, but biologists didn’t realize it came from the Beartooths until this year due to normal delays in processing its genetics.
“For all we know,” van Manen said, “we might already have genetic connectivity, but have just not documented it yet.”