Groups want land agencies to preserve grizzly denning habitat
In an effort to get federal land agencies to preserve what grizzly bear habitat remains, advocates have released another report documenting all the potential bear denning habitat throughout southwestern Montana and northern Idaho.
On Tuesday, biologist Mike Bader and geospatial analyst Paul Sieracki presented the results of their scientific literature review and computer modeling runs that identify all the potential grizzly bear habitat between the western side of the Northern Continental Divide Ecosystem and the Cabinet, Selkirk and Bitterroot ranges to the west.
Their model predicts that a fair amount of medium- and high-quality denning habitat exists not only in the Bitterroot region, but the connectivity area of the Ninemile and the Sapphire Complex, which includes the Sapphires and the Flint Range down to the Anaconda-Pintlers.
“Why grizzly bear denning habitat?” Bader said. “It’s because residential occupancy requires denning habitat. And that’s at the heart of what we call the demographic model.”
Currently, around 2,000 grizzly bears are spread out among three recovery areas, with very few in the Cabinet-Yaak and Selkirk areas. While some may think 800 to 1,000 bears is enough for an area, it’s not enough to prevent eventual damage from inbreeding. To keep grizzlies genetically healthy, conservation biologists say the overall population in all the areas needs to be larger – around 5,000 bears – and bears need to be able to move between populations to interbreed. Right now, neither is the case.
Recently, bear biologist David Mattson published his habitat analysis “Grizzly Bear Promised Land” showing that more of the national forest land around the Bitterroot Recovery Area, particularly in northern Idaho, is capable of hosting grizzly bears, and it needs to for the population to be large enough to be viable over the long term. Bader said his report augments Mattson’s work by identifying the habitat that females need to overwinter and raise their cubs.
Unlike other grizzly recovery areas where bears have been transplanted, grizzlies need to repopulate the Bitterroot region themselves by migrating in from other areas. Males disperse long distances, almost 3 times as far as females. So they have ended up in the Bitterroot, but they can’t start a population by themselves. Female cubs will move away from their mothers but their home territories tend to overlap.
So female migration is slower and requires denning sites along the way. If they have to go too far without finding a good den site, females aren’t likely to make the jump. That’s why preserving habitat in connectivity areas by limiting roads is important, Bader said.
One area the model found to lack good denning habitat is the Salish Connectivity Area between the NDCE and the Cabinet-Yaak recovery areas. Bader said the problem there is the “sea of roads and clear cuts.”
Last year, Bader and the Flathead-Lolo-Bitterroot Citizen Task Force published an analysis of roads in the Ninemile area and found they exceeded the density limit for good bear habitat. Too many roads lead to more human-bear conflict. This led to the group challenging the Lolo National Forest for the amount of road it planned to build and open as part of the Soldier-Butler Forest Management Project in the Ninemile.
All those roads reduce the amount good habitat in the Ninemile, which is needed for bears to move from the Cabinets down to the Bitterroot. But Bader’s model found that 16% of the area still contains medium- to high-quality denning habitat.
Some might question whether these studies or their authors can be trusted because they aren’t in peer-reviewed scientific journals.
Bader said he had three scientists review the study as part of an internal review and he intends to submit it to a journal.
“We let the data speak to us. The sponsors didn’t have any role in determining how we did things or what the results would be,” Bader said. “The Forest Service should (use our report). They use the Fish, Wildlife & Parks report for grizzly bears and it’s never been published in a journal or gone through any extensive peer review that we know of, and that’s used. I think the big issue is we don’t have time to wait.”
To develop their geospatial model, they used location data for 365 known bear dens provided by U.S. Fish and Wildlife Service bear biologist Wayne Kasworm and Montana Fish Wildlife & Parks biologist Cecily Costello.
They then tested 20 environmental variables and found that den location was most dependant on terrain elevation, slope, and distance from roads and water. In other words, sows tend to like somewhat higher, sloped terrain far away from roads and water. Snowpack can also play a role in some locations, but Sieracki said they didn’t use it because the Sapphire Range sits in a snow shadow of the Bitterroot Mountains so the model didn’t work well.
The best model they developed appears to have a strong ability to predict the on-the-ground reality, overlapping the vast majority of the 365 dens. They then applied the model to the entire 42,000 square mile area from the NCDE to the Cabinet and Bitterroot Mountains and portioned the results into low, medium and high quality denning habitat.
Groups such as the Friends of the Clearwater and Friends of the Bitterroot point to the modeling results as another reason to reduce the amount of logging and road building prescribed in the new Nez Perce Clearwater Forest Plan and the proposed Bitterroot National Forest Eastside Habitat project.
Josh Osher of Western Watersheds Project wants more grazing allotments retired in the Sapphire Complex.
“The thing to remember is these connectivity areas have high quality grizzly bear habitat,” Bader said. “We can’t get it done with just male bears. We gotta have the females. They’re knocking on the door. With a little help, we could see (them) in the Bitterroot Ecosystem very soon. And if we do it right, we’re not just protecting the land for the grizzly but for all the ecosystem processes out there.”
Contact reporter Laura Lundquist at firstname.lastname@example.org.