Here’s a very interesting write-up on a study of how grizzly bears disperse across the landscape . . .
If you were a grizzly bear on the move, where would you go and how would you get there?
According to a new study released this month by University of Montana’s Sarah Sells, you’d primarily favor mountainous areas but would also follow waterways through open valley landscapes. But your destination would depend in large part on where you started, and whether you were on a mission to go somewhere else or simply exploring beyond your home range.
The conclusions came from a modeling program that predicted pathways through Montana between the bears’ current core habitat areas. The two biggest, each with about a thousand grizzlies, are the Northern Continental Divide Ecosystem around Glacier National Park and the Bob Marshall Wilderness Complex and the Greater Yellowstone Ecosystem surrounding Yellowstone National Park.
By now most of Yellowstone’s grizzly bears are snug hibernating in winter dens, safe at last from human dangers.
But in the darkness below the snow, mysteries and miracles unfold, apropos of our Christmas season. Researchers have long known the basics of bear hibernation. These bruins don’t eat or drink or excrete waste for between 150 and 180 days. But when grizzly bears crawl out of their dens in spring, they are specimens of health. They lose very little bone strength or lean muscle mass, though they may lose as much as 30 percent of their fall weight.
Unlike deep hibernators like ground squirrels, bears are not unconscious during their winter slumber, which allows mother grizzlies to give birth in the dead of winter to a cub or two, each the size of a teacup, which she groggily nurses in her den until sometime during April or even May.
How does a mother bear pull off this feat? Part of her secret involves obesity. Gorging on foods ranging from bison to ants, she packs on several pounds a day during her late summer and fall feeding frenzy.
Here’s an interesting roads vs. grizzlies study based on DNA data out of British Columbia . . .
It’s simple math, says scientist Clayton Lamb. The closer grizzly bears are to humans, the more ways there are for the bears to die. Put more simply, more roads equal fewer grizzly bears.
In a recent study examining a long-term DNA dataset of grizzly bear activity in British Columbia, Lamb and his colleagues conclusively determined what scientists have long suspected: higher road density leads to lower grizzly bear density, a critical problem for a species still rebounding from a long period of human persecution.
“The problem with grizzly bears and roads is a North American-wide issue. This is the first time that strongly links roads to decreased grizzly bear density,” said Lamb…
Here’s a good overview article from the Daily Inter Lake discussing the complexity of the upcoming decision on delisting grizzly bears in the Northern Continental Divide Ecosystem . . .
For four years, research ecologist Tabitha Graves has studied grizzly bears at the U.S. Geological Survey’s NOROCK West Glacier Field Station.
The hulking ursines bring more than tourists to Northwest Montana. “They have a pretty big role in this ecosystem,” she told the Daily Inter Lake. “We don’t often think about these kinds of details, but they disperse a lot of seeds, [and] they dig a lot,” helping circulate nutrients through the forest floor.
Understanding their benefits requires estimating the number of bears in the region – no easy task in a 16,000-square-mile “demographic monitoring area.” Graves and her colleagues add barbed wire to the tree trunks that bears rub along, then have the hair they collect DNA-sequenced, gaining a sense of which individual bears frequent which spots.
This article really should have been longer; there’s a lot to think about here. Still, it’s worth reading . . .
Grizzly bears continue to expand their range amid an ongoing effort to turn over management of the bears from the U.S. Fish and Wildlife Service to the states of Wyoming, Montana and Idaho, a federal official said.
“We’ve seen an 11 percent change in increasing range in just a couple of years,” Frank van Manen, head scientist of the Interagency Grizzly Bear Study Team, said last week at a meeting in Jackson.
Since coming under the protection of the Endangered Species Act, grizzlies have steadily expanded their habitat outward from the population’s core in Yellowstone National Park.
Here’s a good summary from the Hungry Horse News of the latest grizzly bear mortality and population figures . . .
Recorded grizzly bear mortality in the Northern Continental Divide Ecosystem in 2016 was the same the year before, with 22 total bears killed, primarily by human means.
Removal by wildlife biologists due to human conflicts was the leading cause of death, at nine. One bear, a male, was removed as part of an augmentation program to move grizzly bears from the NCDE to the Cabinet-Yaak ecosystem.
Of the 22 deaths in 2016, 12 were females. Two were unknown sex. Two bears were poached and two were killed by property owners illegally. Three were hit by cars and two deaths were determined to be natural causes, one was accidentally poisoned and one was shot by a hunter who mistook it for a black bear.
The first results from a Northern Continental Divide Ecosystem grizzly bear “family tree” study are encouraging . . .
Using genetic analysis U.S. Geological Survey Scientist Tabitha Graves and Nate Mikle recently completed a first look at the “family tree” of grizzly bears in the Northern Continental Divide Ecosystem.
The 8-million plus acre area stretches from Glacier National Park south to Ovando. The pair looked at genetic data gathered from 1,115 bears in a 2004 study done by researcher Kate Kendall and again in 2009-2012 through hair follicle samples of bears.
The family tree, printed out on one sheet of paper, stretches 20 feet, Graves noted in an interview last week. The thrust of this initial study was to determine the genetic diversity of bears on the fringes of the ecosystem, namely in the southeast and southwest corners.
Here’s a good article by Chris Peterson in the Hungry Horse News discussing how the use of DNA analysis in grizzly bear research is really hitting its stride . . .
This summer, grizzly bears have been confirmed in the Big Hole River Valley of Montana for the first time in the last 100 years.
Montana Fish, Wildlife and Parks bear manager Kevin Frey said they do have hair samples from at least one grizzly from earlier this summer in the Big Hole and the state plans on having the samples analyzed to find out if biologists can track the origins of the bear.
The case is just another illustration of how far DNA analysis of bears has come in the past 25 years.
Wildlife managers continue to work on a plan to remove grizzly bears from the Endangered Species List. Meanwhile, there’s evidence of contact between the two main grizzly population centers . . .
Federal plans to delist the grizzly bear from Endangered Species Act protection will get a second round of public comment.
The U.S. Fish and Wildlife Service’s Tuesday announcement follows its release of a peer-review report generally approving its management plan for allowing state management of grizzlies in the Greater Yellowstone Ecosystem. Coincidentally, it also arrives on the heels of reports that Yellowstone grizzlies may be making contact with their fellows in the Northern Continental Divide Ecosystem north of Missoula.
Montana, Idaho and Wyoming state wildlife managers have all proposed plans for both protecting and hunting Yellowstone grizzly bear populations, assuming they leave federal management. Northern grizzlies are considered a separate population, although they are undergoing a similar delisting process that isn’t as far along as the Yellowstone one.