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SOURCE: Inside Climate News

DATE: May 14, 2019

SNIP: Wally MacFarlane calls them ghost forests. You can tell they didn’t burn because the needles are still intact, the branches flawless except for the gray where there used to be green. When MacFarlane flew over Yellowstone National Park and its surrounding area 10 years ago, the forests were a sea of red, hundreds of thousands of acres lit up by mountain pine beetle infestations, the magnitude of death only visible from above.

“The level of destruction is hard to even fathom until you take people up to see it,” said MacFarlane, a senior research associate at Utah State University who conducted aerial surveys of whitebark pine trees in the region in 2009 and again in 2018. “It’s the deforestation of this ancient forest, arguably something in the order of one of the greatest losses of old-growth forests in the United States, in just the scale.”

Over the past 200 years, these forests provided a last refuge for grizzly bears in the contiguous U.S. from the westward expansion of towns, farms and ranches. In the high-altitude forests, the bears could rely on squirrels’ caches of whitebark pine seeds as an abundant and important food source.

Today, the Greater Yellowstone Ecosystem is one of just two places—along with Glacier National Park—where large populations of grizzly bears can be found in the Lower 48.

But those dying forests signaled trouble for Yellowstone’s grizzly bears and their already diminishing food supply.

As warmer winters allowed the beetles to spread and devastate the whitebark pines, the bears have been increasingly wandering out of the Greater Yellowstone Ecosystem’s high-altitude forests and into more human environments, and they are dying in greater numbers than they have in decades, federal data show.

Government officials say the population is stable. But over the past four years, the number of grizzly bear deaths has risen, the majority of them because the bears became a threat to people or livestock and were euthanized. Almost 250 bears have died over that period in the ecosystem, a swath of land larger than the state of West Virginia that comprises parts of Wyoming, Montana and Idaho.

Grizzly bear researchers and advocates fear the higher number of annual deaths may be putting into doubt the future in the region of one of the slowest reproducing terrestrial mammals.

“I think it’s serious,” said Barrie Gilbert, a retired biologist who spent more than 40 years studying bears. If more bears die than are born, the population will be in trouble, he said. A new international report warns that worldwide, human activities, including those that drive climate change, have put 1 million species of animals and plants on the brink of survival.

A 2018 federal report acknowledged the impact the diminished food supply can have in raising the death toll for the bears: “Historically, grizzly bear-human conflicts and management actions were reduced during years with good food production, including whitebark pine. In areas with widespread whitebark pine mortality, this effect may now be diminishing.”

As grizzly bears wander farther in search of food, they are increasingly encountering humans—drivers, hunters, ranchers—and winding up dead.

More bears died in 2018 in the Greater Yellowstone Ecosystem than in any other year in at least four decades, according to the Interagency Grizzly Bear Study Team. Last year’s 69 deaths more than doubled the average in the decade from 2000 to 2010, when about 27 bear deaths were reported each year.

In the Yellowstone area, the loss of whitebark pine followed the decline of other grizzly bear food sources.

The cutthroat trout population has been decimated by disease and non-native lake trout, which are outcompeting the native species. Plus, the streams where they used to spawn have seen lower water levels because of a declining snowpack.