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‘It’s never been so extreme’: Climate change has varying effect on wildlife, plant species

A helicopter flies low so this bull moose can be darted with a tranquilizer in January 2013 in northeast Minnesota. Moose numbers in northern Minnesota have declined, and researchers attribute at least some of the decline to climate change. Courtesy of the Minnesota Department of Natural Resources

GRAND FORKS — As a fourth-generation resident of Waskish, Minn., on Upper Red Lake, Jonny Petrowske has history on his side when it comes to looking at changes in the weather patterns that affect his livelihood.

A jack of all trades, Petrowske, 43, traps minnows, works as a fishing and bear hunting guide, and rents fish houses in the winter.

Petrowske says dealing with extreme weather patterns has become the new normal. Some years, it’s late springs and early freeze-ups; other years, it’s just the opposite.

When your livelihood depends on the whims of Mother Nature, timing has a big impact on the bottom line, he said.

“Maybe global warming is affecting these weather patterns, but for the most part we’re seeing extremes,” he said. “The old-timers, those are the guys I listen to — these 80- to 90-year-old guys that have been doing it forever — they all say the same thing.

“‘It’s never been so extreme.’”

Research into climate trends supports that assessment. From longer growing seasons on the prairie to changes in the makeup of northern forests; from warming lakes to declining populations of iconic species such as moose, the landscape is changing.

Recreation impact

Changing weather patterns also affect outdoor recreation, especially during the winter months. In northeast North Dakota, snowmobile trails in recent winters have been closed more often than they’re open because there hasn’t been enough snow.

Outdoor skating rinks often close by early March. Downhill skiing destinations are more reliant on snowmaking machines to cover the slopes.

Buying into the science of climate change can be difficult when winter arrives early, as it did this year, but one year does not a trend make, said Mark White, forest ecologist for the Nature Conservancy in Minnesota and the Dakotas based in Duluth.

“You have to look at the longer-term trends,” White said. “Weather is what it’s like now, and climate is sort of a longer-term measure of what conditions are.

“It’s easy to say it’s cold this year, but if you look over the long-term trends, you see that especially the winters are warmer up here. ”

That can make a big difference to a bark beetle that now can better survive winters and attack trees in the spring, White says. Or a moose when winter ticks don’t die off like they used to because it doesn’t get as cold.

Iconic example

Perhaps the most striking example of climate change affecting wildlife is the moose. Once abundant across northern Minnesota, moose have declined to the point where the Department of Natural Resources no longer offers a hunting season.

Moose are doing well overall in North Dakota, but the decline has been evident across the southern range of moose in North America, said Gretchen Mehmel, manager of Red Lake Wildlife Management Area south of Roosevelt, Minn.

“Moose numbers in northwest Minnesota began dropping back in the early 1990s,” Mehmel said. “Before then, when I was working in Thief River Falls, I had to respond to numerous cases where there were too many moose in town and being hit on the highways.

“Now it’s a big deal just to see one.”

Reasons for the decline are complex, White and others say, but rising temperatures that stress moose, making them more susceptible to disease while creating favorable conditions for parasites such as winter ticks and brainworm — play a role.

Results from a University of New Hampshire study published in the Canadian Journal of Zoology found that 70 percent of moose calf mortality in a three-year period from 2014 to 2016 was caused by winter ticks.

Fisheries issues

Climate change also affects coldwater fish such as tullibees, an important forage for species such as walleyes, muskies and pike.

In Minnesota, fisheries managers began looking at declines in tullibee populations about 10 years ago, said Pete Jacobson, fisheries habitat research supervisor for the DNR in Park Rapids, Minn.

A closer look at climate trends since the late ‘70s pointed toward rising temperatures, especially on shallow lakes.

“That corresponded almost precisely with when we started seeing declines in tullibees around the state,” Jacobson said.

For natural resource managers, mitigating the impact of climate change means focusing efforts where management will be most effective.

That could mean protecting the best lakes for tullibees and other coldwater fish by working with private landowners to maintain forested watersheds, Jacobson says.

On the prairie, it might mean a focus on restoring or preserving connected landscapes, said Marissa Ahlering,lead prairie ecologist for The Nature Conservancy in Minnesota and the Dakotas based in Moorhead.

It’s not all gloom-and-doom, but the change can’t be ignored.

“As much as we don’t want to admit it, it’s happening,” said Petrowske, the Upper Red Lake guide and minnow trapper. “Something’s going on, and it’s definitely affecting us.”

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