More forest fires, more moose
Moose numbers are down across most of Northeastern Minnesota, half of what they were a decade ago with little or no improvement on the horizon. The region's warming climate has been named as the overriding problem for moose -- spurring more disea...
Moose numbers are down across most of Northeastern Minnesota, half of what they were a decade ago with little or no improvement on the horizon.
The region’s warming climate has been named as the overriding problem for moose - spurring more disease, more parasites and more heat stress. Add in the impact of predators, namely wolves and bears, and Minnesota moose are dying faster than they are reproducing.
But in the area burned in 2011 by the massive Pagami Creek forest fire in the Boundary Waters, moose are now thriving despite all those problems.
Same with areas burned in 2006 and 2007 in the destructive Cavity Lake and Ham Lake fires at the end of the Gunflint Trail. Same near Trout Lake in Cook County where an intentional fire was lit in 2005.
Across the 52 areas of the core moose range surveyed in January, the median number of moose spotted in each area was 5.5. But surveys in burned areas show two, three even seven times more moose. In the Pagami fire area, surveyors counted 10 moose. At Trout Lake it was 16. At Cavity Lake it was 31. At Ham Lake it was 36.
It’s been known since studies in the 1970s that Minnesota moose seek out and thrive in the lush, new growth that sprouts a few years after forest fires. But the data is showing more clearly, one of Minnesota’s most experienced moose researchers says, that more and bigger forest fires may be the best fix available to help recover the region’s dwindling moose population.
“Based on earlier moose work and the results of this survey over the past five years, I’m increasingly willing to believe the best thing we can do for moose habitat is to put more large fire on the landscape or to mimic (fire) through timber harvest,” Mike Schrage, biologist for the Fond du Lac Band of Lake Superior Chippewa, concluded in a report released last week.
Seven of the 10 highest moose counts in this year's survey, conducted from a helicopter, were in areas where big fires burned over the last decade.
“Those Cavity-Ham Lake fire areas are probably best example we have where the moose numbers have been consistently high after a fire” even as moose across most of the region have declined, Schrage told the News Tribune.
Moose in fire areas are still face brainworm, winter ticks, bears killing calves in May and June and wolves killing all year long. Yet moose numbers in post-fire areas are higher than elsewhere.
“We can’t say for certain yet that habitat can overcome the climate change and parasites and predators. ... But it’s becoming increasingly clear that these are areas moose seek out and are areas where they are still doing well,” Schrage said. “And I think it’s clear that, without good habitat, nothing else we do for moose will matter.”
Massive logging may help
Short of fires, which still carry a social stigma and which can be difficult to control once they start, Schrage and others say logging - especially large clear-cuts - are the next best thing for moose.
For centuries much of far northern Minnesota burned every 50 to 100 years, fire historians have documented. Over the past 125 years, extensive logging created the new growth that moose need to thrive.
But in recent decades, as most forest fires were snuffed before they grew big and as logging has waned with the demise of many Minnesota mills, there has been more older growth trees and less new forest. The decline in habitat hit at about the same time brainworm, ticks, disease and heat stress began to increase.
For moose to benefit from logging as they do from fires, forest management - and public attitudes about it - will have to change. The Pagami Creek fire, for example, burned across 93,000 acres -145 square miles - the largest fire in the state in 80 years. By comparison, most county, state, Forest Service and private land timber sales are a few hundred acres at most.
“We need to start taking about 1,000 acres and 5,000 acres and bigger if we want to help moose,” Schrage said. “If you want moose, we have to get away from this idea that fire is bad, or that big clear-cuts are bad.”
Schrage noted that last week's intentional Foss Lake fire west of Ely, intended to be 78 acres but which grew out of control to more than 1,000, may end up being perfect moose habitat even though the expanding fire raised concerns of residents when it was burning.
Ron Moen, a moose researcher at the Natural Resources Research Institute of the University of Minnesota Duluth, said each clear-cut, or the intentional fire, wouldn't necessarily have to occur all at once.
“The size of the disturbance seems to be a factor. They have to be big to have the big beneficial impact,” Moen said. “But you could do it with a series of progressive clear-cuts, or fires, and eventually get to the size that pays off.”
Schrage said the best cuts for moose have patches of uncut trees, irregular boundaries and are in areas where the regrowth comes in a diverse mix of species.
“If you clear-cut and then replant all red pine or white spruce, it’s not moose habitat,” Schrage noted.
Moen agreed. Woodpeckers and grouse also do well after fires. But goshawks, cerulean warblers and pine martens need old growth.
“If you are managing for moose, you need large areas of disturbance. If you want old growth forest, you don’t do clear-cuts,” Moen said. “The key (for a healthy ecosystem) is you need some of both.”
The big fires of the past decade have helped turn the corner in local areas. But it may take more big logging sites to raise moose numbers across the region in places where big fires aren’t practical.
Glenn DelGiudice, chief moose researcher of the Minnesota Department of Natural Resources, said there’s an obvious relationship between good habitat and good nutrition and thus good health. But he cautioned against putting too much emphasis on habitat over other moose problems.
“There’s no doubt that nutrition is critical to all other aspects of an animal's success,” DelGiudice said. “But the sample size in those survey areas (near burned areas) is so small. And we haven’t seen enough years of data yet. There’s a lot of variation in the data from year to year.”
DelGiudice said habitat projects may be among recommendations the state’s moose advisory committee makes later this year. But they won’t be the only solution proposed.
“I wouldn't disagree with Mike (Schrage) that large disturbances are going to be part of the solution,” he added. “But that's not the only problem. We know moose are not surviving even in some places where they have good habitat.”
The benefits from each fire and large clear-cut will diminish with time, but will last for up to 20 years, Moen said. Moose thrive on the willow pin cherry, paper birch and especially red azure dogwood after a big fire.
“Everybody thinks aspen for moose, and they do eat aspen, but it’s not their biggest thing if they have a choice,” Moen noted.
There seems to be a lag time between the fire and when moose begin to move into the regrowth area. For Pagami Creek, it was five years, with virtually no moose in the area for four years after the fire and 10 moose counted this year.
Moen also said it remains unknown how moose find the burned areas, some of which have virtually no moose remaining immediately after the fire. Studies show most moose are homebodies, living their lives within a few miles of where they are born. But some wander enough to find the new growth after fires.
“The moose we have collared over the years overwhelming aren’t migratory, maybe one or two percent. Yet, somehow, moose eventually do find these big burned areas,’’ Moen said.
Schrage said the best news is not only that adult moose are finding burned areas, but that cows are staying there and having calves that survive there.
Researchers are now surveying key fire and logging areas every year, instead of as part of the random survey usually conducted across segments of the moose range, to document what’s happening. In one area near Greenwood Lake in Cook County, Schrage surveyed in advance of Forest Service plans to cut nearly 2,400 acres, an area Schrage will be watching carefully in coming years for an expected bump in moose numbers.
In another area near Cloquet Lake in Lake County, state sales tax revenue aimed at natural resource projects will help coordinate state, county and federal logging projects and study the results for moose.
“It’s going to take a coordinated effort in areas where you have multiple landowners,” Schrage noted.
Half the moose of a decade ago
If habitat is a potential savior of Northeastern Minnesota moose, more fires and/or more logging better happen soon.
“We’ve got to start the discussion now or it will be too late,’’ Schrage said.
The decline of the region’s moose herd appears to have slowed in recent years, for reasons unknown, but wildlife biologists say they still are worried that moose numbers remain precariously low.
The Minnesota Department of Natural Resources in February released the result of its annual moose survey that estimated this winter's population at about 4,000. That's up a tick from 3,450 moose estimated in 2015, but wildlife experts say the change is statistically insignificant. Overall, Northeastern Minnesota moose numbers remain less than half what they were a decade ago, when the population was at nearly 9,000.
Moose are not recovering in Northeastern Minnesota, DelGiudice said in releasing the survey results earlier this year. “It's encouraging to see that the decline in the population since 2012 has not been as steep,” he said. “But longer-term projections continue to indicate that our moose population decline will continue.”
The same sort of decline hit northwestern Minnesota moose in the 1990s - with plateaus then continued declines - and that population never recovered, dwindling from 4,500 to less than 100 today.
In addition to counting moose, the DNR is leading a broad, multi-agency study of why moose are dying faster than they can rebuild the population. In recent years researchers have confirmed that wolves are taking some of the adult moose that perish. Wolves also are killing a majority of the calves that researchers were able to recover.
But other factors - especially disease, parasites and warm-weather stress - appear to be killing most of the adult moose that researchers are able to find and verify thanks to GPS collars.
Of 47 adult moose captured and collared during the past three years that perished, two-thirds died from health-related causes including brainworm, winter ticks, bacterial infections, liver flukes and severe malnutrition. Wolves killed the other one-third, but even among those, one quarter of them had health issues that made them easy prey.
One striking discovery has been the impact of warm winter weather on moose nutrition and health. When air temperatures reach 23 degrees in winter, DelGiudice said, moose can begin to experience heat stress, increasing their metabolism, heart rates and respiration. When moose are heat-stressed in winter, they aren't eating enough food and eventually succumb to health problems, weakness or wolves.
“So if we have moose dying (because they are too warm to eat well in winter) when we start talking about habitat manipulation, we had better be careful,” DelGiudice said. “We don't want to take away the thermal cover (shade) for animals they need to survive.”