Survey shows little change in Minnesota moose population
Formal estimate is down, but scientists say moose are holding their own here. Barely.
Northeastern Minnesota's moose population may be holding its own, but still shows no signs of bouncing back to healthier numbers.
That was the report Monday from the Minnesota Department of Natural Resources, which estimates the state’s moose herd at about 3,150 this winter.
At first blush, that appears to be down more than 1,000 moose from last year’s estimate of 4,180. But biologists say it’s within the range of statistical variability. This year's population estimate is between 2,400 and 4,320, compared to last year’s range of 3,250 and 5,580.
The 2020 survey is very close to the 2018 survey results and is the third lowest since 2005 when the current survey methods were adopted.
While the survey is considered statistically sound, there's inherent uncertainty when the area surveyed is just a small part of the 6,000-square-mile moose range. Only 52 of a total 436 quadrants in the moose range were actually surveyed this year by biologists flying in helicopters. Most all of the state's moose are in Cook, Lake and northern St. Louis counties.
“Even trying to find a big, dark animal on white snow is hard from a helicopter when there are lots of conifer and cedar trees to hide under,’’ said Glenn DelGiudice, who heads the DNR’s moose efforts. “So there’s always some estimating going on. Even if we counted all 436 survey plots, we’d miss some moose. ... But we do think we capture the trends in this survey.”
This mark’s the ninth year of an ongoing low but stable population that comes after the state's moose numbers crashed rapidly, from a modern high of 8,840 moose estimated in 2006 to just 2,700 in 2013. But this year's midpoint estimate is still less than half the moose counted in 2006. And with Minnesota moose already at the southern edge of their habitat, scientists aren't encouraged about the animal's future here in a warming world. The decline in the state's northeastern herd came after the northwestern Minnesota herd all but disappeared in the late 1990s.
Moose in Minnesota have been hard-hit by a number of factors, including a long-term increase in deer across moose range. Deer carry a parasitic brain worm that, while harmless to whitetails, is fatal to moose. Moose also have been plagued by an increase in parasites, such as ticks that thrive in a warmer climate.
Moose also have seen dwindling habitat, often due to fire suppression, aging forests and past forest management. Scientists have noted that some of the few areas with increasing moose numbers in recent years are where big fires have occurred, clearing the way for a younger forest that has the type of food moose thrive on.
The shrunken moose herd, especially newborn calves, also is more vulnerable to predators, especially wolves, but also black bears.
It's never been entirely clear which factor is having the biggest impact on keeping Minnesota moose numbers down. Survey results indicate calf survival from birth in spring to January continues to be relatively stable but consistently low.
Research shows that wolf predation has consistently accounted for about two-thirds of the calf mortality and one-third of the adult mortality. In some cases, injuries suffered during predation attempts, not the predation itself, ultimately killed the adult moose. In others, sickness or disease likely made the adult moose more vulnerable to being caught and eaten.
In 2005, when the moose population was healthy, more than half of all cow moose surveyed had a calf with them, 52%. Now, that number has dropped to just one-third of cows with calves surviving until January, 32% — a number so low that the overall population can’t trend up.
“Our adult moose are surviving on par with North American numbers, maybe a little lower … but we’d really have to see calf survival increase, and for several years, for the population to start trending up,’’ DelGiudice said.
Mike Schrage, a wildlife biologist for the Fond du lac Band of Lake Superior Chippewa who participated in the survey, said he's "comfortable'' with calling the moose population "stabilized."
"We aren't seeing anything to say that things look better or that things are much worse,'' Schrage said.
The Fond du Lac Band of Lake Superior Chippewa and 1854 Treaty Authority again contributed funding and provided personnel for the annual moose survey.
For more information, go to dnr.state.mn.us/moose .
Moose meeting Wednesday
Tom Rusch, DNR wildlife manager for the Tower area, will give a presentation on moose in Minnesota — including trends and results of the annual moose survey — on Wednesday from 6:30-7:30 p.m. in the Mountain Iron Community Center, 8586 Enterprise Drive.
The event is sponsored by the Sturgeon River Chapter of Minnesota Deer Hunters Association. It’s free and open to the public.
This story originally contained the wrong percentage of cows that had calves. It was updated at 10:16 p.m. (March 9) with the proper percentages. The News Tribune regrets the error.