Minnesota moose holding their own
DULUTH -- Minnesota’s moose population continues to hold its own, with slightly increased numbers this winter compared to 2018.
That was the report Monday, March 11, from the Minnesota Department of Natural Resources, which counts this as the eighth straight year of low but relatively stable numbers for the big forest animal.
That lower but stable period 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.
This year’s aerial survey of several sections of the state’s prime moose range — namely across Cook, Lake and northern St. Louis counties — accounted for an estimated 4,180 moose total. That’s up considerably from last year’s estimate of 3,030. But because there’s such a large range of variability in the survey, the increase is considered statistically insignificant.
The DNR said there's a 90 percent certainty that the population lies somewhere between 3,250 and 5,580 animals. This year’s midpoint estimate is still less than half the moose counted in 2006.
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.
“We’re encouraged that the moose population is not in the steep decline it was,” said Glenn DelGiudice, DNR moose and deer project leader, in a statement Monday. “In the short to medium term, we’re likely to keep seeing moose in the forests, lakes and swamps of Northeastern Minnesota. But their long-term survival here in Minnesota remains uncertain.”
Mike Schrage, a wildlife biologist for the Fond du Lac Band of Lake Superior Chippewa who took part in the survey, said the numbers appear to show stability.
“Show me three years like this one and then maybe I’d say we’ve bottomed out and are maybe going up a little, but I don’t get excited over year-to-year variability,” Schrage said.
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. Even an increase in warm summer weather, when moose stop eating because of heat stress, impacts the big animals’ ability to survive the cold winter.
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 occured, clearing the way for a younger forest that has the type of food moose thrive on.
The shrunken moose herd, especially newborn calves, also becomes more vulnerable to predators, especially wolves but also black bears.
“Habitat, especially an aging conifer forest like we have a lot of (in Northeastern Minnesota moose range) is a limiting issue for moose in Minnesota,” Schrage said. “But so are predators. … Could we increase moose without decreasing wolves? I think we could, but we’d have to change habitat conditions across a big area to do it.”
It’s never been entirely clear which factor is having the biggest impact on keeping Minnesota moose numbers down.
“We know from our research that adult female moose are getting pregnant,” DelGiudice said. “The problem is there aren’t enough female moose that are successfully producing calves and raising them to one year. That’s a significant challenge in our efforts to maintain Minnesota’s moose population.”
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.
“There are many things we still don’t know,” DelGiudice said. “But our understanding of habitat preferences, population structure, nutrition and predation has significantly improved. Our goal is to use this new information to identify management options that better the chances for long-term survival of moose in Northeastern Minnesota.”
Surveyors this year flew over 52 of the total 436 survey plots distributed across Northeastern Minnesota’s moose range between Jan. 3 to Jan. 17. While the survey is statistically sound, there’s inherent uncertainty when the area surveyed is just a small part of the 6,000-square-mile moose range.
The Fond du Lac Band of Lake Superior Chippewa and 1854 Treaty Authority again contributed funding and provided personnel for the annual moose survey.