Minnesota’s moose hold their own for one year; Mortality among adults, calves still too high to sustain population
Minnesota Department of Natural Resources and tribal wildlife officials conducted an aerial survey in January of several areas in the northeastern Minnesota moose range and used those surveys to estimate a total population of about 4,350 animals.
That’s up significantly from the 2,760 estimated in 2013. But officials cautioned that the difference may have been spurred more by changes in survey conditions from year to year and not a true increase in moose on the ground.
“The higher estimate this winter likely is related to ideal survey conditions rather than any actual increase in the population,” said Lou Cornicelli, the DNR’s wildlife research manager. “This year’s heavy snows across northeastern Minnesota made it comparatively easy to spot dark-bodied moose against an unbroken background of white.”
Cornicelli noted that this year’s estimate is very close to the 2012 estimate of 4,230, which suggests that last year’s estimate may have undercounted the population.
“All wildlife population surveys have inherent degrees of uncertainty,” he said, adding that long-term trends are likely more telling than annual estimates and fluctuations.
And for Minnesota moose, the long-term trend has been down.
Ron Moen, a moose researcher at the Natural Resources Research Center at the University of Minnesota Duluth, said wildlife experts in the field saw nothing that would support the big fluctuations indicated by the past two aerial surveys.
“We suspected last year’s survey was an undercount. And we sure haven’t seen anything since then to make us believe the numbers are going up at all,” Moen said, adding that moose are notoriously difficult to count even from helicopters.
Moen said ongoing surveys of GPS-collared moose indicate the number of both calves and adult moose dying in Minnesota each year is about double what it should be for a healthy population.
Researchers said they see no change in the long-term trend of a rapidly declining moose herd that is less than half of the 2006 estimate of 8,800 animals. The population declined to a point last year that DNR officials opted to cancel the state’s very limited moose hunting season after years of scaling back the number of licenses offered.
The DNR said Friday they have not yet decided whether to resume the moose hunt for 2014. They’ll make that decision in coming weeks after talking with tribal resource agencies.
The DNR has joined with numerous other agencies and research groups to study why moose are declining. Crews in recent weeks tranquilized 36 additional moose to fit them with GPS transmitting collars so researchers can see where the big animals go to eat, mate, rest, cool off, have their young, escape predators and — possibly most important — where they die.
It’s the second year of the major research effort, and scientists have been homing in on dead moose as rapidly as possible to harvest key organs and other body parts that can help them determine why the moose are dying faster than they are being born. Another 50 newborn calves will be collared this spring.
Data so far shows that 21 percent of adult moose are dying in the first year they are collared. Moreover, 74 percent of the calves fitted with radio collars perished in the first year, most in the first few months. That’s considered far too low a survival rate to sustain a viable population. Moen said adult mortality should be about 10 percent annually and calf mortality about 40 percent.
“The mortality numbers are very high, and they give me great pause in saying we’ve had any increase like the survey might be showing,’ said Mike Schrage, wildlife biologist for the Fond du Lac Band of Chippewa. “We don’t know if 2013 was way off on the low side or if maybe this year’s count was too high, or both… we do know the long-term trend is down.”