Warmer winters part of MN moose dilemma

GRAPHIC: @MinnesotaBrown

GRAPHIC: @MinnesotaBrown

The Minnesota Associated Press reports that researchers are closer to finding out why so many Minnesota moose have been dying off in recent years.

Theories abounded over the past few years. The truth, as you might expect, is somewhat complex. Wolf kills are an obvious reason for many deaths, but a variety of natural causes such as relatively new wasting diseases, starvation and other factors are being cited in new research.

Preliminary results from tracking 173 adult moose that were captured and fitted with GPS radio collars from 2013 to 2015 show that two-thirds of the 47 that later died succumbed to various health problems. Another third were killed by wolves, but 25 percent of those moose had illnesses that made them easy prey, and some that died from health issues had been injured by wolves.

A Sam Cook piece explored the same information. Some believe the numbers are pointing toward warmer winters as one reason why moose are dealing with a spike in health problems:

“I think the DNR has come a long way in three years and done a good job of answering a lot of the unknowns we had from some earlier moose studies and what the causes of mortality are,” said Mike Schrage, wildlife biologist for the Fond du Lac Band of Lake Superior Chippewa, which has been involved in much of Minnesota’s moose research. “I think they’ve done a good job of getting at some of the interplay between health issues and wolf predation.”

Of particular interest is how winter nutrition in moose affects their health, DelGiudice said. When moose are heat-stressed in winter they aren’t getting enough food and eventually succumb to health problems, weakness or wolves.

“It’s incredible how it’s tracking,” he said. “The heat stress index of moose is tracking very closely with the severity of winter nutrition of these moose. What it’s saying is that winter nutrition could be a key to this.”

That information is based on moose urine samples the DNR has gathered from the snowpack, DelGiudice said.

In summer, he said, moose can go to ponds or streams to cool down when they get too warm. In winter, moose can only lie in the snow and shade, which offers less cooling, DelGiudice said. When air temperatures reach 23 degrees in winter, he said, moose can begin to experience heat stress, increasing their metabolism, heart rates and respiration.

Only further research will tie up some of these questions. Meantime, another warm winter like this one ought to be very revealing as to these theories.

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