ELEPHANT LAKE— Across most of northeastern Minnesota, the whitetail deer herd is rebounding. Recent mild winters have allowed the region’s deer population to recover from high mortality back in …
ELEPHANT LAKE— Across most of northeastern Minnesota, the whitetail deer herd is rebounding. Recent mild winters have allowed the region’s deer population to recover from high mortality back in 2013 and 2014, and that’s allowed the Department of Natural Resources to liberalize bag limits for deer hunters.
But in a broad stretch of northwestern St. Louis County and much of Koochiching County, the deer recovery has been slow— so slow that the deer permit areas in the region have remained largely bucks only.
Now, wildlife managers here are hoping to find out why that is.
They’ve launched a new study, led by DNR biologist Glenn DelGuidice, to better document how deer are using the habitat in the region just south of the border, particularly in permit areas 108 and 119, where the deer population has struggled in recent years.
The first two years of the study will cost $304,000, with funding coming from the state’s Deer Management Account. The Minnesota Deer Hunters Association is also contributing $30,000 toward the effort.
The study may help wildlife biologists better understand the connection between habitat and winter deer survival. By conventional wisdom, the deer population in northwestern St. Louis County should be robust. The area is the primary wood basket for the Boise Paper mill in International Falls and it’s been intensively logged for years. Traditionally, logging and young forests have been seen as beneficial for deer, but wildlife managers, like Tower DNR Area wildlife manager Tom Rusch, believe it’s a more complicated issue. Deer need more than food, notes Rusch, particularly in winter when protective cover contributes at least as much to deer survival as quality browse.
Deer struggle to take in much nutrition during the winter. During the warmer months, when fresh, nutritious grass and other vegetation is readily available, deer thrive. But come winter, when all those nutritious foods are dead and buried under the snow, deer are forced to rely on woody browse. It may be high in fiber, but its nutritional value is limited— and that forces deer to rely heavily on stored fat reserves to get through a northern Minnesota winter.
One of the keys to their survival is minimizing their use of energy, in order to slow the utilization of their fat reserves. One way that deer conserve energy is by putting on a thick, well-insulated coat of fur in the fall. They also eat less, which slows their metabolism. In addition, they spend as much time as possible in dense evergreen cover. Biologists generally recognize that deer tend to “winter” in places like white cedar stands, or under dense pine, spruce, or balsam fir. That’s because these places protect deer from wind, tend to have less snow on the ground, and moderate temperature drops at night. Even a few degrees each night can make a big difference over the course of a winter in terms of a deer’s chances of survival. That’s one reason that wildlife managers try to ensure that there’s enough mature evergreen cover on the landscape. They know that this time of year, cover is more critical than plentiful browse since deer get so little nutrition from woody branches.
Wildlife managers fear that quality winter cover is being sacrificed in the push to intensify timber cutting, particularly on state and county lands, and that it’s beginning to impact the survival of whitetail deer in the border region.
“We’re trying to find out why deer numbers are not recovering,” said Penny Backman, area wildlife manager in Orr. Wildlife managers believe they know why, but in resource management, it usually takes more than a hunch to create changes in policy. “We think we know what they need, but this could put some data behind it,” said Backman.
The study got underway last month with the capture of ten female deer near Elephant Lake.
Using a helicopter, a private firm that specializes in wildlife capture dropped nets on deer after pursuing them through the deep snow. It’s not pretty to watch— and it did generate at least one complaint from an individual who witnessed one of the pursuits— but it’s often less stressful on the animals than traditional tranquilizing, which can have its own set of unwanted side effects.
The capture is necessary to attach GPS collars to the test animals. The GPS units allow researchers to gather data on deer movements almost continuously, 24 hours a day, 365 days a year. “With this, we’ll be able to drill down to what cover type they are in at any point in time,” said Rusch. “This is great data and we’re going to learn some valuable stuff.”
Next year, researchers plan to add 20 more deer in the Elephant Lake area to the study. At the same time, researchers will be studying deer in other parts of the state, including the Grand Rapids area and southeastern Minnesota, to better understand how deer use different types of habitat and how they adapt to distinctly different climate types. We know we have the toughest winters up here,” said Rusch. The question is how do harsh winters impact the way a deer uses its landscape in order to survive.
“What deer need varies by winter and where you are in the state,” said Backman. “It’s a complex issue.”
It’s also a timely issue given the DNR’s recent moves to shorten forest rotation ages, particularly for aspen, which is the predominant timber type in northwestern St. Louis County. Rusch said the best deer cover is typically provided by older aspen stands in that part of the county, particularly where a significant component of balsam fir has developed in the understory. That understory takes years to develop and Rusch worries that shorter rotations will mean sites are logged before critical winter cover has time to develop.
The study will help researchers either put solid data behind their theories or will demonstrate that other factors may be at play. “We need this data,” said Rusch, “but we still don’t know what it will tell us in the end.”