Dec. 15–Deep snow and deep cold already are pushing northern Minnesota’s white-tailed deer into mid-winter patterns. They’re seeking cover in conifers and, along the North Shore, probably will be moving down from the ridges to where snow is less deep, biologists say.
Duluth wildlife photographer Michael Furtman has been in the field, and he has seen deer coping with the snow and cold.
“They’re swimming in this stuff,” Furtman said. “They don’t want to move. They’re yarding up already.”
Deer “yard up,” or gather in numbers, to seek less-deep snow and the thermal advantages of conifer cover.
Mark Johnson, executive director of the Minnesota Deer Hunters Association, said he’s been talking to county foresters from St. Louis, Lake and Cook counties.
“They said the deer are pushing snow,” Johnson said. “That’s a good indication that it’s going to be a tough winter for deer.”
The tough early-winter conditions come on the heels of an already diminished deer population in Northeastern Minnesota. The population has declined over the past few years, partly due to moderate or severe winters and partly because state wildlife managers had been trying to bring the population down from highs a few years ago.
But this fall, the Minnesota Department of Natural Resources had reduced the number of antlerless deer permits available to hunters in hopes of bringing the population back up.
Deer have evolved with snow and cold in northern Minnesota, and they change their patterns to adapt to the deep snows, said Chris Balzer, DNR area wildlife manager at Cloquet.
“Along the shore, they move to the lake,” Balzer said. “Inland, they seek heavy conifer cover. There’s a lot of snow stuck in the spruce and balsam fir trees, and that means less on the ground. They can walk through those areas easier, and they get some thermal protection.”
Typically, that doesn’t happen until later in winter, and some years not at all, Balzer said. But this winter, it’s already happening.
Conifer stands offer warmer micro-climates because they block the wind. In addition, the dark trees absorb more sunlight.
“I walked into one deer yard and saw three bucks and two does,” Furtman said. “They’re all just lying there, biding their time, trying not to burn energy.”
With most of their high-energy food sources now covered by snow, deer are reduced to browsing on the less-nutritious twigs of trees and brush. So, rather than expend lots of energy browsing on twigs, the deer simply minimize their movements.
“They can actually decrease their metabolism — slow it down — so they burn less energy,” said Furtman, who wrote a book called “Deer Tails Trails, the Complete Book of Everything Whitetail.”
The deep snow and cold is hardest on fawns, Furtman said. But bucks also are vulnerable after the whitetail mating season in November.
“Bucks go into winter without body fat on them,” he said.
That body fat has been largely depleted during mating season as bucks cover a lot of ground to leave their scent and to breed does.
“They need this month of December to replenish their body fat, and they’re not going to do it this year,” Furtman said.
In general, deer are well-adapted to cold. Their coats are made up of hair that’s hollow to trap air and insulate well. But extended cold takes its toll, as does deep snow that restricts movement.
The Minnesota DNR keeps Winter Severity Index readings every winter at many locations to determine how harsh the winters are. One point is recorded each day the snow depth is greater than 15 inches, and another point is recorded if the temperature falls below zero. Those points piled up quickly this past week. In Wisconsin, the formula is the same except that snow points are tallied only when the snow depth exceeds 18 inches.
DNR biologists know how much deer mortality to expect each winter based on total WSI readings by the end of the season. Wildlife managers use the WSI readings to help determine how many antlerless deer hunters should be allowed to take the following fall.
Some people may want to feed deer in these harsh conditions, but that can cause problems, MDHA’s Johnson said. A deer’s digestive system is not designed to easily break down grains or hay, Johnson said.
“It’s easy to harm the animals if you don’t put thought into it,” he said.
Most deer will survive without artificial feeding, Johnson said.
“If they can get near browse, that’s all they need from now until spring,” he said. “Their metabolism has already dropped, and they’re already in winter mode. They’ll survive.”