Snow — not cold — is biggest winter threat for deer

Northwoods Notebook

Deer are able to withstand extreme cold with relatively little trouble if in good condition. (Betsy Bloom/Daily News Photo)

Deer are able to withstand extreme cold with relatively little trouble if in good condition. (Betsy Bloom/Daily News Photo)

The winter so far certainly hasn’t been as easy on deer in the region as the past two years.

But it also hasn’t been that bad, despite the stretch of subzero temperatures, experts with the Michigan Department of Natural Resources said.

Though not as ideally suited to far-north living as moose, white-tailed deer are able to withstand extreme cold with relatively little trouble if in good condition, said Terry Minzey, Upper Peninsula wildlife supervisor for the DNR.

While they don’t hibernate, deer do go into a form of winter torpor that slows the metabolism by about 20 percent, so they don’t need as many calories to keep going, Minzey said. It allows them to get by on woody, less nutritious growth.

“They move less, they lie down more,” he explained.

As winter sets in, they seek out spots that offer closed canopies and windbreaks when bedding down, again to conserve heat and energy.

Most adult deer also pack on the pounds during late summer and fall, building up a layer of fat that will provide more insulation plus a reserve for the body to draw on if food become scarce. Does and non-breeding young bucks often will develop a pad of fat on the rump, Minzey said — for a doe, having junk in the trunk apparently is a good thing — but males will burn off these precious reserves during the rut, which can put them at risk if the winter turns out severe or prolonged.

Deer have the added advantage of a thick winter coat that has hollow guard hairs and a dense undercoat that holds air warmed by the body close to the skin and keeps cold air out. That’s why deer during snowfalls will get a coating that doesn’t melt, like the roof of a house with good insulation.

Even the ears are well furnished against frostbite, although wildlife biologist Monica Joseph of the DNR’s Crystal Falls office said she has seen some deer missing ear tips that she suspects were lost to extreme cold.

But for the most part, deer don’t need to fear the cold as much as deep snow, which can bog them down and cost precious energy to plow through if no trail previously has been established.

Fawns would be the most vulnerable, as they have less ability to lay down fat reserves in the first few months of life. The smaller size, too, makes for more trouble with snow and a higher surface-to-body ratio that exposes more of the body to the elements — it’s an advantage in cold temperatures to be bigger, like moose, Minzey said.

Still, if they have a good food source, most deer will do just fine as long as the cold doesn’t stretch too long or come later in the season, such as in March, when those fat reserves have been depleted.

Sleet, too, can be tough on the deer if it soaks them and is followed by a temperature plunge that penetrates and chills, Joseph said.

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The DNR announced this week it is preparing to capture and collar deer in the western Upper Peninsula for a multi-year study on the animals’ movement through the region, especially migration between winter and summer ranges.

The project is intended to map how much deer travel and congregate, which could indicate whether chronic wasting disease might find a way into the U.P. from Wisconsin. While no CWD cases have yet been found here, two captive deer in a Wisconsin facility 30 miles south of the border have turned up positive, Minzey said.

The state also confirmed a new pocket of CWD in lower Michigan thought to have gone undetected for a decade, Minzey said.

“We have not found it in the U.P.,” Minzey said of CWD. “That doesn’t mean it’s not here; we just haven’t found it.”

The initial target areas for trapping all are along the Michigan-Wisconsin border: At Little Girls Point, Devils Creek-Chaney Lake, Lake Gogebic and west Iron County.

The deer will be fitted with GPS tags that should allow for regular tracking over at least four years, according to the DNR. After the project is completed in the western U.P., it will be repeated in the central and eastern parts of the region.

While winter might seem like a bad time to potentially stress the animals by trapping, Minzey said the traps actually are comfortable, sheltered from the elements and predators, in an enclosed space that keeps in body heat.

“It provides a nice little microclimate … they’re happy and content,” Minzey said.

And fitting them with tracking devices actually takes no more than 10 minutes once staff reach the traps, he added.

The DNR will use results of the study as a guide on whether practices that encourage deer to mingle together — such as supplemental feeding — might pose too much of a risk of spreading CWD, Minzey said.

On a related note, the DNR does not plan to authorize supplemental feeding of deer this winter. The snowpack is not sufficient to create a need for now, Minzey said.

“If this real cold weather continues on and on, we may develop some concerns,” Minzey said. “But we’re not overly concerned right now.”

Residents still are allowed to do recreational feeding at home of no more than 2 gallons without a permit, Minzey said.

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The local Audubon Society birding group will meet at 6:30 p.m. Thursday in the history room of the Dickinson County Library, 401 Iron Mountain St. in Iron Mountain.

Bob Doepker, a biologist with the DNR’s Norway field office, will present a program on Blackburnian warblers, a striking variety in which the male has vivid orange and black breeding plumage. They favor mature conifer and mixed conifer and deciduous forests, which should mean they’re right at home in this area.

Anyone who might be interested is welcome to attend. For more information, contact Carlson at pcarlson2561@gmail.com or call 906-774-5868.

Betsy Bloom can be reached at 906-774-2772, ext. 40, or bbloom@ironmountaindailynews.com.

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