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Biologists concerned by prolonged winter on deer condition

Biologists concerned by prolonged winter on deer condition

By Michigan Department of Natural Resources

The prolonged wintry conditions in the Upper Peninsula show no sure sign of relenting soon, a circumstance that has state wildlife biologists concerned about the stressful impact to white-tailed deer.

“A month ago, we were optimistic about the deer herd, with spring on the horizon and the winter we’d had to that point,” said Terry Minzey, Upper Peninsula regional wildlife supervisor. “Now, I’m quite concerned with what we might end up with because of this protracted winter weather.”

Deer radio-collared in the western U.P. as part of an ongoing predator-prey study or a new deer migration study, have suffered a 13.5 percent mortality rate so far this winter, with 11 percent of adult female deer dying.

That mortality rate compares to 15 percent through the entire month of April in 2017.

“The big difference between this year and last year is that as of April 11 last winter, 95 percent of the deer had dispersed from their wintering complexes,” Minzey said. “This year, there have been none. They’re all still there because of the continuing winter conditions.”

An April 9 snow depth map showed more than 2 feet of snow in some northern parts of the region, nearly 2 feet of snow in other places, and several inches on the ground in areas traditionally green with grass by this time of year.

Some snow depth examples included 20 to 26 inches in Hulbert, 12 to 17 inches in Gwinn, 15 to 19 inches at Baraga, 16 to 17 inches at McLain State Park north of Hancock and 17 to 21 inches at Wakefield.

“In general, across the north and west, the deer are starting to look pretty rough and stressed,” said Brad Johnson, a wildlife technician at Baraga. “The Keweenaw is almost up to 300 inches of snow (for the season) and we are listening to Tiger baseball on the truck radio 5 miles out on 2 feet of ice in Lake Superior in April.”

Johnson said DNR staffers are starting to get a lot of calls of stressed deer reported at feeding sites.

Minzey said this winter is different than most others because a comparatively low amount of snow fell during the early part of the winter. Temperatures remain below average for April so far.

“With relatively no green vegetation available, deer are suffering a negative energy balance at the same time they are burning energy used for developing fetuses or antler development,” Minzey said. “Deer expend five times more energy to move through snow than they expend to keep warm.

“Generally speaking walking in 14 inches of snow results in a 50 percent energy expenditure increase as compared to walking on dry ground. If deer are forced to walk through 21 inches of snow, they burn twice the energy compared to walking on dry ground.”

Minzey said when these snow, weather and health conditions exist after mid-March, it typically spells trouble for fawn, and potentially adult deer, survival.

“Overall, my forecast for the northern deer is poor if the weather doesn’t turn soon,” said wildlife technician Caleb Eckloff. “Southern deer in my work area are faring much better, but I still have reservations about a successful fawn crop.”

Overall, with improving winter conditions, the Upper Peninsula deer herd had been rebounding over the past year or so, after three consecutive hard winters in which significant deer mortality was recorded.

A hunter camp survey released in February reviewed last fall’s deer hunting season. Across the region, hunters said the number of deer seen and the percentage of hunters harvesting a buck had increased, while they said the deer herd trend and rating of the season had improved.

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