Harsh winter impacts deer

ESCANABA – While the numbers aren’t in, the effects of two harsh winters on the deer population in the Upper Peninsula are sure to affect hunters this fall.

“We don’t have any hard numbers per se, but we do know the herd did suffer this winter,” said Brian Roell, wildlife biologist at the Department of Natural Resources’ Marquette office.

Hunters may fair better in areas like Menominee County where weather was milder and food was more plentiful for deer this winter, but in areas that experienced heavy snowfall and extreme temperatures there may be fewer deer left in the woods.

“Once it reaches -20 they need to move to keep warm. There just isn’t enough insulation in their fur,” said Roell.

Keeping active might keep deer warm, but it also depletes their energy reserves, especially in deep snow where movement is difficult. To maintain their fat reserves deer must eat more while being active in the winter months, but food may be scarce or buried under deep snow.

“It’s a combination of weather effects, inability to get food, and predation,” said Roell, noting that weak or malnourished deer are more likely to be lost to predation.

Deer between eight and 11 months are particularly at risk during the winter months. While deer of all ages can be killed by harsh winter conditions, young deer are unable to build the fat reserves that older deer are capable of and may be unable to get to food supplies claimed by older deer.

In one recent study, fawns born last spring and other deer in Iron County were fitted with collars last summer and monitored over the ensuing winter months.

“The fawns were the first ones to go, and in that study the fawn survival rate was zero percent,” said Roell.

The deer population is also expected to be affected by lower birth and survival rates for newborn fawns. Pregnant does are at an increased risk of reabsorbing their fetuses when their energy reserves are low, and fawns that are born following difficult winters have poor survival rates if they are born underweight.

According to Roell, because both last winter and the 2013 winter were harder on deer than usual, hunters have essentially lost three generations of fawns either to winter die off or low birth survival rates.

“We need some mild winters,” he said, adding that it would take more than one mild winter for the deer population to fully recover from the last two seasons.

While all hunters are expected to have fewer deer to draw from, hunters who prefer to hunt antlerless deer may have even fewer options.

“I suspect that many units that have had antlerless permits won’t have antlerless permits this year,” said Roell.