LANSING - Michigan's mild winter could mean more deer in the Upper Peninsula this year.
Experts say unusually warm weather could make more food sources available, giving deer access to more forage sites and an advantage over predators.
Those patterns could forecast an exceptional hunting season in the fall.
Several whitetails are seen in this recent photo from Houghton County. Experts say the relatively easy winter the region has experienced to date has been a boon to the deer herd. (Houghton Daily Mining Gazette photo by Kelly Fosness)
Brent Rudolph, deer and elk program leader for the Department of Natural Resources (DNR), said if mild temperatures and low snowfall persist through the rest of winter, deer populations could reproduce in greater numbers.
"The most critical time, in terms of having an impact on population, is early spring," Rudolph said. "In the dead of winter, deer essentially hibernate on their feet. They only need enough energy to survive, but if they do survive in greater numbers, we could potentially see more fawns."
Rudolph said the effect is limited to the U.P. since winters in the Lower Peninsula are not severe enough to significantly affect deer populations.
The past two winters also were mild in the U.P. As a result, does had more success birthing fawns in the spring.
Kristie Sitar, a DNR wildlife biologist in Newberry, said, "In a bad winter, does will preserve energy by reabsorbing their offspring, meaning they wouldn't give birth to fawns they are carrying. There would also be fewer multiple births in spring.
"Every winter, the old deer and the unhealthy deer are going to die off, but in severe winters almost all of the fawns entering their first winter are going to die off. In winters like this, a majority of fawns will survive," Sitar said.
To determine the effects of winter weather on wildlife populations, DNR uses a measure called the winter severity index. It combines data on wind speed, temperature and precipitation to gauge whether conditions in a particular area are mild, moderate or severe.
According to the DNR, a severe winter could result in the starvation death of around 105,000 deer in the U.P. A moderate winter could see around 70,000 deaths and a mild winter could see 35,000 deer perish.
An estimated 270,000 deer live in the U.P.
During winter, deer seek shelter in deeryards, which are coniferous forests with less wind exposure, less snow cover and higher temperatures.
However, U.P. deeryards have been depleted by years of overuse and lack enough resources to carry herds through severe winters, according to Sitar.
"These yards have been browsed-out for decades here in the eastern U.P.," Sitar said. "There isn't enough food available to support large populations, so starvation would be serious."
Rudolph said higher temperatures and decreased snow cover mean deer may venture away from the yards to forage.
Not only can mild winters help deer feed but can also help keep deer off their predators' menu.
Rolf Peterson, a professor at Michigan Technological University, said less snow cover allows deer a better chance of escaping those that would eat them.
"The wolf kill rate is usually higher when deer are facing deep snow, which tends to concentrate deer in predictable places like deeryards," Peterson said. "There is some security in numbers for deer in yards, but wolves will have less trouble testing many deer, singling out the most vulnerable.
"In the second half of winter, crusts on the surface of the snow formed by freeze-thaw will often support wolves, and then they are not slowed down at all by the snow that imprisons deer," Peterson said.
DNR estimates there are 687 wolves in the U.P.
Terry McFadden, a wildlife biologist with the DNR's Marquette Operations Service Center, said no matter what sort of weather comes between now and spring, he expects a substantial increase in deer populations and more incidents of deer damaging crops and property.
McFadden said nuisance deer have been a problem for farms in U.P. counties like Menominee, Iron, Alger, Dickinson, Delta and Marquette. He predicted an increase in the issuance of permits allowing landowners to hunt nuisance deer on their property.
Beyond issuing landowners permits, McFadden said local DNR offices are limited in what they can do to stop nuisance deer. Allowing more antlerless hunting or lengthening hunting seasons would be too broad a solution to help specific homeowners.
"There could be more incidents, but the only thing we can do is work with the individual landowners for now," McFadden said.