Even after a snowstorm this past weekend that dumped upwards of eight inches to a foot of snow on parts of northern Minnesota, the winter of 2012-2013 has been pretty tame, according to Minnesota Department of Natural Resources officials.

That's great news for a deer population still rebounding from one of the toughest winters on record just two years ago.

The DNR measures winter severity by assigning a point for each day the snow depth is 15-inches or more and one point for each day the temperature is below zero and through Feb. 3 the Winter Severity Index (WSI) in and around St. Louis County was 31.

Considering a harsh winter - one that kills fawns and elderly deer - scores 130 or higher by the end of March, a 31 at the start of February means the stress level on deer so far has been pretty much non-existent.

What that means for deer - and the hunters who chase them each fall - is the potential for a excellent spring fawn crop for the second year in a row and a good chance population levels are going to rise in the very near future.

And that could mean extra opportunities for hunters because regardless of what type of management approach the DNR takes with the deer herd - or how many predators may or may not be killing deer each year - survival and fawn crops are most affected by winter, particularly how long it lasts into the spring fawn season.

Deer are generally equipped to handle about 90 days of normal winter conditions and when the season starts to last a little longer than usual, like it did in 2010-2011 when much of the area finished the season with a WSI score in the 140's and 150's, the population begins to suffer. When winter is stretched or reaches a "harsh" condition certain segments of the population, particularly fawns and yearlings, begin to suffer and die.

The antlerless deer, carrying the fawns, are also overtaxed and a long winter can sometimes result in singles (does often give birth to twins and sometimes even triplets) or no fawns being born at all.

When winter is more mild, like it has been this year, it bodes well for the population. And the fact that this is the third - so far - mild winter in four years has a doubling and tripling effect on things.

Tower Area DNR Wildlife Manager Tom Rusch said this week that as it stands he is predicting this winter will end around average, at a WSI score of 120.

"If that is indeed the scenario that plays out, the 2013 fawn crop would be the second consecutive bumper fawn crop in St. Louis County, with back-to-back mild winters," Rusch said. "Consecutive large fawn crops historically have put population growth on the fast track. Time will tell, but the prospects for the northern Minnesota deer population appear to be on the rise. By March first we will have a firm grasp the effects of this winter on our white-tailed deer population."

While no one can predict what Mother Nature has in store for us over the next couple of months, historically, low WSI scores in February translate into low end of season scores. For example, over the past three winters in the Eveleth area the WSI scores in February and March were as follows:
  • The winter of 2009-2010 had a WSI score of 30 on Feb. 5 and ended with a score of 49.
  • The winter of 2010-2011 had a WSI score of 85 on Feb. 5 and ended with a score of 150.
  • The winter of 2011-2012 had a WSI score of 20 on Feb. 5 and by March 21 most areas of northeastern Minnesota were registering WSI scores between 26 and 70 or 80 further north.
Rusch said this year, December was very open with snow depths less than 6 inches and that the first half of January continued to be very mild with temperatures as high as the upper 40’s and rain, which diminished snow cover. Temperatures plummeted in the latter half of January, but snow depths were still less than 10 inches at Tower and Eveleth.  

That meant deer movement was not restricted and they were able to access food sources across their home ranges throughout December and January.

"Deer remained dispersed in fall cover until early February, when they shifted to better winter thermal cover with the wave of cold that moved in," Rusch said, adding that snow depth is the key factor in deer survival in northern Minnesota.

"Snow depth surpassed the 15-inch threshold north of Orr in St. Louis County, and in Northern Lake County, in late January. Snow depth surpassed 15-inches on the Iron Range on Feb. 10, but the next WSI report isn’t until February 18," he said. "Snow points are now accumulating in each deer permit are in the Tower Area and will continue until snow depths again drop below 15 inches in March."

Also, Rusch added, wolf predation, so far, has likely been very light with deer having excellent mobility and wolves being at a disadvantage.

For more information on WSI see: http://www.dnr.state.mn.us/hunting/deer/index.html.