TOWER — Things are looking good for the health of northern Minnesota’s deer herd as winter has now turned the corner toward spring. And, according to the Winter Severity Index (WSI) put out by the DNR, the weather so far has put very little stress on the animals.
Tower Area Wildlife Manager Tom Rusch says this has been an extremely mild winter as of early February, which is the typical midpoint of a winter in our region.
Deer managers use the WSI to compute how the combination of snow cover and temperatures might affect deer survival. From these measurements the DNR can get a look at how the population might decrease in a high value WSI or increase when the numbers are low.
Two years ago the WSI hit an all-time high, and the results were high mortality, which resulted in less deer and had a direct affect on the number of deer that were able to be harvested during the hunting seasons.
The result of two extreme winters — in 2012-2013 and 2013-2014 — was that ‘bucks only’ was the mandate across the Northland during all hunting seasons — archery, firearms and muzzleloader.
Last winter, 2014-2015, was a mild season that helped turn the deer numbers in a positive direction.
Another good winter now would do wonders at helping replenish that which was decimated a couple of years ago. Rusch says one mild is a good start, but two in a row is where the difference can be seen.
“Deer are doing very well this winter,” said Rusch in an email release last week. “Their movement is generally not restricted by snow depth,” which is a key factor in potential deer mortality.
He says that snow depth ranges from 10-20 inches across the Tower work area, and increases from west to east.
“Deer are distributed much wider and utilizing available food sources compared to recent severe winters,” Rusch added.
The WSI is updated weekly on the DNR website, and is described as “a general measure of winter conditions based on the premise that prolonged cold temperatures and deep snow can reduce overwinter survival of white-tailed deer.” End of the season values: Less than 100 equals mild winter; 140 equals moderately severe; greater than 180 equals severe winter; the average Tower winter is 120.
“The WSI currently ranges from 13-31 in the nine local deer permit areas. These are all extremely low/mild numbers for this point in the winter.”
The calculations are based on one point for the number of days in which the snow cover is 15 inches or more, plus a point for the number of days that are below zero.
While snow and cold are the elements used to compute the index numbers, Rusch says snow is the dominant factor in determining the winter survival rate of the deer herd.
At the present time, even though the area has seen additional snow and below zero temperatures since the most recent WSI was released, Rusch is optimistic that a continued mild winter will produce more deer when hunters hit the woods next fall.
“Fawn production should be excellent in spring 2016,” he said.