The winter of 2012-13 has abruptly changed since
the last Winter Severity Index report in early February. Over 30 inches of snow has fallen in
the last month in Northern St Louis County, with three storms in the 6-inch-plus
category.
For northern forest whitetails, the
going has gotten tougher. All snow measurement stations are currently
over the 15 inch threshold.
(Editors note: The Minnesota Department of Natural Resources measures the Winter Severity Index (WSI) by applying a point for everyday the temperature is below zero and applying a point for every day the snow is 15-inches or deeper. A typical Minnesota winter scores a WSI of about 120. Once the WSI begins to rise above that point, a winter is considered harsh, particularly if it reaches the 140 or 150 range.)
Winter severity, specifically snow depth and
duration of snow cover, is the most critical factor affecting
white-tailed deer survival in the northern forest. Deer movement is
now heavily restricted, especially up in the border country. Deer are in heavy conifer cover. With restricted mobility, wolf
predation will increase as the tables have now turned against deer.
Until mid-February, deer had excellent mobility, and wolves were at a
disadvantage, in all but the northern most parts of
St Louis County.
At this point, the WSI is still below average for our
area (northern Minnesota). Because December and January were very open, with snow depths
less than 6 inches (except north of Orr) winter’s effect on deer is still
minimal at this juncture. This winter is going to
end up a bit below average (WSI=120) in the Tower area and milder on
the Iron Range. With longer days and higher sun angle, south aspects
will soon begin to open up and provide improved mobility and forage.
If winter and snow pack fade in late March, the
2013 fawn crop should still be a good one in most of northern St. Louis
County. And, last year’s (2012) fawns, the most vulnerable segment of
the herd, should come through okay. Time will tell,
but the prospects for this winter appear to be short, with warming
temperatures and longer days on the horizon as March progresses into
April.
By April 1 we will have a firm grasp
the effects of this winter on our white-tailed deer population.
Antlerless permit area designation for the 2013 deer season will be made
in mid-April.
Tom Rusch is the Tower Area Wildlife Manager for the Minnesota Department of Natural Resources' Division of Fish and Wildlife headquartered at Tower, MN in northern St Louis County. His dedicated 4 person staff covers 3.1 million acres of State, County, National and private forest land in northern St. Louis and northern Lake Counties. He hunts, fishes, camps, traps, bikes, hikes, snowshoes and shed hunts year round in the swamps, forests, wetlands and lakes of the northwoods of Minnesota, Wisconsin and Ontario. He is a 24-year veteran of the Minnesota DNR and has worked in the wildlife management field for 30 years in Minnesota, Wisconsin and Missouri. He has lived on the Iron Range with his wife, Deb, since 1991. Tom can be reached by phone at 218-753-2580 ext. 240 or by email at tom.rusch@state.mn.us.
