A pretty easy winter for Minnesota whitetails
Grand Rapids, Minn. — Last year, deer across the state – save for a few in the far northeast – experienced the kind of winter custom-made for herd growth: little snow and a lack of cold. The Winter Severity Index in the Grand Rapids area was an atypically low 18, merely a blip on the screen in terms of winter severity. In fact, it was the second-lowest ever recorded since the DNR began using the index.
This winter, officials say, deer might not have it quite as good as last, but there’s little concern in most areas that the WSI will push to a point where noticeable losses – due to starvation or depredation – are likely.
A severe winter this year, as measured by a WSI of around 100 or so, “just isn’t in the cards,” according to Perry Loegering, DNR area wildlife manager in Grand Rapids.
“Around here, (deer) could forage well into December,” Loegering said, adding that the acorn crop was pretty good in the area. Deer were adding weight at a time when they’d normally be in the mode of conserving, he said.
As of earlier this week, the WSI in the Grand Rapids area was in the 50- to 60-point range, Loegering said. A point is recorded for each time the temperature is below zero during a 24-hour period, and each day the snow depth is greater than 15 inches. If the WSI is going to have a chance to reach the severe range – around 120 points – an area would probably need to have reached a much higher WSI by now, according to Loegering.
There are, however, areas in Koochiching, St. Louis, and Lake counties that could reach levels of severe WSI, as some locations in the far northeastern part of the state are nearing 100 points.
Longevity of winter also is a consideration, although “we haven’t had a meaningful snowfall in April in many years,” Loegering said.
The most likely scenario this year for the majority of the state is a WSI under 100, which means those deer-related things associated with severe winters aren’t likely – things like starvation, increased depredation by creatures like wolves (because of the inability of deer to outmaneuver their pursuers), and poor production in the spring. In other words, the northern Minnesota deer herd stands a chance to grow.
The only measurable losses this year might be that of fawns, and it’s something that doesn’t surprise wildlife officials.
“With fawns, you can expect at least some mortality just about any winter,” Loegering said. That’s because they’re still growing, and haven’t had the opportunity to put on fatty reserves.
Not long ago, DNR officials, including deer researcher Glenn DelGiudice, studied winter deer mortality for some 15 years, which included collaring and monitoring does. While they’re usually the last to succumb to severe winter weather, loses can be great given extreme conditions.
For example, DelGiudice said that during the severe winter of 1995-96, 30 percent of the radio-collared does died, many of them taken by wolves, and many of those slowed by deep snow and poor physical condition. That year, the winter began early and extended well into March. The WSI in Grand Rapids reached 195.
The following winter was nearly as severe, and deer hunters and researchers feared similar losses. However, DelGiudice said, only 7 percent of collared does died, for a number of reasons. For one thing, he said, the most vulnerable deer had died the previous winter. Because of the previous year’s loses, there were fewer deer competing for limited forage. Also, most of the surviving does from the previous year had lost their fawns, thus eliminating the need to nurse the following spring.
Of course, those winters were followed by three mild winters, and the rapid recovery of the deer herd in the north provided DNR researchers with a vivid example of how weather extremes can affect deer populations.
DelGiudice said he’s fairly confident deer in most areas aren’t in danger this winter.