REGIONAL—March has come in like a lamb, and that’s more good news for the region’s deer herd, which is experiencing one of its easiest winters in years. While the mid-February cold snap was the longest in half a century, cold temperatures alone don’t provide much of a challenge for whitetail deer, according to DNR biologists. That’s why the Winter Severity Index, or WSI, could well finish up at the lowest level in nearly a quarter century.
As of March 1, the WSI readings across northern St. Louis County are running in the mid-30s and, based on the current extended forecast, there’s little reason to expect the winter’s final index reading to go much higher. The index adds a point for each day with at least 15 inches of snow on the ground and each day with a below-zero temperature reading. This winter’s remarkable snow drought has left most parts of the region with zero snow points on the index so far, and there’s little sign in the forecast that a major snowfall is in the cards through at least mid-March. Temperatures are forecast to remain mild as well, which should preclude any additional points based on below-zero temperatures. Without deep snow, deer can move about easily, either to target quality winter browse or elude predators.
In the past 25 years, only the winter of 1997-98— which finished the season with a WSI reading of just 24 points— ended up with a final reading below 40.
Snow depths across northern St. Louis County ranged from eight-14 inches as of Monday, with at least three days of above-freezing daytime temperatures since. Highs are expected to reach the mid-forties on Sunday, with continued mild weather expected for Monday into Tuesday.
The late winter can often pose challenges for deer, as crusted snow can allow predators to travel atop the snowpack, while deer typically break through, yet the limited snow cover this year is reducing the impact of crusted conditions. And limited snow cover melts more quickly as bare ground is exposed sooner under trees and on open south-facing slopes. Once bare ground is exposed, the intensifying sun quickly eats away at remaining snow cover.
If mild conditions continue in the remaining weeks of winter, it bodes well for strong fawn production, and that could be the start of a recovery of the deer herd, which has been diminished by a string of moderate-to-severe winters. “A couple consecutive years of strong fawn production is the prescription for population recovery, barring a severe winter in the mix,” said Tom Rusch, DNR wildlife manager for the Tower work area. “Snow depth and duration of winter is the most critical factor in deer survival in northeastern Minnesota.”
Even so, Rusch notes that one mild winter likely won’t be enough to allow deer populations to recover to levels of several years ago. “Back-to-back deep snow winters pushed us into this population decline and it will take more than one mild winter for the herd to get out,” he said.