DNR update Winter Severity Index, maps now available
By Paul Vold firstname.lastname@example.org (1/19/21)
(Minnesota) — The Minnesota Department of Natural Resources has recently updated maps for the Winter Severity Index to better help understand the climate for the entire state and help manage the whitetail deer population.
Wildlife research staff have taken a look at the last 36 years of winter weather to update the maps and criteria for mild, moderate, and severe winters. The WSI is calculated weekly from November 1st to May 31st, scores accumulate throughout the winter, with one point for each day with an air temperature of 0 degrees Fahrenheit or lower and an additional point for each day with a snow depth of 15 inches or deeper. Winters with a total WSI value of 50 or lower are considered mild; 51 to 119 moderate; and 120 or higher are severe.
Other factors that influence deer survival beyond snow depth include duration of winter and timing of spring green-up, quantity and quality of habitat and forage, high deer densities and food competition, sex and age composition of the deer herd, wolf density and predation, back-to-back severe winter, and high reproductive potential.
The DNR has posted a new webpage exploring deer survival and the Winter Severity Index, which can be seen with this story at www.rjbroadcasting.com.