How much cold weather can you tolerate? The comment we hear daily goes something like this. “I have lived in Wisconsin for more than 60 years and do not remember a cold snap like this or one that lasted so long. Where is that January thaw that we usually experience?”

We are constantly hearing from folks who appreciate our wild animals that they want to purchase bags of corn to feed the deer. Others are purchasing bales of hay for the deer. Those individuals are under the mistaken belief that if they place corn or hay where the deer can get at it that will help the deer survive the winter. Dean Bortz, writing for the “Wisconsin Outdoor News” said that we might as well save our time and money. He says that the deer may not survive anyway.

If you are interested in feeding deer at this time of the year keep in mind that deer in northern Wisconsin have been eating browse most likely since the end of deer season. Cutting browse will put food at a level where the deer can get at it. Deer can not only digest browse but they can get critical nutrients from the browse. 

Dr. Mike Riggle, a veterinarian from Medford, is a Conservation Congress delegate from Taylor County and a good friend. He says that he has seen this feeding frenzy in the past. The discussions in the boat, when Mike is fishing with us, are extremely interesting. Dr. Mike has been quoted in several publications with the following comments.  “People think that they are doing the right thing, but this feeding actually causes harm. Deer will fill up on hay and not eat the browse that they need. The rumen is full of hay it cannot digest, so they are literally starving to death.” He goes on to say that there is an exception to this situation. “Unless these animals are on hay before snow flies, which was November this year, don’t put hay out.”  

Dr. Mike said that deer are selective however. During the period when there is no snow on the ground they will eat some corn and also some browse.
Prior to 1975, Wisconsin did not have a formal procedure for measuring winter severity and predicting it’s impact on deer herds. Michigan had developed a severity index using a complex system to estimate a snow-hazard factor. Ontario was using the Passmore-Method that also involved collecting relatively complex snow measurements. 

United States Department of Commerce weather data was initially used to measure winter severity because they were easily obtained and initially allowed us to compare Winter Severity Index for previous winters.

The Wisconsin Winter Severity index was developed after testing several procedures for quantifying winter conditions.  The researcher who developed this method was Bruce Kohn. His method uses the number of days with a minimum temperature of less than zero degrees Fahrenheit as a measure of winter air-chill, and the number of days with more than 18 inches of snow on the ground to estimate the snow hazard. Days when both conditions occur are scored as two. These factors are added together from the first of December through the last day of April. 

Winters are considered “mild” if the calculated Winter Severity Index (WSI) is less than 50, “moderate” if it is between 50 and 80, “severe” if it is between 80 and 100 and “very severe” if the WSI exceeds 100. Presently the severity index is in the low 30’s. As previously stated one point will be added for each day of zero or below temperatures and one point when snow depth exceeds 18 inches. These designations are based on observed associations between WSI and winter mortality, fawn production and buck harvest during the following year. 

Historically, severe to very severe winter conditions were commonly reported across the Northern forest region from the early 1960s through the late 1980s. We have experienced moderate winter conditions across the region since the early 1990s.  

Thanks to Bruce Kohn for the information he shared about the Winter Severity Index.

An important consideration for those who are feeding birds during this cold winter is to use caution. If you furnish water for the birds, insure that there is no source of water near the feeders. Birds can have their feet freeze to a metal pole when their feet are wet.

This past week the Oneida County delegation of the Wisconsin Conservation Congress lost one of their delegates when Ben Loma passed away. We will miss Ben on the Conservation Congress.

Longtime Northwoods outdoors personality Roger Sabota writes a bi-monthly column for the Star Journal.