Can cold weather affect when bucks lose their antlers? Absolutely. It’s not common, but as seen here, it can happen when the days of below-zero temperatures start adding up. In fact, this is the fifth trail-cam photo I’ve seen this week of a buck that has already shed its antlers. I’m speculating off of years of experience here, but I’d attribute almost all of these cases to environmental stress on the deer herd.
During normal years, whitetails can withstand almost anything Mother Nature dishes out. Their breaking points, however, are deep winter snow depths and brutally cold temperatures. The bad news is this 2013/2014 winter is shaping up to be a doozy in many Upper Midwest and Northeast states.
Many decades ago, biologists in Minnesota and Wisconsin set out to learn more about winter’s wrath on the whitetail herd. During their studies, the researchers found a direct link between snow depth, wind-chill temperatures and winter dieoffs among whitetails. They also came up with a formula for predicting how bad any given winter would have on the deer herd. It’s called the “Winter Severity Index.” Here’s how it came to be, according to the Wisconsin Department of Natural Resources:
“Prior to 1975, Wisconsin did not have a formal procedure for measuring winter severity and predicting its impact on deer herds. Michigan had developed a severity index that used calorimeters to estimate a winter air-chill factor, and snow depth and sinking-depth measurements to estimate a snow-hazard factor (Verme 1968). The air-chill and snow-hazard factors were summed at the end of each week to derive a cumulative severity index. Ontario was using the Passmore-Hepburn Method, which also involved collecting relatively complex snow measurements (Passmore and Hepburn 1955). Our winter severity index (WSI) was developed after testing several procedures for quantifying winter conditions (Kohn 1975). It used the number of days with a minimum temperature of 0°F as a measure of winter air-chill, and the number of days with 18 inches of snow on the ground to estimate the snow hazard. Days when both conditions occurred are scored as 2. These are added together from 1 December through 30 April to obtain the WSI.”
Winters are considered “mild” if the calculated 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.
Wisconsin’s deer herd is not even near a critical juncture … yet, especially considering the fact that as of today (Jan. 2), only one small pocket of northern Wisconsin had snow depths of more than 12 inches (6 inches below the WSI requirement). However, the big caveat here has been the cold temperatures. Where I live, in Waupaca County (which, by the way, is too far south to be considered a candidate for WSI impacts), we have already experienced 16 days where temperatures have dipped below zero.
Throw in one heavy snowfall — and continued below-zero temps — and we’ll be looking at moderate to severe winter die-offs of last year’s fawns, older bucks and, in some cases, even mature does.
Let’s just hope winter’s worse is already behind us and an early spring is in the cards.