The Mood Swings of Spring Nutrition
Spring is a time of transition. Deer have made it through the winter and are focused on growth. The bucks are budding antlers and the does are in the last stages of pregnancy (except in the south where herds are several months behind). Green growth has started to explode here in the Midwest, but even though spring green up has started, that does not mean that deer are out of the woods in terms of available nutrition. A recent storm system brought snow to the Upper Midwest, and torrential rain to the lower Midwest. This sudden swing in temperature has set back growth. Flooding in the lower Midwest has wiped out plants in low lying areas.
So how do we, as managers, deal with Mother Nature’s mood swings? The clear answer is to supplement nutrition using feed and/or minerals. When you have an active feed or mineral station, deer have something to fall back onto to keep them healthy in times of nutritional stress. The carrying capacity of an area is never fixed. It fluctuates as plant growth increases or decreases based on growing conditions. So if we have a snowstorm or flooding set back growth, deer on supplemental feed will be better off than those un-supplemented because you take away the “boom or bust” fluctuations in the carrying capacity. A consistent source of feed is always better for a deer’s digestive system, so having something available this time of year is crucial for optimal herd health.
You may think that just because spring is here that you don’t need to feed anymore, but you are doing your herd a disservice by relying on natural growth to be consistent. Supplementing the diet is like an insurance policy for the natural plant growth. If a flood or drought ruins your food plot, at least your deer will not fall back to zero in that area.
Here is a good example of the late spring transition regarding kidney fat percentage. Kidney fat is an indicator of reserves that an animal has. This study focused on Mule Deer, but the results apply to white-tail as well. You can see from the graph that April and May are low points, even though available nutrition is higher in those time periods than in Feb/March. The bad part about poor nutrition in May (like what we have this year) is that fat reserves are depleted, so deer have no reserves at that time of year. This just shows that the best way to beat the mood swings are to give your deer a boost in nutrition.
-Tim Neuman, Wildlife Biologist