August 15, 2022
By Dr. James C Kroll
The nutritional needs of whitetails are ever-changing, influenced by habitat quality, weather and the unique physiological needs of bucks, does and fawns over the annual “deer cycle.” There are two stress periods for deer, late summer/ early fall, and late winter/early spring. These are transition times, in which the physiological needs of deer change dramatically.
I often have said that whitetail bucks and does might as well be separate species. When bucks are fat, does are skinny; and when bucks are skinny, does are fat! A buck comes out of the winter having lost as much as 30 percent of his body weight. In spring, he must quickly recoup lost resources, grow a summer coat and grow antlers. This creates a very high demand for digestible energy, protein and minerals, with energy needs often approaching thousands of calories per day! In late summer/early fall, bucks store fat and build up their muscles for the combat period. In turn, buck survival depends on coming out of winter with some reserves.
Comparatively, does come out of winter in generally good condition; then they spend all summer nursing one or two fawns. The whitetail doe is one of the few ruminant animals with the potential to wean offspring totaling more than her body weight. Years ago, we conducted a study on milk production of does from birth to weaning, discover- ing they produce from 16-72 ounces of milk per day during this time.
By late summer/early fall, a doe is at her lowest body weight; yet, she still must molt her summer coat, grow a winter coat (the second largest nutritional demand) and store fat before she is ready to breed. Fawns should not be left out in this discussion. The rut is timed so that fawns are born at a favorable time of the year, then wean at a time when there are abundant, high-nutrition foods, since they are on their own from that point on. That is why South Texas whitetails tend to breed in mid-December, so their fawns wean during or just after the hurricane season, when rainfall is highest.
In considering all the above, the success of your management program often boils down to being programmed for fall food! Programming for optimum fall nutrition involves management of both native and supplemental foods. Native foods require long-term planning and management, while supplemental foods can be both long-term and short-term. Whitetails exist over a wide range of climatic conditions, often limiting how much emphasis can be placed on native versus supplemental nutrition. So, let’s have a look at what we have learned over the years.
Programming for native fall foods
Years of research taught me the most important nutrient for deer is digestible energy, followed by phosphorus! Protein is a distant third in importance. Ask any deer hunter what the favorite food of deer is, and almost every time the answer is acorns. Why are acorns so attractive to deer? They contain large amounts of carbohydrates, fats and are low in protein.
There was a time when deer in the eastern U.S. had a much differ- ent preference for a digestible energy source — chestnuts! One of the greatest ecological disasters in the last 200 years was the disappearance of the American Chestnut from eastern forests. In fact, there was a time when almost everything and everybody ate chestnuts.
Importation of oriental varieties during the Victorian Age introduced chestnut blight, and in some areas 60 percent of the forest died. It has not been until recently that the American chestnut has begun to return to our forests, primarily due to development of blight-resistant varieties. Today, the job of supplying digestible energy falls directly on oaks.
In much of the eastern U.S., the long-term strategy for increasing native fall foods involves manipulating species composition and vigor of oaks in your forest. In many cases, the forest stands on your property fall into one of three categories: oaks are not present, oaks are too young to produce acorns, or oak stands are too old and dense. The solution to each of these is plain old forest management.
You should seek professional guidance in developing a forest management plan aimed at sustainability of acorn production. Factors affecting sustainability include diversity of oak species, age of stands and density of trees. Most oak stands today are in desperate need of thinning! A good density of oaks is about 25-30 trees per acre; and a good species mix is equal portions of red and white oak species. This assures less variation in your annual acorn crop.
Acorns are not the only source of digestible energy. Actively growing herbaceous plants can provide large amounts of energy. Disturbance by disking encourages herbaceous plant growth, but timing is critical. A spring disking produces plants alright, but these plants grow through the summer, then flower and die by fall.
A late summer disking, however, stimulates growth of plants that begin growth in fall, go dormant during the winter and emerge to mature in the spring. The early fall growth is rich in digestible energy, making summer disking an effective fall food program. We also fertilize after disking, using a balanced formula fertilizer.
Supplemental fall food
Late summer/early fall food plots can do a great deal to prepare your deer for winter stress by bringing them into the rut in optimal condition. Although there are a host of food plot varieties, cereal grains provide more digestible energy than any other variety. Oats in particular have significantly higher concentrations of water and alcohol soluble carbohydrates and are more nutrient dense than other plants.
Oats also are faster growing than wheat and rye. An effective supplemental fall food program produces high yields prior to the first hard freeze. This will accomplish two goals: 1. Allow your deer plenty to eat for storing fat; 2. Provide a standing crop of forage that can be banked for winter use.
Our northern management strategy is to have a large standing crop of forage prior to the first snowfall. If there is a heavy snow cover over your plots, the average temperature below the snow is not lethal to food plot plants. The included map shows the approximate distribution of snowfall in the United States. The high snowfall areas require forage banking, while areas below the heavy snow fall line often continue to put on some growth throughout the winter.
The last strategy for programming supplemental fall food is to develop “deer orchards” on your property. A deer orchard contains a variety of fruit and nut species/varieties that guarantee digestible energy over the longest period of time. Trees normally are planted in groves of trees about 25 feet apart. Most of our deer orchards are a quarter acre in size (17-18 trees). The suite of mast producers we use includes chestnuts, early producing oaks, apples, pears, persimmons and grapes.
In the South, we often plant sawtooth oaks, Shumard oak and live oaks; all of which tend to produce acorns within 12 years of planting. Chestnuts will do well in most areas where there are oaks. Regarding apples, pears, grapes and persimmons, there also are varieties that tend to mature fruit from early summer into October, November and even later in the South.
Apple varieties such as Northern Spy and Granny Smith mature fruit in late October; while pear varieties such as Kieffer, Olympic Giant and Dr. Deer will hold fruit as late as November. Japanese persimmons (Fuyu and Suruga) hold fruit into the fall in many areas. Strive for a deer orchard with varieties that mature fruit from late July to at least September. Wildtree Nursery offers orchard packages by USDA hardiness zone.
Developing a sound program for fall foods is one of the most important strategies for improving the quality and quantity of deer on your land. A successful program accounts for both native and supplemental foods, so deer come into the rutting season in excellent condition. This approach helps bring deer through harsh winters without using up energy reserves. Hopefully, I have given you some ideas for managing deer on your land.