Whitetail 101: What Do Deer Eat?
November 03, 2015
To the hunter, understanding what deer eat and how they adjust their diets over the year to meet changing nutritional requirements will not only increase your chances of killing a good buck, but also your enjoyment of whitetail hunting.
To the landowner or deer manager, it is critical to effectively manage deer for maximum productivity and antler quality. One of the most important woodsman skills is to be able to identify and find the plants and foods deer prefer. When I am in the woods I am constantly assessing the availability of prime deer foods, and how much is being utilized by the deer.
Deer are not cows!
One of the most common statements I hear about what deer eat is, "Why there is plenty of green stuff for them here, they can't be starving." If green made deer food, I could go to the hardware store, buy some green paint and make deer food!
Deer and cows represent the opposite end of the spectrum that represents ruminant (those that have a four chambered "stomach") food habits.
Viewed from above, cows have a broad nose and wide tongue they use to eat a wide array of plant species, especially grasses. Their rumen (1st stomach chamber) is very large, holding at least 49 gallons of plant and liquid material and is filled with a very diverse population of bacteria, protozoa, yeasts and other organisms that each have a specialty function for digesting specific groups of plants. Grasses are the most fibrous and indigestible of plants, yet cows easily digest them. Cattle belong to a group of ruminants we call Roughage Eaters.
Whitetails, on the other hand, are classified as Concentrate Selectors. From above, the head of a whitetail is sharply pointed to permit reaching into plants and selecting specific plant parts. Their tongue is long and slender, allowing them to extract succulent stems and leaves. A whitetail rumen holds about 2 gallons (4% of cow's rumen), and deer must replenish its contents every 3-4 hours in order to maintain a much less diverse and more specialized rumen flora and fauna.
What do deer eat preferably?
Whitetail foods can be classified as browse (leaves and twigs of woody plants), forbs (weeds), grasses, nuts and fruits and mushrooms. Each of these food items vary in availability, depending on the time of year and climatic conditions.
Although every study proves that whitetails prefer forbs over all food types, these plants cannot be depended on to be around when deer need them. Forbs generally are more digestible and nutrient rich. Freezing temperatures and extended dry periods prevent the growth of weeds, so they are an ephemeral food supply at best.
The real mainstay food item of deer is browse. Browse plants can be shrubs or young trees within reach of deer. Browse plants will always be available in one form or another, no matter what the weather conditions. Even though browse plants can lose their leaves during drought or cold weather, their stems and twigs remain reasonably nutritious; unlike weeds that simply disappear.
Acorns, nuts and fruits are generally called mast. They supply high-energy sources during times of thermal stress or rapid body and antler growth. Fruits such as grapes, blackberries, mulberry and plums are used by deer as a high-energy source rich in carbohydrates during antler growth. In fact, digestible energy is the limiting factor for a healthy deer herd. Other soft fruits such as apples and pears provided needed energy in the fall, when deer are storing fat for the winter.
The two most important nuts are acorns and chestnuts, but each of these supplies a very different nutritional need. Acorns are high in fat and carbohydrates, but low in protein, while chestnuts are high in protein and carbohydrates. Deer prefer chestnuts to acorns because chestnuts are lower in tannins, which inhibit digestion.
Grasses rarely are a preferred food item of whitetails, except during the early growth stages when the grass shoots are more digestible. Cereal grains, such as oats, wheat and rye are highly preferred. However, cereal grains have been selectively bred for about 5,000 years to be more palatable.
Lastly, mushrooms are the most over-looked delicacy for what deer eat. Mushrooms supply the second most important element, Phosphorus, as well as protein. You would be surprised how many pounds of mushrooms per acre are produced naturally, even in drier climates. Locating concentrations of mushrooms can help you hone in on prime feeding areas.
What do deer eat seasonally?
Whitetails begin the year in early spring, trying to regain weight lost during the fall rut and ensuing winter. That's when forbs really come into play! They are highly digestible and high in energy, vital minerals and antioxidants. Since phosphorus is in high demand for antler growth and growing fawns, mushrooms become a true prize.
As spring winds down and summer begins, deer shift to browse plants, particularly the 1st choice plants. Mid and late summer sees a shift in what deer eat to 2nd choice browse plants and early fruits, such as grapes and berries. As fall approaches, whitetails must find and consume large quantities of carbohydrate rich foods such as acorns, chestnuts, apples and pears. Nuts and mushrooms are high in phosphorus, which is needed to replace what is taken from a buck's flat bones (ribs and skull) for antler mineralization.
What do deer eat regionally?
Wildlife biologists classify browse plants into three categories: 1st, 2nd and 3rd choice. In each geographic area, there are browse plant species representing these three classifications, and knowing the 1st choice plants will allow you locate prime deer feeding areas.
It is interesting that some browse species may be a 1st choice in one geographic area and 2nd choice in another. Dogwood is considered a 1st choice plant in eastern Canada, but 2nd choice in the southeastern U.S.
In general, the best browse plants are those that have an indeterminate growth pattern; meaning they tend to remain somewhat evergreen and put on new growth when rainfall and temperature conditions permit. These usually are vining plants such as Japanese honeysuckle, green brier, blackberry and Alabama supplejack. Less preferred browse plants tend be determinant plants that limit new growth to spring and early summer. After that, these plants are less digestible.
What do deer prefer in my area?
Most state game agencies, the Natural Resources Conservation Service and agricultural universities have publications available on the preferred whitetail food plants in your state. The Quality Deer Management Association offers a poster highlighting preferred species.
However, the best way to learn browse plants is to obtain a plant identification book with color photographs, then go to your favorite deer woods and just wonder around looking for signs of browsing. You can tell the difference between deer and rabbit browsing by the fact that deer (having no upper front teeth) pinch off leaves and shoots, while rabbits have sharp incisors and leave a characteristic, angled clean cut on the twig. It will not take you long to find the species that tend to be heavily browsed and those that are not.
Here's a simplified guide of what deer eat based on preference for where you live.
1st choice: beaked hazel, white cedar, ground hemlock
2nd choice: maples, service berry, yellow beech
Northeastern United States
1st choice: greenbrier, blackberry, dogwood
2nd choice: sassafras, maples, staghorn sumac
Southeastern United States
1st choice: greenbrier, Japanese honeysuckle, Alabama supplejack
2nd choice: maples, American beautyberry, dogwood
Central United States
1st choice: quaking aspen, common snowberry, dogwood
2nd choice: skunkbush sumac, Saskatoon serviceberry, bearberry
Southern United States/Mexico
1st choice: catclaw acacia, granjeno, kidneywood
2nd choice: lime prickly ash, bluewood condalia, lotewood condalia