Make Sure to Provide Enough Browse for Your Deer

It would have been interesting to be in North America in the Pleistocene Epoch to see the awesome diversity of mammal species inhabiting the continent at that time! Species such as the Giant Sloth, Wolly Mammoth, Mastodon, Wooly Rhinoceros, Longhorn Bison, Giant Peccary, and the monstrous Stag Moose roamed over huge expanses of tundra, prairie and forests; pursued by giant predators such as the Saber-tooth Cats, Cave and Short-nosed Bears, and Cave and Dire wolves.

The plant eaters represented the largest group of species, with every adaptation in feeding habits you could imagine! All these species had been “at war” with plants for many centuries, adapting to new defenses by plants to keep from being eaten. The grasses were perhaps the greatest winners in the battle, with much of their bodies protected beneath the ground, and the parts growing above ground having heavier cell walls and harder to digest cellulose fiber.

Woody plants, with their thinner cell walls and higher digestibility, developed thorns, bad tastes, waxy leaves and stinging structures. At the same time, there was competition between the herbivores themselves. The plant eaters developed two different ways to digest plants — the fore-gut fermenters and the hind-gut fermenters.

Instead of the high acid producing, simple stomachs of predators, herbivores enlisted micro-organisms such as bacteria, protozoa, fungi and archaea (microscopic organisms that lack a nucleus) to the battle to breakdown tough plant fibers and cells.

The fore-gut fermenters had a four-chambered “stomach,” the first three of which weren’t really stomachs, but pockets in the esophagus; the largest of which is the rumen. These animals basically collected plant parts, swallowed them quickly, then retired to safety to process the raw food. Then they regurgitated the mass of plant material and use specialized teeth to grind them into finer particles.

This process was repeated until the plant material was reduced to a fine texture. The first chamber (rumen) contains water, partially digested plant material and a complex of microorganisms. Lining the rumen are fingerlike projections called papillae, which are responsible for absorbing the waste products (volatile fatty acids, VFAs) of the microorganisms, along with minerals.

The second two chambers, the Reticulum and Omasum, are responsible for retrieving and recycling the water in the rumen material, as well as removing foreign particles and materials. The final “stop” through this system is the actual stomach, the Abomasum, which at a pH of three or less, “thanks” the microorganisms by killing and digesting them, adding to the nutrition of the animal.

Each species of ruminant has developed its own unique assemblage of microorganisms that specialize in breaking down the various types of plants consumed. The total number of species reflect the complexity and difficulty of digesting the typical diet of that species. There can be as many as 8,000-10,000 species of microorganisms, depending on the animal. Cattle and bison tend to have a more complex diet and have more species than deer; elk also have a more complex microorganism community than deer.

The second type of herbivore is the hind-gut fermenters that ferment plant material in a specialized pouch after the stomach called a cecum (known in humans as the Appendix). Horses, rhinoceros and elephants are examples of hind-gut fermenters. Their large intestine tends to be longer. As with the rumen, the cecum also contains microorganisms specialized in breaking down high fiber materials.

Yet, it turned out that hind-gut fermenters are not as efficient in digestion as the fore-gut fermenters; and most of these species lost out in the “race” to be the most efficient plant digester! Many, in fact disappeared from North America, leaving behind species such as deer, elk, bison and pronghorn antelope.

MOUTHS ON THE RANGE

Among the winners in the “arms race” between North American herbivores were the deer, especially the white-tailed deer. In general, whitetails prefer wetter climates and areas on the landscape; and although mule deer and white-tailed deer both prefer forbs and deciduous shrubs, mule deer tend to eat shrubs with higher tannins and lower digestibility. The biggest difference is mule deer can exist on a much higher fiber diet than whitetails.

Every food habits study on whitetails has concluded that deer subsist on the leaves and twigs of woody plants and young trees, but they’d rather eat the more succulent weeds (forbs) when they are present. Grasses are only consumed when they are in the early digestible growth stages. Forb availability is directly related to rainfall, and unfortunately, these plants can be entirely absent in droughty times!

So, that leaves browse as the most important food item for whitetails. Trees and shrubs tend to have deep roots and are fully capable of surviving most drought periods by being “drought deciduous.” Yet, that eliminates the most succulent parts of these plants, the leaves. Some shrubs are even classified as drought deciduous, meaning they cast their leaves on purpose in a drought. Yet even then the bare stems still offer some nutrition. So, it is not possible for deer to survive without browse!

Now, just because there are shrubs and young trees on your land, does not mean that there is adequate nutrition for your deer. Deer have definite preferences for shrub and tree species. And they are highly adapted to feeding on certain parts of the plant. If we look down on a deer’s head, it is shaped very differently from a cow! Cattle and bison have a wide nose (mouth) and heavy tongue, both designed to take in large quantities of forage at a time, with little consideration of species.

The whitetail, on the other hand, has a pointed nose and long tongue, which they use to go from plant to plant, picking the most tender leaves and twigs, which are more digestible and higher in energy. In fact, if we rate the nutritional needs of whitetails, the number one need is digestible energy, not protein.

So, what are the characteristics of a preferred browse plant? Trees and shrubs, as I noted earlier, have evolved a host of defenses against being browsed, among which are thorns, bad taste and waxy coatings on their leaves. In addition, there are two growth habits of browse plants: determinant and indeterminant. The difference can be explained by considering the two types of green beans commonly planted in gardens.

One is a bush bean that you plant; it comes up, grows into a bush and puts on beans. The growth stops once the beans develop. The second type of garden bean is the “pole bean,” which comes up, begins climbing, stops momentarily, flowers and produces a bean; then keeps growing as a vine. Beans are put on over a long period of time, instead of as a single crop.

The advantage of bush beans to a large-scale food producer is obvious; they only must pick once. To a home gardener, however, there is a sustained supply of beans with pole beans! So it is with browse plants that tend to grow early in spring, mature and stop growing. Since growing vegetation is more nutritious, the value of these plants to deer is short-lived.

Other plants, such as blackberries, green briar, Japanese honeysuckle and grapes put on fresh growth, usually in response to rainfall, providing a sustained supply of highly digestible food.

THE DEER ZONE

I have likened managing deer browse to a “war against vegetation!” A whitetail’s world is from the ground surface to around 4 1/2 feet off the ground; this is what I call the “Deer Zone.” Everything a deer needs nutritionally must be in that zone; however, plants tend to grow up toward the sun, taking them well above the deer zone in 5-10 years! If you thin or clear-cut a forest, the vegetative response is impressive, whether you are in the warm, humid South or the cold, shorter growing season North.

So, managing for year-round deer nutrition involves developing a plan to keep highly digestible browse within reach of your deer 365 days a year! Yes, there is browse in winter, provided by the last growing season’s stems. Two questions arise: how on earth do you do this? And how much of my land do I need to devote to deer browse?

My research over the last five decades has revealed that a white-tailed deer in eastern North America would “like” to roam over a mere 80 acres during the non-rutting season! Now, in most areas, deer cover more area than this, but that’s because the landscape does not provide everything they need in this “management unit.” There are deficiencies that force them to cover more land area for their needs.

Our standard recommendation for managing your deer landscape is to inscribe an 80-acre grid over your property. If you have less than 80 acres, go ahead and place an 80-acre grid square over your land; then, develop a plan that considers both your land and the other land outside of your property.

Ask yourself, what does my property supply that deer need, and what uses do my neighbor’s land serve? Then you can develop a forage management plan for your property. We recommend that 60 percent of your property be dedicated to natural deer forage, and 20 percent to cover (escape, summer and winter thermal).

Now, that does not mean that all 60 percent be treated one way and at one time! How you choose to manage deer forage on your property can be highly variable, including food plots. Yet, I do not recommend you devote more than 2-3 percent of your land to food plots; the rest should be as sustainable browse. By “sustainable,” I mean that some part of your land has adequate browse in the deer zone each year.

A “rule-of-thumb” I use is to divide your browse management area by the length of time trees and shrubs tend to grow out of reach of your deer, into the acreage represented by your 60 percent. For example, in the northern portion of the country, browse tends to grow out of reach in 10-12 years. In this case, you need to treat one-tenth of your browse area each year. But what is a “treatment?”

There are a host of treatments you can use to encourage browse production, including burning, mowing, roller-chopping, chemical treatment and timber harvest/thinning. In the latter, you may have to compromise the size of your treatment area to fit economic reality! If you have merchantable timber, you may not find anyone to harvest a small part of your property; that is just the reality of land management! Remember also, the term “cover,” can be included in your browse production area in many cases.

Native Americans routinely used fire as a game management tool, as well as to control tick populations. Burning is one of the best browse management tools available to the deer manager. However, it has become more difficult to burn as the deer landscape continues to be fragmented! In addition, public support for prescribed fire is waning, due to misconceptions created by the coverage of wildfires and the loss of life and property this creates.

Yet, the number one way to reduce wildfires is to reduce dangerous fuel loads through planned burns. I am the first to admit, however, that prescribed burning is not something for the untrained to attempt. There are professionals whose services can be contracted, and more and more states offer certification training for landowners.

We have shown that fertilization of native browse plants according to soil tests, will produce effective and economical improvement in deer nutrition. Our research has demonstrated that deer can recognize plants that have been fertilized. You even can obtain first choice browse plant seedlings and plant them along edges or in “browse patches,” you maintain by “weeding” them from invading plants with lower deer preference.

In managing your deer land, realize that the first step always is to develop a long-term, sustainable plan for producing native browse in the Deer Zone. Other practices, such as food plots, are there as supplements to your overall deer nutrition program, not the primary source of sustainable nutrition.

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