Al Brothers’ Rules of Thumb for Deer Management

Al Brothers’ Rules of Thumb for Deer Management

Article by Steve Nelle

Photos by Rita Frey, Steve Nelle, David Smith, Joseph Richards


Al Brothers is a household name in the world of white-tailed deer management. He is regarded as the godfather of quality deer management; no person has had greater influence in the realm of the whitetail.

I was fortunate to work with Al when I lived in Webb County starting in the late 1970s. Even though Al was busy running livestock, hunting and irrigation operations for the H.B. Zachry Ranches, he took the time to help a young conservationist learn about deer management and how it dovetails with livestock ranching and land stewardship.

This article is based on a presentation Al gave in South Texas in about 1980. He was asked to boil down his deer management experience into some basic rules of thumb which are listed below in bold. Keep in mind that these are general rules, not rigid formulas.

They are intended to guide managers to what is generally true in most situations; but, as with all general rules, there will be some exceptions. These rules have withstood the test of time and are just as relevant today as they were 40 years ago.

Rule #1: The most cost-effective way to increase the deer food supply is to reduce the number of animals on the range (deer, livestock or exotics). In this age when supplemental feeding has become so common, this is a good reminder that nutrition can also be increased by old-fashioned habitat management. As animal numbers are reduced, each animal can be more selective in what they eat, choosing a higher quality diet and receiving better nutrition. Remember, too, exotics and all classes of livestock can interfere with the deer food supply, especially where animal numbers are excessive.



Rule #2: Maintain deer densities at what they should be for the worst possible year. The principle here is anticipating the bad years and not letting deer numbers increase too much during the good years. Wise managers know that the next drought is just around the corner and that bad wrecks occur when you have too many deer especially in dry times.

Rule #3: Kill does until you scare yourself into thinking you have taken too many—then you may be close. If you do take too many, don’t worry, repopulation will replenish numbers in a relatively short period of time. This advice is hard to carry out. Many deer hunting operations suspend the doe harvest when hunters report not seeing many does. Does get extremely skittish and wary when they are heavily hunted and can outwit good hunters. Hunting techniques often need to change when does stop coming to feeders, but don’t stop hunting. Harvesting does early in the season is always good advice.

Rule #4: Never do brush control on more than 50 percent of acreage. If quality deer (mature trophy bucks) are a high priority, never control more than 25 percent. Always do brush control in a good pattern. This rule emphasizes the need to retain plenty of brush for prime deer habitat. Taking out half of the brush in a good pattern is okay for some operations; but, if the objective is sustaining an optimum number of mature quality bucks, then more brush is usually needed. Mature bucks have a special affinity for thick brush, while younger and middle-aged bucks are often content with less brush.

Rule #5: The best census method is the helicopter, but it always undercounts. Much debate and confusion can be eliminated by understanding this basic truth. In South Texas and other semi-arid regions, helicopters have proven to be an excellent means of obtaining good deer herd information. When flown under proper conditions and with an experienced pilot and observer, there is nothing that can match the information gained from a helicopter survey. But it almost always provides a conservative estimate on numbers since some deer are not seen. This undercounting builds an automatic buffer into the management which helps ensure that bucks are not over harvested. For small places, heavily wooded areas or when the cost of a helicopter is prohibitive, other survey methods can be used.

Rule #6: Be cautious about recommending an increased buck harvest based on an adjusted helicopter survey. Since helicopter surveys usually underestimate deer numbers, some well-meaning biologists and managers add a fudge factor to the survey in an attempt to correct for the undercount. This can be dangerous since no one knows what percent of deer are unseen and what percentage to add back. Adjusting the survey numbers can very easily lead to over-harvest of bucks and damage to the age structure.

Rule #7: In a herd with good age structure, some bucks will be dying of old age each year. We all feel some disappointment in seeing the skull and antlers of a massive old mature buck that died of natural causes. The buck would have made any hunter happy and to see such a buck die of old age seems like a waste. But we all know that some mature bucks are so elusive that they are rarely if ever seen by hunters. That old buck is not lost or wasted; he has some offspring running around to carry forth his genes.

Rule #8: Illegal kill is usually higher than you think. Poachers are often smart, cunning, dedicated and have no regard for the law, your property or ethical sportsmanship. With the technology of cell phones, GPS, noise suppression and night vision optics, poachers are bolder and more effective than ever before. Always be vigilant.

Rule #9: The first good indicator of overpopulation is a decrease in yearling weights. Field dressed weights have long been one of the most important barometers of deer herd health. The yearling age class is the most sensitive to habitat and nutritional change. Yearling animals are growing bone, muscle and internal organs and have high nutritional demands. When there are too many deer, nutrition declines and weights will go down, especially on yearling bucks and does. While we may not know what the true carrying capacity is, if we notice a decline in yearling weights, it is a sure indicator of too many deer and a signal to increase harvest.

Rule #10: Antler measurements and deer weights are of minimal value without corresponding ages. When age, weight and antler measurements are taken consistently year after year, it provides a very good way to see what is happening with the deer herd and habitat long before it would otherwise be noticed. The weak link in some record keeping efforts is getting a reliable age. Too many hunters within deer camps guess at the age or make a rough estimate by running their fingers across the lower jaw teeth. While the tooth wear and replacement method isn’t perfect, it has proven to be good enough for management purposes, especially when it is done consistently by the same person each year. Extracting the jawbone and examining closely under good light is the only way to make a valid age determination.

Rule #11: Most losses to predation are an aid to deer management. Across most of Texas, the number one problem with deer management is too many deer. Hunting alone often cannot keep the population in balance. Predators are needed in most cases to help trim the herd and reduce fawn survival. However, some places have such high numbers of coyotes that it keeps the deer herd well below carrying capacity. Where coyote or mountain lions are keeping the deer population extremely low, it makes sense to manage predators, at least until deer numbers increase.

Rule #12: A properly managed deer herd is sometimes worth more in net income per acre than livestock. Even on ranches that focus primarily on livestock production, the net income derived from deer hunting is often vital for economic stability. Over the past four decades, income from deer hunting has shown a steady increase while income from livestock is less predictable and is more influenced by factors outside the ranch’s control.

Rule #13: A high fence can pay out with proper management. High fences are an expensive investment, but they can be economically justified in some cases. Consider a well-managed ranch that is surrounded by smaller places that over-harvest bucks. The net loss of bucks of all ages can ruin even the best management program. If two bucks are lost per mile of perimeter each year on a 12-section ranch that amounts to a loss of 28 bucks per year. Stopping that loss with a high fence will allow those bucks to grow to maturity. The income gained by eliminating the loss of bucks can, over time, pay for a high fence. Other benefits include stricter management of sex ratio, age class, deer density and elimination of yearling dispersal. All of these factors have economic advantages.

Rule #14: In a supplemental feeding program, beware of maintaining too many deer and their effect on preferred food plants. This rule needs to be shouted loud and often in many areas of Texas. Supplemental feeding does have some obvious benefits and many are willing to endure the high cost, but the side effects are significant and can be damaging. Fawn crops invariably increase under supplemental feeding. It is not uncommon for feeding programs to have 70 percent to 100 percent fawn crops every year. With that kind of reproduction, it is extremely difficult to keep numbers from increasing to the detriment of preferred browse and forbs. Great care and caution should accompany any plans to begin a feeding program. Even though the deer may get much of their feed from the sack, they still prefer to forage on native plants.

Rule #15: When using food plots, plant one acre per two deer for dryland crops and one acre per three deer for irrigated crops. Food plots can be an important source of seasonal forage where soil and rainfall allow and if enough acres are planted. Planting too small a plot usually results in the forage crop being destroyed before it establishes or the crop producing so little forage that it does not help. Using this rule, a 3,000-acre ranch with a density of one deer per 15 acres would need 100 acres of dryland food plots to provide a significant forage source.

Rule #16: Most individuals have higher expectations for success than is usually possible in actual practice. Deer management is not easy and the results are often not as rapid or as satisfying as we hope. Every manager and hunter dreams of big bucks, but our dreams and wishes sometimes exceed what is realistic under natural conditions. In the end, it is important to remember that hunting is not as much about the buck’s size as it is the experience, the memories and the people involved.

These 16 rules of thumb don’t cover all aspects of deer management, but they do shed light on some important principles. Al always reminded his listeners of the importance of habitat health as the basis for successful deer management.

We can all be grateful that people like Al Brothers and Murphy Ray discovered the keys to good deer management and have been generous to teach others what they learned. If you have not read Producing Quality Whitetails, published by TWA, I recommend it as essential reading for landowners, hunters, managers or anyone interested in sound wildlife management.

Stay Informed