The proper age-class distribution of the harvest depends on the manager’s objectives. If increased antler size is a goal, then the majority of bucks harvested should be at least 4 years old. The annual harvest rate should not exceed 15 percent of the available bucks. Harvesting of does is warranted where population levels are approaching or have surpassed carrying capacity, or when deer are causing crop damage, but harvesting should be carefully regulated. Doe harvesting may be desirable to correct the sex ratio of the buck to doe ratio may vary from 1:2 to 1:4, depending on the manager’s objectives. Currently, doe harvests are closely regulated and available on a permit-basis only. In areas where natural mortality is high, a large number of does may be necessary to maintain the population at the desired level.
Controversy has arisen recently regarding the harvest management of spike bucks. Much of this debate has resulted from applying whitetail management to mule deer. Deer from a 12-inch rainfall zone are typically on a lower nutritional plane that those from a 30-inch rainfall zone. Spike bucks are products of youth and/or poor nutrition and/or poor genetics. In recent years, some deer managers have advocated “spike eradication programs”. Such “vendetta management” should be approached cautiously especially with regard to mule deer.
Spike mule deer bucks are probably largely the result of poor nutrition, so removal of all spike bucks during a dry year would essentially remove an entire age class. Always consider past weather conditions when contemplating spike management plans. In dry years spikes may constitute up to 80 percent of yearling bucks, whereas in “good” years only about 25 percent of yearling bucks are spikes. Preliminary results of ongoing research indicate that a substantial number of yearling spike bucks will produce desirable antler growth as age increases. If spikes are to be culled, try to do so in a “good” year and select the “trophy spikes” (i.e., those with spikes more than 12 inches long). These trophy spikes are more likely to be older than yearlings. They may be a result of poor genetics and should be culled from the herd. If survey data indicate more than five does per buck, do not harvest spike bucks at all.
Mule deer destinies vary from one site to another. Numbers may range from fewer than two deer per section (640 acres) to as many as 30 deer per section. The greatest destinies are generally found in Brewster, Pecos and Terrell counties. Each ranch has a certain carrying capacity or maximum sustainable population than should serve as an upper threshold for deer density. The carrying capacity for any particular ranch varies with the kinds and amounts of livestock present, plant species present, soil fertility and precipitation patterns. When deer numbers become too high they can damage desirable browse plants, thus reducing the long-term carrying capacity of the range. It’s best to try to keep the deer population somewhat below the carrying capacity as means of “drought insurance.”
Population trends should be monitored annually by conducting some form of deer survey during October and November. Surveys can be made by spotlighting counts, aerial counts (helicopter or fixed-wing), and/or incidental counts in which all deer observed during routine ranch activities are recorded. Each of these methods has certain advantages and disadvantages; some provide good information on destinies but not on age/sex data and vice versa. Determining the most appropriate survey technique depends upon labor availability, time, topography, road network and costs. Consult your local county Extension agent or Texas Parks and Wildlife Department personnel for the method recommended for your area.
Harvest records should be maintained as a method of determining animal conditions and evaluating progress in deer management. Typical records include ages, weights, antler measurements and some estimate of body condition. For more information about collecting deer harvest records, ask your county Extension agent for “Interpreting Deer Harvest Records” (B-1486) and ” The Age of a Deer” (B-1453).