A Balance in Nature

Thousands of acres of undisturbed land have been lost since the first European settlers arrived in the 1850's. Before the arrival of the European settlers, fires were common which when uncontrolled, encouraged biodiversity. Land grazing patterns changed as domestic animals were introduced and the buffalo population began to shrink. Predator populations were also reduced as a result of habitat shrinkage and deliberate removal by humans. All of these factors, and many other we are just beginning to understand, disturbed the natural balance in which wildlife thrived. Recent development in the Georgetown area has resulted in the loss of many acres of deer habitat. Continued development around Lake Georgetown threatens the ecological balance and will affect all species of wildlife that reside in the area. One alteration to the natural balance of an ecosystem results in a domino effect which may affect many animals.

Development by man requires an intervention by man to maintain an area in its natural balance. The animals in the area are dependent upon all of us in maintaining an environment in which they can flourish. With the environmental changes humans have caused, directly and indirectly, management programs must mimic the natural processes of nature prior to settlement.

Resource managers at Lake Georgetown have been actively involved in restoring a balance of nature with its ecosystem management programs since 1980. The threat to white-tailed deer and other wildlife species around Lake Georgetown is of great concern to the U.S. Army Corps of Engineers. Deer management is a part of a much larger and comprehensive effort to manage natural ecosystems. By ensuring a functional and natural environment that is balanced as nearly as may be, all of our native plants and animals can thrive, including white-tailed deer.

The Impact

An overpopulation of deer has far reaching effects. The incidence of injury to humans due to attacks by buck (male) deer are on the rise in Texas. Unfortunately, reports of encounters with aggressive buck deer are not “stories” as they were once regarded. Traffic accidents with deer are also on the rise, causing an average of $1500 in damages per incident. These are in addition to the adverse effects on the deer, other wildlife and the environment.

The Potential Loss

Both plants and animals are important to ecosystems. Decreased plant populations lead to loss of plant and animal species and a gross alteration of native plant communities. These communities provide food for many animals, prevent erosion and control evaporation rate of water. Observations indicate that white-tailed deer are removing selected species of plants, and that deer grazing is reducing total plant species diversity (number of species) and total ground cover. Plants are the foundation of the ecosystem’s food chain. When this foundation begins to crumble, all other levels of the food chain and other species of wildlife including insects, birds and mammals are affected. Too many deer threaten the health of native ecosystems. The endangered Golden Cheeked Warbler nests on the Lake Georgetown Project. Overpopulation of deer threatens the regeneration of Ashe Juniper in which these birds use for nesting material. The destruction of the hardwood seedlings in the area by deer affects the Golden Cheeked Warblers future food source, as well as that of many others.

Deer Details

The white-tailed deer ( Odocoileus virginianus ) is the largest wild mammal in Williamson County. Adult males, called bucks, generally weigh between 95 and 130 pounds. Adult females, called does, generally weigh between 55 and 90 pounds. Deer are herbivores, eating both woody (trees and shrubs) and herbaceous (wildflowers, grasses, etc.) vegetation. White-tailed deer prefer forbs. These are what most people call “weeds”. These species of plants offer deer the most complete nutrition of any plants available in this area. Their secondary food is browse. This portion of their diet is the leaves and tender stems of various woody plants. Browse helps them make it through the winter or during times forbs are not available. The last resort food is grasses and undesirable woody plants. Deer cannot digest mature grasses and can actually starve to death with a full stomach of these plants. Biologists refer to this category of food as “stuffer” plants. These are either low in protein or the deer cannot extract the protein available in these plants. A deer’s diet depends to a great extent on the season. In areas with large oaks, acorns can make up a substantial part of the fall diet. Farm crops, if available, can comprise a large portion of a deer’s yearly diet.

Grazing of “stuffer” plants is a clear indication of overpopulation of white-tailed deer. Biologists agree that Ashe juniper is absolutely a last resort food for deer and many other animals. The appearance of a browse line in Ashe juniper is a clear indication that deer populations are out of balance with the environment. Each area has what is referred to as the “carrying capacity” of the land. Wildlife managers make observations to arrive at the number of animals the land support, then select an intervention to achieve and maintain this number. Annual deer census are conducted at Lake Georgetown to determine the numbers of deer in the area.

Although a favorite food for deer, corn ranks very low for nutritional value. Deer corn could be called “deer candy.” Corn contains about eight percent protein and is high in carbohydrates. The white-tailed deer needs a daily diet that contains sixteen percent protein for optimum development. Aflatoxin is also present in much of the corn sold for “deer corn.” This toxin is produced by a fungus and is present in corn which is grown under stress. While deer are less susceptible to the effects of aflatoxin, consumption can make the animal ill. Waterfowl and turkey who consume the contaminated corn often die.

How Many is Too Many?

Deer in particular are prolific breeders and have the capability of doubling or even nearly tripling their population in one year. Many factors influence the fawn crop of white-tailed deer. The ecological carrying capacity of an ecosystem, or maximum number of deer an ecosystem can support and remain healthy, varies due to the makeup of vegetation in the area. A key sign of overpopulation is the appearance of a browse line (reduced density of vegetation up to fifty inches above ground level). Small body size and poor antler development is a result of poor nutrition due to overpopulation. The makeup of the herd is as important as the number. The buck to doe ratio should never exceed 1:3 and ratios of 1:2 or 1:1 are preferred. Close control of this ratio will prevent future overpopulation problems.

The parks at Lake Georgetown have very few limiting factors which control their numbers. Winters are not severe enough in this area to significantly reduce deer populations. The white-tails predators, the mountain lion and wolf, have not been present in this area since the early 1870's. While coyote populations and motor vehicles have increased even in urban Williamson County, they are not and never have been an effective control of deer populations. Supplemental feeding of deer by the public within the parks has also contributed to the high numbers of deer.

What to Do?

Throughout North America increasing numbers of white-tailed deer are a concern to natural resource managers and others concerned about the environment. Municipalities and natural resource agencies are evaluating the impact of deer and implementing deer population management programs on public and private lands. Feeding of the deer has caused a highly concentrated population within the parks at Lake Georgetown. In an effort to restore the natural balance, deer feeding was restricted in October of 1995. Deer surveys will be conducted annually to determine if further intervention is necessary.

What Can I Do to Help?

All of us can help encourage good health of the deer by not feeding them. Care should be exercised when fawns are born in the spring time. People should never touch fawns. Although the person may intend to help, the scent of a human can cause the doe to reject her offspring. Every year there is a number of fawns that will not survive. White-tailed deer have tremendous reproductive capability and if conditions are not right one year, the herd will rapidly rebound. Finally, visitors can assist the resource managers at Lake Georgetown by reporting any wildlife that behaves aggressively or animals that appear to be ill.

Summary

Lake Georgetown resource managers have the legal and ethical responsibility to protect native ecosystems. Human activities have concentrated an increasing deer population within woodland preserves. Increasing deer populations are negatively impacting these ecosystems that the managers are mandated to protect. The public and the environmental community have expressed support for this program to preserve native ecosystems and we need your help.

For further information on deer management and natural resource programs at Lake Georgetown, call 512/930-5253.