High Fences: Compliment or Curse? - Part I

High Fence History
The construction of high fences is definitely on the increase in Texas. Although high fences are common place today, the history behind the high fence invasion is not well documented. I was able to piece together a short history of high fencing in Texas after talking with several deer biologists and well established fence builders.

The first high fences in Texas were built in the Hill Country in the mid to late 1930's. These high fences were built solely for exotics, either to hold the animals in or to keep the animals out. South Texas saw its first high fences in the early 1950's. In contrast to Hill Country high fences, most of these high fences were built with white-tailed deer in mind.

High fence construction steadily increased during the next 30 years, reaching a peak in the mid 1980's. The economical boom at this time caused an explosion in high fence construction. More and more people had the excess money necessary and chose to invest in high fences. Once the 1980's boom turned to bust, the high fence business slowed.

During the 1990's, another increase in the number of high fences being built occurred. Today, more than 15 percent of the land area in the Texas Rio Grande Plains is under high fence, with well over one million acres under high fence throughout Texas.

Why are we experiencing another increase in high fences? Well, it is definitely not due to a huge economic boom similar to what occurred in the 1980's. The causes for the current increase are much more wildlife management oriented. People are witnessing good results from areas that were previously high fenced. These positive results are influencing more landowners to build high fence.

The majority of the landowners building high fence today are spending that money because they have a strong desire to have more control over their deer herds. People are growing tired of the status quo in deer management and they want to take the next step in improving their deer herds.

High Fence Advantages – Herd Control
The most obvious advantage to building high fence is the landowner now has much more control over the deer herd. Deer movement, through dispersal, immigration, and emigration across the boundary is now much reduced. The advantages of this are two-fold. First, deer on the neighboring ranches are forced to stay where they are - on the neighboring ranch. Second, deer on the high-fenced ranch are forced to stay on the high-fenced ranch, so they are no longer subject to harvest by the neighbors. This is especially important if the deer management philosophies differ across the fence boundaries.

Once a high fence is built, neighboring deer can no longer cross over the boundary to fill voids created from the removal of deer through harvest. This allows the high-fenced landowner to more effectively reduce deer numbers to keep the herd within the carrying capacity of the habitat (the ability of the habitat to support deer). The increased doe harvest will also obviously improve the adult sex ratio and allow the manager a better ability to maintain this balanced ratio.

Deer populations are now so high in some areas that they are causing permanent damage to the habitat. This deer population increase has caused landowners interested in deer to become concerned. These landowners have few other options but to build a high fence so that they can better control population growth. Without a high fence, deer from neighboring properties quickly disperse to any area where deer have been removed to fill the temporary void.

Young and middle-aged bucks being protected within the high-fenced ranch will no longer be vulnerable to harvest across the fence by the neighbors. Increased buck survival will obviously result in an improved buck age structure as well.

Better Surveys = Better Management
A second major advantage to high-fencing a property is biologists can now get better estimates of the various deer population parameters. The herd is now essentially a “closed” population that can be surveyed without concern there will be changes in deer numbers following the survey that result from deer crossing the boundary.

A single pre-season helicopter survey for example, will allow the biologist to determine accurate estimates of the deer population size, adult sex ratio, fawn production and recruitment, buck age structure, and overall antler quality. As a result, the biologist can make more accurate and precise harvest recommendations. The results of these recommendations can be better monitored, allowing the landowner to reach his management objectives much sooner than would otherwise be possible without the high fence.

Additional Advantages
A third advantage of high fences relates to the ever expanding deer population. The number of traffic deaths related to collisions with deer is increasing every year. High fences within a few hundred yards of public roads significantly reduce, or even eliminate deer-vehicle collisions.

Fourth, once a high fence is in place it increases the property value. The flip side is that property taxes will also probably increase.

The fifth advantage is a little harder to understand. Research shows the doe, and not the buck, forces many buck fawns and yearlings to disperse to areas outside of the mother's home range. These dispersing bucks often travel several miles before they establish a new home range. The dispersal itself is also very stressful and is thought to be one of the leading causes of yearling buck mortality.

A high fence would greatly reduce the ability for bucks to disperse from your property and would also likely increase yearling buck survival. This increased survival will no doubt increase the number of bucks surviving to maturity, increasing the pool of mature bucks available for harvest.

High Fence Disadvantages
The most obvious disadvantage is the enormous initial investment that is required to build the high fence. These costs are so high that most of us would first need to win the lottery!

A second disadvantage is you will not see immediate results. Even with proper management, the deer herd will take several years to improve.
Third, a high fence changes deer movement patterns inside and outside the high fence. Deer that previously had home ranges overlapping the new fence boundary are now forced to alter their home range. Depending upon the habitat and the ranch, these deer may be forced to travel further distances to reach a particular food or water source.

Fourth, is that any buck harvested within the high fence is no longer eligible for recognition and entry in the Boone and Crockett Club because high fences violate the club's Fair Chase requirements. In fact, even if only three sides of the property are high fenced, the buck is still no longer eligible. If the ranch is fenced on only two sides the buck again may not be eligible. The Boone and Crockett Club examines these situations on a case-by-case basis.

Fifth, once you have constructed the high fence you are now forced to manage the deer herd. The deer population may quickly begin to expand (especially on smaller areas). If you are not willing to significantly increase deer harvest then the deer herd may eventually reach a point where they are over the carrying capacity of the habitat.

Sixth, once a high fence is in place it attracts more poachers, especially if the land is adjacent to a public road. Poachers are attracted to high fences because of the belief that the deer herd is better managed. Yearling bucks and even mature bucks during the rut travel these high fence borders making them easy targets for poachers.

An additional concern involves genetics. At present, the genetic changes that occur in deer populations contained within high fences are not clear. However, landowners with small high fenced properties (less than 1000 acres for example) may have reasons for concern.

Wildlife researchers have long known that small isolated animal populations may be vulnerable to loss of genetic diversity due to the effects of inbreeding. Researchers have also shown that high genetic diversity in white-tailed deer is correlated with increased body size, number of antler points, and antler mass.

Landowners with small high-fenced properties may be able to reduce the loss of genetic diversity by bringing in deer from outside sources. Even small numbers of deer brought into a high fenced population may be enough to reduce the risk and undesirable effects of inbreeding.

Conclusions
The landowner must seriously weigh and consider all advantages and disadvantages because of the high costs involved with constructing a high fence. Also, after the high fence is built there is no turning back; the landowner is now committed to management. If deer population growth is not controlled, the deer herd will expand to the point that the habitat is severely and permanently damaged. Once the habitat is damaged, a massive deer die-off is inevitable. The high fence itself will not manage the deer herd; it is up to the landowner and the biologist. If proper management is not followed, then the deer herd itself will suffer.

Next week in Part II, I’ll discuss the reasons why not to build your high fence against your existing low fence, and the negative effects of deer population explosion.

Posted by Dr. Mickey W. Hellickson