Fencing is another fundamental factor in wildlife management, without it management will not be easy or even impossible. Immediately after erecting a fence around certain area, management should be incorporated. A good fence in the first instance is needed to keep game on the farm, to keep predators out, to maintain a friendly relationship with the neighbours and the environment, and to protect the property. Quality fencing is important as wildlife has escalated in value during the previous decade. The height of fence is determined by the game that it kept. Fencing becomes even more essential if valuable animals are kept on the game ranch. Furthermore, certain types of game can be a threat to public if not confined properly. Every game ranch owner or manager should evaluate his/her situation and consult the local agricultural extension officer or conservation authority with the regard to specific prescriptions or requirements before erecting a fence. When choosing an effective fence to be erected the type of animals to be kept should be considered, the nature of the terrain, the type and availability of material and the available finances.
A good wildlife fence should meet the following requirements (Van Rooyen, Du Toit and Van Rooyen 2002):
- erected fence should be straight and vertical
- all the straining posts should be firmly and vertically anchored
- all the posts should extend to the same height above ground level by corresponding to the terrain form
- the straining posts and droppers should not be too far apart, the closer they are, the firmer the fence
- each wire strand should be firmly attached to the standards or line posts at a specific height above ground level and should be a certain distance apart from each other
- the droppers should be neatly and evenly spaced between the standards. The wire strands should be firmly attached to maintain the proper space between the strands and to prevent vertical movement
- fences should be constructed using good quality material
The height of the fence on a game ranch depends on the types of animals that are kept. Wild animals can be grouped into various categories on the basis of their potential to move over, under or through fences. It should, however, be noted that most wild animals will only resort to crossing fences when they are under some kind of stress or duress. The following fence-crossing groups can be distinguished (Van Rooyen, Du Toit and Van Rooyen 2002):
- Animals that usually jump over fences:kudu, impala, eland, waterbuck, mountain reedbuck Redunca fulvorufula and grey rhebok Pelea capreolus
- Animals that crawl underneath or through fences: warthog, duiker, steenbok, gemsbok, red hartebeest, springbok Antidorcas marsupialis, sable antelope Hippotragus niger, tsessebe Damaliscus lunatus, jackals Canis mesomelas, caracalFelis caracal, cheetah Acinonyx jubatus, leopard Panthera pardus and lion Panthera leo
- Animals that break fences:buffalo, giraffe, waterbuck, white and black rhinoceroses Ceratotherium simum and Diceros bicornis and eland, blue wildebeest and sable antelope bulls
- Animals that usually do not jump over fences:blesbok, steenbok, duiker, springbok and oribi Ourebia ourebi A 17 to 21 wire strand fence of 2.25 to 2.4 m is high enough for fencing in those animals that are capable of jumping. A standard 1.5 wire mesh fence with a strand of wire 150 mm above the mesh and another one 150 mm above this should keep most non-jumping animals within the fence (Van Rooyen, Du Toit and Van Rooyen 2002). Closer spacing of 80 to 125 mm of the lower wire strands in contrast to 130 to 170 mm of the top of the wires prevents animals from crawling through the fence.
Fences over dongas, streams and rivers
These areas require special care because fences over such features can become insecure and lead to the escape of valuable animals or provide access to predators. The two guidelines for making the fence more secure, the first one is on temporary streams and dongas, and the second one is on perennial streams (Van Rooyen, Du Toit and Van Rooyen 2002). The second guideline will not be discussed as there is no perennial stream/s crossing the ranch:
The movement of animals can be easily controlled by electrified fences, as animals are sensitive to electric shocks. As in many other cases, electrification is an economical way to control the movement of large mammals. Electrified fences can be erected on its own or in combination with a normal wire fence. An electric fence on a game ranch has the following advantages (Du Toit 2002):
- it is inexpensive in relation to the degree of effectiveness that is achieved
- it controls most animals species effectively · it can be erected with a low labour input
- it requires low maintenance, provided that the fence has been correctly planned and erected
- it limits the entry of poachers and thus decreases animal losses
An electric fence on a game ranch has the following disadvantages (Du Toit 2002):
- it is not effective for keeping animals in such as giraffe bulls and warthogs, which may damage the fence
- its effectively is subject to environmental factors (plants growing against the fence may cause short-circuits and veld fires may damage the galvanizing of the wire)
- the visibility of electrified fences for animals is low, but this can be improved by attaching tin cans, metal sheets or other shiny or visible material to the fence
- a drop in voltage occurs in the dry winter months when the dry soil surface earths the animal more weakly and therefore results in a weaker shock to be effective, an electrified fence should meet at least the following requirements (Du Toit 2002):
- the fence should be planned and designed for the specific animal species that it must control
- the costs of the fence should be as low as possible, but inferior quality material should not be used
- the fence should be neat and permanent and require minimum maintenance. It should allow faults to be traced as quickly as possible
- the after-sales service by the manufacturers should be of high standard
- the fence should be safe for contact by humans A standard electrified fence consists of an energizer, insulators, wire strands, a digital voltmeter and lightning protectors.
The number of energizers required is determined by the length of the fence and the number of electrified wire strands in the fence. The current should be strong enough to maintain a minimum of 4000 volts at any point along the fence. The energizer is the most expensive item. The electrified wire strand should be at least 2.24 mm thick. When the wire is too thin, the current from the energizer cannot be conducted fully. The function of an insulator is to prevent contact between the electrical current and contact or short-circuit points. Insulators should be fire resistance (porcelain or fiberglass). A digital voltmeter is used to determine whether the electrical current in the wire strand is still correct (Du Toit 2002). Insulators made of porcelain or fiberglass prevents contact between the electrical current and points of contact. There are two types of of insulators, which are the bobbin insulator secures the electrified wire to the fence by means of offset brackets. The distance between wires and fence should equal 225 millimeters. The insulator need to be strong enough to withstand the the tension placed on it. Barbed wire should never be electrified.
Recommendations for Highlands Wilderness
The current fence structure on Highlands Wilderness satisfy request for specifications of the local conservation authority in keeping the current game. However, if dangerous animals such as buffalo or rhinoceros are considered to be kept on the ranch, the current fence line construction will require upgrading to include electrification. It is advisable to check the fence regularly because at some places the fence might broke by animals or poachers. The silver plates uses for visibility on the fence are rusty on other parts of the ranch especially on the mountains. All rusty plates must be painted again.