By Roelof Bezuidenhout
Burrowing animals like porcupines, diggers like jackals, and small antelope such as steenbok can create ongoing problems by forcing their way through and underneath fences, leaving holes that require constant repairs to keep your livestock secure. One way to reduce this workload is to give these animals a permanent passage. Many will quickly adapt and consistently use the designated route rather than creating a new hole each night. Having animals funnel through the same points also makes it easier to monitor their movements using cameras or tracking their spoor.
One of the major drawbacks of game-proof fencing – which continues to expand alongside the growth of the private wildlife industry in Southern Africa – is that these structures restrict the movement of free-ranging wild animals. This disruption can have a negative impact on essential ecological processes such as dispersal, emigration and immigration, particularly for large predators and their prey. The biological cost of tightly fenced systems is significant. Because an animal’s range is often determined by the availability of food and water, any solid barrier that cuts across these ranges can compromise its ability to survive stressful environmental conditions, such as drought or dry seasons.
Using discarded tyres to create passageways and installing swing gates are two simple, effective options for restoring some degree of connectivity between neighbouring farms.
Discarded tyres
In 2010, a study led by Dr Florian Weise of the N/a’an ku sê research programme in Windhoek, Namibia, assessed the use of 49 tyres installed in a wildlife-proof fence along the boundary of a wildlife farm to see whether it would reduce regular warthog damage to the fence. The tyre locations were chosen according to where warthog activity – resulting in repeat fence maintenance – was the highest. This was usually in sandy soil, but there was no fixed distance between the tyres. They were anchored in the soil using short metal poles on either side and were wired to the fence for stability.
Prior to the study, the fence, which had been erected to contain kudu, gemsbok, red hartebeest, springbok and several valuable species, was patrolled and repaired between 4 and 5 hours daily – with more than 30 holes having to be fixed per day. After the installation of the tyres this number decreased to 13 holes per day. Consequently, time allocated for fence patrols and repairs could be reduced by more than 50%, to less than 2 hours per day.
The researchers monitored one of the tyres, which connected the wildlife reserve with an adjacent cattle farm, with a motion-triggered infrared trail camera for 96 days. During fence patrols, spoor of cheetah, leopard and brown hyaena had been repeatedly seen at this site. Out of 100 recorded observations, 11 mammal species passed through the tyre, six of which were carnivores. Black-backed jackals and porcupines used the tyre most frequently, followed by cheetahs and warthogs. One pair of black-backed jackals was photographed 27 times out of a total 44 recordings.
An experienced tracker identified spoor of aardvark, black-backed jackal, caracal, baboon, duiker, guineafowl, honey badger, springbok and steenbok that had used the other tyres.
The study revealed that medium- to large-bodied carnivores passed through the tyre more frequently than other animals, thus maintaining unrestricted and regular movements between farms. These passageways offered resident predators an opportunity for natural movements and thus access to alternative prey sources on other properties.
Different sizes of tyres will enable a higher degree of selectivity towards the species of wildlife that can pass through them. Of course, there is the risk that tyres facilitate carnivore movements into areas with high-value game or livestock. In this case, swing gates may be a better solution.
Swing gates
In a separate study in Namibia to assess the effectiveness of swing gates, a 4,8 km section of game fencing was monitored before and after the installation of swing gates – trip cameras were used to identify species that used the gates. Warthogs, aardvarks and porcupines commonly used the gates, and the number of holes they dug under the fence was significantly reduced. No predators were observed using the swing gates. The cost of installing these swing gates was significantly lower than that of electrifying a fence.
How and where
Install old car tyres at strategic points along the fence, buried halfway beneath the bottom wire. This creates a stable opening that allows harmless animals to pass through without compromising the integrity of your fencing.
If you have a predator problem, swing gates provide a cost-effective and environmentally friendly alternative to electrified fencing. These gates consist of a metal frame (typically 45 cm x 30 cm) covered with mesh and mounted in the fence using iron standards and droppers. The gates swing open when pushed by animals and return to a closed position afterwards. They enable warthogs, aardvarks and porcupines to pass through without digging holes; these species even teach their young to use the gates. Importantly, they leave no obvious gaps for predators such as leopards, cheetahs and jackals to get in – leopards can climb most fences anyway.
Gate placement matters. Research shows that holes deeper than 20 cm are more likely to be reopened than shallower ones, indicating good spots to place a gate. In rocky terrain, where digging is difficult, animals are more likely to use existing routes. Consider the location of water sources when choosing gate sites, as these tend to attract regular wildlife traffic.
Given the high cost and maintenance requirements of electrified fencing – and reports that it’s only about 50% effective at keeping out predators – swing gates are a more affordable and practical solution, particularly for managing cheetah intrusion.
Also read:
Opinion: Greedy, selfish and corrupt officials prevent transformation in the wildlife industry
Unusual visitors seek relief in a maize field
Cooperation needed for predator problems
Tackling the challenge of problem animals on farms
 | Roelof Bezuidenhout is a fourth-generation wool, mohair, mutton and game farmer and freelance journalist. Attended Free State University, majoring in animal husbandry and pasture science. Other interests include agricultural extension and rural development. |
