There are many advantages to using old tyres, bicycle wheels, or flap doors as thoroughfares for wild animals.
The maintenance of wire fences, especially where aardvarks, bush pigs or warthogs crawl through, usually places farmers into one of two groups. The first group becomes almost obsessive about it, closing each and every hole, while the other accepts defeat and allows God’s creatures to wander across God’s land. From an ecological viewpoint, the latter is of course the way it should be.
Whichever way you look at it, holes in fences cost money, not just in regular repairs, but also in terms of what you stand to lose as a result of what comes in, or goes out.
According to Dr Florian Weise, a biologist who conducted research at N/a’an ku sê Lodge near Windhoek in Namibia, artificial thoroughfares made with old vehicle tyres can reduce the maintenance costs of game fences. They can also reduce predator stress in game enclosures.
By introducing thoroughfares in the fencing at strategic points (such as near watering holes), the number of holes made by crawling creatures is reduced. Jackals and other predators then use these thoroughfares.
Prior to Dr Florian and his team installing 49 vehicle tyres (with a diameter of 40cm) in an un-electrified Bonnox fence (2.4m high and 19km long) on a game farm, the owner had to spend four or five hours a day patrolling the fence and repairing an average of 30 holes. After the installation of the tyres, the number of holes dropped to 13 per day and the work required to just two hours a day.
The tyre openings need to be scraped out periodically to remove soil.
THE MOVEMENT OF GAME
Dr Florian carried out his research on the boundary between a game farm and a commercial cattle farm. The movement of animals through one of the tyres was observed by means of an infra-red camera. Out of 100 observations, 11 types of mammals made use of the tyre. Black-backed jackals and porcupines were the main users, closely followed by cheetah and warthog.
He says, according to the spoor, warthog used all 49 of the tyres, and baboon, duiker, guinea fowl, steenbok and honey badger also used them from time to time. Only once were there signs of a springbok and a young red hartebeest.
Dr Florian believes that the tyres would also be useful along interior fences by allowing selected animals to move more freely. Tyres of various sizes will help to limit the type of animal.
FLAP DOORS AND BICYCLE WHEELS
If the movement of predators needs to be limited, simple flap doors can be installed, as shown in another experiment carried out in Namibia. This research indicated that the flap doors were a cost-effective alternative to electric fences in areas where cheetah are a problem, as the electric fences require a lot of maintenance.
The flap doors consist of a metal framework (45cm x 30cm) covered with wire mesh. This is simply hung on the fence so that it can swing freely back and forth to allow easy access for certain animals that then no longer need to dig holes. Aardvark, warthog, and porcupine apparently quickly learn how to use these flap doors.
Another method involves a bicycle wheel that is cut in half and on which a “curtain” of chains is hung. This is then placed in the fence with the loose ends of the chains hanging at ground level.