Wolf Management: Non-lethal Control
5. Fencing
Surrounding livestock by erecting barriers to prevent predators access to them is an ancient method of protection. Barriers include building earthworks, pits, rock banks and planting thickets of vegetation. Wires and posts are more usual as a barrier nowadays, being quicker and less labour intensive to construct. In Australia and parts of Africa whole regions are fenced off against predators. But in Europe and much of the US, the largest fenced areas are usually just a few fields, lambing pastures or night-time enclosures.
Electric Fencing
Electric fences to keep livestock from wandering have been on the market for a few decades. They have been adapted with some success to keep medium size predators, like coyotes, away from livestock and even deny bears a free meal of honey by encircling apiaries. Improvements with material and design over the last few years have now made fencing more effective and an economic option for protecting sheep from wolves.
Livestock grazing within fenced areas is usual in Sweden and where fences are well constructed and electrified few if any livestock are lost to wolves or bears (Levin 2000). These electrified fences are built to be permanent structures. Poles are stout (10-15 centimetre - 4-6 inches - diameter) hammered into the ground and connected with five strands of wire (topmost strand 1.1 metre (3.5 feet) above ground with 20 centimetres (8 inches) between strands). They are electrified by at least 4,500 volts from mains or batteries, enough to shock any bear.
Portable Electrics
Electric fences may have more of a psychological than a physical impact on predators, which may be why flimsier, portable fences can make good wolf barriers in some conditions. Portable electric fences date back at least to the 1970 and there are several types.
Practical tests with portable fences in the Romanian Carpathians have been carried out to protect sheep at night from wolves and bears (Mertens et al 2002). Shepherd were at first sceptical of trying the fences but began adopting them when two shepherds tried them successfully.
The shepherds tried a number of large pens (each about 20 x 20 metres or 20 x 20) made from a role of five wires held up by plastic spikes (1.6 metre or 5.2 feet high) with iron tips driven into the ground. Each fence was powered by a car battery sending an electric pulse along it of up to 6,000 volts per second. Once a fence was initially set up it could thereafter be taken down and reassembled somewhere else in up to two man-hours: the posts were simply pulled out of the ground and the fence wound in a bundle ready to be unrolled at the next site. Sheep always kept well away from a fence after one experience of touching it; they have little motivation to force their way out provided they have plenty of food and water on the inside.
Fladry
For centuries a traditional trick in eastern Europe and Russia for bagging wolves has been the use of fladry (eg Musiani 2000). It is an unusual kind of fencing, makeshift and frail, but effective. Fladry, an east European term, is simply a string of closely spaced strips of cloth. The string is hung completely around some unsuspecting wolves and when the hunters are ready they drive the wolves into a bottleneck at one end where waiting guns shoot them. What is remarkable is that wolves never cross the line, even when there is nothing else there but fladry to prevent them; they seem too frightened to cross it, even if they are desperate to get out.
Ideally, the strips of cloth should be 10 centimetres (4 inches) wide by 50 centimetres (20 inches) long, set less than 50 centimetres apart, and just touch the ground. When the flags are too far apart or the string is too high off the ground, wolves are likely to slip through.
Advantages & Disadvantages
Fence for fence, electric fencing can cost less than good conventional fencing and be as effective. Where good permanent fences already exist they can be electrified by fitting them with one or more strands of electric wire. Permanent fences may be most useful and cost-effective around small tracts of land and smaller enclosures. But when fences are used over large areas, depending on their length, height and structure, they fragment the habitat, lower its quality for wildlife and are unsightly.
Portable electric fences at least can up stakes and relocate. The advantage of portable electric fencing is that it can make temporary pens to hold livestock at night or during other activities like birthing. However, in poor countries like Romania the purchase price would have to be very low if it is to catch on.
Sometimes livestock are enclosed in such a way that a predator gets among them and they cannot escape (see Surplus Killing). If a wolf gets into an electrified pen he might kill several animals, reversing the intended purpose of the enclosure. There is also the possibility that a naive sheep or lamb can get entangled and die in the electrified strands, especially of a relatively flimsy portable fence, if no alert shepherd is around.
It is claimed that fladry can make an occasional and temporary barrier to exclude wolves from livestock. But if used a lot on the same wolf pack the wolves might find their legs and run past the flags.
The use of fladry as a tool in wolf management is currently being tested. Ungulates do not seem to be afraid of fladry and cannot be captured with it. When fladry was tested on cows in Minnesota. They simply ate the cloth!
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