Electric Deer Fencing
Highlighting the Techniques using Electric Fencing to exclude Deer.
Deer have become an increasing problem in nearly all areas of the United Kingdom and the deer population is thought to be higher now than at any time in history. Coppice re-growth and natural regeneration of trees is impossible in many places without fencing or other protection and in some areas Muntjac deer are causing significant damage to the ground flora of woodlands. Deer fencing is erected for any of the following purposes:
- To exclude deer from woodlands, including plantations, coppiced woodlands, newly planted amenity woodlands and those where natural regeneration is needed to maintain or extend woodland cover.
- Exclosure fences may also be needed to protect high-value horticultural and agricultural crops.
- To enclose deer in a farm or park.
- Exclude deer from private property.
A study conducted by the National Wildlife Research Center, a division of the U.S. Department of Agriculture, found that electric fencing "was an effective and economical deer barrier."
"From August 1979 through September 1981, two electric fences were used in Allegheny hardwood clearcuts in northern Pennsylvania to prevent browsing by white-tailed deer (Odocoileus virginianus). A five-strand vertical fence, 58 inches high, and a "figure four" three-strand fence, 43 inches high, were used. The fences were charged with a battery-powered energizer having a maximum output of 5,800 volts. Average time between battery charges was about six weeks. More than 33 percent of all the seedlings in the unfenced portion of one clearcut were browsed annually while inside the fence no browsing was detected. At least one deer penetration occurred at each fence, but the effect of browsing on forest regeneration inside the fences was negligible. The "figure four" fence was not as effective as the five-strand vertical fence in preventing deer browsing. "
Deer - Animals of Habit.
Where they choose to feed, rub, walk and breed is a habit learned over time and reinforced every time they do it safely. To exclude a deer herd from a food source, area or trail to which they are habituated forces the herd to break this habit. Thus the first day, week and month of denial of use (by a fence) is the key period. Once the habit is broken, the change in routines and location is easier to maintain. However, you are only fencing out the animals desire so don't expect success in persuading a starving deer herd to feed elsewhere if your site is its only food source. The greater the desire - the more substantial the barrier has to be.
Full-height (1.8m) wire netting for deer fencing was designed for deer farming, and is not always suitable for woodland exclosures or other uses. The rolls of netting are extremely heavy and require machine access along the fence line, and the netting is difficult to fit neatly on undulating ground. Traditional Deer fences can be a significant source of mortality to low flying ground nesting birds, particularly capercaillie and black grouse.
There are four basic approaches to controlling deer damage to woodlands, which may need to be used in combination:
- Fencing or tree guards. Netting or mesh fences are necessary, as deer can push between the wires of line wire fencing. Muntjac can push under netting, which must be lapped or buried as for rabbits. Tree guards must be of sufficient height and robust enough to resist damage.
- Providing alternative grazing and browsing to divert attention away from the areas you want to protect.
- Culling of population. Culling has to be organised on a local area basis, as deer will rapidly move into woodland where culling has taken place. Contact the local Forestry Commission office as there may be a deer management group in your area.
- Electric Fencing is highly effective and being intrinsically lighter than conventional fencing is substantially cheaper and easier to erect.
Note that deer can easily injure themselves by attempting to jump normal stock fences. Standard height stock netting fences topped with one or two lines of barbed or plain wire, giving a total height of about 2m, are a frequent cause of injury. As the deer tries to jump, its leg can get entangled in the top wires, where it dies a lingering death. Electric fences interact with the deer's brain instead of the body and siting and erecting the fence should bear that in mind and should be managed with an awareness of a deer herds habits within your area and the new fence.
These generally utilise wooden posts combined with suitable ring insulators. Plain hotStop wire is the most suitable due to its longevity and most important, its excellent conductivity. The number of strands depends on the type of deer being excluded and is based at the average nose height of the animal. All mammals use their noses to investigate a fence or unfamiliar objects so the first wire goes in at that height as that is the nose height at rest and the nose is highly enervated (lots of sensitive nerve endings) and the greatest effect is felt there.
Muntjac Deer are small (size of a medium dog) at 50cm, through Fallow Deer 100cm to the taller Red Deer at 130cm.
Muntjac have the habit of going under wire so put in 2 lines below that and one 20cm above. So for Muntjac spacing would be 15,30,50 and 70cm above ground.
Red Deer have a habit of jumping so 5 wire fence is preferable at 50, 80,110,130, 155 and possibly 180cm. A total exclusion fence for deer would therefore be a combination of the two and require 7 strands. (It is important you read the section on Training the Deer)
An additional improvement developed in Australia is to slant the fence towards the direction from whence the deer approach, this probably replicates the 3 Dimensional fence talked about later
Deer have a natural insulation due to the hooves and hair and this has proved to be a problem in the past. Electric fencing has in the past been thought to be not totally effective but this has been rectified by new technology and improved exclusion techniques. It is recommended that the hotShock or HoriSmart energisers are used. These run at higher voltages than standard models to enable them to bridge this natural insulation. (Again the section on Training the Deer is important)
Poly Posts are very useful in temporary situations. They are very simple to use and are quite adequate. Use the longest available, especially for Red Deer and at 150cm above ground they are adequate for most situations. The ends and corners still need to be wooden posts to enable you to tension the wires adequately. For temporary fences, Poly twines or rope is preferable to wire as they are easily handled and easily wound onto reels for transporting to another site.
There are reports coming out of the USA where an additional single line 1 meter on the pressure side of the fence greatly improves fences that are less than 150cm high. The principle is based on the belief that deer have less than ideal depth perception so are more tentative with wide fences rather than tall. Leaning the fence towards the deer probably replicates this effect.
This theory has recently been exposed as possibly incorrect by a trial in Allegheny hardwood clearcuts in northern Pennsylvania where "two fences were used to prevent browsing by white-tailed deer (Odocoileus virginianus). A five-strand vertical fence, 58 inches (148cm) high, and a "figure four" three-strand fence, 43 inches (109cm) high, were used...... More than 33 percent of all the seedlings in the unfenced portion of one clearcut were browsed annually while inside the fence no browsing was detected. At least one deer penetration occurred at each fence, but the effect of browsing on forest regeneration inside the fences was negligible. The "figure four" fence was not as effective as the five-strand vertical fence in preventing deer browsing."
The video above highlights the reaction of deer to a shock. They typically emit a warning that causes the whole herd to retreat from the danger for a short distance. This stimulates the Socially Conditioned Avoidance syndrome typical of all herd type animals. The deer show no ill effects of the shock at all.
Remember we need to change the deer's habits built up over a period of time. There are two methods of increasing the effectiveness of the fence. The first is by clearing the brush about 3-5 meters away from the fence. The smaller deer have an inbuilt tentativeness crossing open areas that is reinforced by contact with the fence.
Red Deer in particular have a habit of not investigating the fence and simply jump over it. This is in common with the Springbuck and Impala of Southern Africa (both of which do comfortably clear a 2 meter high fence) and consequently an effective technique has evolved there whereby the fence is initially baited to attract the target to investigate the fence.
With deer this is done by two methods;-
1/. Little metal Bait Caps containing cotton wool soaked with an apple scented essence attached to the fence. (Neat apple cordial works well.) These are fixed and may be left on the fence and re-baited when necessary.
2/. Lengths of kitchen foil smeared with peanut butter, molasses/treacle or syrup wrapped around the wires at strategic positions of the fence. The possibility of these being detached from the fence creating litter is great so should be removed and replaced if pressure on the fence re-occurs.
The Deer are attracted to these fences by their appearance or smell and are lured into sniffing the fence with their sensitive noses getting an effective sting from the fence. This then creates the psychological barrier in the animal's brain. This shock is a very strong stimulus and deer learn to avoid the fenced area creating a barrier that they are unable to see and consequently do not know how high it goes. To illustrate this further, foxes, rabbits and badgers do not dig under electric fences for the same reason. The deer seldom attempt a second try. This may sound harsh, but the technique is VERY effective and after the first few animals get a sting the rest will learn from their experiences, termed "Socially Conditioned Avoidance," and the fence will be left alone.
The bait may be removed after a week or two. Baiting may be necessary again if another herd comes into the area, the deer begin to test the fence again or after the fence has been off for a while.