Farming Magazine - March, 2013
FENCING & CONTAINMENT EDITION
Keeping Deer and Bear Out
What's the best fencing for you?
For whatever reason, problems with deer, bear and smaller wildlife are increasing. Causes may include population increases, loss of habitat, crop appeal or all of the above. "When I began selling fencing 35 years ago, 75 to 80 percent was to keep livestock in; now 75 percent is to keep wildlife out," says David Kennard, sheep farmer and owner of Wellscroft Fence Systems in Harrisville, N.H. "In some areas of the Northeast, wildlife pressure on crops has increased as much as tenfold," he adds.
In the Northeast, a number of fencing options are available to deter or exclude Pooh Bear and Bambi. Along with fencing, non-fence techniques may also be used, such as chemical repellents, natural repellents, noisemakers, guard dogs and hunting.
When deciding how to protect your area from wildlife, consider the following:
- What wildlife do you want to exclude? Is there more than one species involved?
- Is the crop to be protected annual or perennial?
For perennials, such as young fruit trees, a physical fence should be used. An electric fence will not be as effective as a physical fence when the ground is dry or covered by dry, frozen snow, unless the system is bipolar. A bipolar system, which alternates positive and negative wires, will shock deer's feet. For an annual crop, say a pumpkin patch, a psychological (electric) fence will suffice.
- Will the fence be temporary or permanent? Will the fence need to be removed annually? Is the land leased, and if it is, for how long?
Electric fencing must be removed at the end of the growing season so that deer do not learn to run through it.
- What is the extent of the problem? What is the degree of wildlife pressure?
- How much exclusion is necessary? What is the crop damage relative to the value of the crop? Does exclusion need to be 100 percent, or is 95 percent enough?
- For how much of the year does the crop need protection - 12 months, nine months or less? Will the fence need to withstand snow and ice?
Unless it is a permanent bipolar system, electric fencing should always be put up a week or two before crops are planted and taken out before the ground freezes.
- Are there aesthetic considerations? Does the fence need to be attractive and visually unobtrusive?
- Do you want a psychological (electric) or physical (nonelectric) barrier?
Electric fences are permanent; they're less expensive but require more maintenance. Nonelectric fences require less maintenance and are the most effective, but they must be very strong to keep wildlife from going under, over, around or through.
Eight-foot-high woven wire deer fence with a 98-inch-by-10-foot gate with 4x4 mesh.
Protecting crops from deer
Electric fences suitable for deer exclusion range from one to three tapes or ropes to 3-D tape or rope fence (two fences 4 feet apart) to eight-wire, vertical, high-tensile electric fence to woven wire topped by an electric wire. Baited 2-D tape is very effective because it flutters in the breeze, scaring deer. The cost of electric fences for deer exclusion range from 30 cents to $2.90 per foot.
Although it is excellent for containing domestic animals, poly wire should not be used to try to exclude deer. Deer need the visual thickness of tape or rope and seem to think poly wire looks like twigs that they can walk through, explains Kennard.
Nonelectric fences designed to exclude deer range from an easily installed and moved anti-deer mesh or net at $1.60 to $2.40 per foot to 8-foot-high woven wire at $1.30 to $2.25 per foot.
Of all the systems designed to keep deer out, an 8-foot-high, fixed-knot, woven wire fence is the most effective and, in the long run, most economical, says Kennard. Although it requires more labor to erect than net or electric fencing, many farmers find that it pays for itself in crop savings in the first two years. One-piece verticals resist snow and ice as well as penetration by deer. To be effective and long-lasting (25 to 30 years or more), fixed-knot, woven wire fences must be braced. Cost of materials runs $2.25 to $4.25 per foot.
Where woodchucks, raccoons, skunks and the like are also a problem, a baited electrical offset wire can be added to prevent them from climbing over or digging under a physical fence.
Electric and effective
Whichever electric fence you choose, you must:
1 Keep the fence energized and properly grounded at all times. An animal's first encounter with a fence will influence its behavior in the future. Therefore, be sure to energize the fence at the end of every workday during the time when the fence is being installed.
2 Remove brush and maintain a clear lane on the outside of the fence so that wildlife can see the fence. The fence should be at least 6 feet from the edge of any wooded area.
3 It is very important to bait the fence. The shock to the nose or mouth that wildlife receive when they investigate scent caps or aluminum foil-wrapped peanut butter will keep them away from the fence and the crops within.
4 Run at least 3,500 volts through the fence. Use a fence tester to check voltage and a fence alert to confirm that the fence is active.
5 Remove psychological fences at the end of the growing season. If non-energized fencing is kept in place, deer will learn to run through it.
Eight-foot-high, fixed-knot, black woven wire deer fence is probably the most cost-effective and permanent way to exclude deer.
The buzz on bears and hives
Whatever their motivation, be it crunchy pupae, larvae, eggs and immature bees full of fat and protein (as a few researchers have suggested) or, as more commonly accepted, the sweetness of honey, bears need a lot of persuasion to keep them from the contents of a beehive. The best way to keep bears from hives depends to a large extent on whether the exclusion needs to be seasonal or temporary, semipermanent or permanent. Whatever the choice, the fence should have an electrical component.
Fencing for a while - or longer
Seasonal or temporary exclusion - For beehives that need seasonal protection, periodic access or shielding as they are moved from crop to crop, electric netting is the easiest and most convenient fencing. It will also keep skunks out of hives. Easy to set up and take down, electric net fences are more durable and less unwieldy than poly wire or tape systems. Kennard recommends either ElectroNet or Quick Ground netting powered by a plug-in 110-volt battery or solar energizer. Four D-cell batteries will power the system for eight weeks.
Semipermanent exclusion - For beehives in a more or less permanent location, Kennard suggests an electric, four-strand, low-tension wire or tape fence, an electric rope or tape fence, MaxiShock cable, or 14-gauge wire spaced 8, 16, 24 and 32 inches above the ground. This method is somewhat less effective than electric netting at keeping out skunks. In dry areas, ground the fence either by making one of the wires negative or by laying chicken wire down under the fence.
Permanent exclusion - For permanently located beehives, the best fencing is constructed of high-tensile woven wire with an electric offset at the top. Use either a 110-volt plug-in charger or a solar energizer to power the system. To discourage theft, hide the energizer in a bee superstructure. Permanent fencing installation tends to be more expensive and is initially more labor-intensive than other methods.
Easily installed, plastic anti-deer mesh resists light deer pressure. Smaller wildlife will chew through it.
Effective beehive fencing depends on:
- Grounding - For electric fencing to operate effectively it must be grounded. If soil is dry, lay a 36-inch-wide strip of chicken wire outside the electric net to connect the energizer to the ground field.
- Baiting - Peanut butter, bacon strips or a partially opened can of tuna fish are the roses and chocolate of bear attraction. Bait will attract bears to the fence, but it will not make their hearts go pitter-patter. Instead, it will shock their heads, teaching them what an electric fence can do. Electric shocks are less effective on other, more densely furred parts of bears' bodies.
- Clearing a strip of vegetation - Keep vegetation down under net or smooth wire fences by centering a 12-inch-wide strip of landscape cloth or black felt paper under the fence.
- Spacing between fence and hives - To keep bears from touching hives, install fencing 6 to 8 feet away from hives on all sides.
Tips for installing and using beehive fencing
Energizers should be placed on a wooden block or concealed inside a superstructure inside the fence and above the ground to prevent accidental bear damage, theft, and insects and moisture from damaging electronics. Spray insecticide inside the energizer case once a year to keep small insects from shorting out the circuit board.
Electric netting, such as ElectroNet, is the easiest and most convenient seasonal or temporary fencing for beehives.
Where the ground is dry or there is snow, alternating positive with negative (Pos/Neg) wires in a four-wire system gives bears a strong shock when they touch both the positive and negative wires at the same time.
To add visibility and movement to a multi-strand fence, add a strand of .5-inch electric tape.
Some newer electric fencing components:
- Unigizers are dual 110-volt and 12-volt energizers that can be plugged in or run on batteries, as well as providing the flexibility to convert to a solar energizer (as can any other 12-volt energizer).
- Remote-capable energizers, 6 to 36 joules, can be turned on and off by touching a remote control to a fence anywhere in the system.
- Fault finder detects the location of electrical faults. The remote control model switches the fence on and off anywhere on the fence line, finds and locates faults, and checks fence voltage. The regular model finds faults and checks fence voltages.
- Fence Alert attaches to wire, tape or rope fences and flashes when a fence lacks adequate current to power it. Operates on a watch battery.
- Suitcase solar energizers include an energizer, a solar panel, batteries and a wiring harness in a metal carrying case. Suitcase models, more compact than other models, range from .5 to 2 joules. In the Northeast, where winter sunlight is limited, an extra-large solar panel will be needed to run the energizer.
Making the right fence decision
Contact your local county agents or fencing suppliers for help in designing and selecting the best fencing for your situation, and remember to add "Electric Fence" signs to your completed system.
Kathleen Hatt is a freelance writer and editor and a contributor to Farming since 1998. She lives in Henniker, N.H.