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Electric Fencing:
Electric fencing is extremely useful for areas where a
bear attractant exists and cannot be removed such as landfills,
orchards and apiaries. Seasonal electric fences have also
been used with great success to eliminate human-bear interactions
at two high use visitor areas, including a campground, in
Lake Louise in Banff National Park (Hal Morrison, pers.
comm.).
Factors affecting the effectiveness of electric fences
include the type of wire, fence height, and spacing between
wires. Overhangs, mats, concrete footing or buried chain
link fences at a depth of 1-1.5 m (3-5 ft) prevent bears
from digging under or climbing over fences. Electric fences
deliver pulsating charges of electricity. For safety, the
interval between pulses should not be less than ¾
of a second (Ciarniello 1997).
Electrical considerations include the wire strength and
the existence of a reliable fence charger and grounding
system (Hunt 1985). The intensity of the electrical charge
is also an essential factor determining the success. Long-haired
animals require a minimum voltage of 5,000 volts to receive
a shock. The voltage can be 10,000 to 12,000 V with an amperage
of one or less to deliver a painful shock depending on the
grounding system and the total amount of resistance (Wooding
et al. 1988, Heuer 1993, Ciarniello 1997). If barb wire
is used, its points may better penetrate into the hair of
bears increasing the likelihood of shock, but it can endanger
people whose clothing might become snagged during accidental
contact preventing escape from the charge (Hunt 1985, Ciarniello
1997).
Once a fence has been installed, it is essential that it
be properly maintained in order for it to be effective as
bears may periodically retest fences. Maintenance includes
keeping the chargers working properly and removing weeds
and other debris from touching and shorting out the fence.
A good grounding rod is also essential.
Portable electric fence units have become fairly inexpensive
and simple to erect. Even a backpackers version is available.
They have been used by field researchers and hunters for
years to successfully deter bears from field camps. A biologist
in Minnesota reported good success deterring bears from
repeated attacks on beehives by using a temporary prefabricated
fence with a charger powered only by D-cell flashlight batteries.
The key in this instance was liberally applying foil strips
smeared with peanut butter and honey to the hot wires about
20"-24" in (50-60 cm) above ground or at head
height for the bears. The strips would be torn off by morning,
but the bears respected the jolt they received and did not
break down the fence. Solar charged units are also available.
Download
instructions on setting up a portable elctric fence.
Researchers have adapted portable fence units to other
items that they want bears to stay away from. For example,
the "electric lunchbox" is a small picnic cooler
that has been fitted with an apparatus adapted from a portable
electric fence unit that gives the bear a shock when it
tries to remove the bait. In initial tests, the electric
lunchbox has caused black bears to run from the area and
avoid the cooler when they returned. Chicken coups and even
regular livestock fences have been successfully hot-wired
to deter bears.
Download
instructions on electrifying a cooler or garbage can.
For more information on ordering electric fence products,
click
here.
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