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Abstract
This publication suggests various management practices to help
prevent or control damage by deer to field crops, orchards, landscapes
and gardens.
Table of Contents
Introduction
This publication suggests various management practices to help
prevent or control damage by deer to field crops, orchards, landscapes
and gardens. Because every field, orchard, landscape, and garden
is different, there is no way any or all of these management practices
will achieve perfect deer control, but they should help reduce the
damage.
Usually, deer damage plants by browsing on new vegetation during
the growing season. However, when food is scarce, deer will eat
just about anything to survive. One of the reasons that deer are
becoming more of a problem in many parts of the United States is
that their numbers are increasing. An Associated Press article on
October 15, 2000 stated:
The national deer population, now estimated at
25 million to 30 million, has been growing for decades. Not only
have deer adapted to encroaching suburbia, but they have benefited
from a series of mild winters, an increase in newly developed
areas being declared off limits for hunters and a decline in hunting
in some parts of the country . . . Some forecasters believe there
could be a point when the deer population will become so large
it just can't sustain itself. But no one knows when. "We're
not certain when it will max out," Curtis [wildlife biologist
Paul Curtis of Cornell University] said. "Deer populations
are already at densities a biologist wouldn't have dreamed of
10 years ago." (Associated Press, 2000)
The cost of damage by deer will vary greatly, according to the
crops and plants being grown in relation to the number of deer browsing.
In the article "Oh, Deer" in the June-July 2002 Farmer's
Digest, Jim Armstrong, associate professor and wildlife specialist
with Auburn University, explained that it is not uncommon for some
growers in the Southeast to have $20,000 to $30,000 in crop damage
(peanuts and cotton) during a crop year. He says:
It's a widespread problem in agriculture. The
problem is that it tends to be very site-specific. Depending on
the habitat around the field, one person can have no damage and
the next can have a lot of problems. Deer prefer a fragmented
habitat that consists of both woodland for cover and open cropland.
Farmers may notice more feeding near the edges of the fields near
woods, where the deer can feed without straying too far from cover.
(Mullen, 2002)
The USDA estimates that total deer damage from auto collisions
and crop and timber losses reaches at least $1 billion a year. (Mullen,
2002)
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Regulations and Assistance
Because deer are protected by game regulations in all states, as
well as all Canadian provinces, I strongly suggest you contact the
specific wildlife, natural resource, or conservation agency that
enforces your state's wildlife regulations before implementing any
deer control practice. Some state agencies have specific programs
for technical assistance or to compensate for deer damage. Other
states, or even local municipalities, may have laws restricting
some options for deer management. Producers need to keep current
with their state laws and regulations, because they can change from
year to year.
The Wildlife Services (WS), an arm of the Animal and Plant Health
Inspection Service (APHIS) charged with helping to prevent or reduce
wildlife damage, provides technical assistance or direct control.
For more information about assistance, contact any state APHIS office.
The address and phone number of each state's Wildlife Services State
Director and the state's Wildlife
Services activity report is available by calling the national
Wildlife Services Operational Support staff at (301) 734-7921.
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Management Practices
There are five general methods for preventing or controlling deer
damage to crops. These include exclusion, cultural methods, scare
devices, repellents, and culling or harvest. The referenced and
enclosed materials provide more detailed information on the use
of these methods.
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Exclusion
Several methods of exclusion are available. They can involve permanent
or temporary fences, a wireless deer fence, or other methods of
keeping deer from getting to the plants to browse.
Fencing
The most effective method for exclusion is a well-designed fence,
and there are several designs available to meet specific needs.
Temporary electrified fences are simple, inexpensive, and useful
in protecting garden and field crops during snow-free periods. "Baiting"
the fence with peanut butter, apples, etc. may enhance the effectiveness
of electrified fences. Deer are attracted to these fences by their
appearance or smell and are lured into contacting the fence with
their noses. This causes an effective shock that trains deer (sometimes)
to avoid the fenced area. Permanent, high-tensile, electric fences
provide year-round protection from deer and are best suited to high-value
specialty or orchard crops.
Permanent woven-wire fences provide the ultimate deer barrier.
They require little maintenance but are very expensive to build.
In fact, the cost of constructing effective fences often limits
their use to areas of intensive agriculture, such as orchards or
private gardens.
The Cornell publication Managing White-Tailed Deer in Suburban
Environments: A Technical Guide states:
For a given deer density, the potential for damage
will often be greater on large plantings than smaller ones. (Caslick
and Decker, 1979; McAninch et al., 1983)
Consequently, large areas often require more substantial fencing
designs to achieve a level of protection similar to small areas.
Based on anecdotal reports and research experiences in New York,
vertical electric fence designs seldom provide reliable protection
for plantings larger than five acres under intense deer foraging
pressure. Slant-wire, electric-fencing systems can protect plantings
approximately 50 acres in size. Blocks larger than 50 acres usually
require eight-foot-high, woven-wire fencing to reliably prevent
deer from entering the area if feeding pressure is high. (DeNicola
et al., 2000)
The same publication suggests that fencing systems such as the
baited electric wire, fences with three-dimensional outriggers,
and slanted and vertical fences up to 11-feet high have kept deer
out under some conditions. However, it continues:
Often simple designs are effective only under
light deer pressure (Brenneman, 1983; McAninch
et al., 1983) or for relatively small areas. Low-cost, easily
constructed fences may perform quite well for small areas (less
than ten acres) during the growing season when alternative foods
are available to deer. Low-profile fences, however, are seldom
satisfactory for protecting commercial orchards or ornamental
plantings in winter, especially if snow restricts deer from using
alternative food sources. Landowners must also check local ordinances
and covenants to determine if electric fences can be used, or
if fences of any kind can be constructed on their property. (DeNicola
et al., 2000)
This 52-page publication discusses many other methods to reduce
deer problems, including repellents, scare tactics, and some experimental
techniques. It includes an excellent 10-page appendix listing many
deer damage control suppliers and materials. The publication (147IB245)
can be ordered for $10.50 postpaid + $5.00 shipping in the U.S.
(NY residents add 8.25% sales tax) from:
The Resource Center
Cornell University
P.O. Box 3884
Ithaca, NY 14852-3884
(607) 255-2080
Fax: (607) 255-9946
The publication is also available at www.cce.cornell.edu/store
The enclosed publication Controlling
Deer Damage in Missouri contains information and illustrations
on constructing and using electric, high-tension, and woven-wire
fencing, including the peanut-butter electric fence, the polytape
electric fence, the offset electric fence, the vertical electric
fence, the slanted electric fence, the electric spider fence, and
the wire or plastic mesh fence.
Wireless Deer Fence
A new, patented Wireless Deer Fence consists of just a post less
than 2 feet high, a deer-attractant reservoir, and a battery-powered
high-voltage shocker. It is recommended that 3 to 6 posts be used
for one-third acre, or 15 to 18 per acre. (Williams
and Williams, 2002) For information on price, maintenance, and
installation for the Wireless Deer Fence posts, visit their website
or contact the distributor at:
Wireless
Deer Fence
P.O. Box 5604
Bloomington, IN 47407-5604
(866) 468-3337 or (812) 333-5307
Other Exclusion Methods
Another way to exclude deer from small garden areas is to use floating
polyester row covers over the crops to be protected. The floating
row covers need to be put on each evening and removed in the morning.
This method of exclusion was reported to have worked very well by
a gardener in Massachusetts. (Bye, 2000)
Tree protectors or shelters are used to prevent deer from browsing
on young trees. The protectors can be made of polypropylene tubing,
plastic tree wrap, or even woven-wire cylinders. Polypropylene tubes
are commercially available and come in different diameters for trees
or seedlings. Four-or 5-foot shelters are generally needed in areas
of heavy deer pressure. (Pierce and Wiggers, 1997)
Anecdotal reports suggest that fencing a few pigs in a pen surrounding
the garden will keep deer out. It was reported that the deer didn't
like something about the pigs (smell, size, or sound) and avoided
the garden and pig pen until the pigs were removed.
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Cultural Methods
Deer damage to landscape plants and flowers usually occurs when
the deer's natural browse is low, generally in the late fall through
early spring. By choosing species that are undesirable to deer,
you can reduce the amount of damage to these plants. Plants with
a bitter or spicy taste, milky sap, or thorny, hairy, or tough leaves
and stems are unpalatable to deer. However, the presence of undesirable
plants does not deter deer from feeding on other nearby plants that
they do find palatable. If there is intensive feeding pressure caused
by drought or snow or a high deer density, deer will browse even
the most undesirable plants, and other methods will be necessary
to control damage.
For more information on deer-resistant plants, see the publications:
Controlling
Deer Damage in Missouri, and Resistance
of Ornamentals to Deer Damage (PDF / 1.10MB).
Many other states have publications listing additional deer resistant
plants that are more adaptable to the region. Three of these sites
are Texas' Deer
in the Urban Landscape, Montana's Deer-resistant
Ornamental Plants for Your Garden, and Colorado's Preventing
Deer Damage.
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Scare Devices
Methods for frightening or hazing deer may be effective and economical
in some situations, especially at the first sign of a problem. Once
deer establish a pattern of movement, it is difficult to get them
to change. Propane cannons or gas exploders set to detonate at irregular
intervals are the most common scare devices, and they are sometimes
available for loan from wildlife refuges or wildlife agencies. Strobe
lights and sirens can also be effective; even fireworks and gunfire
can be used as a temporary method. Playing a radio that goes on
and off during the night will work for a short time, as will attaching
a sprinkler system or lights to motion detectors. The problem with
all scare devices is that deer become accustomed to them within
a week or two, even when the devices are moved occasionally. Varying
the scare devices every week may extend the protection for a longer
period. Scare devices are usually a great short-term solution, but
don't depend on them for a whole growing season.
Dogs
Another scare option is the use of dogs that are kept behind an
"invisible" fence by the use of a radio transmitter, an
underground copper wire, and a special dog collar with receivers.
Stationed inside the invisible fence, the dogs chase the deer out
of the dogs' territory. The collar, when activated by the underground
wire, first gives an audible signal, and if the dogs don't stop
they receive a mild, harmless shock. The dogs must be trained to
heed the signals. Placing the dogs' kennel and water in one area
and the food in another area may help keep the dogs moving around
their territory.
The Cornell publication Managing White-Tailed Deer in Suburban
Environments: A Technical Guide suggests that the effective
area covered by 2 dogs behind invisible fence is about 60 acres
or 500 yards from their kennel during the summer. The area is reduced
to about 10 acres during winter, when snow restricts the movement
of the dogs, though snowfall doesn't affect operation of the electronics.
(DeNicola et al., 2000)
The same publication cautions that care and feeding of the dogs
can be time-consuming and that a family pet may not provide adequate
protection, because it is not patrolling all the time. The authors
explain: "The breed and disposition of the dog will influence
effectiveness of this technique. Large dogs that aggressively patrol
the area appear to work best. The complete protection of plant materials
should not be expected, as deer react to dogs similar to other scare
devices or repellents." (DeNicola et al., 2000)
(Ordering information for this publication is provided above in
the Exclusion section.)
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Repellents
Repellents are best suited for high-value crops in orchards, nurseries,
and gardens. High cost, limitations on use, and variable effectiveness
make most repellents impractical on row crops, pasture, or other
large areas. There are two kinds of repellents: contact and area.
Contact repellents are applied directly to the crop plants and repel
by taste. Some of these contact repellents use inedible egg solids
to repel deer, while others are derived from cayenne pepper extract
and cannot be applied to the edible portion of the crop because
they will leave a hot taste. Repellents made from rotten eggs have
worked better than several other products in an Alabama Experiment
Station test. (Anon., 2000) Area repellents
are applied near the plants to be protected and repel deer by smell
alone. Some area repellents use ammonium soaps of fatty acids, bone
tar oil, and/or putrefied meat scraps. Bags of human hair and suspended
bars of ordinary hand soap can also be used as area repellents for
deer.
The deer's learning ability causes many repellents to fail over
time. A good way to counter such acclimation is to switch repellents
periodically and to alter their positions near the crop. But as
with planting unpalatable ornamentals, remember that hungry
deer will ignore both taste and odor repellents.
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Culling or Harvest
Culling the animals is another management option. Some states issue
permits to landowners to shoot deer outside the normal sport hunting
season. Only those animals that are damaging crops can be removed,
and such permits are often publicly controversial.
Sport hunting can reduce deer populations and damage over larger
regional areas. To be effective over the long term, does (female
deer) must be removed from the deer population. A "bucks-only"
deer hunt does little to reduce the deer population or the damage
done by overpopulated deer herds. Landowners can reduce the deer
population in their area by soliciting hunters who have "either-sex"
deer permits and who will shoot does. By allowing hunting, landowners
can provide controlled public access to a recreational resource
while reducing deer damage.
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Deer Feeding
A 36-page educational booklet entitled Feeding Wildlife...Just
Say No! is available from the Wildlife Management Institute.
This publication helps explain why supplemental feeding of big game
is costly and rarely beneficial to wildlife in the short or long
run. It helps explain to the public why wildlife should not be fed,
particularly during winter and other times of stress. (Anon.,
2001) The booklet is available for $3.25 per copy postpaid from:
WMI Publications
P.O. Box 34646
Washington, DC 20043
(202) 371-1808; Fax: (202) 408-5059
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Conclusion
The value of the crop, the amount of deer pressure, and other variables
will affect the suitability and cost effectiveness of various deer
control practices. Check with your state's appropriate wildlife
or natural resource agency on any game regulations that may restrict
your deer management choices.
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References
Anon. 2000. Rotten deer repellents.
Organic Gardening. July–August. p. 15.
Anon. 2001. Wildlife feeding booklet
a huge hit. Outdoor News Bulletin. July 16. p. 4.
Associated Press. 2000. Deer
population posing problems. Environmental News Network Web site.www.enn.com/news.
October 15. 2 p.
Brennemen, R. 1983. Use of electric
fencing to prevent deer browsing in Allegheny hardwood forests.
Eastern Wildlife Damage Control Conference. Vol. 1. p. 97–98.
Bye, Muriel. 2000. Easy,effective
deer control. Organic Gardening. May–June. p. 66.
Caslick, J. W., and D. J. Decker.
1979. Economic feasibility of a deer-proof fence for apple orchards.
Wildlife Society Bulletin. Vol. 7. p. 173–175.
DeNicola, Anthony J., Kurt C. VerCauteren,
Paul D. Curtis, and Scott E. Hygnstrom. 2000. Managing White-Tailed
Deer in Suburban Environments: A Technical Guide. Cornell University.
147IB245. 52 p.
McAninch, J. B., M. R. Ellingwood,
and R. J. Winchcombe. 1983. Deer damage control in New York agriculture.
New York State Department of Agriculture and Markets, Division of
Plant Industry, Albany, N.Y.
Mullen, Matt. 2002. Oh, deer. Farmer's
Digest. June–July. p. 84–87.
Pierce II, Robert A., and Ernie
P. Wiggers. 1997. Controlling deer damage in Missouri. University
of Missouri–Columbia. MP685. November 1. 21 p. http://muextension.missouri.edu/xplor/miscpubs/mp0685.htm.
Williams, Greg, and Pat Williams.
2002. Fenceless deer fencing? HortIdeas. March. p. 32.
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Enclosures
Kays, Jonathan S., Lisa Curtis, and Michael V. Bartlett. No date.
Resistance of ornamentals to deer damage. Maryland Cooperative Extension.
Fact Sheet 655. 8 p. www.agnr.umd.edu/MCE/publications/PDFs/FS655.pdf.
(PDF / 1.10MB)
Pierce II, Robert A., and Ernie P. Wiggers. 1997. Controlling deer
damage in Missouri. University of Missouri–Columbia. MP685.
21 p. http://muextension.missouri.edu/xplor/miscpubs/mp0685.htm.
Deer Control Options
By Lance E. Gegner
NCAT Agriculture Specialist
Paul Williams, Editor
Cole Loeffler, HTML Production
CT 131
Slot 105
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