UMass Extension Vegetable Program

Preventing Deer Damage

Introduction

White-tailed deer (Odocoileus virginianus) are widespread, abundant, and increasing both their numbers and range in North America. In Massachusetts, our best estimate puts the 1999 population at about 85,000 statewide. In some parts of the state, particularly southeastern Massachusetts, the population is increasing by 15% per year. Deer are tremendous opportunists, eating well over 700 species of plants. They have adapted very well to human development of the landscape. Indeed, the types of habitat that have been and are being created in suburban eastern Massachusetts provide near optimum conditions for deer. Interspersed housing developments, with planted gardens and ornamental shrubs, woodlots, and small farms, orchards, and nurseries provide a mix of food, cover, and security that were rare in pre-colonial Massachusetts.

Deer require large amounts of food during the late spring, summer, and fall. Normal adult deer will eat anywhere between 6 and 10 pounds of food per day during the growing season. Contrary to popular opinion, deer are not grazers and can not digest grass very efficiently, with the exception of new shoots in early spring. When seen "grazing" in fields they typically selecting weeds and broad-leaved plants not eating grass. This places most planted crops at risk to damage from deer. Some of the crops most susceptible to damage are pumpkins, squash, beans, peas, lettuce, strawberries, and most other fruits and the plants that bear them, including grapevines. There is no provision in state law or regulation for compensation to landowners for deer damage. Thus, it is to the benefit of landowners to try to prevent crop damage by deer before a significant problem develops.

Damage caused by deer is usually easy to identify. Deer tracks are the familiar cloven-hoof type. Because deer do not have upper incisors, they tear plants when they browse them, rather than making a clean cut like a woodchuck or rabbit. Deer will also gnaw pumpkins and squash, leaving tooth marks in the fruits that can eventually rot.

Fencing

Fencing, the construction of a barrier between the crop and the deer, is the most effective long-term solution to deer damage. The basics of fencing apply to both electric and non-electric fencing. It is important to understand that deer can easily jump a fence 10 feet high, but much prefer not to. Deer prefer to go under or through a fence than to jump it if at all possible. Thus, the bottom wire of an electric fence should be no more than 10 or 12 inches off the ground and non-electric fences should either have an even lower bottom wire (about 6 inches) or be of mesh construction.

Fence maintenance is critical in both applications. If a tree falls on the fence or a hole is cut in the fence, the fence should be repaired immediately. Once deer have gotten inside and discovered the crop, it will be harder to keep them out, even with an electric fence. No gaps should exist in the fence, access must be provided through gates that are closed at all times. Fences should have a clear perimeter, at least 5 or 6 feet on the outside of the fence, so deer have to cross an opening before encountering the fence. This also enhances visibility of the fence to the deer. Deer will blunder into a fence placed tight to a wooded edge and can actually damage or take down sections of a fence simply because they do not see it very well, especially smooth wire designs. Having a clear border will increase the effectiveness of the fence and aid in maintenance.

Electric fencing

Electric fencing need not be a tremendously costly remedy to deer damage. Many small fields can be protected by portable units that can be put up and taken down in half a day. Larger farmers and orchards may want to invest in permanent fences, but even here costs can be reduced by using solar chargers and having clear perimeters.

For small fields of a few acres or less, portable fences either of regular electric wire or a product called "Hot Tape" will provide relief from deer. Hot tape is a wide, colored tape with several wires embedded inside. It enhances protection by being very visible to deer, even at night, while providing an electric shock on contact. As few as two strands of electric wire can be used to protect crops if it is put up immediately after planting, it is baited initially (explanation to follow), it is always "hot", and is maintained properly (e.g., do not let weeds or grass grow up into the fence). The effect that being shocked by an electric fence has on deer behavior and their subsequent avoidance of the fence allows a landowner to use a lower fence than in the non-electric case. Baiting the fence is quite simple but enhances the deterrent powers dramatically. Deer are extremely well-insulated over most of their body with fur. Couple that with their tendency to go under or through a fence, where they are most likely to contact the fence with their back or neck and it is easy to see how deer can penetrate an electric fence and not be shocked too badly.

Baiting the fence, usually with a metal tab smeared with peanut butter, will make the deer contact the fence with it’s nose and tongue, wet parts that will conduct the electricity quite well. This first contact and the resulting shock on sensitive parts will educate a deer to respect the fence for quite some time. Obviously, the fence must be off to apply the tabs and bait, but turn it on immediately upon finishing. Space the tabs about 30 feet apart and keep the fence baited for several weeks after the fence is installed. When the deer have become acquainted with the fence the baits can be removed if desired. However, deer will occasionally test a fence that has shocked them and new deer may enter the area so keeping the fence baited is not a bad idea. Most important is to keep the fence hot at all times. Deer will try to go under or through the fence, thus keep the bottom wire 10 to 12 inches above the ground. In a two-wire fence, the second wire can be at a height of 30 to 36 inches above the ground. A three-wire fence can have strands at 12, 24, and 40 inches. Keep in mind that adult deer are about 36 inches at the shoulder. Fence posts do not need to be as stout as with the non-electric fence. Fiberglass posts driven into the ground at 30 to 40 foot intervals, close enough to keep the fence from sagging are adequate. It is the electric shock that provides the deterrent here, not the strength of the fence. Electric fence supplies can be found at farm supply centers or through fencing specialty companies. Three fencing specialists in the Northeast are:

Wellscroft Farm
167 Sunset Hill
CheshamHarrisville, NH 03450
(603) 827-3464

Kiwi Fence Systems
1145 E. Roy Furman Hwy.
Waynesburg, PA 15370
(724) 627-5640

Walnut Grove Farm
50 Cartland Rd.Lee, NH 03824
(603) 659-2044

Non-electric fence

The non-electric fence does not work as a behavioral barrier to deer the way the electric fence does; thus it needs to be constructed differently. To be effective, these fences should be a minimum of 8 feet tall. There are two styles to consider: smooth wire strands or mesh. The mesh can be either woven wire or plastic mesh, both will work well. Non-electric fences usually are permanent structures. Because the wire needs to be tensioned, the fence posts must be very secure and corners constructed carefully. Here the fence itself provides the deterrent. Deer will attempt to push through a non-electric fence and are strong enough to exploit weaknesses in fence design. The result will be a break in the fence and crop damage.

Many designs exist for non-electric fencing. For stranded wire, they involve gradually increasing distances between wires as the height of the fence increases. Again, this is because deer prefer to go under or through a fence and are not likely to jump through the top strands. Keep the spacing between the lowest strands (below four feet) to no more than 10 inches, with the bottom strand about six inches above the ground. The strands above four feet can be spaced at 15 to 20 inches. Attaching streamers or flagging to the strands increases the visibility of the fence and provides an additional deterrent. Woven wire or mesh designs are used extensively at captive deer facilities to keep deer inside pens and do just as good a job keeping deer out. The woven wire designs typically have small spaces at the bottom and progressively larger spaces toward the top. Mesh construction may be easier to maintain than stranded wire and more resistant to the attempts of deer to push through. In places where appearance is a concern, heavy-duty plastic mesh, usually black in color, can be used.

Repellents

Repellents are advertised to reduce deer damage by making the target crop taste or smell unpalatable to deer. For most problems they do not work. All repellents are billed to reduce, not eliminate, deer damage. To achieve this reduction, they must be consistently applied and reapplied as directed. If applied after deer damage has occurred, repellents likely will not repel deer from something they have already eaten. Given the amount of effort required to use repellents according to instructions, fencing is almost always a better option.

Dogs

The use of dogs to harass deer from crops has limited applications. Most jurisdictions have laws regarding unleashed dogs. The Massachusetts Division of Fisheries and Wildlife has had a restraining order in effect statewide since 1977 prohibiting dogs from running at large. Deer quickly acclimate to restrained dogs, determining that they are not a threat and feeding as normal, even within feet of the dog.The development of invisible fencing systems for dogs may allow dogs to be more effective at harassing deer from specific properties if the dog will respect the fence when pursuing a deer. The invisible fence system consists of an electric wire buried at the property perimeter and a collar on the dog. As the dog approaches the wire, it gets an electric shock. The shock gets stronger as the dog gets closer to the wire. The difficulty with this approach is that not all dogs will respect the fence while in pursuit of a deer and will cross the boundary, running the deer through adjacent properties.

Harassment

Harassment is not an effective long-term solution to deer damage problems. Deer quickly acclimate to noise-making devices like propane cannons placed in fields, radios, lights, and other ingenious inventions. If protection is only desired for a week or at most two weeks, harassment may serve the purpose. However, in high-noise areas, deer may acclimate more quickly and only respond to the harassment for a few days.

Shooting

Property owners in Massachusetts are entitled to destroy deer causing property damage under Massachusetts General Laws chapter 131, section 37. No permit is required. Note that this does not allow a property owner to use an artificial light to take deer at night. A permit, from the Division of Fisheries and Wildlife, is required to use a light to take deer at night. The law is very specific as to who can destroy deer. It must be the property owner (or tenant), the immediate family of the owner (or tenant), or permanent employees of the owner (or tenant). A property owner can not hire a contractor or agent to kill deer and can not have other unpaid persons kill deer outside of the legal hunting seasons. The Division of Fisheries and Wildlife, the Division of Law Enforcement (Environmental Police), and local or state police can not destroy deer for property owners. Deer killed under this law must be surrendered to the Environmental Police (call 800-632-8075) and a written report submitted to the Division of Fisheries and Wildlife within 24 hours (Deer Agent, MassWildlife, Field Headquarters, Westboro, MA 01581 or FAX 508-792-7275).In most cases shooting deer does not solve the long-term problem of deer damage. It may make the property owner feel better that some action was taken, but in reality little will be accomplished. A few individual deer may be killed but not all of them. What is most likely to happen is the remaining deer will simply change their habits to come to the crops at different times or after dark.

Hunting

Hunting differs from shooting in that hunting is conducted by licensed hunters during the regular statewide hunting seasons. Thus, in effect, hunters pay for the privilege of controlling deer. Hunters are entitled to keep the animals they kill and must have them tagged by the Division of Fisheries and Wildlife within 48 hours. Hunters must obey state regulations regarding bag limits and weapons. Hunting should be viewed as a way to control local deer populations for the long-term. Hunting season dates and bag limits can change from year to year, so it is best to consult the Division of Fisheries and Wildlife if there are questions about a particular location.

Several general laws and regulations apply to hunters in Massachusetts. It is unlawful to discharge a weapon (gun or bow) within 500 feet of a building in use without the permission of the owner or occupant. It is unlawful to shoot within 150 feet of a road. During shotgun season, hunters must wear at least 500 square inches of "hunter orange" clothing on their head, chest, and back. These laws have made hunting one of the safest participatory outdoor activities. Massachusetts usually has fewer than 6 hunting accidents during the deer seasons each year, rarely a fatality, and non-hunters are almost never involved. Normally, when a hunting accident does occur it is either self-inflicted, the result of careless gun handling, or the result of a law or regulation being broken.

In Massachusetts, the basic limit for deer hunters is two deer per year, however, some Deer Management Zones (DMZs) have higher limits. During the archery season hunters can take one antlerless deer (no permit required). During the shotgun season a DMZ-specific permit is required to harvest an antlerless deer. In certain DMZs hunters can purchase more than one antlerless deer permit. During the primitive firearms season, in most DMZs, hunters can again harvest one antlerless deer without a permit (provided they have not already taken one during the other seasons). The key to any successful hunting program that is intended to control numbers or reduce damage locally is harvesting adequate numbers of antlerless deer (the term antlerless is used instead of female because hunters intending to kill females will take a percentage of male fawns, without visible antlers). Bucks eat crops, too, but without controlling the female component of the herd, hunting will not succeed in limiting crop damage. Some hunters may be resistant to taking antlerless deer, especially if an area has not been hunted for some time. The landowner who gives permission to hunt should demand that hunters kill antlerless deer before taking antlered deer, provided the hunters are legal in doing so. Hunting of deer during the regulated seasons can help to reduce local densities of deer and reduce crop damage. As with other techniques, hunting works better as a preventive measure than a reactive measure. That is, by allowing hunting on a farm before deer damage is severe, a farmer may prevent severe damage in the future. Conversely, if deer numbers are allowed to build to high levels, damage is severe and persistent, and then hunting is allowed, hunters likely will not be able to take enough deer to reduce damage during the growing seasons.

This information is for educational purposes. The recommendations contained here are based on the best available knowledge at the time of printing. Any reference to commercial products or trade names is for information only, and no endorsement or approval is intended. Always read the label before using any pesticide. The label is the legal document for product use. Disregard any information in this fact sheet if it is in conflict with the label
 

John E. McDonald, Jr., Massachusetts Division of Fisheries and Wildlife, Westboro, MA
Craig S. Hollingsworth, Department of Entomology, University of Massachusetts