During the winter months, deer consume evergreen and dry leaves, as well as dormant buds. In the spring and summer, they eat new growth on woody and herbaceous plants. From late summer to early winter, fruits and nuts compose a large part of a deer’s diet.
The white-tailed deer is one of the most widely distributed and well-known mammals of North America, and it is a common species throughout Pennsylvania. Deer prefer early successional forests that are in the shrub-tree sapling stage. They are also abundant in agricultural areas where field crops and orchards are interspersed with forest habitat.
General biology and behavior
Deer are most active during early morning and evening hours. They have a home range of several hundred acres, but this varies with season, habitat, sex, and even individual characteristics. Whitetails are creatures of habit; most use the same home range year after year. They also tend to establish one part of their home range as a feeding area, and another part for resting. For instance, if deer establish an orchard as a source of food, they will habitually move into the area a little before sunset to feed, and move back to the woods before dawn to rest.
White-tailed deer can mate from September to late January. Adult bucks are polygamous, mating with as many does as possible. A doe's reproductive ability is influenced by her age and nutritional condition. Adult does will usually bear twins, while younger does more often bear single fawns.
Deer cause damage to orchards year-round, but the most serious damage occurs in the winter months when the availability of natural foods is limited. Dwarf, semidwarf, and young standard fruit trees are the most susceptible because most of the tree is within reach of the deer. In winter, browsing on dormant terminal buds may lead to stunted or misshapen growth in standard fruit trees under 3 years old. Browsing on fruit buds of dwarf and semidwarf trees may lower fruit production. In either case, severe winter browsing can reduce tree vitality and even cause death.
During the spring and summer, natural sources of forage are readily available to whitetails. However, they may browse new growth on orchard trees and eat ripening fruit. In autumn, deer may continue to browse and eat fruit within the orchard. Additionally, they can cause severe damage by rubbing their antlers on trees. This can result in broken limbs, girdling of the trunk, and subsequent death of the tree if the deer removes enough bark.
The extent of damage caused by deer can be monitored through direct and indirect observation. They may be caught "in the act" during active periods of evening and early morning. Indirect observation means recognizing signs that deer leave behind. Whitetails selectively browse leaves and twigs from various plants, but prefer some species over others. In spite of this preference, they may heavily browse one plant while ignoring another of the same species that is close by.
Lacking upper incisor teeth, deer characteristically tear off vegetation, leaving jagged edges that you can use to identify browsed trees. In comparison, browsing by rodents and rabbits leaves a clean-cut surface.
However, the height of the damage may be all you need to eliminate any mammal other than deer. Another method for determining deer as the source of damage is to search for tracks. They leave a distinctive split-hoofed track that can easily be seen in damp soil or snow. Monitoring your orchard for damage is an important, ongoing process and the first step in a successful management plan.
Effective management begins by anticipating the extent of damage by regularly monitoring deer signs and responding with the appropriate control.
Before deciding on a control method, if any, you should consider the cost benefits of the control program. If the damage you incur is economically greater than the cost of a control measure, you should apply the control measure. In most instances, an integrated pest management (IPM) plan is the best approach. This strategy combines ongoing population management of the local deer herd with either repellents or fencing, depending on the extent of damage.
In Pennsylvania, the game commission is authorized to manage the size of the deer herd through regulated hunting of antlered and antlerless deer. As a landowner, you should encourage hunting in your area, especially if your orchard is subject to heavy deer damage. Posted areas that are closed to hunting serve as refuges for deer during the hunting season and may compound the damage to an orchard by concentrating the deer population.
If a commercial orchard is your primary means of gaining a livelihood, those members of your immediate family living on the premises, as owner, lessee, or tenant, as well as any hired help regularly and continuously assisting in the cultivation of the land, may hunt without a license during regular hunting season on the property, and on detached lands that are operated under written lease as part of the same operation. This applies only to persons who are otherwise eligible to be issued a hunting license. Consult your local wildlife conservation officer for information on opening your land to hunters, or on eligibility requirements for hunting.
To assist hunters in locating land that is open to public hunting, the Pennsylvania Game Commission maintains a detailed map that shows the location of all private landowners that are enrolled in any of the agency's public access programs. If you are not currently enrolled in the Safety Zone, Forest Game, or Farm Game Cooperative Program, please contact your local wildlife conservation officer to find out details about each of these public access programs. For more information on the public access programs or to view the statewide map detailing these properties, visit the game commission website.
The Red Tag Program is a special permit for deer control related to agricultural depredation. Applications for the deer control permits provided under this program are obtained through the local wildlife conservation officer. Applications are accepted only from landowners who have been enrolled in one of the commission's public access programs (Farm Game Project or Safety Zone) for a minimum of two years and are currently enrolled in the program. The permit authorizes the landowner (permittee) to enlist the aid of licensed hunters (sub-permittees) who are not associated with the farm to come on the property and harvest depredating deer. The permit is valid for antlerless deer only.
The Deer Management Assistance Program (DMAP) is designed to help landowners manage deer numbers on their properties. Qualified landowners participating in DMAP receive a limited number of coupons (determined by acreage) that they may make available to hunters. The coupons are then redeemed for a DMAP anterless deer permit to hunt on the property for which they were issued.
Even though your land is open for hunting, you may still experience problems with deer when they are no longer in season. Because of this, you may be eligible to kill any deer witnessed to be causing or about to cause damage to your orchard, outside of the regular hunting season. You must contact your local wildlife conservation officer when you plan to shoot deer. There are procedures and regulations that you must follow if you are planning to protect your orchard in this manner. If the property is open to hunting, the orchard owner may keep one deer for personal use; all other deer must be field-dressed and turned over to the game commission. If the land is not open to hunting, all deer must be field-dressed and turned over to the game commission. Be sure to contact the local wildlife conservation officer before you act to ensure complete understanding of all the regulations.
Repellents are most effective when integrated into an IPM plan that includes population management. If you have had damage in the past, apply repellents before the first sign of damage to prevent deer from establishing a feeding pattern at the site.
There are two types of repellents: area and contact. Area repellents repel deer by odor and are applied close to plants in need of protection. By applying the repellents along the orchard borders, you can protect many trees at a relatively low cost. Area repellents include tankage (putrefied meat scraps), ammonium soaps, bone tar oil, blood meal, and human hair.
Contact repellents work by taste and must be applied directly on the plant. These repellents work best if you apply them in the dormant season on dry days when temperatures are above freezing. Examples of contact repellents are putrescent egg solids, thiram, kaolin clay, and hot pepper sauce. Remember, whenever you apply a commercial repellent, the law requires strict compliance to the label. Hinder (ammonium soap) and Deer Stopper (certified organic food product) are currently the only products registered for use on edible plant materials.
Repellents have variable results; what works for one grower may not work for another, and success differs from year to year. Some repellents do not weather well and require repeated applications during the season. Also, if deer are very hungry and the area lacks other, more palatable food resources, they may ignore the repellents. Success must be measured by how much the damage has been reduced, since it is rarely eliminated. In areas where deer density is low and damage is light, repellents may be a cost-effective part of your IPM strategy.
Fencing deer out of the orchard is the most efficient way to reduce damage when deer density is high and damage extensive. The conventional 8-foot woven-wire fence effectively excludes deer by forming a barrier around the orchard. The fence consists of two widths of 4-foot woven wire and 12-foot posts. To prevent deer from crawling under, keep the wire close to ground level. Unfortunately, deer-proof fencing is expensive, but it is effective, long lasting, and requires little maintenance. High tensile wire is recommended.
An alternative to barrier fencing is the use of an electric fence. This type of fence is designed to change the deer's behavior. Although deer can easily jump an electric fence, they will instead try to go through or under. An electric fence takes advantage of this behavior and successfully trains the deer to stay 3 to 4 feet away from the wires. Adding an attractant such as peanut butter on aluminum strips will entice deer to touch the fence with their mouth and nose. Touching the fence with sensitive tongue and lips will aid in training them to avoid the fence.
Researchers at Penn State have developed a low-cost, five-wire electric fence. Through tests conducted statewide, the design has shown to be an adequate means of deer control. The fence incorporates high-tensile steel wire; in-line wire strainers; and high-voltage, low-impedance energizers. High-tensile fence can absorb the impact of deer and tree limbs, thereby eliminating some of the problems associated with softwire fences. In addition to Penn State's five-wire fence, other high-tensile electric fence designs are available.
The disadvantages of electric fences are that they require high maintenance and regular inspections.
You must maintain a 6- to 8-foot mowed strip along the fence perimeter to discourage deer from jumping and to decrease the weed load on the fence. You must also check the electric current regularly to ensure that the shocking power is sufficient for turning the deer. The advantages include a relatively low cost and, when properly maintained, a long-lasting fence.
Some growers have successfully protected their orchards by keeping dogs within the orchard. Deer tend to avoid these orchards because of the dogs, and any that do enter are chased out. The dogs are kept in the orchard by an invisible electric fence. Growers who want to obtain food safety certifications - Good Agricultural Practices (GAP) - are no longer using this management option.
Source: Penn State Tree Fruit Production Guide.
Sources of supplies
Most nurseries and home centers sell commercial repellents and fencing materials. Some companies that manufacture repellents and the product they supply are listed below.
PO Box 5277
Janesville, WI 53547-5277
Bonide Products, Inc.
6301 Sutliff Rd
Oriskany, NY 13424
(Repellent and Bulb Saver)
Messina Wildlife Management
55 Willow Street, Suite 1
Washington, NJ 07882
Miller Chemical and Fertilizer Corp.
Box 333, 120 Radio Road
Hanover, PA 17331
(Hot Sauce Animal Repellent)
Nott Products Co., Inc.
PO Box 975
Coram, NY 11727