This report is hardly a cure-all for every farmer, tree nursery owner, gardener, part-time landscaper, or orchard operator contending with white-tailed deer. Rather, it's a combination of ideas and recommendations that may help people more comfortably live with deer.
Beyond the discussion of means of mitigating deer impacts, this document makes an implicit appeal for humans to exhibit greater tolerance for wildlife. Historically, people have routinely killed -- by shooting, trapping, or poisoning -- wildlife as a matter of convenience, as a way of dealing with a conflict. Such prejudice and intolerance for wildlife is, however, less acceptable today. The ethical challenge is to secure our convenience and our livelihoods and to let wild animals live in peace.
It is axiomatic that wild animals -- in the course of their search for food, shelter, and other daily needs -- will have an impact on people. Chipmunks, for instance, are notorious for unearthing freshly planted bulbs. Squirrels find their way into partitions and attics. Field mice prefer the lower chambers of the household -- eventually moving into basements. And skunks and raccoons tip over garbage cans to gain the goods. Sometimes wildlife come in bigger, and seemingly more dangerous, packages. Yet people, in many instances, have demonstrated a remarkable ability to live with these animals. Alaskans adjust to brown bears and moose traveling through their backyards at night. In Florida, people have learned to have alligators safely removed from swimming pools and transplanted unharmed back into area swamps and rivers. And even in some housing developments in the Pocono Mountains of northeastern Pennsylvania, residents live harmoniously with black bears, by doing such things as placing their refuse in bear-proof garbage cans.
In between the squirrels and the bears -- in size and abundance -- is the white-tailed deer. Principally, because of wildlife management practices designed to increase deer numbers and land use practices that result in the creation of suitable deer habitat, more deer may now inhabit the eastern half of the United States than at any time in the past 150 years.
Of course, many people are fond of deer, cherishing an opportunity to catch a glimpse of the graceful creatures. Others, however, claim they are little more than overgrown pests, browsing vegetation and crossing roads. Such polar views inspire the debate over deer management. Specifically, while some people claim deer should receive protection, others claim they must be hunted.
Deer are the smaller-sized, but the wider-ranging relatives of elk and moose in the United States. While moose inhabit the northernmost states (WA, OR, ID, MT, ND, WY, CO, MN, WI, MI, NY, VT, NH, ME) and elk in the western states (WA, OR, CA, NV, AZ, NM, CO, UT, ID, MT, WY, ND, SD, NE, OK, KS), deer inhabit every state except Hawaii. From sitka deer in Alaska to sika deer in Maryland, from black-tailed deer in Oregon to white-tailed deer in Iowa, and from mule deer in Arizona to key deer in Florida, deer in slightly varying sizes and colors, are America's widest ranging large mammal.
Some subspecies are, of course, less wide-ranging than others. The key deer, for instance, is close to extinction, with only slightly more than 100 individuals surviving; for them, the key to survival is more habitat and less direct killing by poachers and automobiles. Like Florida's diminutive deer subspecies, the Columbian deer, which inhabits the Pacific Northwest, is also a federally listed endangered species. But there is often more talk of the abundance of deer than of their scarcity. The white-tailed deer, for instance, which inhabits all areas of the Rocky Mountains, numbers in excess of 15 million individuals nationwide (including 4 million in Texas). There may be as many as 5 million mule deer, which mull around the Rockies and other portions of the western landscape.
One of the most controversial issues within the field of wildlife management concerns deer hunting. People often confuse issues when discussing deer hunting in particular. While it is clear that deer can sustain an annual kill and not be severely depleted, that is not the same as saying that deer must be hunted.
In fact, it is clear that many land areas across the United States -- varying in size and location -- maintain healthy deer herds, but no deer hunting. For instance, the Natural Park Service -- which manages 80 million acres of land -- generally operates with a no-hunting credo (except for some large land areas in Alaska). Acadia, Shenandoah, Everglades, Big Bend, Voyageurs, Rocky Mountain, Yellowstone, Glacier, Grand Canyon, and Sequoia are just a few national parks where deer hunting is outlawed.
Also, deer reside on hundreds of smaller-sized areas, such as state and city parks, where no deer hunting is permitted. Such areas occur in all regions of the country, from the Pacific Northwest to the Southeast to the heart of the Mid-West. These land areas provide ample evidence that there is no absolute biological need to have human hunters kill deer.
Not surprisingly, deer densities -- as influenced by climate, vegetation, composition, forest maturity, and abundance of predators -- differ by region. For instance in Vermont, where the growing season is relatively short and winters can be severe, deer densities are rather low: 10 deer per square mile on average. In the West, especially west of the 20-inch rain line, water is more of a limiting factor, especially as it affects the vegetative community, and deer densities are correspondingly low. In the mid-Atlantic states, however, where winters are not severe, where human suburbia creates "edge" habitat, and where few predators exist, deer densities can be significant: more than 30 deer per square mile.
Though deer densities may be relatively high in certain regions, it does not follow that hunting must be employed to limit deer numbers. Ultimately, natural regulating factors will limit deer numbers in those regions as well. For instance, deer populations are limited by a variety of decimation factors, death by disease, extreme heat or cold, parasites, predation, or starvation. If some of those factors do not exert a significant impact in a particular region (e.g. absence of predators), the other factors exert a proportionately greater influence.
Populations do not maintain equilibrium, however, just by the death of individuals. Surviving deer also decrease their rate of reproduction under less than ideal conditions. For instance, rather than produce twins or triplets, does will produce a single fawn or won't produce at all. This phenomenon is not exclusive to deer. Outside of Yellowstone National Park, where coyotes are hunted, trapped, and poisoned, females produce six to eight pups per litter. Inside Yellowstone, where they are protected, coyotes produce two to four pups per liter. It's nature's way of tightening the reproductive faucet.
Deer demonstrate some other noteworthy reproductive strategies to limit their numbers. John Ozoga and Louis Verme of the Michigan Department of Natural resources point out that does will bear more males than females in times of stress. This alteration of normal sex ratios decreases the reproductive potential of the population; obviously, males do not bear young. Thus, the fewer the number of females in a population, the less reproductively capable the population.
The point is, nature ultimately regulates deer numbers. As stated in White-Tailed Deer Management and Ecology, the bible of deer management for wildlife managers, "Most wildlife biologists and managers can point to situations where deer populations have not been hunted yet do not fluctuate greatly nor cause damage to vegetation. Certainly deer reach overpopulation in some park situations, but the surprising thing is how many parks containing deer populations have no problem."
There are, however, select circumstances when deer do have a visible impact on a forest community. Generally speaking, the deer are not reducing plant biodiversity, but reducing plant biomass. Some noted ungulate ecologists point out that such impacts are short term. Says Dr. Grahaem Caughley, "I do not know of any system dislocated permanently by a bout of overpopulation. The phenomenon is temporary and its remission spontaneous. Most treatments of overpopulation are justified by a dire prediction of what might have happened had the treatment been withheld. A more convincing case would be made by demonstrating that the effects of untreated abundance is irreversible."
Thus, the question of deer management is not one of the biological carrying capacity, but of the cultural carrying capacity -- how many deer will people tolerate in their environment? Of course, this depends not so much on the behavior of the deer population, but on the options of the human population. Two people, for instance, may view a deer eating a yew in the backyard in an entirely different manner. One person may be happy that his or her backyard is providing food for a deer. Another person may be angered that "his" yew tree is being aesthetically damaged by deer browsing. Fundamentally, it is a question of attitude, not science. Ungulate ecologist Caughley sums up the controversy: "Is containment of an eruption (dramatic rise in deer numbers) necessary? That is a scientific question and I interpret the evidence available as implying that it is seldom or never necessary. Is containment of an eruption desirable? That is not a scientific question. I can boast no qualifications that would make my opinion any more valuable than those of my two immediate neighbors, a garage mechanic on one side and an Air Vice-Marshall on the other."
Just like any wild animal, deer will behave in ways that occasionally inconvenience people. Expensive ornamental plants used to enhance the value of a home and to increase the landscaping aesthetics can be planted one day only to be severely browsed overnight by local deer. After long hours of work to produce a small vegetable crop, gardeners can have their broccoli, corn, beets, carrots, and other vegetables eaten by deer. Still other people plant a few fruit trees for the fruit as well as a hobby. These, too, can be heavily damaged by local deer in a short time. And, people who move to the country may not be accustomed to watching for deer while driving the roads. As a result, deer-auto collisions can occur.
These concerns are ineradicable, as long as we choose to allow wildlife to live in our midst. In some areas, these problems can seem severe. In Pennsylvania, for instance, vehicles struck an estimated 40,000 deer in 1990. Deer browsing of ornamentals around New York was estimated to cost homeowners hundreds of thousands of dollars per year in the mid 1980s. And landowners in certain parts of Rhode Island have complained in recent years that growing simple vegetable gardens is almost an impossibility.
Even though these problems appear to be on the increase, there is no reason to think that such problems cannot be reduced to a significant degree. Many people comfortably live in regions highly populated by deer. These people maintain beautiful ornamentals and bountiful vegetable gardens and safely drive rural roads. These people have learned to tolerate deer and to cope with the limited way in which they inconvenience our lives.
An understanding of animal behavior will put you on the path in resolving your problems. Keep in mind that deer are opportunistic feeders, capable of utilizing hundreds of plant species and incapable of recognizing property boundaries. As such, any new home that's built in prime deer habitat that also has ornamental plants, a garden or other preferred deer foods will eventually be investigated and tested. If the deer like the human-modified environment, they will establish a feeding pattern.
A second reason why a new homeowner may experience severe deer damage to his or her planting relates to the surrounding habitat. For example, a mature forest is not deer habitat. A forest consisting of large trees, which shade the forest floor and deprive young trees and shrubs of life-giving sunlight, offers little for deer. Deer are, however, attracted to forest edges, where sunlight reaches the ground and which provides palatable and available plants for deer. Putting a house or housing development in the middle of a large expanse of mature forest will create a favorable environment for deer, by creating much "edge" habitat (see "Figure 1" below).
Another landscaper's concern is the palatability of plants. When a homeowner unknowingly chooses varieties of plants that are more appealing than a deer's regular menu of native species, he or she is inviting trouble.
Palatability studies indicate that deer prefer certain ornamentals over others. And, in at least in some situations, certain ornamentals are not preferred by deer at all. Obviously, it would be a direct benefit for homeowners to know which ornamentals are preferred by deer and which are not. A complete listing of these plants is provided later in this report.
Deer damage is basically seasonal. Garden damage, obviously, occurs in late spring, summer, and early fall - the growing season. However, the browsing of ornamental plants around houses is almost solely a winter problem. As such, homeowners only have to contend with troublesome deer and ornamental browsing from January through march in most areas of the country.
From April through June, grass shoots and fresh leaves are available for deer. At that time, deer seem to prefer these fresh foods over most other plants, even ornamental species. However, if they do happen to wander into one's garden, they will no doubt sample some of the plants. It is during this time that gardeners must take care, because once deer identify your garden as a potential food source, thy will return.
The least troublesome time for deer is July through September -- a time when wildlife foods are readily available. The deer are often broken into groups of only a few individuals, and does with fawns move less at this time. Bucks also move infrequently, since their freshly sprouted velvet antlers are painfully delicate and damage easily when bumped against tree branches or other structures. Thus, deer are dispersed and their consumption is not concentrated, spreading out their impact.
By October, the bucks have polished the velvet from their now hardened antlers and are preparing for the autumn breeding season, known as the rut. Last spring's fawns are feeding more on vegetation instead of their mother's milk; this freedom from their young allows the does to begin preparation for the rut. The rutting season, combined with the availability of mast (acorns, beechnuts, and other wild nuts), makes the fall period also one of infrequent deer damage to homeowners.
By early winter, though, the situation is quite different. Many deer are physically drained from the rut and in search of increasingly sparse food supplies. If the mast crop was light, most of the wild nuts may have already been eaten by deer, squirrels, raccoons, turkeys, grouse, or other wild animals. Deer also gather into larger groups during winter. And wild plants are dry and leafless and no doubt less palatable.
Given these circumstances, it is little wonder that deer can sometimes cause severe damage to ornamentals in winter. Ornamental species, like holly trees, rhododendrons and yews, may be the only available green, leafy vegetation. And, since these plants are succulent and easily obtained, they become a popular food source for deer.
Thus, for most homeowners, the winter months are the worst for deer damage. As such, repellents, fencing, or other damage-prevention techniques need to be only temporary. By April, fresh native vegetation will be available again, and deer problems should dramatically decline at this time.
There are a number of means to minimize, or eliminate nuisance deer impacts to your property. It is important to understand, however, that the degree of success of any preventative measure will depend on a number of factors. As such, the homeowner must bear the ultimate responsibility for bringing deer or other animal-related problems to a reasonable and moral conclusion.
If you wish to have a vegetable garden in deer range, then you should consider a fence. No other device or strategy will provide such vegetation protection. When properly installed, a fence can be nearly 100 percent effective in eliminating deer impacts, providing long and lasting benefits.
A variety of fences are available on the market. Hardware stores, hardware sections within larger department stores, and agriculture/animal feed stores are just some of the places fencing information and catalogs can be found. When choosing a fence, consider the topography of the site, the animal species you are excluding, and the overall size of the area. The following basic fence designs and accompanying explanations were taken from Deer Damage Control in New York Agriculture, published in 1983 by the Department of Agriculture and Markets with funding from the New York State Legislature.
These fences have been field tested and proven effective. However, if they do not fit into your garden site, the by all means do not hesitate to modify any of these designs or create you own. The following is a list of companies that produces fences, or fencing materials. These manufacturers will no doubt have other fencing designs available and will certainly share them with you upon request.
Kiwi Fence SystemsWhen deer are being chased or are running scared, they can jump and 8-foot high barrier. However, fences of shorter height have proven successful in preventing deer from entering gardens. Deer will usually try to either crawl under or squeeze through a wire fence before jumping over it.
(412) 627-5640
RD 2, Box 51-A
Waynesburg, PA 15370Live-Wire Products
(207) 365-4438
Box 307
Sherman Mills, ME 04776Tech Fence
(207) 327-1398
Advanced Farm Systems
Box 364 RFD
Bradford, ME 04410
Conditioning deer from the beginning is much more effective than trying to stop deer from entering a garden once they have found it. A first time gardener should always incorporate a well-designed fence into the initial garden creation. This fence, if not electrified, should also include repellent bags or other deterrents for the first year. Once deer learn to avoid this site and not consider it a feeding area, you should not have problems in the future. However, if you are trying to deter deer from a garden after the fact, so to speak, you will have to go to greater extremes. Breaking bad habits is just as difficult for deer as it is for humans.
Along with fencing, there are a number of companies that produce plastic netting. In some respects, stiff, plastic netting can be used effectively as a fence. Primarily, though, netting material can be used as a temporary cover for ornamentals during critical times. For instance, most plastic nets are made for small fruit trees, such as dwarf cherries, or for berry bushes, like blueberries and blackberries. Their purpose is to prevent heavy berry or fruit raiding by birds. When draped over or attached to poles engulfing the small tree or bush, these nets provide adequate protection.
In recent years, there has been an increasing use of these plastic nets for deer control. Many homeowners drape them over large ornamental bushes during winter months to deter deer from browsing. They are inconspicuous and much more difficult to see from a distance than fencing. They are also easily placed and removed. However, they do not prevent browsing, but rather prevent severe over-browsing of a particular plant. The degree of success or failure of plastic netting is subject to a high number of variables.
Almac Plastics, Inc.
(301) 485-9100
6311 Erdiman
Baltimore, MD 21205-3585Green Valley Blueberry Farm
(707) 887-7496
9345 Ross Station Road
Sebastapol, CA 95472Orchard Supply Company of Sacramento
(916) 446-7821
PO Box 956
Sacramento, CA 95812Conweb Corporation
(800) 422-9123
Plastic Division
2640 Patton Road
Roseville, MN 55113Internet, Inc.
(612) 541-9690
2730 Nevada Avenue North
Minneapolis, MN 55427Wildlife Control Technology
(209) 294-0262
2501 North Sunnydale Road
Fresno, CA 93727
Most repellents are designed to be either put directly onto the plant or close to it. They are designed to act in one of two ways: either as a repelling odor or repelling taste. A few chemical repellents may utilize both strategies.
It is important for all homeowners considering chemical repellents to assess both the product and the problem situation. For example, many chemical repellents are not recommended for garden use. Also, some repellents may contain certain chemicals that may "burn" or in some way damage certain species of ornamental plants. Always read labels thoroughly and do not hesitate to contact product manufacturers for additional information. Their addresses and phone numbers should be on the repellent container.
If you contact a manufacturer of a chemical repellent, be sure to request any and all information regarding the product. This includes any surveys that may have been conducted comparing the effectiveness of one manufacturer's product against another. In recent years some testing has been done by certain companies that clearly indicates one repellent may be superior to another under certain conditions. One word of caution: when reviewing a survey report, make sure the testing was done under field, rather than laboratory conditions.
If you own a few fruit trees and/or small garden and wish to try repellents but are afraid of the chemicals, there are two non-chemical, non-commercial repellents that are available. These are human hair and tankage (dried animal fecal and sewage residues available as organic or natural fertilizers). Both of these repellents are odor-based and can be applied either on the ground or hung in bags. Human hair can be obtained at barber shops or local beauty salons and should be placed 1/8" or less mesh made from Vexar (Dupont) bags. (These are commonly used in fruit and vegetable packing and often used around the house as onion or suet bags.) Add a few fistfuls of hair to a mesh bag and simply hang 25 to 35 inches above the ground on a fruit tree or on a pole in the garden. Dry tankage can be put into a light cloth, or cheesecloth bags (1/2 to 1 cup) and hung in a similar way.
The results of using human hair and tankage are inconsistent. Some homeowners have used them with impressive results and some have not been so lucky. Such things as rainfall, humidity, wind, how often the bags are replaced, and even the deer themselves will play a role in determining the success of these two non-chemical repellents.
In 1979, Penn State University conducted a deer repellent study at their deer research facility. The results from this study were published in the Journal of Wildlife Management, Vol. 47, No. 2, 1983, p. 517. The data listed under "Deer Repellent Guidelines" at the end of this document were taken from that study and may aid you in your search for an effective deer repellent.
Few plants are totally deer resistant. Like humans, deer are extremely adaptable animals and can eat a whole variety of foods. However, there are a considerable number of plants that deer do not necessarily prefer and may actually avoid if they have ample wild foods available to them. The following is a list of plants, mostly ornamental species, that will make your property less appealing to local deer herds.
Besides planting undesirable ornamentals and fencing your garden, many people must learn to watch for deer while driving. Deer have a habit of suddenly appearing in one's headlights and then freezing in the middle of the road. Automobiles annually kill and injure tens of thousands of deer.
Deer/auto accidents can be reduced in most areas through a three step method coordinated with local police. They are:
Learning to live with deer, as with most wildlife, does not necessarily require a lot of effort on our part. Knowing what ornamental varieties of vegetation to plant, constructing proper fencing around gardens, and taking special precautions while driving are simple, logical things to do. And learning more about the species we share our world with will inevitably help us to understand these creatures more fully and see them as companions in the environment.
Each repellent is listed with its active ingredient in parentheses and its % effectiveness.
Other repellents were tested. However these were only the only ones to finish above 50% effectiveness.
Stanley H. Anderson, 1985, Managing Our Wildlife Resources, Charles E. Merrill Publishing Company, Columbus, Ohio.
M. Carpenter, 1967, "Control of Deer Damage," Virginia Wildlife, Vol. 28, No. 5, pp. 8-9.
Lowell K. Halls, 1984, White-Tailed Deer Ecology and Management, Wildlife Management Institute, Stackpole Books, Harrisburg, Pennsylvania.
Mark T. Harris, William L. Palmer, and John L. George, 1983, "Preliminary Screening of White-Tailed Deer Repellents," Journal of Wildlife Management, Vol. 47, No. 2, pp. 516-519.
Jay B. McAnich, Mark R. Elingwood, and Raymond J. Winchcombe, 1983, Deer Damage Control in New York Agriculture, Institute of Ecosystem Studies, New York Botanical Garden, Cary Arboretum, Box AB, Milbrook, New York 12545.
Tony Povilitis, Fall 1989, "Living with Deer," HSUS News, Humane Society of the United States, Washington, D.C.
