For suburban gardeners, rural farmers, and urban-agriculturalists alike, there is a growing scourge that threatens their personal Edens, their livelihoods, and their careful acts of creation. This pestilence can sweep through a well-kept garden or acreage causing catastrophic damage in hours, all while adapting to a wide variety of environmental conditions and plant species. Present across almost the entirety of the U.S., escape is futile and the best an aspiring grower can do is manage expectations and be willing to start anew. I am of course referring to rats with hooves — otherwise known as deer.
Photo courtesy of Pixabay
To provide context for the scope of this issue, in the U.S alone, deer are responsible for hundreds of millions of dollars of crop damage and insurance claims involving vehicular-deer collisions, reaching roughly $1.2 billion dollars annually. Through collisions with motorists, deer are actually the leading cause of human death involving wildlife, tallying roughly 150 casualties annually. Deer also host and transport ticks, which are a significant vector of zoonotic diseases in the U.S., as well as many other internal parasites that are communicable to both livestock and mankind. The U.S. is home to an estimated 30 million deer, ranging from the most common White-Tailed (Odocoileus virginianus) to the giant Moose (Alces americana) with appetites to match; an adult White-Tail can consume up to 10 pounds a day, while an adult Moose can eat as much as 45 pounds. When both population and daily food consumption are considered together, it can be a frightening imposition. (Facts and figures found here: Hart, Rhonda Massingham. Deerproofing Your Yard & Garden. 2nd ed., Storey Publishing, 2005.)
Fortunately for all of us who share space with these bottomless gluttons, several management strategies exist that work to alter behavior, assault the senses, and/or scare these rambunctious Cervids. However, before we get into methodology and practices, it’s important to know the enemy intimately. Deer are almost entirely instinctively driven, with their hierarchy of drives being the following: 1. Don’t become dinner. 2. Eat. 3. Rest. 4. Establish dominance/territory. Given this hierarchy, deer are generally skittish creatures of habit, often sticking to established paths, foraging grounds, and shelter. Deer are also capable of clearing great heights and distances in a single bound, with the common White-Tail being know to reach heights over 12 feet and distances of 30 feet. Their eyes, while lacking color cones, are loaded with rods developed enough to pick up on the slightest of movements. Their noses are capable of detecting a wide variety of chemical signatures undetectable to humans. Their hearing ability also puts ours to shame, allowing them to hear the slightest disruption while their ears flex and rotate constantly, allowing them to identify the direction of the threat. It is these abilities that have made deer expert survivalists and cunning midnight thieves of vegetable gardens and shrubbery alike.
Given their ability to clear great heights and proclivity for populating suburban and even urban landscapes, deer-proof fences and “dispatching” (use your imagination) problem animals can often be prohibitively expensive or illegal in your area. So how do we counter a creature that on paper seems to be an unstoppable whirlwind of destruction? We turn its greatest strengths into weaknesses — starting with the composition of your garden. Many of the most common and loved landscape ornamentals have analogs/substitutes that deer loathe, whether due to their foul taste, texture, smell, or simply being difficult to consume or lacking in nutrients. If you live in an area that has high deer pressure, this is where you should start.
To protect plants favored by deer, a wide variety of repellents exist that mimic the natural defenses in deer-resistant plants. These repellents can make desirable foliage for the deer taste foul (usually consisting of emulsified eggs or capsaicin), can overload their sense of smell hiding vulnerable plants, or in the case of blood meals create a fear response that sends deer heading for the hills. Just be sure that whenever you apply a regulated pesticide/repellent, you do so according to the appropriate uses and concentrations on the label.
Photo courtesy of Pixabay
A number of motion sensing sirens and high-pitched sound emitters are also available on the market, although these alarms rarely have a lasting impact in reducing damage and should be used in conjunction with other tactics. Avoid any devices that claim to be ultrasonic as the hearing of deer, while incredible, cannot pick up ultrasonic sound. Due to their shy nature and neophobia (fear of new things/environments), a rotating, varied combination of controls is generally much more effective than any single method as an ever-changing environment will prevent deer from making your landscape a dinner-time destination. Other methods that have been tested with some utility include motion-sensing lights/sprinklers, hidden mono-filaments to scare with unexpected touch and barriers, visual deterrents, kinetic/mechanical sculptures, propane cannons, electrified fencing, and the most time-honored deer repellent there is: the family dog.
Finally, the most important part of any pest management plan is record-keeping and adaptation. Deer are a crafty and flexible foe. Keeping accurate records of management strategies and damage will allow you to fine-tune your methodology for deer management specific to your property. Keep track of what works and what doesn’t and switch up the application of controls so your unwelcome guest never knows what to expect. Good luck and Godspeed!