University of Vermont Extension 
Department of Plant and Soil Science

Anytime News Article

DEER DETERRENTS—SIGHT AND SOUND

Dr. Leonard Perry, Extension Professor
University of Vermont

Before resorting to expensive fences to keep deer from your garden, consider repellents.  In addition to methods that deter through smell, taste, and touch, there are several inexpensive ones that use unexpected sights and sounds. Rhonda Massingham Hart, in her revised book on Deerproofing Your Yard and Garden, gives a nice summary of these deterrents.

The main goal of deer is to survive, whether this means obtaining food (eating your plants), or avoiding danger (getting eaten themselves).  An unexpected motion or sound, especially if new or unknown, signals potential danger and the need to flee. Deer are smart though, and learn patterns quickly.  If you use the same motion or sound product repeatedly, they will get used to it and no longer be afraid. As with any deer repellents, one key is to rotate them often.

Rotation is especially important with visual deterrents, which deer get used to quickly if they don't change location.  Almost anything that flutters and moves can be used, so use your imagination.  I like to string up old CDs, and all those free ones that come as junk in the mail.  There are all manner of mechanical products you can buy as well. Just move them around your garden every few days.

Another important aspect to visual deterrents relates to the poor eyesight of deer.  They often may not recognize a scarecrow for instance as a human form, until they are close to it.  Then another factor clicks in, what is termed their "flight distance."  They flee if something comes too close, within a certain distance.  But, if that unknown object is already within that zone, and not chasing them, they may just figure all is well and continue about their business of feeding on your plants.

One visual deterrent you may try for whitetail deer are white flags about the shape and size of a deer tail (about ten inches long and five inches wide).  They see this "tail" move, but no deer, and they often get spooked and flee.

A visual deterrent I personally have found effective is a motion-activated light.  It has a timer, so turns off after a few minutes.  And it is solar powered, so no need for electrical cords.  I have it mounted on a stand that can be moved every few days.  One year while I was on vacation it didn't get moved, so the deer got used to it and it lost its effectiveness.

Everything from pie pans rattling in the wind to radios to sound canons can be used as sound deterrents.  Deer have large ears and very sensitive hearing, so even the ticking of a watch can startle them.  Their ears are a key defense against danger.  So unexpected or unusual noises can scare them, even if soft.  Pie pans and aluminum cans may be effective for both their sounds and movement. If using radios, they must of course be kept out of the weather.  Some gardeners swear by talk radio, others by certain types of music.

Ultrasonic devices are often sold to repel wildlife, including deer.  The principle of them is that they emit sounds at wavelengths animals can hear (above 20 kilohertz), but people can't.  The only problem with deer is that they hear in a different range, from two to six kilohertz, so studies have shown them not to be effective against deer. (Yes, scientists even have done hearing tests on deer.)

As for any deterrent, sound ones need to be moved often and combined with others.  This applies even to dogs if they are chained.  Deer have been shown to learn the range of chained dogs, and then continue feeding just outside this limit, even with a dog madly barking.

Especially in suburban areas deer quickly learn that people are noisy, and learn to tune them and their noises out.  This is the reason a sound deterrent may work in a rural setting but not an urban one.  Sounds, especially if loud, may not be desirable especially if they keep you, family, or neighbors awake at night!


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