Wherever whitetail deer occur they present a challenge for gardeners. The internet offers abundant advice on this, but too often it is simplistic gardening myth such as scattering human hair or planting garlic.
Historically in deer control literature there have been occasional observations that deer hesitate to enter an area which looks too small or constrained for rapid escape. Finally, it came time to acknowledge and test this theory.
Green Island Preserve and the University of Minnesota Extension set about investigating this possibility through their Regional Sustainable Development Partnership (RSDP) program which provides support to community-benefit projects in partnership with private citizens and organizations. The test site was a 60 acre rewilded forest inside a small northern city. Deer pressure was heavy with resident herd numbers varying from 16-30 animals during the trial.
The first issue was defining a “small space” for testing the theory. In all the literature only one other trial of this concept could be found. It was conducted in Wisconsin with traditionally fenced spaces ranging from 15 ft by 15 ft to 21 ft by 21 ft feet during part of one summer. The Minnesota Green Island Preserve and RSDP trial chose 16 feet by 16 feet based upon the dimensions of manufactured, ridged cattle panels. These panels are 50 inches in height and 16 ft long and tend to be readily available at Fleet or Home stores even in suburban areas. If successful, their advantage would be very easy set-up and portability at a reasonable cost.
What was the result? Over 2 years of trial, this test demonstrated 95% success. Six micro-exclosures were established and planted within forested and forest edge locations in a zone of heavy deer pressure. During an observation period of 730 days, only one instance of deer browse occurred inside a micro-exclosure.
This success rate is more impressive because these fences are not a physical barrier to deer entry. They are strictly a psychological deterrent. This places them in much the same class as flashing lights, sound cannon, water spray, etc., but according to this study’s data, they’re actually more effective. All psychological deterrents have a failure rate dependent on application, monitoring, seasonality, rainfall, and more. But micro-exclosures show a low failure rate, without maintenance. If a deer breach does occur, the solution is simply to make the exclosure appear even smaller. This can be done by stretching rope across the center holding noticeable flagging. It can be lifted off when tending plants.
This is a highly promising discovery which merits further controlled testing by universities and professionals. The Minnesota Green Island Preserve and RSDP trial was specifically targeted to white tail deer predation while other ungulates present browse problems in other geographies. Rabbits were not addressed. However, until further and definitive research is conducted, citizen-scientist gardeners can contribute by testing versions of this method for themselves and adding their data to the general deer-control knowledge base. In using and testing micro-exclosures, gardeners will fare infinitely better than by spreading human hair, interplanting garlic, or buying “ultrasonic” gizmos.
This post was provided by Kent Scheer. Kent is a career sculptor with a side mission for reforestation and environmental compassion. He is the editor of three handbooks on sustainable agriculture resources and owner/ manager of a rewilded pine forest in northern Minnesota created for environmental education and awareness. You can contact Kent at kentscheer@outlook.com.
We have fluctuating numbers of deer from 8 to 12 to 30 depending g in time of year. I am planning my first enclosed garden (formerly shared a neighbor’s garden with high fence) so this article crossed my path just in time! I was drawing a 20’ x 16’ with raised beds and paths, but will reconsider! Thanks for sharing knowledge and experience.
Susan,
According to the only other trial of this method your 16′ by 20′ may work. And if it does not, it is super easy to correct that by stretching light rope across with hanging flagging. Just create the appearance of a more complex space. If the ropes are attached with a screen door spring at one side that will keep each tight but you can easily lift the end off to do garden chores inside.
Actually the fence doesn’t have to be that sturdy, I was successful at keeping deer out of my garden by simply laying old window screens side by side held in place with vertical rods for support. Ran fishing line above the screens to prevent the deer from wanting to reach over to nibble.