University of Vermont
Department of Plant and Soil Science

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WOODCHUCKS IN THE GARDEN

Dr. Leonard Perry, Horticulture Professor Emeritus
University of Vermont

Woodchucks, or groundhogs, are a common problem in gardens from their large burrows and digging, and by eating plants.  Fencing, frightening, and fumigants are some of the methods you might consider for control.

Woodchucks are most common in, and areas adjoining, open farmland, as well as in woody or brushy areas near open land.  Their burrows can be found in fields, along fence rows and stone walls, near (even under) building foundations and trees, and along roads.  These burrows are easily found by the large mound of earth outside the opening, which can be up to 10 inches wide.  There is often a second opening, well-hidden and dug from below so with no soil outside, used to escape danger.  The main opening descends at a sharp angle, then levels into a smaller tunnel leading to the ďliving areaĒ and the separate toilet area. 

New burrows that appear in fall are usually from older woodchucks, leaving the established burrows for their offspring, or for other mammals such as rabbits.  Woodchucks generally live for three to four years.  Their main enemies are hawks, owls, foxes, coyotes, bobcats, weasels, dogs, and humans and their cars.

Knowing their behavior is the first step towards knowing whether woodchucks will be a problem, and to controlling them.  They usually venture only 50 to 150 feet from their burrows, in order to retreat if they sense danger.  If your garden is farther away than this, you may not have a problem.  Woodchucks are true herbivores, only feeding on vegetables, grasses, legumes, herbaceous flowers, and some landscape plants.  They feed mainly in early morning and evening, and can climb trees to feed.

Fencing, or exclusion, is the most permanent and effective means of control and works on other mammals as well.  Make fences three feet above ground, and of heavy poultry wire, heavy gauge rabbit fencing, or 2-inch mesh wire.  Bury the lower edge one foot in the ground to prevent burrowing, with the lower six inches bent outward in an L-shape.  You may bend the top foot or so of wire mesh outward at a 45-degree angle to inhibit climbing.  If you want even more insurance, place an electric wire about five inches off the ground and five inches outside the fence.  This, too, will prevent digging as well as climbing. 

If woodchucks arenít a serious problem, or your area is too large for fencing, you may try any number of repellents available at garden stores, farm stores, and online.  These work by either disagreeable smells to the woodchucks (such as garlic, old tennis balls soaked in ammonia, or used smelly kitty litter), or tastes when sprayed on susceptible plants (such as from hot pepper sauce).  If the population is large and feeding pressure high, these may not work.  (Iíve had a woodchuck eat ornamental kale after it was sprayed with a blood-based repellent.)

Frightening may work too, either from noise (as from radios), or light (as from motion lights).  Just make sure they are portable, and moved every few days, otherwise the woodchucks will learn they are of no harm.

Live trapping also is used by some.  Since woodchucks are a potential rabies vector, trapping in many states is illegal unless you are moving them on your own property or humanely euthanizing them.  Beware that by relocating them in fall they may not be able to find a den for hibernation, and that relocation in spring may cause death to their young.  Such large wire traps also might catch non-target mammals such as pets, or even skunks! 

If using a large wire cage trap (10 by 10 by 24 inches), place it near a burrow opening or along major paths they travel.  Conceal it with brush or a black cloth, and replace the bait daily.  Bait may consist of apple slices, carrots with tops, lettuce, cabbage, or cantaloupe pieces.  Check traps at least in morning and evening, so trapped animals can be removed.  Often it helps to fix the trap open for a few days so they get used to it, before then setting it.  You may need to use wood or concrete blocks to create a tunnel between their burrow and the trap so they donít bypass it.

Fumigants and gas cartridges produce toxic gases (such as carbon monoxide) when placed into burrows, which are then sealed.  These are toxic to other wildlife species too, so only use them on active burrows and strictly according to directions.  Do not use ignited cartridges near or under combustible materials, such as woodpiles and buildings, to avoid potential fires.

Before attempting control, check to make sure the products and measures youíll use are legal in your area, can be done safely, and are not restricted by game control regulations.  Many states allow shooting, if woodchucks are damaging property.  If you donít feel up to the task of woodchuck control or arenít having any luck, check locally or with your state wildlife agency for pest control specialists.

More interesting facts on woodchucks, and details on control, can be found in a wildlife leaflet from Pennsylvania State University Extension (extension.psu.edu/woodchucks).   

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