Woodchucks in the garden

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 adjoining open farmland, and woody or brushy areas near open land. Their burrows can be found in fields, along fence rows and stone walls, near building foundations and trees, and even 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 “living area” and the separate toilet area.

New burrows that appear in fall are usually from older woodchucks, leaving the established burrows for their offspring, or 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 behavir 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, so to retreat if 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 vegetation on landscape plants. They feed mainly in early morning and evening, and can even 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 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 aren’t 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), or tastes when sprayed on susceptible plants (such as from pepper). If the population is large and feeding pressure high, these may not work.

Frightening may work too, either from scarecrows, 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, relocating the woodchucks. Just make sure before doing this that it is legal in your area, that caught woodchucks are moved far enough away to not return, and that you don’t create problems for someone else by moving them. Beware that by relocating in fall they may not be able to find a den for hibernation, and that relocating in spring may cause death to their young. Such large wire traps might also catch non-target mammals such as pets, or even skunks!

If using wire cage traps, place near burrow openings or along major paths they travel. Conceal with brush or black cloth, and replace 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.

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 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 measures you’ll use are legal in your area and not restricted by game control regulations. If you don’t feel up to the task, check the phone book or with your local state wildlife agency for pest control specialists.

Dr. Leonard Perry is Extension Professor, Department of Plant and Soil Science at the University of Vermont. Visit his website at http://www.uvm.edu/~pass/perry/index.html