Woodchucks in Massachusetts
Background and Natural History
Woodchucks are common and abundant in Massachusetts. They are found everywhere in the state except on Marthas Vineyard and Nantucket. Often called "groundhogs" or "whistle-pigs," they are not in the pig family at all. Woodchucks are burrowing members of the squirrel family (Sciuridae), which includes tree squirrels, flying squirrels, and chipmunks. In the western U.S., there are five related species called "marmots."
Woodchucks (Marmota monax) are medium-sized, chunky, ground-dwelling squirrels. Males are larger than females, but otherwise the sexes look similar. Adults measure 20-27½ inches in total length, with the tail averaging 4-7 inches. Adult weight will vary widely through the year, from an average of 7 pounds in the early spring to an average of 10½ pounds in the fall. This is because they are deep hibernators, and their weight will differ substantially between den entry and emergence.
The woodchuck has rather coarse, reddish-brown fur grizzled with guard hairs that are gray with yellow tips; brown or black tail, legs, and feet; and a black face. Melanistic (black) animals occur but are uncommon. Woodchucks have short powerful legs and short ears. The incisor teeth grow continually and must be worn down when feeding or else the tooth will grow to a length that injures or impairs the animal.
Woodchucks are an "edge" species, living in hedgerows or brush clumps along old fields, pastures, or croplands intermixed with small woodlands. Burrows are dug in well-drained soil along woodland edges and brushy hedgerows, often on rather steep slopes. The animal will also burrow under sheds, porches, decks, or walkways. Burrows are a critical feature of their life style, and typically include multiple entrances. The main shaft may be up to 50 feet in length, with many side passages. The 'chuck usually piles up a mound of dirt and rocks at the burrow entrance, but the entry may otherwise be well-concealed.
Woodchucks are generalist plant feeders, consuming a wide variety of herbaceous (soft or leafy) vegetation. Studies in Maryland identified 34 plants while a study in Pennsylvania found 46 that were eaten by woodchucks. Clover, wild lettuce, grasses, chickweed, and dandelion appeared among the preferred species. The animals also readily eat hay grasses, alfalfa, corn, and a variety of common garden or commercial crops. Woodchucks readily climb trees and may feed on leaves of certain species, such as mulberry. They may also gnaw woody stems or trees, primarily in spring.
Woodchucks mate in March and April shortly after emergence from hibernation. They can first breed as yearlings (i.e., in their second summer), however only 20-40% of female yearlings do breed. The tiny, feeble young are born in the burrows after a gestation period of 30-32 days. Based on data from studies of captive animals, litter size averages four to five young. The pups emerge from the den at about 33 days and are weaned at about 42 days.
Woodchucks are typically daytime animals. During most of the year, their activity peaks in mid-morning and again in the late afternoon, but declines at mid-day. Early and late in the season they may be active only in the afternoon. They enter hibernation in late fall and emerge in early spring. The hibernation period is about 4-4½ months in Pennsylvania and 5 months in upper New York. Their home range is determined by food availability, but is typically between ¾-2¼ acres. Home ranges of adult males may overlap those of females, but usually not those of other males. Woodchucks disperse from their birth area when less than 1 year old, females traveling perhaps ¼ mile and males mile. Woodchucks are quite wary and on the alert around their burrow entrance and while feeding.
Woodchuck damage to home vegetable or flower gardens is often difficult to control. Homeowners need to keep in mind that, when populations are high and food sources are abundant, new woodchucks will quickly replace those that have been eliminated. To avoid or reduce damage and make your property less attractive to woodchucks, consider the following options:
- Exclusion: Fencing can help alleviate woodchuck damage, but woodchucks are good climbers, so fences should be at least 3 feet high, constructed of heavy chicken wire or 2-inch mesh welded wire. Bury the lower edge 10-12 inches deep to prevent 'chucks from burrowing under it. An electric wire 4-5 inches off the ground and 4-5 inches from the fence, powered by an approved fence charger, will discourage woodchucks from climbing. Electrified netting is also effective. Contact your local farm supply business or a MassWildlife district office for information on electric fences. As an alternative, bend the top 15 inches of the fence outward at a 45° angle.
- Structures: Woodchucks may burrow under sheds, porches, walkways, or other structures. Be proactive and securely block up all possible crevices, cracks, and holes prior to any use by woodchucks. Examine these areas regularly. Boards, fencing, or stones may have to extend 12 inches or more into the ground to prevent tunneling. If 'chucks get into these places, you may have to block them repeatedly. Be careful not to block such places when woodchucks may be trapped inside.
- Fumigants: Woodchucks may be killed in their burrows with commercial gas cartridges that produce carbon monoxide and other gases. First, you need to find the main burrow entrance and all secondary holes. Block all holes except the main one with a chunk of sod. Ignite the cartridge, throw it down the hole, and block up the hole. Watch for smoke emissions, which indicate a poor seal. Follow all directions on the cartridge. Do not use gas cartridges under sheds, porches, or other buildings. Do not use the cartridges on other animals. Remember that woodchucks are abundant and new animals may try to reoccupy the area later.
- Repellents: Commercial animal repellents such as "Hot Sauce Animal Repellent"®, Hinder®, emetics, and insecticides have been used to deter woodchucks from damaging squash, tomatoes, lettuce, and other crops, generally with minimal success*. Efficacy may relate to palatability and frequency of exposure. Some repellents may not be legal for use on woodchucks or on products used for human consumption. Repellents tend to deteriorate on exposure to the elements and may not be long-lasting. Poisons of any kind should never be used. Not only is it illegal to use poisons to eliminate wildlife, even if the animals are in a building, but woodchucks may only be sickened by poisons, and dead, poisoned woodchucks may cause secondary poisoning of raptors, domestic pets, and other scavengers.
- Trapping: Woodchucks can sometimes be captured in wire cage traps, placed at the main burrow entrance or in travel ways. Apples slices, carrots, or unwilted lettuce are good baits. However, if the available foods are attractive, woodchucks may be reluctant to enter traps. Before attempting to trap woodchucks, be aware that, in Massachusetts, wildlife may not be relocated. Do not trap woodchucks unless you are willing to release them on site (such as an animal removed from a cellar) or to destroy them humanely.
- Shooting: Shooting is quick, simple, and effective in rural areas where firearms discharge is safe and lawful. A .22 caliber centerfire rifle is commonly used for this purpose. At close ranges (<25 yards), a 12-gauge shotgun with #4-6 shot may be effective. This method will be most useful when targeting a few persistent animals. But, again, during population peaks, or when foods are particularly attractive, new woodchucks will quickly move in to replace those that have been removed.
Because they are abundant, Massachusetts has a 50-week hunting season on woodchucks. A hunting license is required. Nevertheless, they are not a particularly desirable game species for most hunters. If you have questions or are experiencing problems with woodchucks, contact your nearest MassWildlife district office. Further information on other wildlife is also available.
*Please note that brand names are used for illustrative or comparative purposes only. This is not a specific recommendation by the Division of Fisheries and Wildlife.