GROUNDHOG (WOODCHUCK): (Marmota monax) 

The groundhog, also known as a woodchuck or whistle pig, is one of Missouri's most widely distributed mammals. The groundhog’s feeding and burrowing habits, such as in hay or crop fields, home gardens, orchards, and nurseries, can result in conflicts with property owners. Burrows and mounds can be hazardous to farm equipment or horses and riders, and burrows can undermine concrete building foundations, porches, and driveways.

 

Health and Safety Concerns

Woodchucks occasionally scare homeowners by aggressive displays known as bluff charges. Healthy woodchucks will flee from people, although woodchucks will defend themselves when cornered. Pets and children should not approach woodchucks. Although rare, woodchucks may be infected with rabies, tularemia, and hepatitis. A variety of ectoparasites, including ticks, that are disease vectors, also infest woodchucks. Dens may cause safety issues for pedestrians and wheeled vehicles, particularly on hillsides.

 

Identification

Woodchucks are the largest member of the squirrel family, is also known as the “ground hog” or “whistle pig.” It is closely related to other species of North American marmots. It is usually grizzled brownish gray, but white (albino) and black (melanistic) individuals can occasionally be found. The woodchuck’s compact, chunky body is supported by short strong legs. Its forefeet have long, curved claws that are well adapted for digging burrows. Its tail is short, well furred, and dark brown.Both sexes are similar in appearance, but the male is slightly larger, weighing an average of 5 to 10 pounds (2.2 to 4.5 kg). The total length of the head and body averages 16 to 20 inches (40 to 51 cm). The tail is usually 4 to 7 inches (10 to 18 cm) long. Like other rodents, woodchucks have white or yellowish-white, chisel-like incisor teeth. Their eyes, ears, and nose are located toward the top of the head, which allows them to remain concealed in their burrows while they check for danger over the rim or edge. Although they are slow runners, woodchucks are alert and scurry quickly to their dens when they sense danger.

 

Range

Woodchucks occur throughout eastern and central Alaska, British Columbia, and most of southern Canada. Their range in the United States extends throughout the East, northern Idaho, northeastern North Dakota, southeastern Nebraska, eastern Kansas, and northeastern Oklahoma, as well as south to Virginia and northern Alabama.

 

Habitat

In general, groundhogs prefer open farmland and the surrounding wooded or brushy areas adjacent to open land. Burrows commonly are located in fields and pastures, along fence rows, stone walls, roadsides, and near building foundations or the bases of trees. Burrows are almost always found in or near open, grassy meadows or fields. Woodchuck burrows are distinguished by a large mound of excavated earth at the main entrance. The main opening is approximately 10 to 12 inches (25 to 30 cm) in diameter. There are two or more entrances to each burrow system. Some secondary entrances are dug from below the ground and do not have mounds of earth beside them. They are usually well hidden and sometimes difficult to locate. During spring, active burrows can be located by the freshly excavated earth at the main entrance. The burrow system serves as home to the woodchuck for mating, weaning young, hibernating in winter, and protection when threatened.Food HabitsWoodchucks prefer to feed in the early morning and evening hours. They are strict herbivores and feed on a variety of vegetables, grasses, and legumes. Preferred foods include soybeans, beans, peas, carrot tops, alfalfa, clover, and grasses.

General Biology, Reproduction, and Behavior

Groundhogs are primarily active during daylight hours. When not feeding, they sometimes bask in the sun during the warmest periods of the day. They have been observed dozing on fence posts, stone walls, large rocks, and fallen logs close to the burrow entrance. Woodchucks are good climbers and sometimes are seen in lower tree branches.Woodchucks are among the few mammals that enter into true hibernation. Hibernation generally starts in late fall, near the end of October or early November, but varies with latitude. It continues until late February and March. In northern latitudes, torpor can start earlier and end later. Males usually come out of hibernation before females and sub-adults.Males may travel long distances, and occasionally at night, in search of a mate. Woodchucks breed in March and April. A single litter of 2 to 6 (usually 4) young is produced each season after a gestation period of about 32 days. The young are born blind and hairless. They are weaned by late June or early July, and soon after strike out on their own. They frequently occupy abandoned dens or burrows. The numerous new burrows that appear during late summer are generally dug by older woodchucks. The life span of a woodchuck is about 3 to 6 years. Woodchucks usually range only 50 to 150 feet (15 to 30 m) from their den during the daytime. This distance may vary, however, during the mating season or based on the availability of food. Groundhogs maintain sanitary den sites and burrow systems, replacing nest materials frequently. A burrow and den system is often used for several seasons. The tunnel system is irregular and may be extensive in size. Burrows may be as deep as 5 feet (1.5 m) and range from 8 to 66 feet (2.4 to 19.8 m) in total length. Old burrows not in use by woodchucks provide cover for rabbits, weasels, and other wildlife.When startled, a woodchuck may emit a shrill whistle or alarm, preceded by a low, abrupt “phew.” This is followed by a low, rapid warble that sounds like “tchuck, tchuck.” The call is usually made when the animal is startled at the entrance of the burrow. The primary predators of woodchucks include hawks, owls, foxes, coyotes, bobcats, weasels, dogs, and humans. Many woodchucks are killed on roads by automobiles.

 

Damage and Damage Identification

On occasion, the groundhog's feeding and burrowing habits conflict with human interests. Damage often occurs on farms, in home gardens, orchards, nurseries, around buildings, and sometimes around dikes. Groundhogs are often a major problem for home gardeners. Woodchucks can cause significant damage to crops such as beans, lettuce, peas, carrots, cabbage, clover, and plantain. Trees may be severely damaged or killed by chewing and territorial marking. Fruit trees and ornamental shrubs are damaged by woodchucks as they gnaw or claw woody vegetation. Woodchucks may strip apples or cherries from trees in the vicinity of dens. Woodchucks readily climb fruit trees, causing damage to limbs and fruit. Broken limbs of fruit trees can be mistaken for damage by raccoons. Gnawing on underground power cables has caused electrical outages. Damage to rubber hoses in vehicles, such as those used for vacuum and fuel lines, has also been documented. Mounds of earth from the excavated burrow systems and holes formed at burrow entrances present a hazard to farm equipment, horses, and riders. Woodchuck burrows undermine foundations of buildings, pools, and sidewalks. Woodchucks are not a threat to livestock.

 

Damage Prevention and Control Methods

In Missouri, groundhogs are classified as a game mammal that may be taken during the prescribed hunting season. Taking groundhogs during the prescribed season can help control their numbers. Cage-type traps are allowed as a hunting method. Damage-causing groundhogs may be controlled to prevent further damage. Control methods can include exclusion, habitat modification, trapping and removal. Our technicians will help you determine the best options for your situation.

 

• Exclusion - Fencing can reduce damage, but groundhogs are good climbers and can easily scale wire fences unless precautions are taken. The cost of exclusion should be compared to other forms of control and the value of the resources being protected. Fences should be at least 3 feet high and made of heavy poultry wire or 2-inch mesh woven wire. Bending the top 15 inches of the wire fence outward at a 45-degree angle will prevent groundhogs from climbing over the fence. To prevent burrowing under the fence, bury the lower edge 10 to 12 inches below ground, or bend the lower edge in an L-shaped angle leading outward and buried 1 to 2 inches below ground. Prevent groundhogs from burrowing under concrete slabs by burying L-shaped wire mesh along the edge.An electric wire used in conjunction with fencing can enhance effectiveness. Place an electric wire 4 to 5 inches off the ground and the same distance outside the fence. When connected to a UL-approved fence charger, the electric wire will prevent climbing and burrowing. In some instances, an electric wire alone, placed 4 to 5 inches above the ground, can deter groundhogs from entering gardens. Vegetation in the vicinity of any electric fence should be removed regularly to prevent the system from shorting out.

• Habitat Modification - Close sheds and make them tight to prevent entry by woodchucks. Remove piles of rock, wood, and brush that may be attractive den sites. Keep fields and ditch banks mowed to expose woodchucks to predators.Frightening Devices - Scarecrows and other effigies can provide temporary relief from woodchuck damage. Move them regularly and incorporate a high level of human activity in the susceptible area.

• Fumigants/Repellents - No effective repellents are known. Mothballs, in particular, are not effective. The naphthalene they contain is toxic, and the vapor harmful to humans. Gas cartridges, which are available at farm- and garden-supply stores, have proven to be effective. They produce carbon monoxide that accumulates in lethal amounts when confined within the burrow system. Gas cartridges are filled with combustible materials that are ignited by lighting a fuse. They are not bombs and will not explode if properly prepared and used.

• Trapping - Cage-type traps are generally the most effective option for trapping groundhogs. For best and quickest results, have an experienced professional perform trapping. There are many effective methods for trapping groundhogs, however, a great deal of experience is required to effectively trap groundhogs. Body-gripping traps are not allowed for dry-land sets in Missouri. Foothold traps are effective but require special skill and experience. Many people oppose trapping with foothold traps, especially in urban situations. The most common objections to foothold traps include the perception that traps are cruel and inhumane, and concern over catching non-target animals, especially pets. When used properly, traps are effective, selective, and safe, especially when used by an experienced trapper. Restrictions on use apply and our technicians will determine the best option for your situation while following all applicable laws and regulations.

• Shooting – In some situations shooting ranks high among the choices for removing a groundhog. Although shooting may remove a problem woodchuck, research has shown that empty burrows may be quickly reoccupied during the growing season. Safety is a critical factor that in some circumstances may preclude the use of firearms (for example, local laws may prohibit shooting, or neighbors may be too close). Shooting is best left to professionals. In many urban areas, firearms may not be discharged, in most situations local authorities have regulations and restrictions regarding the use of firearms.

• Other Methods - Woodchucks can be flooded out of dens and into nets. Be prepared to euthanize the netted woodchuck.

 

Economics of Damage and Control

There are few studies available on the damage caused by Groundhogs. The damage they do is localized and is usually more of a nuisance than an economic loss.