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The groundhog or woodchuck (Marmota monax) is a husky, waddling rodent in the squirrel family Sciuridae, order Rodentia. The groundhog is a type of marmot (genus Marmota), and is also closely related to the ground squirrels and gophers. The natural habitat of the groundhog is forest edges and grasslands, ranging from the eastern United States and Canada through much of the Midwest, to parts of the western states and provinces. However, the groundhog is also a familiar species in agricultural landscapes within its range, occurring along roadsides, fence-rows, pastures, the margins of fields, and even in some suburban habitats.

The groundhog is a rather large marmot, typically weighing about 6.6-13.2 lb (3-6 kg). One captive animal, however, managed to achieve a enormous 37.4 lb (17 kg) just prior to its wintertime hibernation, when these animals are at their heaviest. The fur is red or brown, with black or dark brown feet.

Groundhogs have a plump body, a broad head, and small, erect ears. The tail and legs are short, while the fingers and toes have strong claws, useful for digging. When frightened, groundhogs can run as fast as a person, but they are normally slow, waddling animals, tending to stay close to the safety of their burrows. Groundhogs can climb rather well, and are sometimes seen feeding while perched in the lower parts of trees or shrubs.

Groundhogs are enthusiastic diggers, and they spend much of their time preparing and improving their burrows and dens. Woodchucks dig their burrow complexes in well-drained, sandy-loam soils, generally on the highest ground available. Their sleeping dens are lined with hay-like materials, both for comfort, and to provide insulation during the winter. There are separate chambers for sleeping and defecation.

Groundhogs are social animals, sometimes living in open colonies with as many as tens of animals living in a maze of interconnected burrows. Groundhogs are not very vocal animals, but they will make sharp whistles when a potential predator is noticed. This loud sound is a warning to other animals in the colony.

Groundhogs are herbivorous animals, eating the foliage, stems, roots, and tubers of herbaceous plants, and sometimes the buds, leaves, flowers, and young shoots of woody species. Groundhogs also store food in their dens, especially for consumption during the winter. Groundhogs are very fat in the autumn, just prior to hibernation. If they are living in a colony, groundhogs snuggle in family groups to conserve heat during the winter. They occasionally waken from their deep sleep to feed. However, groundhogs lose weight progressively during their hibernation, and can weigh one-third to one-half less in the springtime than in the autumn.

Groundhogs have a single mating season each year, usually beginning shortly after they emerge from their dens in the spring. After a gestation period of 30-32 days, the female usually gives birth to four or five young, although the size of the litter may vary from one to nine. Born blind and naked, young groundhogs acquire a downy coat after about two weeks. Soon the mother begins to bring soft plant stems and leaves back to the den for them to eat. Young groundhogs follow their mother out of the burrow after about a month and are weaned about two weeks later.

Groundhogs are sometimes perceived to be pests. They can cause considerable damage by raiding vegetable gardens, and can also consume large quantities of ripe grain and other crops. In addition, the excavations of groundhogs can be hazardous to livestock, who can break a leg if they step unawares into a groundhog hole, or if an underground burrow collapses beneath their A woodchuck sitting on its hind legs to view the surrounding area. Photograph by Leonard Lee Rue, III. Photo Researchers, Inc. Reproduced by permission.
weight. For these reasons, groundhogs are sometimes hunted and poisoned. However, groundhogs also provide valuable ecological benefits as prey for a wide range of carnivorous animals, and because these interesting creatures are a pleasing component of the outdoors experience for many people.

A Midwestern American folk myth holds that if a woodchuck comes out of its burrow on February 2, also known as Groundhog Day, and sees its shadow, then the cold wintertime weather will soon be over. However, if that day is cloudy and the woodchuck does not see its shadow, it goes back into hibernation, and the winter weather will last a while longer. Of course, there is no basis in natural history to this belief. Nor, contrary to common wisdom, do woodchucks chuck wood.

See also Marmots; Rodents.



Banfield, A.W.F. The Mammals of Canada. Toronto: University of Toronto Press, 1974.

Barash, D. Marmots. Social Behavior and Ecology. Stanford: Stanford University Press, 1989.

Bill Freedman


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—A deep, energy-conserving sleep that some mammals enter while passing the wintertime. In groundhogs, hibernation is characterized by a slowed metabolic rate, and a decrease in the core body temperature.

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