The groundhog, also known as a woodchuck, is a rodent of the family Sciuridae, belonging to the group of large ground squirrels known as marmots. It was first scientifically described by Carl Linnaeus in 1758. The groundhog is also referred to as a chuck, wood-shock, groundpig, whistlepig,whistler, thickwood badger, Canada marmot, monax, moonack, weenusk, red monk and, among French Canadians in eastern Canada, siffleux. The name “thickwood badger” was given in the Northwest to distinguish the animal from the prairie badger. Monax (Móonack) is an Algonquian name of the woodchuck, which meant “digger” (cf. Lenape monachgeu). Young groundhogs may be called chucklings. Other marmots, such as the yellow-bellied and hoary marmots, live in rocky and mountainous areas, but the groundhog is a lowland creature. It is found through much of the eastern United States across Canada and into Alaska
The groundhog is the largest sciurid in its geographical range. Adults are 16 to 20 inches (40–50 cm) long, including a six-inch (15 cm) tail. A large woodchuck thought to weigh twenty pounds when carried was exactly half that weight when weighed by scale.Woodchuck weight ranges from five to twelve pounds. Extremely large individuals may weigh up to 15 pounds. Seasonal weight changes indicate circannual deposition and use of fat. Groundhogs attain progressivly higher weights each year for the first two or three years, after which weight plateaus. Groundhogs have four incisor teeth which grow 1⁄16″ (1.5 mm) per week. Constant usage wears them down again by about that much each week.Unlike the incisors of many other rodents, the incisors of groundhogs are white to ivory-white.Groundhogs are well-adapted for digging, with short, powerful limbs and curved, thick claws. Unlike other sciurids, the groundhog’s tail is comparably shorter—only about one-fourth of body length.