Groundhog

The groundhog is the largest sciurid in its geographical range, excluding its presence in British Columbia where its range may be comparable to that of its somewhat larger cousin, the hoary marmot. Adults may measure from 41.8 to 68.5 cm (16+7⁄16 to 26+15⁄16 in) in total length, including a tail of 9.5 to 18.7 cm (3+3⁄4 to 7+3⁄8 in). Weights of adult groundhogs typically fall between 2 and 6.3 kg (4 lb 7 oz and 13 lb 14 oz).

Male groundhogs are slightly larger than females on average and, like all marmots, they are considerably heavier during autumn (when engaged in autumn hyperphagia) than when they emerge from hibernation in spring. Adult males average year-around weight 3.83 kg (8 lb 7 oz), with spring to fall average weights of 3.1 to 5.07 kg (6 lb 13 oz to 11 lb 3 oz) while females average 3.53 kg (7 lb 13 oz), with spring to fall averages of 3.08 to 4.8 kg (6 lb 13 oz to 10 lb 9 oz). Seasonal weight changes reflect circannual deposition and use of fat. Groundhogs attain progressively higher weights each year for the first two or three years, after which weight plateaus. Groundhogs have four incisors, which grow 1.5 millimetres (1⁄16 in) per week. Constant usage wears them down by about that much each week. Unlike the incisors of many other rodents, the incisors of groundhogs are white to ivory-white. …

The groundhog dwells in lowland habitats, unlike other marmots that live in rocky and mountainous areas. Marmota monax has a wide geographic range. The groundhog prefers open country and the edges of woodland, being rarely found far from a burrow entrance. It can typically be found in small woodlots, low-elevation forests, fields and pastures, and hedgerows. It constructs dens in well-drained soil, and most groundhogs have summer and winter dens. Human activity has increased food access and abundance, allowing M. monax to thrive.

W.J. Schoonmaker reports that groundhogs may hide when they see, smell, or hear an observer. Marmot researcher Ken Armitage states that the social biology of the groundhog is poorly studied. Despite their heavy-bodied appearance, groundhogs are accomplished swimmers and occasionally climb trees when escaping predators or when they want to survey their surroundings. They prefer to retreat to their burrows when threatened; if the burrow is invaded, the groundhog tenaciously defends itself with its two large incisors and front claws. Groundhogs are generally agonistic and territorial toward each other and may skirmish to establish dominance. Outside their burrow, individuals are alert when not actively feeding. It is common to see one or more nearly motionless individuals standing erect on their hind feet watching for danger. When alarmed, they use a high-pitched whistle to warn the rest of the colony, hence the name "whistle-pig". Groundhogs may squeal when fighting, seriously injured, or caught by a predator. Other vocalizations include low barks and a sound produced by grinding their teeth. David P. Barash wrote that he witnessed only two occasions of upright play-fighting among woodchucks and that the upright posture of play-fighting involves sustained physical contact between individuals that may require a degree of social tolerance virtually unknown in M. monax. …

Common names for the groundhog include chuck, wood-chuck, groundpig, whistle-pig, whistler, thickwood badger, Canada marmot, monax, moonack, weenusk, red monk, land beaver 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 means "digger" (cf. Lenape monachgeu). Young groundhogs may be called chucklings. The etymology of the name woodchuck is not related to wood nor any sense of chucking. It stems from an Algonquian (possibly Narragansett) name for the animal, wuchak. The similarity between the words has led to the popular tongue-twister:

How much wood would a woodchuck chuck if a woodchuck could chuck wood? A woodchuck would chuck all the wood he could if a woodchuck could chuck wood!