The groundhog is a marmot in the family Sciuridae, and is also called a woodchuck, whistle-pig, and land-beaver. Unlike some other breeds of marmots, the groundhog is a lowland creature instead of a mountainous one. Groundhogs are found from regions in Alabama to as far north as Alaska.
The groundhog is very large for its group, being the largest sciurid in its geographical range. It reaches about 16-26 in., with a tail about 6 in. long, and weighs about 4-9 lbs. But when in an area with a small amount of predators and large amount of alfalfa, groundhogs can reach 30 in. and 31 lbs. Groundhogs were built for digging, with short powerful limbs and thick curved claws. It differs from other sciurids not only in size but in shape, with a spine more curved, like that of a mole, and a shorter tail, only reaching about ¼ of its body length. Because of their temperate habitat, they have two coats of fur: a grey undercoat and a coat of longer banded guard hairs, which give it its frosted appearance.
Although groundhogs can live up to 6 years in the wild, they usually live only 2-3. In captivity, they live about 9-14 years, with the highest reported being 22 years. Being a rodent, groundhogs have many predators including wolves, coyotes, foxes, bobcats, large hawks, dogs, and bears. The young groundhogs are also at risk of being eaten by snakes, which can easily enter the burrow.
Not being as omnivorous as other sciuridae, groundhogs usually feed on wild grasses, berries, agricultural crops, and other vegetation, when available. When not enough is available, they will also eat grubs, grasshoppers, snails, and other insects and small animals. They have been seen eating nuts such as shagbark hickory sitting up, like squirrels, but unlike squirrels, they do not bury them to eat later. Instead of drinking from a natural water source, groundhogs usually get all their water from the vegetation they eat.
Groundhogs live in burrows, and are excellent at making them. They use their burrows for sleeping, rearing young, and hibernating. Groundhogs have been estimated to move about 710 lbs when digging a burrow. Several individuals may occupy the same burrow, despite the fact that groundhogs are the most solitary of all the marmots. To easily escape from predators, they make their burrows with 2-5 entrances. The burrows can cause a serious threat to agricultural and residential development by damaging farm equipment and undermining house foundations, because of their enormous burrows, usually reaching 5 ft underground with 46 ft of tunnels.
Because they hibernate, groundhogs often build a ‘winter burrow’ for this purpose. It is usually dug below the frost line in a woody of brushy area, and will remain a stable temperature above freezing for the time of its hibernation, usually from October to March or April. In order to survive the winter, they eat until they reach their maximum weight before hibernating, and wake up with enough fat left to survive until the warm weather produces enough food for them to eat. Although they look rather heavy, groundhogs are actually accomplished swimmers and climbers, for when they want to escape from predators or survey the area. When threatened, they usually retreat to their burrow, but will defend themselves tenaciously with their two large incisors and front claws if their burrow is invaded. Groundhogs may fight amongst each other to establish dominance because they are agonistic and territorial. When not feeding, groundhogs are usually very alert outside of their burrow, standing nearly motionless on their hind legs. The name ‘whistle-pig’ comes from the whistle they make when they spot danger. If they are caught, are fighting, or injured by an enemy, they may squeal loudly. Groundhogs can also make low barks or teeth grinding. When frightened, the hair on their tails will stand up, making it resemble a hairbrush.
When groundhogs are one or two years old, they will begin to breed. Their breeding season lasts from March to April. The pair stay together for the 31-32 day pregnancy of the female, until towards the end of the pregnancy, when the male leaves. The female is left to produce her annual litter of 2-6 blind, hairless, helpless young alone. They don’t stay together long, as the young are ready to leave and make their own burrows at 5-6 weeks of age.
Groundhogs are wonderful dwellers of open country and woodland edges, and are the clumsy weather reporters of the animal kingdom.