NJ Woodchuck Hunting Guide

Also known as: Groundhog, Whistle pig, Marmot

The groundhog (Marmota monax), also known as the woodchuck, is a rodent of the family Sciuridae, belonging to the group of large ground squirrels known as marmots.

A lowland creature of North America, it is found through much of the Eastern United States, across Canada and into Alaska.

It was given its scientific name as Mus monax by Carl Linnaeus in 1758, based on a description of the animal by George Edwards, published in 1743.

The groundhog, being a lowland animal, is exceptional among marmots. Other marmots, such as the yellow-bellied and hoary marmots, live in rocky and mountainous areas. Groundhogs are considered one of the most solitary of marmot species. They live in aggregations, and their social organization and long-term pair bonds varies across populations. The groundhog's male and female interactions are usually limited to the mating season and copulation. However, certain populations of groundhogs have been observed to form long-term adult male-female association throughout the year, and often from year to year.

The groundhog is an important contributor to the maintenance of healthy soil in woodlands and plains; as such, the species is considered a crucial habitat engineer. The groundhog is an extremely intelligent animal, forming complex social networks and kinship with its young; it is capable of understanding social behavior, communicating threats through whistling, and working cooperatively to accomplish tasks such as burrowing.

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. Groundhogs are well-adapted for digging, with powerful, short legs and broad, long claws. The groundhog's tail is shorter than that of other Sciuridae—only about one-fourth of body length.

Habitat & Range

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.

Life History

Behavior: 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. Alternatively, upright play-fighting may be a part of the woodchuck's behavioral repertoire that rarely is shown because of physical spacing and/or low social tolerance.

Reproduction: Groundhogs are considered the most solitary of the marmot species. They live in aggregations, and their social organization also varies across populations. Groundhogs do not form stable, long-term pair bonds, and during mating season male-female interactions are limited to copulation. Groundhogs in Ohio, however, have been observed to have different social organization than groundhogs elsewhere, with adult males and females associating with each other throughout the year and often from year to year. Usually groundhogs breed in their second year, but a small proportion may breed in their first. The breeding season extends from early March to mid- or late April, after hibernation. Woodchucks are polygynous but only alpine and woodchuck marmot females have been shown to mate with multiple males. A mated pair remains in the same den throughout the 31- to 32-day gestation period. As birth of the young approaches in April or May, the male leaves the den. One litter is produced annually. Female woodchucks give birth to one to nine offspring, with most litters rangin

Diet: Mostly herbivorous, groundhogs eat primarily wild grasses and other vegetation, including berries, bark, leaves, and agricultural crops, when available. In early spring, dandelion and coltsfoot are important groundhog food items. Some additional foods include sheep sorrel, timothy-grass, buttercup, persicaria, agrimony, red and black raspberries, mulberries, buckwheat, plantain, wild lettuce, alfalfa, and all varieties of clover. Groundhogs also occasionally eat small animals, such as grubs, grasshoppers, snails, and even bird eggs and baby birds, but are not as omnivorous as many other Sciuridae.

An adult groundhog can eat more than 1 lb (0.45 kg) of vegetation daily. In early June, woodchucks' metabolism slows, and while their food intake decreases, their weight increases by as much as 100% as they produce fat deposits to sustain them during hibernation and late winter. Instead of storing food, groundhogs stuff themselves to survive the winter without eating. Thought not to drink water, groundhogs are reported to obtain needed liquids from the juices of edible plants, aided by their sprinkling with rain or dew.

Hunting Season

Bow/Shotgun: Mar 1, 2025 - Feb 21, 2026 (year-round). Rifle: Mar 1 - Oct 1, 2025 and Mar 2 - Sep 30, 2026. Sunday hunting prohibited.

References

• New Jersey — Woodchuck