Figure 1. The woodchuck Marmota monax
The woodchuck (Marmota monax, Fig. 1), a member of the squirrel family, is also known as the “ground hog” or “whistle pig.” It is closely related to other species of North American marmots. It is usually grizzled brownish gray, but white (albino) and black (melanistic) individuals can occasionally be found. The woodchuck’s compact, chunky body is supported by short strong legs. Its forefeet have long, curved claws that are well adapted for digging burrows. Its tail is short, well furred, and dark brown.
Both sexes are similar in appearance, but the male is slightly larger, weighing an average of 5 to 10 pounds (2.2 to 4.5 kg). The total length of the head and body averages 16 to 20 inches (40 to 51 cm). The tail is usually 4 to 7 inches (10 to 18 cm) long. Like other rodents, woodchucks have white or yellowish-white, chisel-like incisor teeth. Their eyes, ears, and nose are located toward the top of the head, which allows them to remain concealed in their burrows while they check for danger over the rim or edge. Although they are slow runners, woodchucks are alert and scurry quickly to their dens when they sense danger.
Woodchucks are primarily active during daylight hours. When not feeding, they sometimes bask in the sun during the warmest periods of the day. They have been observed dozing on fence posts, stone walls, large rocks, and fallen logs close to the burrow entrance. Woodchucks are good climbers and sometimes are seen in lower tree branches.
Woodchucks are among the few mammals that enter into true hibernation. Hibernation generally starts in late fall, near the end of October or early November, but varies with latitude. It continues until late February and March. In northern latitudes, torpor can start earlier and end later. Males usually come out of hibernation before females and subadults.
Males may travel long distances, and occasionally at night, in search of a mate. Woodchucks breed in March and April. A single litter of 2 to 6 (usually 4) young is produced each season after a gestation period of about 32 days. The young are born blind and hairless. They are weaned by late June or early July, and soon after strike out on their own. They frequently occupy abandoned dens or burrows. The numerous new burrows that appear during late summer are generally dug by older woodchucks. The life span of a woodchuck is about 3 to 6 years.
Woodchucks usually range only 50 to 150 feet (15 to 30 m) from their den during the daytime. This distance may vary, however, during the mating season or based on the availability of food. Woodchucks maintain sanitary den sites and burrow systems, replacing nest materials frequently. A bur-row and den system is often used for several seasons. The tunnel system is irregular and may be extensive in size. Burrows may be as deep as 5 feet (1.5 m) and range from 8 to 66 feet (2.4 to 19.8 m) in total length (Fig. 3).
Old burrows not in use by woodchucks provide cover for rabbits, weasels, and other wildlife.
When startled, a woodchuck may emit a shrill whistle or alarm, preceded by a low, abrupt “phew.” This is followed by a low, rapid warble that sounds like “tchuck, tchuck.” The call is usually made when the animal is startled at the entrance of the burrow. The primary predators of woodchucks include hawks, owls, foxes, coyotes, bobcats, weasels, dogs, and humans. Many woodchucks are killed on roads by automobiles.
Woodchucks occur throughout eastern and central Alaska, British Columbia, and most of southern Canada. Their range in the United States extends throughout the East, northern Idaho, northeastern North Dakota, southeastern Nebraska, eastern Kansas, and northeastern Oklahoma, as well as south to Virginia and northern Alabama (Fig. 2).
Normally, woodchucks prefer open farmland and the surrounding wooded or brushy areas adjacent to open land. Burrows commonly are located in fields and pastures, along fence rows, stone walls, roadsides, and near building foundations or the bases of trees. Burrows are almost always found in or near open, grassy meadows or fields. Woodchuck burrows are distinguished by a large mound of excavated earth at the main entrance. The main opening is approximately 10 to 12 inches (25 to 30 cm) in diameter. There are two or more entrances to each burrow system. Some secondary entrances are dug from below the ground and do not have mounds of earth beside them. They are usually well hidden and sometimes difficult to locate (Fig. 3). During spring, active burrows can be located by the freshly excavated earth at the main entrance. The burrow system serves as home to the woodchuck for mating, weaning young, hibernating in winter, and protection when threatened.
Woodchucks prefer to feed in the early morning and evening hours. They are strict herbivores and feed on a variety of vegetables, grasses, and legumes. Preferred foods include soybeans, beans, peas, carrot tops, alfalfa, clover, and grasses.
Rene M. Bollengier. Jr. Assistant Regional Director (retired). USDA-APHIS-Wildlife Services. Concord, New Hampshire , 03302-2398