Woodchucks (Marmota monax) are medium-sized, chunky, ground-dwelling squirrels. Males are larger than females, but otherwise the sexes look similar. Adults measure 20-27½ inches in total length, with the tail averaging 4-7 inches. Adult weight will vary widely through the year, from an average of 7 pounds in the early spring to an average of 10½ pounds in the fall. This is because they are deep hibernators, and their weight will differ substantially between den entry and emergence.
The woodchuck has rather coarse, reddish-brown fur grizzled with guard hairs that are gray with yellow tips; brown or black tail, legs, and feet; and a black face. Melanistic (black) animals occur but are uncommon.
Woodchucks have short powerful legs and short ears.
The incisor teeth grow continually and must be worn down when feeding or else the tooth will grow to a length that injures or impairs the animal.
Woodchucks are common and abundant in Massachusetts. They are found everywhere in the state except on Martha’s Vineyard and Nantucket.
Often called groundhogs or whistle-pigs, they are not in the pig family at all. Woodchucks are burrowing members of the squirrel family (Sciuridae), which includes tree squirrels, flying squirrels, and chipmunks. In the western U.S., there are five related species called "marmots."