UNIVERSITY PARK, Pa. — The groundhog, also known as a woodchuck or whistle pig, is one of Pennsylvania's most widely distributed mammals. Derived from the Pennsylvania Dutch superstition that winter will continue if a groundhog emerges from its burrow and sees its shadow, Groundhog Day is a popular North American tradition observed in the United States and Canada on Feb. 2. 

Here are 10 facts to know about the groundhog, courtesy of Penn State Extension experts:  

1. The groundhog’s compact, chunky body is supported by short, strong legs. Its forefeet have long, curved claws that are well adapted for digging burrows. 
2. Groundhogs usually are a grizzled brownish-gray, but white (albino) and black (melanistic) individuals can occasionally be found. Both sexes are similar in appearance, but the slightly larger males weigh an average of 5 to 10 pounds. 
3. 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.  
4. In general, groundhogs prefer to construct their burrows in open farmland and wooded or brushy areas adjacent to open land. Burrows commonly are located in fields and pastures, along fence rows, and stone walls, roadsides, and near building foundations or the bases of trees. Groundhog burrows can be identified by the large mound of excavated earth at the main entrance. 
5. A single nest chamber, used for sleeping and raising young, is formed at the end of the burrow. Other rooms are used as toilet areas. By separating nest areas from toilet areas, the den is kept relatively clean and free from disease. 
6. 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. When not feeding, they sometimes bask in the sun during the warmest periods of the day. Groundhogs are also good climbers and sometimes can be seen in lower tree branches. 
7. Groundhogs are among the few mammals that enter into true hibernation. Hibernation varies with latitude, but generally begins near the end of October or early November and continues until late February and March. 
8. Groundhogs breed in March and April. A single litter of two to six (usually four) 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. 
9. Groundhogs have a life span of about three to four years. Their primary predators include hawks, owls, foxes, coyotes, bobcats, weasels, dogs and humans. Many groundhogs are killed on roads by automobiles. 
10. A groundhog can be deterred by using a well-placed scarecrow when its feeding and burrowing habits conflict with human interests.  

More information about groundhogs is available online through Penn State’s College of Agricultural Sciences and Penn State Extension.