“Groundhogs, also called woodchucks, are large burrowing members of the squirrel family found across much of North America. They eat plants, dig extensive burrows, and are true hibernators, slowing their heartbeat and body temperature dramatically through winter. Groundhog Day is a folk tradition, and groundhogs aren’t reliable weather forecasters.”
Every February, a groundhog in Pennsylvania becomes a national celebrity. But for the rest of the year, groundhogs lead quiet lives digging burrows, eating clover, and fattening up for one of the most impressive hibernations in the animal kingdom. Here’s what makes these hefty rodents so interesting, and why gardeners sometimes have mixed feelings about them.
Groundhog Quick Facts
| Trait | Details |
|---|---|
| Scientific name | Marmota monax |
| Other names | Woodchuck, whistle-pig |
| Family | Squirrels (Sciuridae); a type of marmot |
| Weight | About 4 to 13 pounds |
| Length | About 16 to 20 inches plus a short tail |
| Range | Eastern and central U.S., much of Canada, into Alaska |
| Diet | Grasses, clover, dandelions, garden plants, some insects |
| Lifespan | Often 2 to 3 years in the wild; longer in captivity |
A Giant Squirrel
It’s easy to forget, but groundhogs are squirrels. They belong to the marmot group, the largest members of the squirrel family, and they’re relatives of prairie dogs, chipmunks, and tree squirrels. Unlike most marmots, which live in mountains, groundhogs prefer lowland fields, meadows, and woodland edges. See types of squirrels and compare groundhogs with a mountain cousin in capybara vs marmot.
Why Are They Called Woodchucks and Whistle-Pigs?
“Woodchuck” likely comes from an Algonquian word for the animal, rather than anything to do with chucking wood. “Whistle-pig” comes from the high-pitched whistle groundhogs give when alarmed. So how much wood could a woodchuck chuck? Not much; they don’t eat wood.
Master Diggers
Groundhogs are excellent excavators. A burrow system can include multiple entrances, a main tunnel several feet underground, separate sleeping and toilet chambers, and a hibernation chamber below the frost line. Burrows can stretch 20 feet or more in total length. Abandoned groundhog burrows become shelters for foxes, rabbits, skunks, and other animals.
What Do Groundhogs Eat?
Groundhogs are mostly herbivores. They graze on grasses, clover, alfalfa, dandelions, plantain, and wild berries, and they occasionally eat insects and snails. They also love garden vegetables, which can put them in conflict with gardeners. In late summer, they eat heavily to build fat stores for winter.
True Hibernators
Groundhogs are one of the best-known true hibernators. From roughly late fall to late winter or early spring, depending on latitude, they retreat to their hibernation chamber and enter deep torpor. During hibernation:
- Body temperature drops from around 99°F to as low as about 40°F.
- Heart rate falls from around 80 beats per minute to just a handful.
- Breathing slows dramatically.
- They live off stored fat, losing a significant share of their body weight.
They wake periodically for short periods during hibernation, which scientists think may be important for body maintenance. Learn how other rodents handle winter in do rodents hibernate.
The Story of Groundhog Day
Groundhog Day, held each February 2, grew out of European traditions tied to Candlemas, when people believed a sunny day meant more winter ahead. German immigrants in Pennsylvania adapted the tradition, using the local groundhog instead of the badger or hedgehog of Europe. The famous Punxsutawney celebration dates to the late 1880s.
According to the tradition, if the groundhog sees its shadow, there will be six more weeks of winter; if not, spring comes early. In reality, forecasts from groundhogs are no better than chance. Timing of when groundhogs emerge is actually driven by mating season, as males leave their burrows in late winter to visit females’ territories. Discover more rodents in folklore in rodents in culture and history and famous rodents.
Family Life
Groundhogs are mostly solitary. After mating in early spring, females give birth to a litter of about four to six young after roughly a month of pregnancy. The young stay with their mother through the summer before leaving to dig their own burrows.
Groundhogs Can Swim and Climb
Despite their stocky build, groundhogs can swim and climb trees to escape predators or survey their surroundings. Their main predators include foxes, coyotes, hawks, eagles, bobcats, and dogs.
Living With Groundhogs
Groundhogs can damage gardens and dig burrows under sheds, decks, and foundations. Humane options include:
- Fencing gardens with wire that’s buried at least a foot deep and bent outward
- Removing brush piles and tall grass near buildings
- Using one-way doors to let groundhogs leave a burrow and not return, outside of the baby season
- Filling abandoned burrows once you’re sure they’re empty
Relocating wildlife is illegal in some states and often harms the animal, so check local rules. See humane rodent control.
Groundhogs in Science
Groundhogs have been studied for decades because of their hibernation and because they’re susceptible to a hepatitis virus closely related to human hepatitis B, which has made them a valuable model in medical research.
Groundhogs vs Capybaras
Both are large grazing rodents, but groundhogs are solitary burrowers that hibernate, while capybaras are social, semi-aquatic, and active year-round. Capybaras are also roughly ten times heavier. See capybara vs groundhog and our rodent size comparison.
How to Spot Groundhog Signs
You’re more likely to see signs of groundhogs than the animals themselves. Look for large burrow openings, about 10 to 12 inches across, often with a fan of fresh dirt at the main entrance. Secondary “plunge holes” may have no dirt around them. Chewed garden plants close to the ground, flattened trails through tall grass, and a groundhog sunning itself on a stump in the morning are other clues. They’re most active in the early morning and late afternoon.
Groundhogs and Other Rodents
Groundhogs share many traits with other ground-dwelling squirrels. Like prairie dogs, they whistle alarms and dig burrows, but they live alone rather than in towns. See prairie dog facts for the social version of the burrowing lifestyle, and types of rodents for where they fit in the rodent family tree.
Frequently Asked Questions
Is a groundhog the same as a woodchuck?
Yes. Groundhog and woodchuck are two names for the same animal.
Are groundhogs dangerous?
They avoid people but can bite if cornered. Don’t try to handle wild groundhogs.
How long do groundhogs hibernate?
Typically about three to five months, depending on climate.
Is Groundhog Day accurate?
No. Groundhog forecasts are a fun tradition, not a reliable weather prediction.