Groundhogs Are More Than Just Meteorologists


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Groundhogs typically stay fairly close to home, guarding the entrance to their burrow and ensuring themselves a safe place to hide. Sean Gallup/Getty Images

You might not know this, but there's an American folk song about groundhogs (Marmota monax). Like most songs written by people whose lives were very different from our own, it's almost entirely incomprehensible, including lyrics like,

He's in here boys, the hole's wore slick,
Run here Sam with your fork and stick, groundhog!

The song describes hunting, cooking and eating a groundhog, which was the original selling point of Groundhog Day (celebrated Feb. 2 today), a secular holiday invented in 1887 by German immigrants at Gobbler's Knob near Punxsutawney, Pennsylvania to replace the tradition of looking for a hedgehog or badger to see if it cast a shadow on Candlemas, a Christian festival of lights. The first Groundhog Days involved finding a groundhog, discovering whether or not it cast a shadow, and then killing it and serving it up a variety of different ways, including in a beverage called "groundhog punch."

So, in the United States we have a 13-decade tradition of putting groundhogs in charge of deciding what climatic conditions to expect nationwide between the months of February and May, whether we eat the animal afterward or not. But what is a groundhog besides an old-timey source of meat and meteorological advice?

Groundhogs Don't Chuck Wood, But They Do Burrow

Groundhogs are also called woodchucks, which is misleading because they don't concern themselves with wood at all — this name probably came from a phonetic interpretation of a Native American name, which was something like wuchak. These large, docile rodents, native to the eastern portion of the United States and all of Canada, can weigh up to around 15 pounds (6.8 kilograms), are actually squirrels, belonging to the branch of that family that includes marmots, prairie dogs and chipmunks — all powerful diggers with four toes on their front feet and five toes on the back. So, though they don't "chuck wood," whatever that means, groundhogs spend a lot of their time excavating intricate underground burrow systems, which is a huge ecological service, as it aerates the soil, promotes nutrient circulation, and provides a home for other animals like foxes, snakes and opossums, which aren't as good at constructing their own homes.

Their burrowing habit, though great for ecosystems, is not celebrated by everyone — especially homeowners and golf course custodians:

"Because they burrow, they can cause damage in lawns and landscaping, and since they're pretty adaptable, they do well in neighborhoods," says Steven Castleberry, a professor of wildlife ecology and management at the Warnell School of Forestry and Natural Resources at the University of Georgia. "Their burrows can cause damage and they will eat plants in flower and vegetable gardens."

But even though we don't love having groundhogs digging around in our azalea bushes and nibbling our tomato plants, they're actually not that bad. Unlike gophers, which look like woodchucks in miniature but are actually in an entirely different family of rodents, groundhogs are omnivorous and eat just the fruit and green parts of plants. Gophers eat tubers and roots, which can wreak havoc on landscaping. While both animals are omnivorous, groundhogs come out of their burrows pretty often because that's where their food source is, so they also help out around the yard picking off above-ground pest species like snails and slugs, grubs and other insects.

Groundhogs Hibernate for Three Months Each Year

Another reason groundhogs are way better for your garden than gophers is that they peace out for part of every year.

"Groundhogs, like all marmots, are hibernators," says Castleberry. "Their body temperature drops to near the surrounding air temperature during hibernation."

After having gotten fat on grass all summer, groundhogs find a comfy spot in their burrows and fall asleep for the better part of three months. They are among the largest true hibernating species, meaning they don't just fall asleep but descend into a deep torpor — their body temperature plummets from around 99 degree F (37 degree C) to as low as 37 degree F (3 degree C). To put that in perspective, a 3 degree F (1.6 degree C) drop in a human's core temperature is considered mild hypothermia, a 14 degree F (8 degree C) drop will cause you to lose consciousness, and a 26 degree F (14 degree C) drop would most likely kill you. A hibernating groundhog's heart rate slows from around 88 beats per minute to just five, and during their 150-day sleep, they lose around a quarter of their body weight.

When a hibernating groundhog comes out of its den, it's time to get busy: eat a whole bunch, find a mate, mate, gestate, have babies, raise babies, etc. before winter comes again. So, around Groundhog Day every year in the U.S., males emerge into the chilly February air to scout out the best female burrows and let themselves in. After mating, the female gestates for only 32 days — an insanely short time for mammals — before having a litter of between two and 10 babies, all of whom have to grow up fast.

Aside from mating season, though, groundhogs are pretty solitary and stay close to home — their home territories are only about 2 to 3 acres (0.8 to 1.2 hectares), making it extremely easy for the people of Gobbler's Knob to find Puxatawney Phil when they need him.