This Is Every Kind of Groundhog In The U.S.A., Ranked By the Size of Its Shadow

The groundhog is a rodent, broadly related to squirrels but specifically placed in the marmot genus. Marmots all sort of look like the groundhog: big, stocky, ground-bound fellows who prefer colder, hilly environments.


Every year we look to the groundhog for a deranged ceremony in west-central Pennsylvania. Punxsutawney Phil—well, the series of groundhogs who have held that title—have produced weather predictions that are correct only 36 percent of the time since 1969, when weather monitoring achieved modern accuracy.

The groundhog is a rodent, broadly related to squirrels but specifically placed in the marmot genus. Marmots all sort of look like the groundhog: big, stocky, ground-bound fellows who prefer colder, hilly environments. Here are the five marmot species found in the United States (ranked by the size of their shadow).

Olympic Marmot

Brown groundhog sitting in the flowers.
Roughly the size of a large domestic cat, the Olympic marmot can get as large as 30 inches long and 24 pounds in weight; it’s a close race between this species and the hoary marmot for largest, but the Olympic is, on average, just slightly larger.
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Scott Costello/Wikimedia Commons

One of the most localized marmots in the world, the Olympic marmot can only be found in the center of the Olympic Peninsula, across the Puget Sound from Seattle, Washington. DNA research suggests that it might be the ancestral form of the Alaska and hoary marmots, a vestige from the past that is reduced to a small population in a tight area.

Groundhog lying on rock
Its fur color changes through the year.
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Chad Collins/Wikimedia Commons

Its fur color actually changes through the year; in the spring and summer, it’s a reddish-tan with a white patch on the muzzle, but it gets progressively darker, and by the time the Olympic marmot heads in for hibernation, it’s dark brown.

Groundhog
The vast majority of Olympic marmots live in Olympic National Park, where it prefers to live in alpine meadows.
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Helen Rickard/Wikimedia Comons

It’ll eat pretty much any plant, though it prefers young, tender shoots of plants, as well as flowers. It’s one of the rarest of all marmots; its population dropped dangerously during the 2000s, though it’s bounced back a little bit since then. It reproduces rarely, only every other year, and it’s vulnerable to climate change, as it can only live in one small area. If that area changes—say, more forests, less water, or hotter daytime temperatures—it may have trouble surviving.

Hoary Marmot

Very large groundhog sitting on a rock.
The hoary marmot lives in the upper Rockies, in Alaska, British Columbia, and down into a bit of Washington, Idaho, and Montana.
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Trougnouf/Wikimedia Commons

It’s a huge marmot, at two and a half feet long and up to 30 pounds in weight, one of the biggest in the world—and, in turn, it casts the largest shadow. Like most of the other marmots, it has grizzled greyish fur, usually with some white around its muzzle. Apparently the word “hoary” refers to a greyish-white color, which is a weird fact I bet you didn’t think you’d learn today.

Groundhog lying on a rock.
Generally the hoary marmot lives above the tree line, high up in the Rockies, preferring those alpine meadows or sometimes rocky steppes.
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Walter Siegmund/Wikimedia Commons

Because it needs some mountain climbing abilities, there’s no fur on the pads of its paws. That gives them some extra grip, almost like climbing gloves, so they can safely scramble around their dangerous habitats.

Groundhog sniffing purple flowers.
You might know that the groundhog is sometimes known as the whistlepig.
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Steven Pavlov/Wikimedia Commons

The hoary marmot gets a similar nickname, “whistler,” because of its communication style. Hoary marmots are social animals, and when one sees a predator—bears, coyotes, wolves, eagles—it makes a piercing whistling noise to alert its crew. The ski resort town of Whistler, British Columbia is actually named after the hoary marmot.

Groundhog looking out into the landscape.
Because they live in such cold areas, the hoary marmot hibernates for up to eight months each year, totally skipping the ski season.
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Eemeli Haverinen/Wikimedia Commons

Its burrows are around 10 feet deep, with multiple branches, some lined with collected grasses for comfort, and some deeper still for the long hibernation period. To deal with the cold even when they’re not hibernating, hoary marmots are frequently seen sunbathing on rocks, absorbing as much warmth and sunlight as they can during the day.

Alaska Marmot

Tiny groundhog sitting on a grassy knoll.
The Alaska marmot was believed to just be the northern distribution of hoary marmots until some DNA testing revealed that it’s a totally different species of marmot.
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groundtruthtrekking.org/Erin McKittrick/Bretwood Higman

They live in pockets of the northern Alaskan mountains, from the coast to possibly as far east as the Yukon Territory, though scientists aren’t totally sure if they live there. Though it looks a bit like the hoary marmot (sans the white patch on the face), the Alaska marmot is quite a bit smaller, only around eight pounds. Still, at up to 26 inches long, it’s quite a big rodent, with a big shadow.

Groundhog sitting on the grass by the water.
The Alaska marmot mostly eats plants, flowers, leaves, and lichens, and needs an awful lot of them to store up fat for hibernation.
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groundtruthtrekking.org/Erin McKittrick/Bretwood Higman

Hibernation lasts from September to May, and during that time, no marmot will leave the burrow. In fact, the marmots even plug up the entrance to their burrows with grasses, mud, and other plants, to disguise their home and discourage any predators from digging them out during the winter.

Groundhog

Groundhog standing up in the grass
The groundhog is the most common marmot in the United States; you can find it throughout the entire Appalachian and Great Lakes areas, as far south as Georgia and even into a bit of the Great Plains.
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Marumari/Wikimedia Commons

It’s also found in some of the northern Rockies, in Canada and even Alaska. In Pennsylvania, where the famous Punxsutawney Phil lives, it’s a common sight, lumbering around local roads and parks. Because lives further south than any of these other marmots, it’s also often the smallest; it doesn’t need to store as much fat for the winter.

Chunky groundhog lying in the dirt
Known by several names, including the woodchuck, whistlepig, and according to some sources, thickwood badger, the groundhog is up to two feet long and 14 pounds in weight, though that would be a big groundhog indeed.
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cgpgrey.com/Wikimedia Commons

Its fur is thick and short, a brownish-greyish-reddish color depending on the specific location each groundhog calls home. They mostly live on the ground, with powerful forelimbs and claws to create elaborate burrows.

Groundhog chewing on a flower.
Groundhogs are known as a gardener’s pest; they eat copious amounts of vegetation, up to a pound a day, and are not particularly picky about what it is.
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Shenandoah National Park/Wikimedia Commons

If you’re growing something tasty, chances are a groundhog will think it’s tasty, too. But their burrows can also create problems, providing homes for other pests like mice and sometimes becoming so large that they can cause the collapse of buildings.

Groundhog looking out into the landscape.
One of the most amazing things about groundhogs is that they are the largest “true” hibernating animals in the United States.
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Virginia State Parks/Wikimedia Commons

True hibernators undergo a crazy change in their behavior; their heart rate drops from 80 times per minute to four or five, and they cannot be “woken up.” They breathe only once every few minutes, and their body temperatures can drop to near-freezing. Bears, on the other hand, go into more like an extended sleep: they don’t have such dramatic physical adaptations, and they can be woken up, and sometimes will, to go find some food.

Yellow-Bellied Marmot

Chubby groundhog sitting on a rock.
Look, you have to take the yellow-bellied marmot’s name literally.
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Inklein/Wikimedia Commons

It is not a cowardly animal; it simply has a yellowish coloring on its chest fur. Slightly smaller than the groundhog, its coloring is otherwise mostly greyish, sometimes with a sassy white patch around the eyes. Its greyish hairs are actually banded, giving it the same grizzled look as some tabby cats. The largest yellow-bellied marmots are just barely larger than the largest Alaska marmots, giving it the edge.

Groundhog sunbathing on rock
You can find the yellow-bellied marmot throughout the Rockies, even down into the northern parts of New Mexico and Arizona and as far north as little chunks of southern British Columbia, Canada.
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Donald Hobern/Wikimedia Commons

Mostly it prefers meadows, around 2,000 feet above sea level of elevation, but during the day, you’re most likely to find these animals on rocky outcroppings. Why, you might ask? Sunbathing!

Groundhog in rocks.
This species, like the prairie dog, is highly social, and lives in colonies of a dozen or so.
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Paxson Woelber/Wikimedia Commons

It communicates with various chirps and whistles and other vocalizations. It, like the groundhog and prairie dog (the latter of which is not a marmot), constructs multi-use, complex burrow systems: different ones for hibernation or daily use, areas for pups to be raised. Given its environment, typically these burrows are under rocks; that protects them from predators like coyotes and wolves.

Groundhog on rock
Since their environment has less water than the lush hills of the east where the groundhog lives, the yellow-bellied marmot doesn’t drink much, instead getting its water from the plants (and occasionally eggs and insects) it eats. Jon Sullivan/PDPhoto.org

But it won’t eat just anything; it avoids certain plants that have defensive mechanisms (like bad-tasting chemicals) and will eat different plants in the summer compared with the fall, when it’s fattening up for hibernation.


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