Rodents with large front teeth and bushy tails are common across North America, but two you may encounter and confuse are nutria and groundhogs. If you catch a fleeting glimpse of one, it can be tricky to identify which is which.
However, learning to distinguish these similar-looking animals by their key characteristics will help you correctly identify them.
If you’re short on time, here’s a quick answer to your question: The nutria is an invasive, semi-aquatic rodent with a round tail and orange teeth. The groundhog is a common burrowing rodent with a flat tail and prominent claws for digging.
They have different habitats, behaviors, and physical features that set them apart.
Appearance: Size, Tail, and Other Markings
Nutria Have a Round, Rat-Like Tail
One of the most telling ways to distinguish a nutria from a groundhog is to look at the tail. Nutria have long, round tails that resemble a rat’s, while groundhogs have much shorter, flatter tails (more on that below).
An adult nutria’s tail is about 15 inches long from base to tip, making up about a third of their total body length. They use their tails for balance and steering while swimming.
Groundhogs Have Flat, Wide Tails
In contrast to the nutria, groundhogs have very short and flat tails that are only about 4-7 inches long. Their tails are slightly furry and usually a bit darker brown or black than the rest of their coat.
Groundhogs don’t rely on their tails for swimming or balance since they spend most of their time on land rather than in the water.
Nutria Are Larger in Size
On average, nutria tend to be considerably larger than groundhogs. An adult nutria reaches about 2 to 3 feet long from head to rump and weighs 5 to 20 pounds. Groundhogs rarely surpass 2 feet in length and are more in the range of 4 to 14 pounds fully grown.
So if you spot a very large semi-aquatic rodent, it’s likely a nutria rather than a groundhog.
Groundhogs Have Long Front Claws
Groundhogs use their long, curved claws on their front feet which can grow over 2 inches, to dig extensive burrows and tunnels. They spend lots of time excavating underground chambers and tunnels. Nutria have smaller claws more suited to grooming, food handling, and grabbing vegetation. With webbed hind feet, they don’t tend to burrow underground.
Nutria Have Orange Teeth
Finally, if you get close enough to see inside its mouth, a nutria has vibrant orange-red colored teeth from the orange enamel coating. This helps keep their teeth strong to gnaw through tough plant materials. A groundhog’s teeth do not have this orange enamel and look yellowish-white instead.
Habitat and Behavior Differences
Nutria Are Semi-Aquatic
In contrast to the burrowing groundhog, nutria actually prefer aquatic habitats near rivers, lakes, wetlands, and marshes. They build dens in the banks close to the water, with multiple entrances and tunnels. Nutria spend a significant amount of time swimming and foraging in the water.
Their webbed hind feet and large, rudder-like tail make them well-adapted swimmers.
Groundhogs Live in Burrows
Groundhogs are very territorial animals that dig out their own deep burrow systems. These burrows can be over 30 feet long with multiple tunnels and chambers, allowing the groundhog to eat, sleep, mate, bear young, and hibernate underground over winter.
Nutria Are Aggressive and Invasive
Introduced nutria have become a problematic invasive species in certain parts of the United States. They are voracious feeders that damage aquatic vegetation, which disrupts native ecosystems. Their burrowing erodes banks and shorelines.
In the wild, nutria can also carry harmful parasites like roundworms, liver flukes, and blood flukes.
Additionally, nutria are quite bold and can be aggressive when threatened, unlike the shy groundhog. They have attacked pets and chased people. The US Department of Agriculture even classifies nutria as “harmful non-native wildlife”.
Groundhogs Are Shy and Solitary
Groundhogs are generally shy, harmless creatures that prefer to avoid confrontation. While the large rodents can deliver a nasty bite, attacks on people or pets are extremely rare as groundhogs tend to flee from threats.
Groundhogs are also solitary and territorial—only one adult occupies a burrow system at a time. Females areexceptions, as baby groundhogs live in their mother’s burrow for around two months before dispersing to dig their own burrows.
| Trait | Nutria | Groundhog |
|---|---|---|
| Habitat | Semi-aquatic | Underground burrows |
| Diet | Mostly vegetation | Omnivore |
| Social Style | Can form large groups | Solitary |
| Temperament | Aggressive when threatened | Docile, shy |
Geographic Range in North America
Nutria Originated in South America
The nutria (Myocastor coypus) is not native to North America. These large, semi-aquatic rodents actually originated in South America. Nutrias are native to subtropical and temperate regions of central and southern South America, including parts of Brazil, Uruguay, Argentina, Chile and Bolivia.
Nutrias were introduced to other parts of the world, including North America, for fur farming in the late 19th and early 20th centuries. Some escaped or were released from captivity, leading to feral populations establishing in areas outside of their native range.
Today, nutrias are considered an invasive species in many parts of Europe, Asia and North America.
Groundhogs Are Native to North America
Unlike nutrias, groundhogs (Marmota monax) are native to North America. They are one of six marmot species found in North America and the only one that lives east of the Mississippi River.
Groundhogs are found across much of Canada and the eastern and central United States. Their geographic range extends from southeastern Alaska to as far south as northern Alabama and Georgia. Groundhogs are well adapted to live in temperate forests, meadows and grasslands.
Some key differences in the native ranges of nutrias and groundhogs in North America:
- Nutrias originated in South America, groundhogs are native to North America
- Nutrias are invasive in many parts of North America, groundhogs are native
- Groundhogs have a larger native range in North America extending into Canada
Conclusion
While at first glance nutria and groundhogs may look similar, their distinct physical characteristics, habits, and ranges reveal they are quite different animals. Learning to identify the nutria’s round tail, semi-aquatic nature, and large size compared to the groundhog will help you distinguish between them.
This knowledge allows you to better understand and appreciate the wildlife around you, whether it’s a rare nutria sighting or a common groundhog burrowing in your backyard.
