“Nutria, also called coypu, are large, semi-aquatic rodents native to South America with orange front teeth, webbed hind feet, and round, rat-like tails. Brought to the U.S. and Europe for fur farming, they escaped or were released and became invasive, destroying marsh vegetation and speeding coastal erosion, especially in Louisiana and the Chesapeake Bay.”
If you’ve ever seen a large, brown rodent swimming in a Louisiana bayou and wondered whether it was a beaver, a muskrat, or a giant rat, it may well have been a nutria. These South American natives are a textbook example of how introducing an animal to a new place can go wrong. They’re also fascinating animals in their own right, and distant cousins of the capybara.
Nutria Quick Facts
| Trait | Details |
|---|---|
| Scientific name | Myocastor coypus |
| Other names | Coypu, river rat, swamp rat |
| Native range | Southern South America |
| Introduced range | U.S. Gulf Coast, Pacific Northwest, Europe, Asia, Africa |
| Weight | About 9 to 20 pounds |
| Length | About 17 to 25 inches plus a 12 to 17 inch tail |
| Diet | Aquatic plants, roots, stems, crops |
| Reproduction | Multiple litters per year |
How to Identify a Nutria
- Orange front teeth, often visible even when the mouth is closed
- White whiskers on a blunt, whitish muzzle
- A long, round, sparsely haired tail, unlike the beaver’s flat paddle or the muskrat’s thin, flattened tail
- Webbed hind feet
- Coarse brown fur over a dense, soft underfur
In the water, nutria swim with their head and back showing, while beavers usually show only their head. See our beaver vs muskrat vs nutria comparison for side-by-side identification tips.
A Unique Adaptation for Nursing
Female nutria have their teats high on their sides rather than on the belly. This allows the young to nurse while the mother floats in the water, a clever adaptation to semi-aquatic life.
How Nutria Came to North America
In the late 1800s and early 1900s, nutria were imported to the U.S. and Europe for fur farming. Their dense underfur was marketed as a luxury product. When fur prices dropped, many farms failed, and animals escaped or were released into the wild. Some were also released deliberately in the belief that they would control unwanted aquatic plants. Instead, they multiplied rapidly in the warm, wet habitats of the Gulf Coast and elsewhere.
Why Nutria Are So Destructive
Nutria eat the roots and base of marsh plants, not just the leaves. When large numbers feed in an area, they can strip the vegetation completely, leaving bare mud. These “eat-outs” have serious consequences:
- Marsh soil, no longer held by roots, washes away
- Coastal wetlands turn into open water
- Habitat for fish, birds, and other wildlife is lost
- Natural storm protection for coastal communities is reduced
- Crops such as rice and sugarcane are damaged
- Burrowing weakens levees, dikes, and riverbanks
Louisiana, which was losing wetlands to many causes, found nutria to be a significant added pressure. See invasive rodent species for other examples.
Control Efforts
Louisiana
Louisiana runs a long-standing coastwide nutria control program that pays registered hunters and trappers a bounty for each nutria tail they turn in. The program has removed large numbers of nutria each year and is credited with reducing marsh damage.
Chesapeake Bay
On Maryland’s Delmarva Peninsula, a multi-agency eradication project began in the early 2000s after nutria damaged thousands of acres of marsh at Blackwater National Wildlife Refuge and nearby areas. The project has been widely cited as one of the most successful invasive mammal removal efforts in the country.
California and the Pacific Northwest
Nutria were rediscovered in California’s Central Valley in 2017, prompting an eradication program aimed at protecting the state’s wetlands and water infrastructure. They’re also established in parts of Oregon and Washington.
Europe
Great Britain eradicated its coypu population by the late 1980s after a focused trapping campaign. Coypu remain widespread in much of continental Europe.
Nutria in Their Native Range
In South America, nutria are a normal part of wetland ecosystems, kept in check by predators, disease, and competition. They’re hunted there for fur and meat. The contrast shows how the same animal can be harmless at home and destructive elsewhere.
Nutria vs Capybara
Both are semi-aquatic South American rodents in the broad cavy-like group, but capybaras are much larger, far more social, and native only to South America and Panama. Nutria are smaller, more solitary, and have spread worldwide. Read our full capybara vs nutria comparison.
Are Nutria Dangerous?
Nutria are not aggressive toward people but can bite if cornered, and their large teeth can cause serious wounds. They can also carry parasites and diseases. Never handle wild nutria. See rodent diseases that can spread to humans.
Can You Eat Nutria?
Yes. Nutria meat is lean and has been promoted in Louisiana as a way to encourage harvest, sometimes with the slogan “eat the invaders.” It never became widely popular, partly because of the animal’s rat-like appearance.
Nutria Behavior and Daily Life
Nutria are mostly active at night, especially around dusk and dawn, and spend much of the day resting in dense vegetation or in burrows dug into banks. They also build floating platforms from plant material where they groom, feed, and rest. Although they can live in loose family groups, they’re far less social than capybaras. Nutria are excellent swimmers and can stay underwater for several minutes. On land, they move with a slow, hunched gait but can run short distances when startled.
Their reproduction is a big part of why they spread so fast. Females can breed year-round in warm climates, have litters of several young, and become pregnant again soon after giving birth. Young nutria are born furred and can swim within hours. In the absence of their native predators and diseases, populations can grow rapidly.
What to Do If You See a Nutria
In many states, nutria sightings outside their established range are valuable information for wildlife agencies trying to prevent spread. Note the location, take a photo if you can do so safely, and report it to your state wildlife agency. Don’t try to trap or handle the animal yourself unless you’re authorized to do so.
Frequently Asked Questions
Are nutria and beavers the same?
No. Beavers are larger and have flat, paddle-shaped tails. Nutria have round, rat-like tails.
Why are nutria teeth orange?
Like beavers, nutria have iron-rich enamel on the front of their incisors, which makes them orange and strong.
Where do nutria live in the U.S.?
Mainly along the Gulf Coast, especially Louisiana, as well as parts of the Pacific Northwest, California, and the mid-Atlantic.
Why are nutria bad for wetlands?
They eat plant roots, which destroys marsh vegetation and leads to erosion and loss of wetland.