The nutria (Myocastor coypus), a large, semi-aquatic rodent native to 

South America, was originally brought to the United States in 1889 for 

its fur. When the nutria fur market collapsed in the 1940s, thousands of 

nutria escaped or were released into the wild by ranchers who could no 

longer afford to feed and house them. While nutria devour weeds and 

overabundant vegetation, they also destroy native aquatic vegetation, 

crops, and wetland areas. 

Recognized in the United States as an invasive wildlife species, nutria 

have been found in at least 20 States and most recently in California. 

The nutria’s relatively high reproductive rate, combined with a lack of 

population controls, helped the species to spread. In many regions they 

cause severe damage. 

Nutria are most abundant in the Gulf Coast States, but they also cause 

problems in other southeastern States, the Pacific Northwest, and along 

the Atlantic coast. In addition to damaging vegetation and crops, nutria 

destroy the banks of ditches, lakes, and other water bodies. Of greatest 

significance, however, is the permanent damage nutria can cause to 

marshes and other wetlands. 

In these areas, nutria feed on native plants that hold wetland soil together. 

The destruction of this vegetation intensifies the loss of coastal marshes 

that has been exacerbated by rising sea levels.

Identification

Nutria are approximately two-feet long, with a large head, short legs and 

a stout body that appears hump-backed on land. They are dark brown 

Factsheet

April 2020

Nutria, An Invasive Rodent

Wildlife Services, a program 

within the U.S. Department 

of Agriculture’s (USDA) 

Animal and Plant Health 

Inspection Service (APHIS), 

provides Federal leadership 

and expertise in managing 

conflicts between people 

and wildlife to help protect 

the Nation’s agricultural and 

natural resources, property 

and infrastructure, and public 

health and safety. 

Increased populations and 

ranges of invasive species 

can harm native ecosystems, 

impact agricultural resources, 

and increase disease 

transmission. An Executive 

Order directs Federal agencies, 

including WS, to address 

invasive species damage, 

including that caused by nutria.

Sometimes mistaken for beaver or 

muskrat, some characteristics can 

assist in identifying nutria. These 

include large front teeth that are yellow 

to orange in color; a heavy, rat-like 

tail thinly covered in bristly hairs; 

and noticeable white whiskers that 

protrude from either side of their nose 

(USFWS photo).

Animal and Plant Health 

Inspection Service

Wildlife Services
in color although occasional light colored and albino 

animals are observed. Because nutria spend much of 

their time in the water, they are highly adapted for a 

semi-aquatic existence.

Their hind feet are partially webbed for swimming, 

and their eyes, ears, and nostrils are set high on their 

heads, so they can stay above the waterline when 

swimming. Nutria are excellent swimmers and valves 

in their nostrils and mouths seal out water when 

submerged to swim or feed. When pursued, they can 

swim long distances underwater, seeing well enough to 

evade capture. Female nutria have teats located high 

on their backs so that their young can suckle when 

floating in the water. From a distance, nutria are often 

mistaken for beavers and muskrats.

All three species are dark brown in color and semiaquatic. However,nutria have visible large front teeth 

that are yellow to orange in color. Adults weigh 15 to 

20 pounds for adults, this is about one-third the size 

of an adult beaver (>45 pounds) and 5-8 times larger 

than an adult muskrat (2-4 pounds).

Additionally, the tails and whiskers of the three species 

are distinctly different. Beavers have large broad flat 

tails that they often smack loudly on the water to signal 

alarm. Muskrats have long narrowly flattened tails that 

can be seen whipping snake-like behind them when 

swimming the water. Nutria have a heavy, rat-like 

tail thinly covered in bristly hairs that trails smoothly 

behind when swimming. In northern climates, nutria 

often suffer frostbite to their tails and may retain only a 

stub tail following a cold winter. Another distinguishing 

characteristic of nutria are long (3-5”) white whiskers 

that protrude from either side of their nose and are 

easily seen from a distance. Beavers and muskrats 

have subtle black whiskers that can only be viewed 

from very close.

Nutria adapt to a wide variety of habitats but are 

usually closely associated with water. In the United 

States, the largest nutria populations are located in 

freshwater marshes in coastal areas along Gulf Coast 

States. These regions have an abundance of small 

trees, shrubs and vegetation with under-water roots 

and surface leaves. In these areas, nutria live in farm 

ponds and other fresh water impoundments such 

as drainage canals, rivers, bayous, freshwater and 

brackish marshes, and swamps. In cities, they can 

be found under buildings, in overgrown lots, on golf 

courses, and in storm drains.

Beavers create lodges from mud and sticks and 

muskrats create mounded huts from mud and 

A small bay area along Maryland’s Chesapeake 

Bay shows recovery in the 2 years after invasive 

nutria were removed by Wildlife Services biologists 

and specialists.

The nutria’s preferred diet includes the roots, rhizomes

and tubers of cattails, cordgrass, and bulrush.
vegetation. Unlike beaver and muskrat that construct 

protective shelters from mud, sticks, and or vegetation, 

nutria do not build structures to protect themselves 

from the elements. Nutria sometimes live in burrows 

and in marshes, often creating flat, nest-like platforms 

of dead vegetation for feeding, loafing, grooming, and 

birthing. Sometimes nutria will burrow into muskrat 

houses and displace their residents.

Damage

Nutria damage is evident to varying degrees in 

every area they are found. Burrowing causes the 

most noticeable damage. Nutria are notorious in 

Louisiana and Texas for undermining and breeching 

water-retention levees in flooded fields used to 

produce rice and crawfish. Nutria burrows can also 

damage flood-control levees that protect low-lying 

areas; weaken the foundations of reservoir dams, 

buildings, and roadbeds; and erode the banks of 

streams, lakes, and ditches.

Nutria damage, however, is not limited to burrowing. 

Crop damage is well documented. In the United States, 

sugarcane and rice are the primary crops damaged 

by the nutria. Grazing on rice plants can significantly 

reduce yields, with severe localized loss. Other crops 

damaged by the nutria include corn, milo, sugar and 

table beets, alfalfa, wheat, barley, oats, peanuts, 

various melons, and a variety of vegetables. This 

depredation can lead to significant losses, especially 

for small farmers.

The negative impact this invasive species has on 

native vegetation and associated wetlands is critically 

important. In Louisiana, some nutria feed on seedling 

bald cypress with such intensity that the trees cannot 

survive. Similarly, nutria can severely damage coastal 

marshes by decimating native plants that hold marsh 

soils together and support the survival of native 

wildlife species. 

The impact of nutria on disappearing marshlands 

along the Gulf Coast and the Chesapeake Bay in 

Maryland has been well documented. Nutria have 

caused widespread ecosystem changes. In some 

cases, nutria damage to marsh vegetation and soils is 

so severe that these resources are permanently lost. 

The destruction of these marshlands also increases 

the vulnerability of adjacent upland sites to erosion 

and flooding during storms.

To address the threat and protect the Chesapeake 

Bay area of Maryland from further environmental 

damage, numerous partners joined forces in the mid1990’s and the project to remove nutria from nearly 

800 square miles, officially began in 2002. Within two 

years, the eradication team had nearly eliminated 

nutria from the Blackwater National Wildlife Refuge 

and by 2006, they expanded the eradication zone into 

surrounding counties, where the effects of eradication 

were immediately observable. 

Expansion to the landscape level required the 

cooperation, or partnership, of hundreds of private 

landowners as well as the governmental, academic, 

and private partners. It took 12 years, working on 

nearly half a million acres, and the removal of 14,000 

nutria to accomplish the goal and in 2020 the area 

is still being monitored to confirm the absence of the 

invasive rodent.

Nutria also can impact public health and safety. The 

rodents can serve as hosts for several pathogens, 

including tuberculosis and septicemia, which can 

infect people, pets, and livestock. In addition, nutria 

can carry parasites, such as blood flukes, tapeworms, 

and liver flukes and a nematode known to cause a 

rash called “nutria itch.” Many of these organisms—

found in nutria feces and urine—can contaminate 

drinking water supplies and swimming areas.

Their eating, digging, rooting, and swimming causes massive erosion, converting 

healthy marsh and habitat for native species into open water habitat.
How Wildlife Services Manages the Damage

Wildlife Services is authorized by Congress to resolve 

damage caused by wildlife. A 1997 Executive Order 

also directs USDA to provide national leadership and 

oversight in managing invasive species, such as the 

nutria, in cooperation with other Federal agencies.

When WS is asked to provide nutria assistance, 

program specialists work closely with Federal, State, 

and local governments to develop comprehensive 

management plans that include provisions for 

protecting native vegetation, marsh soil, and other 

natural resources against nutria damage.

Preventative measures should be used whenever 

possible, especially in areas where nutria damage 

is common. Habitat management can help reduce 

rodent numbers by manipulating vegetation and water 

sources attractive to nutria. 

Wildlife Services is not the only source of wildlife damage management services available to the public. Private-sector wildlife damage management providers may 

also be available. Wildlife Services does not endorse or recommend any specific private-sector provider or the use of any specific product over another.

USDA is an equal opportunity provider, employer, and lender.

APHIS 11-15-004

Highly adapted for a semi-aquatic existence,

from a distance, nutria often are mistaken for

beavers and muskrats while swimming.

Small areas, such as gardens, can be enclosed by 

partially buried fences. Wire tubes can be used 

to protect bald cypress and other tree seedlings 

from nutria damage and bulkheads can be used 

to deter burrowing into banks. These methods can 

be expensive to implement and may not always be 

effective or practical.

When damage cannot be resolved by nonlethal 

measures, WS has the expertise to remove nutria 

populations in problem areas. Because nutria are 

an invasive species and threaten both native wildlife 

species and vegetation, relocation is not a viable nutria 

option. Relocating nutria to a new area just relocates 

the problem, and can lead to the establishment of new 

colonies and new damage concerns.

Additional Information

For more information about this and other WS 

programs or to request assistance from your WS 

State office call 1-866-4USDA-WS (1-866-487-3297). 

Find more information at www.aphis.usda.gov/

wildlife-damage.