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

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

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

of nutria were released into the wild by ranchers who could no longer 

afford to feed and house them. Entrepreneurs began selling the herbivores to control noxious weeds. Wildlife agencies further expanded 

the range of the nutria by introducing the species into new areas of the 

United States. While the nutria did devour weeds and overabundant 

vegetation, they also destroyed native aquatic vegetation, crops, and 

wetland areas.

Recognized in the United States as an invasive wildlife species, 

nutria have been found in 22 States, and are currently established in 16 

States. The nutria’s relatively high reproductive rate combined with a 

lack of population controls have resulted in a proliferation of the species. 

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 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 signifi cance, 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 intensifi es the loss of coastal 

marshes that has been stimulated by rising sea levels.

Identifi cation

Nutria are approximately 2-feet long, with a large head, short legs and a 

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

color, although occasional light-colored and albino animals are 

observed. Because nutria spend much of their time in the water, 

Factsheet

October 2010

Nutria, an Invasive Rodent Protecting People

Protecting Agriculture

Protecting Wildlife

Wildlife Services

Wildlife Services (WS), a 

program within the U.S. 

Department of Agriculture’s 

(USDA) Animal and Plant 

Health Inspection Service 

(APHIS), provides Federal 

leadership and expertise 

to resolve wildlife confl icts 

that threaten the Nation’s 

agricultural and natural 

resources, human health and 

safety, and property. 

The increased population 

and range of invasive species 

can harm native ecosystems, 

impact agricultural resources, 

and increase disease 

transmission. Under an 

Executive Order that directs 

Federal agencies to address 

invasive species damage, the 

WS program works to control 

and prevent damage caused by 

nutria.

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.
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 

fl oating in the water. From 

a distance, nutria often are 

mistaken for beavers and muskrats. All three species are dark brown in color and semi-aquatic with 

large front teeth that are yellow to orange in color. 

However, at 15- to 20-pounds for a large adult, nutria are about one-third the size of an adult beaver 

(45 pounds) and 5 to 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 fl at tails that they often smack loudly on the 

water to signal alarm. Muskrats have long narrowly 

fl attened tails that can be seen whipping snake-like 

behind 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 the long (3–5 inch) noticeable white whiskers 

that protrude from either side of their nose and can 

be easily seen from a distance. Beaver and muskrat 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 underwater 

roots and surface leaves. In these areas, nutria 

live in farm ponds and other fresh water impoundments, 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.

Beaver create lodges from mud and sticks and 

muskrat create mounded huts from mud and vegetation. Nutria do not create their own shelters from 

the elements. Nutria sometimes live in burrows; in 

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 and can be easily 

seen from a distance (USFWS photo).

Included in the nutria’s preferred diet are the roots, rhizomes 

and tubers of cattails, cordgrass, and bulrush.
marshes they often create fl at, nest-like platforms of 

dead vegetation for feeding, loafi ng, 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 fl ooded fi elds used to 

produce rice and crawfi sh. Nutria burrows also can 

damage fl ood-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. Depredation on crops is well documented. 

In the United States, sugarcane and rice are 

the primary crops damaged by the nutria. Grazing 

on rice plants can signifi cantly 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 signifi cant 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 

fl ooding during storms. 

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 fl ukes, 

tapeworms, and liver fl ukes 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. 

How Wildlife Services Manages the Damage 

WS 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 requested, WS provides nutria assistance; WS program specialists work closely with 

Federal, State, and local governments to develop 

comprehensive management plans that include 

Highly adapted for a semi-aquatic existence, 

from a distance, nutria often are mistaken for 

beavers and muskrats while swimming.

Their eating, digging, rooting, and swimming causes massive 

erosion, converting healthy marsh and habitat for native species 

into open water habitat.
provisions for protecting native vegetation, marsh 

soil, and other natural resources against nutria 

damage.

Preventive 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. 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 are not always effective or practical. 

When damage cannot be resolved by nonlethal 

measures, WS has the expertise to remove nutria 

populations in problem areas. Relocation is not a 

viable option; nutria are an invasive species that 

threaten both native wildlife species and vegetation. 

Relocating nutria to a new area just relocates the 

problem, and can lead to the establishment of new 

nutria colonies and new damage concerns.

Additional Information

For more information about this and other WS 

programs or to request assistance from your 

WS State offi ce call 1-866-4USDA-WS 

(1-866-487-3297). Find more information at 

www.aphis.usda.gov/wildlife_damage.

The U.S. Department of Agriculture (USDA) is an equal opportunity provider and employer. 

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United States Department of Agriculture

Animal and Plant Health Inspection Service