Nutria destroy the very fabric of wetlands.

Nutria, an invasive species, are one of the biggest culprits of wetland loss in Louisiana and other US wetlands. These semi-aquatic, otter-like mammals are responsible for the destruction of approximately 100,000 acres of critical marsh habitat between 1993 to 2001. Like most invasive species, Nutria not only destroy habitat but also impact native species such as otter, muskrat, beaver, birds, crustaceans, and fish—all of whom rely on healthy wetlands.

About Nutria

The generic name “Nutria” is derived from two Greek words (mys, for mouse, and kastor, for beaver) that translate as mouse beaver. The specific name coypus is the Latinized form of coypu, a name in the language of the Araucanian Indians of south-central Chile and adjacent parts of Argentina for an aquatic mammal that was possibly this species. In most of the world the animal is called coypu, but in North America the animal is called nutria. In south Louisiana, the name is frequently mispronounced “nutra” or “neutral.” Nutria are so omnipresent in wetlands that some people do not realize they are an invasive, non-native” species that destroys marsh.

Invasive species have been characterized as a “catastrophic wildfire in slow motion.” Thousands of non-native invasive plants, insects, fish, mollusks, crustaceans, pathogens, birds, reptiles, amphibians, and mammals (like Nutria) have infested hundreds of millions of acres of land and water across the nation, causing massive disruptions in ecosystem function, reducing biodiversity, and degrading ecosystem health in our forests, prairies, mountains, wetlands, rivers, and oceans. Invasive organisms affect the health of not only these environments but also of wildlife, livestock, fish, and humans.

A species is considered invasive if it meets these 2 criteria:

  1. 1.It is nonnative to the ecosystem under consideration, and

  2. 2.Its introduction causes or is likely to cause economic or environmental harm or harm to human health.

This definition is derived from a Presidential Executive Order issued February 3, 1999.

Because of the shape of their tail, some people call Nutria “swamp rats.” While they do share the same taxonomic order “Rodentia” (as do about 40% of all mammals, including squirrels, rabbits, beaver, and guinea pigs), they are not rats. Nutria are most closely related to porcupines or South American capybaras.

The Nutria’s original range was South America and included Argentina, Brazil, Bolivia, Chile, Paraguay, and Uruguay.


Nutria are smaller than a beaver but larger than a muskrat with prominent yellow incisors and long white whiskers. Males are slightly larger then females weighing an average of 12 pounds (5.4 kg). The forelegs are exceedingly efficient at excavating marsh roots, rhizomes, and burrowing. 

Nutria were intentionally brought to America for fur ranching. During World War II fur prices collapsed and many ranchers lost interest. The animals were released and/or escaped into marshes where they quickly became established. Nutria are very adaptable and are currently reported in 18 states across the U.S. They destroy native habitat wherever they go.

Nutria are highly prolific and breed year round. Litters average four to five however, they can have up to thirteen young per litter and three litters per year. Add to this the fact that young are born fully furred and active—able to swim and destroy marsh within five days of birth. As an example of their proliferation: in 1938, 20 individual nutria were introduced into Louisiana and within 20 years, the nutria population exceed 20 million animals. By 1962, Nutria had replaced the native muskrat as the leading furbearer in Louisiana.

Nutria are vegetarian and consume approximately 25 percent of their weight daily. They predominately feed on the base of plant stems and dig for roots and rhizomes in the winter. Over 60 Louisiana plant species are consumed by Nutria. Being “generalists,” there’s not much they won’t eat.

Nutria will also happily consume agricultural crops like rice and sugarcane. Their messy feeding habits make them particularly wasteful as they only consume 10% of what they cut down.

Nutria inhabit fresh, intermediate, and brackish marshes, rivers, bayous, farm ponds, freshwater impoundments, swamps and various other types of wetlands.

The biggest impact made by Nutria is to marsh. They can quickly convert productive grassy marsh into unproductive open water by attacking the very structure that holds the marsh together, the vegetative root mat. Once Nutria chew through a mat and expose mud, tidal currents and wave action lead to erosion. The pitted marsh surface sinks and vegetation is lost to flooding. Areas destroyed by nutria become permanent, open water ponds called “eat outs.” The swim canals are called “runs.” The photo at the top of this page illustrates Nutria destruction. On the upper right we see an “island” of fenced marsh and damage caused by Nutria all around it. Because the roots are destroyed, the marsh will only come back if replanted.

Nutria also compete for habitat and food with native mammals like muskrat, beaver, and otter; destroy crops like sugar cane and rice; and compromise levees, dikes, roads, and banks by burrowing. 

In 2002, the Coastwide Nutria Control Program was implemented to reduce the Nutria population (and its impact on marsh). The program, supported by CWPPRA (Coastal Wetlands Planning Protection and Restoration Act), has shown significant progress. It consists of an economic incentive payment per nutria delivered by registered participants to collection centers established in coastal Louisiana. The Louisiana Wildlife and
Fisheries implement and license harvesters during regulated seasons. The goal of the Program is to encourage the harvest of Nutria from coastal Louisiana thereby reducing damage to marsh.

Unfortunately, only a small percentage of harvested Nutria are utilized in any manner—leaving  this otherwise high-quality protein source to go to waste. In response, Marsh Dog created its line of dog products made with wild Nutria. Utilizing an invasive species that is already being harvested to control its impact on wetlands is about as sustainable as it gets.

Organizations such as The Barataria-Terrebonne National Estuary Program
support educational and environmental initiatives aimed at Nutria control, education, and wetland conservation. Marsh Dog is honored to be a recipient of a BTNEP grant.

Nutria are known internationally as Coypú, Ragondin, and Castorino.

Nutria are marsh-destroying machines consuming up to 25 percent of their weight daily.

With few natural predators and a high reproductive rate, the marsh stands little chance without control programs.

Since the introduction of the Coastwide Nutria Control Program, the number of impacted acres has dropped from over 100,000 acres to 6,296 acres, but the challenge of population control still exists.

Invasive plants and animals like Nutria pose a serious threat to estuaries, wildlife habitat, commerce, drainage, navigation, and so much more. 

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About Nutria

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Nutria construct burrows in the banks of rivers, sloughs, and ponds, sometimes causing considerable erosion. Burrows can weaken roadbeds, stream banks, dams, and dikes, which may collapse when the soil is saturated by rain or high water. Rain action can wash out and enlarge collapsed burrows and compounds the damage.