Nutria

For the colour, see Nutria (colour).

"Coypu" redirects here. For the boat, see Coypu (dinghy).

The nutria or coypu (Myocastor coypus)^[1][2] is a large, herbivorous,^[3] semiaquatic rodent from South America. Classified for a long time as the only member of the family Myocastoridae,^[4] Myocastor is now included within Echimyidae, the family of the spiny rats.^[5][6][7] The nutria lives in burrows alongside stretches of water and feeds on river plant stems.^[8] Originally native to subtropical and temperate South America, it has since been introduced to North America, Europe, Asia, and Africa, primarily by fur farmers.^[9] Although it is still hunted and trapped for its fur in some regions, its destructive burrowing and feeding habits often bring it into conflict with humans, and it is considered an invasive species in the United States.^[10] Nutria also transmit various diseases to humans and animals, mainly through water contamination.^[11]

Nutria Temporal range: Late Pliocene – Recent PreꞒ Ꞓ O S D C P T J K Pg N ↓
Conservation status
Least Concern (IUCN 3.1)^[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Rodentia
Family:	Echimyidae
Subfamily:	Echimyinae
Tribe:	Myocastorini
Genus:	Myocastor
Species:	M. coypus
Binomial name
Myocastor coypus (Molina, 1782)
The range of the Nutria Regions   Extant (resident)   Extant & Introduced (resident) Countries   Extant & Introduced (resident)   Extant (resident)   Extant & Introduced

Etymology

The genus name Myocastor derives from the two Ancient Greek words μῦς (mûs) 'rat, mouse', and κάστωρ (kástōr) 'beaver'.^[12][13][14] Literally, therefore, the name Myocastor means 'mouse beaver'.

Two names are commonly used in English for Myocastor coypus. The name nutria (from the Spanish word nutria 'otter') is generally used in North America, Asia, and throughout countries of the former Soviet Union; however, in most Spanish-speaking countries, the word nutria refers primarily to the otter. To avoid this ambiguity, the name coypu or coipo (derived from Mapudungun) is used in South America, Britain and other parts of Europe.^[15] In France, the nutria is known as a ragondin. In Dutch, it is known as beverrat 'beaver rat'. In German, it is known as Nutria, Biberratte 'beaver rat', or Sumpfbiber 'swamp beaver'. In Italy, instead, the popular name is, as in North America and Asia, nutria, but it is also called castorino 'little beaver', by which its fur is known in Italy. In Swedish, the animal is known as sumpbäver 'marsh/swamp beaver'. In Brazil, the animal is known as ratão-do-banhado 'big swamp rat', nútria, or caxingui (the last from Tupi).

Taxonomy

 

Skull

The nutria was first described by Juan Ignacio Molina in 1782 as Mus coypus, a member of the mouse genus.^[16] The genus Myocastor was assigned in 1792 by Robert Kerr.^[17] Geoffroy Saint-Hilaire, independently of Kerr, named the species Myopotamus coypus,^[18] and it is occasionally referred to by this name.

Four subspecies are generally recognized:^[16]

• M. c. bonariensis: northern Argentina, Bolivia, Paraguay, Uruguay, southern Brazil (RS, SC, PR, and SP)
• M. c. coypus: central Chile, Bolivia
• M. c. melanops: Chiloé Island
• M. c. santacruzae: Patagonia

M. c. bonariensis, the subspecies present in the northernmost (subtropical) part of the nutria's range, is believed to be the type of nutria most commonly introduced to other continents.^[15]

Phylogeny

Comparison of DNA and protein sequences showed that the genus Myocastor is the sister group to the genus Callistomys (painted tree-rats).^[19][7] In turn, these two taxa share evolutionary affinities with other Myocastorini genera: Proechimys and Hoplomys (armored rats) on the one hand, and Thrichomys on the other hand.

Genus-level cladogram of the Myocastorini.

root                         Callistomys (painted tree-rat)   Myocastor (nutria)             Thrichomys (punaré)             Hoplomys (armored rat)   Proechimys

The cladogram has been reconstructed from mitochondrial and nuclear DNA characters.^[5]^[6]^[20]^[19]^[21]^[22]^[7]

Appearance

 

Large orange teeth are clearly visible on this nutria

The nutria somewhat resembles a very large rat, or a beaver with a small, long and skinny hairless tail. Adults are typically 4–9 kg (9–20 lb) in weight, and 40–60 cm (16–24 in) in body length, with a 30 to 45 cm (12 to 18 in) tail. It is possible for nutria to weigh up to 16 to 17 kg (35 to 37 lb), although adults usually average 4.5 to 7 kg (10 to 15 lb).^[23][24][25] Nutria have three sets of fur. The guard hairs on the outer coat are three inches long.^[26] They have coarse, darkish brown midlayer fur with soft dense grey under fur, also called the nutria. Three distinguishing features are a white patch on the muzzle, webbed hind feet, and large, bright orange-yellow incisors.^[27] They have approximately 20 teeth with four large incisors that grow during the entirety of their lives.^[28] The orange discoloration is due to pigment staining from the mineral iron in the tooth enamel. Nutria have prominent four inch long whiskers on each side of their muzzle or cheek area. The mammary glands and teats of female nutria are high on her flanks, to allow their young to feed while the female is in the water. There is no visible distinction between male and female nutria. Both are similar in coloring and weight.

A nutria is often mistaken for a muskrat (Ondatra zibethicus), another widely dispersed, semiaquatic rodent that occupies the same wetland habitats. The muskrat, however, is smaller and more tolerant of cold climates, and has a laterally flattened tail it uses to assist in swimming, whereas the tail of a nutria is round. It can also be mistaken for a small beaver, as beavers and nutria have very similar anatomies and habitats. However, beavers' tails are flat and paddle-like, as opposed to the round tails of nutria.^[29]

Life history

Nutria behaviours
view in Full HD

Nutria can live up to six years in captivity, but individuals uncommonly live past three years old. According to one study, 80% of nutrias die within the first year, and less than 15% of a wild population is over 3 years old.^[30] A nutria is considered to have reached old age at 4 years old. Male nutria reach sexual maturity as early as four months, and females as early as three months; however, both can have a prolonged adolescence, up to the age of nine months. Once a female is pregnant, gestation lasts 130 days, and she may give birth to as few as one or as many as 13 offspring. The average nutria reproduction is four offspring. Female nutria will mate within two days after offspring are born. The years of reproduction cycle by litter size. Year one might be large, year two litter size will be smaller and year three the litter size will be another larger size. Females can only produce six litters in her life, rarely seven litters.^[26] A female on average will have two litters a year.

Nutria generally line nursery nests with grasses and soft reeds. Baby nutria are precocial, born fully furred and with open eyes; they can eat vegetation and swim with their parents within hours of birth. A female nutria can become pregnant again the day after she gives birth to her young. If timed properly, a female can become pregnant three times within a year. Newborn nutria nurse for seven to eight weeks, after which they leave their mothers.^[31] Nutria have been known to be territorial and aggressive when caught or cornered. They will bite and attack humans and dogs when threatened.^[32] Nutria are mainly crepuscular or nocturnal, with most activity occurring around dusk and sunset with highest activity around midnight. When food is scarce, nutria will forage during the day. When food is plentiful, nutria will rest and groom during the day.^[33]

Distribution

 

Nutria occurrence records from 1980 to 2018 in Europe.^[34]

Native to subtropical and temperate South America, its range includes Chile, Argentina, Uruguay, Paraguay and the southern parts of Brazil and Bolivia. It has been introduced to North America, Europe, Asia, and Africa, primarily by fur ranchers. The distribution of nutrias outside South America tends to contract or expand with successive cold or mild winters. During cold winters, nutria often suffer frostbite on their tails, leading to infection or death. As a result, populations of nutria often contract and even become locally or regionally extinct as in the Scandinavian countries and such US states as Idaho, Montana, and Nebraska during the 1980s.^[35] During mild winters, their ranges tend to expand northward. For example, in recent years, range expansions have been noted in Washington and Oregon,^[36] as well as Delaware.^[37]

According to the U.S. Geological Survey, nutria were first introduced to the United States in California, in 1899. They were first brought to Louisiana in the early 1930s for the fur industry, and the population was kept in check, or at a small population size, because of trapping pressure from the fur traders.^[15] The earliest account of nutria spreading freely into Louisiana wetlands from their enclosures was in the early 1940s; a hurricane hit the Louisiana coast for which many people were unprepared, and the storm destroyed the enclosures, enabling the nutria to escape into the wild.^[15] According to the Louisiana Department of Wildlife and Fisheries, nutria were also transplanted from Port Arthur, Texas, to the Mississippi River in 1941 and then spread due to a hurricane later that year.^[38]

Habitat and feeding

A nutria in a canal in Milan

Besides breeding quickly, each nutria consumes large amounts of aquatic vegetation.^[39] An individual consumes about 25% of its body weight daily, and feeds year-round.^[31][40] Being one of the world's larger extant rodents, a mature, healthy nutria averages 5.4 kg (11 lb 14 oz) in weight, but they can reach as much as 10 kg (22 lb).^[41][42] They eat the base of the above-ground stems of plants, and often dig through soil for roots and rhizomes to eat.^[43] Nutria eat parts and whole plants, and go after roots, rhizomes, tubers and black willow tree bark in the winter. Their creation of "eat-outs", areas where a majority of the above- and below-ground biomass has been removed, produces patches in the environment, which in turn disrupts the habitat for other animals and humans dependent on wetlands and marshes.^[44] Nutria eat the following plant varieties: cattail, rushes, reeds, arrowheads, flatsedges, and cordgrasses. Commercial crops that nutria also eat are lawn grasses, alfalfa, corn, rice, and sugarcane.^[26]

Nutria are found most commonly in freshwater marshes and wetlands, but also inhabit brackish marshes and rarely salt marshes.^[45][46] They either construct their own burrows, or occupy burrows abandoned by beaver, muskrats, or other animals.^[10] They are also capable of constructing floating rafts out of vegetation.^[10] Nutria live in partially underwater dens. The main chamber is not submerged underground. Nutria are considered to be a species that lives in colonies. One male will share a den with three or four females and their offspring. Nutria use "feeding platforms" which are constructed in the water from cut pieces of vegetation supported by a structure like a log or branches. Muskrat dens and beaver lodges are also often used as feeding platforms.^[26]

Commercial use and issues

 

Myocastor coypus

Farming and the fur trade

Local extinction in their native range due to overharvesting led to the development of nutria fur farms in the late 19th and early 20th centuries. The first farms were in Argentina and then later in Europe, North America, and Asia. These farms have generally not been successful long-term investments, and farmed nutria often are released or escape as operations become unprofitable. The first attempt at nutria farming was in France in the early 1880s, but it was not much of a success.^[47] The first efficient and extensive nutria farms were located in South America in the 1920s.^[47] The South American farms were very successful, and led to the growth of similar farms in North America and Europe. Nutrias from these farms often escaped, or were deliberately released into the wild to provide a game animal or to remove aquatic vegetation.^[48]

Nutria were introduced to the Louisiana ecosystem in the 1930s, when they escaped from fur farms that had imported them from South America. Nutria were released into the wild by at least one Louisiana nutria farmer in 1933 and these releases were followed by E. A. McIlhenny who released his entire stock in 1945 on Avery Island.^[49] In 1940, some of the nutria escaped during a hurricane and quickly populated coastal marshes, inland swamps, and other wetland areas.^[50] From Louisiana, nutria have spread across the Southern United States, wreaking havoc on marshlands.

Following a decline in demand for nutria fur, nutria have since become pests in many areas, destroying aquatic vegetation, marshes, and irrigation systems, and chewing through man-made items such as tires and wooden house panelling in Louisiana, eroding river banks, and displacing native animals. Damage in Louisiana has been sufficiently severe since the 1950s to warrant legislative attention; in 1958, the first bounty was placed on nutria, though this effort was not funded.^[51]: 3 By the early 2000s, the Coastwide Nutria Control Program was established, which began paying bounties for nutria killed in 2002.^{[51]: 19–20} In the Chesapeake Bay region in Maryland, where they were introduced in the 1940s, nutria are believed to have destroyed 2,800 to 3,200 hectares (7,000 to 8,000 acres) of marshland in the Blackwater National Wildlife Refuge. In response, by 2003, a multimillion-dollar eradication program was underway.^[52]

In the United Kingdom, nutria were introduced to East Anglia, for fur, in 1929; many escaped and damaged the drainage works, and a concerted programme by MAFF eradicated them by 1989.^[53] However, in 2012, a "giant rat" was killed in County Durham, with authorities suspecting the animal was, in fact, a nutria.^[54]

Food products

A small number of game meat websites on the internet sell nutria meat for consumption. There are no restaurants that advertise nutria meat dishes currently. In 1997 and 1998, Louisiana attempted to encourage the public to consume nutria meat. Nutria meat is leaner with a lower fat content and lower in cholesterol compared to ground beef.^[55] In an effort to encourage Louisianians to eat nutria, several recipes were distributed to locals and published on the internet.^[56] People in poor and rural Louisiana have trapped and consumed nutria meat for decades.

Marsh Dog, a US company based in Baton Rouge, Louisiana, received a grant from the Barataria-Terrebonne National Estuary Program to establish a company that uses nutria meat for dog food products.^[57] In 2012, the Louisiana Wildlife Federation recognized Marsh Dog with "Business Conservationist of the Year" award for finding a use for this eco-sustainable protein.^[58] A claimed environmentally sound solution is the use of nutria meat to make dog food treats.^[59]

In Kyrgyzstan and Uzbekistan, nutria (Russian and local languages Нутрия) are farmed on private plots and sold in local markets as a poor man's meat.^[60] As of 2016, however, the meat is used successfully in Moscow restaurant Krasnodar Bistro, as part of the growing Russian localvore movement and as a 'foodie' craze.^[60] It appears on the menu as a burger, hotdog, dumplings, or wrapped in cabbage leaves, with the flavour being somewhere between turkey and pork.^[61]

Ecological impacts

Herbiviory and habitat degradation

 

Zoo animal on logs

Nutria herbivory "severely reduces overall wetland biomass and can lead to the conversion of wetland to open water.^[40] " Unlike other common disturbances in marshlands, such as fire and tropical storms, which are a once- or few-times-a-year occurrence, nutria feed year round, so their effects on the marsh are constant. Also, nutria are typically more destructive in the winter than in the growing season, due largely to the scarcity of above-ground vegetation; as nutria search for food, they dig up root networks and rhizomes for food.^[43]

While nutria are the most common herbivores in Louisiana marshes, they are not the only ones. Feral hogs, also known as wild boars (Sus scrofa), swamp rabbits (Sylvilagus aquaticus), and muskrats (Ondatra zibethicus) are less common, but feral hogs are increasing in number in Louisiana wetlands. On plots open to nutria herbivory, 40% less vegetation was found than in plots guarded against nutria by fences. This number may seem insignificant, and indeed herbivory alone is not a serious cause of land loss, but when herbivory was combined with an additional disturbance, such as fire, single vegetation removal, or double vegetation removal to simulate a tropical storm, the effect of the disturbances on the vegetation were greatly amplified.^[40] "

As different factors were added together, they resulted in less overall vegetation. Adding fertilizer to open plots did not promote plant growth; instead, nutria fed more in the fertilized areas. Increasing fertilizer inputs in marshes only increases nutria biomass instead of the intended vegetation, therefore increasing nutrient input is not recommended.^[40]

Wetlands in general are a valuable resource both economically and environmentally. For instance, the U.S. Fish and Wildlife Service determined wetlands covered only 5% of the land surface of the contiguous 48 United States, but they support 31% of the nation's plant species.^[62] These very biodiverse systems provide resources, shelter, nesting sites, and resting sites (particularly Louisiana's coastal wetlands such as Grand Isle for migratory birds) to a wide array of wildlife. Human users also receive many benefits from wetlands, such as cleaner water, storm surge protection, oil and gas resources (especially on the Gulf Coast), reduced flooding, and chemical and biological waste reduction, to name a few.^[62] In Louisiana, rapid wetland loss occurs due to a variety of reasons; this state loses an estimated area about the size of a football field every hour.^[63] The problem became so serious that Sheriff Harry Lee of Jefferson Parish used SWAT sharpshooters against the animals.^[64]

In 1998, the Louisiana Department of Wildlife and Fisheries (LDWF) conducted the first Louisiana coast-wide survey, which was funded by the Coastal Wetlands Planning, Protection, and Restoration Act and titled the Nutria Harvest and Wetland Demonstration Program, to evaluate the condition of the marshlands.^[65] The survey revealed through aerial surveys of transects that herbivory damage to wetlands totaled roughly 36,000 hectares (90,000 acres). The next year, LDWF performed the same survey and found the area damaged by herbivory increased to about 42,000 hectares (105,000 acres).^[45] The LDWF has determined the wetlands affected by nutria decreased from an estimated minimum of 32,000 hectares (80,000 acres) of Louisiana wetlands in 2002–2003 season to about 2,548 hectares (6,296 acres) during the 2010–2011 season.^[66] The LDWF stresses that coastal wetland restoration projects will be greatly hindered without effective, sustainable nutria population control.

Pathogenic and viral reservoirs of zoonotic diseases

In addition to direct environmental damage, nutria are the host for a roundworm nematode parasite (Strongyloides myopotami) that can infect the skin of humans, causing dermatitis similar to strongyloidiasis.^[67] The condition is also called "nutria itch".^[68] Other parasites they can host are tapeworms, liver flukes, and blood flukes. Waterbody contamination by nutria occurs through urine and feces.^[69] Nutria also host fleas, ticks and chewing louse.^[70] They can carry several zoonotic diseases (diseases transmitted from animals to humans). They are reservoirs for salmonellosis, encephalomyocarditis virus, chlamydia psittaci^[71] and antibiotic resistant bacteria, Aeromonas spp.^[72] Other zoonotic disease of concern they are host reservoirs for are mycobacterium tuberculosis, septicemia, toxoplasmosis, and rickettsiosis.^[73] According to the CDC, nutria carry two out of eight diseases of concern for the United States, rabies and salmonellosis.^[74] Nutria are considered a global alien species and have potential to spread disease to livestock and humans. Nutria are found on every continent except Australia and Antarctica. Native to the southern hemisphere and spreading globally requires preventive monitoring for zoonotic disease transmission. Currently nutria immigration is monitored for habitat destruction of wetlands, farmlands, marshes and is measured in habitat loss in acres.^[75] Increased local awareness of viral, bacterial and parasitic transmission from nutria to humans and livestock will be of greater importance as climate change progresses.

Control efforts

As a global alien species, nutria are monitored and managed throughout the world. Many countries have attempted eradication efforts with varying degrees of success.

 

Nutria burrow on bank

Nutria are predicted to expand their range northward over the next century as global temperatures increase.^[76]

European Union

This species is included since 2016 in the EU list of Invasive Alien Species of Union concern (the Union list).^[77] This implies that this species cannot be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union.^[78]

Ireland

A nutria was first sighted in the wild in Ireland in 2010. Some nutria escaped from a pet farm in Cork City in 2015 and began breeding on the outskirts of the city. Ten were trapped on the Curraheen River in 2017, but the rodents continued to spread, reaching Dublin via the Royal Canal in 2019.^[79][80][81] Animals were found along the River Mulkear in 2015. The National Biodiversity Data Centre issued a species alert in 2017, saying that nutria "[have] the potential to be a high impact invasive species in Ireland. […] This species is listed as among 100 of the worst invasive species in Europe."^[82]

Great Britain

In the UK, nutria escaped from fur farms and were reported in the wild as early as 1932. There were three unsuccessful attempts to control nutria in east Great Britain between 1943 and 1944. Nutria population and range increased, causing damage to agriculture in the 1950s. During the 1960s, a grant was awarded to rabbit clearance societies that included nutria.^[83] This control allowed for the removal of 97,000 nutria in 1961 and 1962. From 1962 to 1965, 12 trappers were hired to eradicate as many nutria as possible near the Norfolk Broads. The campaign used live traps allowing non-target species to be released while any nutria caught were shot. Combined with cold winters in 1962 to 1963, almost 40,500 nutria were removed from the population. Although nutria populations were greatly reduced after the 1962–1965 campaign ended, the population increased until another eradication campaign began in 1981. This campaign succeeded in fully eradicating nutria in Great Britain. The trapping areas were broken into 8 sectors leaving no area uncontrolled. The 24 trappers were offered an incentive for early completion of the 10-year campaign. In 1989 nutria were assumed eradicated, as only three males were found between 1987 and 1989.^[84]

Japan

Nutria were introduced to Japan in 1939. They were imported from France during World War II to support food shortages as well as the fur trade. After the war in 1950, many nutria were released en masse or escaped, and became one of Japan's worst invasive species, damaging river banks, rice fields and other valuable crops.^[85] In 1963 an eradication program was started to remove nutria but has shown little to no success. Nutria are still present in Japan and there is currently a restriction on importing, transporting and obtaining nutria per the Invasive Alien Species Act established in 2004.^[86]

New Zealand

Nutria are classed as a "prohibited new organism" under New Zealand's Hazardous Substances and New Organisms Act 1996, preventing it from being imported into the country.^[87]

United States

 

Trap for capturing nutria

Atlantic Coast

An eradication program on the Delmarva Peninsula, between Chesapeake Bay and the Atlantic Coast, where nutria once numbered in the tens of thousands and had destroyed thousands of hectares of marshland, had nearly succeeded by 2012.^[88] In September 2022 government officials announced that nutria have been completely eradicated on the Maryland Eastern Shore.^[89][90]

California

The first records of nutria invading California dates from the 1940s and 1950s, when the species was found in the agriculture-rich Central Valley and the south coast of the state, but by the 1970s the animals had been extirpated statewide.^[91] They were found again in Merced County in 2017, on the edge of the San Joaquin River Delta. State officials are concerned that they will harm infrastructure that sends water to San Joaquin Valley farms and urban areas.^[92] In 2019, the California Department of Fish and Wildlife (CDFW) received nearly $2 million in Governor Gavin Newsom's first budget, and an additional $8.5 million via the Delta Conservancy (a state agency focused on the Delta) to be spent over the course of three years.^[93] The state has adopted an eradication campaign based on the successful effort in the Chesapeake Bay, including strategies such as the "Judas nutria" (in which individualized nutria are caught, sterilized, fitted with radio collars, and released, whereupon they can be tracked by hunters as they return to their colonies) and the use of trained dogs.^[93] The state has also reversed a prior "no-hunting" policy, although hunting the animals does require a license.^[93] California currently has a restriction on importation and transportation without a permit.^[11] If nutria are found or captured in the state of California, local authorities must be notified right away and the nutria cannot be released. Licensed hunters in the state of California may hunt nutria as a non-game animal. Eradication programs are not advised in California due to native species of muskrat and beaver being misidentified.^[94]

Louisiana

The Louisiana Coastwide Nutria Control Program provides incentives for harvesting nutria. Starting in 2002, the Louisiana Department of Wildlife and Fisheries (LDWF) performed aerial surveys just as they had done for the Nutria Harvest and Wetland Demonstration Program, only it is now under a different program title. Under the Coastwide Nutria Control Program, which also receives funds from CWPPRA, 308,160 nutria were harvested the first year (2002–2003), revealing 33,220 hectares (82,080 acres) damaged and totaling $1,232,640 in incentive payments paid out to those legally participating in the program.^[66] Essentially, once a person receives a license to hunt or trap nutria, then that person is able to capture an unlimited number. When a nutria is captured, the tail is cut off and turned in to a Coastal Environments Inc. (CEI) official at an approved site. As of 2019, each nutria tail is worth $6, which is an increase from $4 before the 2006–2007 season.^[95] Nutria harvesting increased drastically during the 2009–2010 season, with 445,963 nutria tails turned in worth $2,229,815 in incentive payments.^[66] Each CEI official keeps record of how many tails have been turned in by each individual per parish, the method used in capture of the nutria, and the location of capture. All of this information is transferred to a database to calculate the density of nutria across the Louisiana coast, and the LDWF combines these data with the results from the aerial surveys to determine the number of nutria remaining in the marshes and the amount of damage they are inflicting on the ecosystem.^[66]

Another program executed by LDWF involves creating a market of nutria meat for human consumption, though it is still trying to gain public notice. Nutria is a very lean, protein-rich meat, low in fat and cholesterol with the taste, texture, and appearance of rabbit or dark turkey meat.^[96] Few pathogens are associated with the meat, but proper heating when cooking should kill them. The quality of the meat and the minimal harmful microorganisms associated with it make nutria meat an "excellent food product for export markets".^[46]

Several desirable control methods are currently ineffective for various reasons. Zinc phosphide is the only rodenticide currently registered to control nutria, but it is expensive, remains toxic for months, detoxifies in high humidity and rain, and requires construction of expensive floating rafts for placement of the chemical. It is not yet sure how many nontarget species are susceptible to zinc phosphide, but birds and rabbits have been known to die from ingestion.^[97] Therefore, this chemical is rarely used, especially not in large-scale projects. Other potential chemical pesticides would be required by the US Environmental Protection Agency to undergo vigorous testing before they could be acceptable to use on nutria. The LDWF has estimated costs for new chemicals to be $300,000 for laboratory, chemistry, and field studies, and $500,000 for a mandatory Environmental Impact Statement.^[97] Contraception is not a common form of control, but is preferred by some wildlife managers. It also is expensive to operate - an estimated $6 million annually to drop bait laced with birth-control chemicals. Testing of other potential contraceptives would take about five to eight years and $10 million, with no guarantee of FDA approval.^[97] Also, an intensive environmental assessment would have to be completed to determine whether any non-target organisms were affected by the contraceptive chemicals. Neither of these control methods is likely to be used in the near future.^{[citation needed]}

In Louisiana, a claimed environmentally sound solution is the killing of nutria to make dog food treats.^[59]

Gallery

•  
  Nutria heart
•  
  Skull from various perspectives
•  
  By the river Ljubljanica
•  
  Feral nutria in Oise river in France
•  
  10-day-old baby nutria
•  
  track

References

1. Ojeda, R.; Bidau, C.; Emmons, L. (2017) [errata version of 2016 assessment]. "Myocastor coypus". IUCN Red List of Threatened Species. 2016: e.T14085A121734257. Retrieved 12 March 2022.
2. "Myocastor coypus". ITIS. from the original on 18 October 2011. Retrieved 23 September 2011.
3. "Myocastor coypus (coypu)". Animal Diversity Web, Museum of Zoology. University of Michigan. 1999. from the original on 2017-08-25. Retrieved 2017-08-25.
4. Woods, C. A. (1982). "The history and classification of South American Hystricognath rodents: reflections on the far away and long ago". In Mares, M. A.; Genoways, H. H. (eds.). Mammalian Biology in South America. Pittsburgh: University of Pittsburgh. pp. 377–392.
5. Galewski, Thomas; Mauffrey, Jean-François; Leite, Yuri L. R.; Patton, James L.; Douzery, Emmanuel J. P. (2005). "Ecomorphological diversification among South American spiny rats (Rodentia; Echimyidae): a phylogenetic and chronological approach". Molecular Phylogenetics and Evolution. 34 (3): 601–615. doi:10.1016/j.ympev.2004.11.015. PMID 15683932.
6. Upham, Nathan S.; Patterson, Bruce D. (2012). "Diversification and biogeography of the Neotropical caviomorph lineage Octodontoidea (Rodentia: Hystricognathi)". Molecular Phylogenetics and Evolution. 63 (2): 417–429. doi:10.1016/j.ympev.2012.01.020. PMID 22327013.
7. Fabre, Pierre-Henri; Upham, Nathan S.; Emmons, Louise H.; Justy, Fabienne; Leite, Yuri L. R.; Loss, Ana Carolina; Orlando, Ludovic; Tilak, Marie-Ka; Patterson, Bruce D.; Douzery, Emmanuel J. P. (2017-03-01). "Mitogenomic Phylogeny, Diversification, and Biogeography of South American Spiny Rats". Molecular Biology and Evolution. 34 (3): 613–633. doi:10.1093/molbev/msw261. ISSN 0737-4038. PMID 28025278.  
8. Taylor, K.; Grace, J.; Marx, B. (May 1997). "The effects of herbivory on neighbor interactions along a coastal marsh gradient". American Journal of Botany. 84 (5): 709. doi:10.2307/2445907. ISSN 0002-9122. JSTOR 2445907. PMID 21708623.  
9. LeBlanc, Dwight J. (1994). (PDF). Animal and Plant Health Inspection Service. Archived from the original (PDF) on 3 February 2007.
10. "Living with Wildlife - Nutria". from the original on 2019-03-22. Retrieved 2019-03-22.
11. Ca.Gov, Department of Fish and Wildlife. "California's Invaders:Nutria". from the original on 2022-04-30. Retrieved 2022-05-08.
12. Bailly, Anatole (1981-01-01). Abrégé du dictionnaire grec français. Paris: Hachette. ISBN 978-2010035289. OCLC 461974285.
13. Bailly, Anatole. "Greek-French dictionary online". www.tabularium.be. from the original on 2022-03-18. Retrieved 2017-01-24.
14. Nutria Biology 2013-10-22 at the Wayback Machine. Nutria.com. 2007. Retrieved on September 5, 2007.
15. Carter, Jacoby (29 January 2007). "Worldwide Distribution, Spread of, and Efforts to Eradicate the Nutria (Myocastor coypus) – South America". United States Geological Survey. from the original on 18 February 2017. Retrieved 4 September 2007.
16. Woods, Charles A.; Contreras, Luis; Willner-Chapman, Gale; Whidden, Howard P. (1992). (PDF). Mammalian Species (398): 1–8. doi:10.2307/3504182. JSTOR 3504182. Archived from the original (PDF) on 2017-10-08.
17. ITIS Report. "ITIS Standard Report: Myocastor". from the original on December 1, 2007. Retrieved September 5, 2007.
18. ITIS Report. "ITIS Standard Report: Myopotamus". from the original on October 23, 2011. Retrieved December 19, 2007.
19. Loss, Ana; Moura, Raquel T.; Leite, Yuri L. R. (2014). "Unexpected phylogenetic relationships of the painted tree rat Callistomys pictus (Rodentia: Echimyidae)" (PDF). Natureza on Line. 12: 132–136. (PDF) from the original on 2021-06-23. Retrieved 2017-10-08.
20. Fabre, Pierre-Henri; Galewski, Thomas; Tilak, Marie-ka; Douzery, Emmanuel J. P. (2013-03-01). "Diversification of South American spiny rats (Echimyidae): a multigene phylogenetic approach" (PDF). Zoologica Scripta. 42 (2): 117–134. doi:10.1111/j.1463-6409.2012.00572.x. ISSN 1463-6409. S2CID 83639441. (PDF) from the original on 2019-11-18. Retrieved 2019-11-18.
21. Fabre, Pierre-Henri; Vilstrup, Julia T.; Raghavan, Maanasa; Der Sarkissian, Clio; Willerslev, Eske; Douzery, Emmanuel J. P.; Orlando, Ludovic (2014-07-01). "Rodents of the Caribbean: origin and diversification of hutias unravelled by next-generation museomics". Biology Letters. 10 (7): 20140266. doi:10.1098/rsbl.2014.0266. ISSN 1744-9561. PMC 4126619. PMID 25115033.
22. Upham, Nathan S.; Patterson, Bruce D. (2015). "Evolution of Caviomorph rodents: a complete phylogeny and timetree for living genera". In Vassallo, Aldo Ivan; Antenucci, Daniel (eds.). Biology of caviomorph rodents: diversity and evolution. Buenos Aires: SAREM Series A, Mammalogical Research — Sociedad Argentina para el Estudio de los Mamíferos. pp. 63–120.
23. Capel-Edwards, Maureen (1967). "Foot-and-mouth disease in Myocastor coypus". Journal of Comparative Pathology. 77 (2): 217–221. doi:10.1016/0021-9975(67)90014-X. PMID 4291914.
24. Doncaster, C. P.; Micol, T. (1990). "Response by coypus to catastrophic events of cold and flooding". Ecography. 13 (2): 98–104. doi:10.1111/j.1600-0587.1990.tb00594.x.
25. Hillemann, Howard H.; Gaynor, Alta I.; Stanley, Hugh P. (1958). "The genital systems of nutria(Myocastor coypus)". The Anatomical Record. 130 (3): 515–531. doi:10.1002/ar.1091300304. PMID 13559732. S2CID 12757377.
26. "national trappers". 2012–2021. from the original on 2022-07-02. Retrieved 2022-05-08.
27. "Myocastor coypus (Molina 1782) - Encyclopedia of Life". eol.org. from the original on 2019-05-31. Retrieved 2019-03-22.
28. Valentin, Fischer (March 17, 2022). "Species-specific enamel differences in hardness and abrasion resistance between the permanent incisors of cattle and ever-growing incisors of nutria". PLOS ONE. 17 (3): e0265237. doi:10.1371/journal.pone.0265237. PMC 8929658. PMID 35298510.
29. "Species Profile: Castor canadensis – North American Beaver". Bella Vista Property Owners Association. Bella Vista, Arkansas. 5 February 2019. from the original on 6 October 2019. Retrieved 6 October 2019. They could be mistaken for a nutria, but nutria do not have the large flat paddle-shaped tail like beavers.
30. Nolfo-Clements, Lauren E. (September 2009). "Nutria Survivorship, Movement Patterns, and Home Ranges". Southeastern Naturalist. 8 (3): 399–410. doi:10.1656/058.008.0303. ISSN 1938-5412. S2CID 86801126.
31. "Biology". Nutria. Louisiana Department of Wildlife and Fisheries. from the original on 22 October 2013. Retrieved 2 March 2014.
32. species and habitats, Washington Department of Fish and Wildlife (April 22, 2022). "Nutria Conflict". from the original on 2022-03-31. Retrieved 2022-04-22.
33. researched based wildlife damage management information, Internet center for wildlife damage management (April 22, 2022). "Nutria Biology". from the original on September 29, 2022. Retrieved September 29, 2022.
34. Schertler, Anna; Rabitsch, Wolfgang; Moser, Dietmar; Wessely, Johannes; Essl, Franz (17 July 2020). "The potential current distribution of the coypu (Myocastor coypus) in Europe and climate change induced shifts in the near future". NeoBiota. 58: 129–160. doi:10.3897/neobiota.58.33118. ISSN 1314-2488. S2CID 221089826. from the original on 15 April 2023. Retrieved 15 April 2023.
35. Carter, Jacoby and Billy P. Leonard (Spring, 2002.) "A Review of the Literature on the Worldwide Distribution, Spread of, and Efforts to Eradicate the Coypu (Myocastor coypus)" Wildlife Society Bulletin 30(1): 162–175.
36. Sheffels, Trevor Robert; Sytsma, Mark (December 2007). Report on Nutria Management and Research in the Pacific Northwest (Report). Center for Lakes and Reservoirs Publications and Presentations, Portland State University. from the original on 2016-09-27. Retrieved 2016-09-24.
37. Montgomery, Jeff (2012), "Invasive nutria found in Kent County", The News Journal (published 19 Jan 2012), delawareonline, from the original on 28 July 2014, retrieved 19 Jan 2012, 'It was a surprise, frankly,' Steve Kendrot, a U.S. Department of Agriculture wildlife services program manager, said Wednesday. 'We didn't expect to find anything that far up.'
38. "History; Nutria Population Dynamics – A Timeline". Nutria.com. Louisiana Department of Wildlife and Fisheries. 2007. from the original on 18 September 2011. Retrieved 10 October 2011.
39. D'Elia, Guillermo. "Myocastor coypus (coypu)". Animal Diversity Web. from the original on 2023-02-17. Retrieved 2023-01-11.
40. McFalls, Tiffany B.; et al. (September 2010). "Hurricanes, floods, levees, and nutria: vegetation responses to interacting disturbance and fertility regimes with implications for coastal wetland restoration". Journal of Coastal Research. 26 (5): 901–11. doi:10.2112/JCOASTRES-D-09-00037.1. ISSN 1551-5036. S2CID 55697728.
41. Hygnstrom, Scott E.; Timm, Robert M.; Larson, Gary E., eds. (1994). . Internet Center for Wildlife Damage Management. Archived from the original on 7 September 2013. Retrieved 2 March 2014.
42. . Barcelona Zoo. Spain: Barcelona City Council. Archived from the original on 26 September 2013. Retrieved 2 March 2014.
43. Carter, Jacoby; et al. (March 1999). "Modeling the effects of nutria (Myocastor coypus) on wetland loss". Wetlands. 19 (1): 209–19. doi:10.1007/BF03161750. ISSN 1943-6246. S2CID 23151277. 
44. Ford, Mark A.; Grace, James B. (1998). "Effects of vertebrate herbivores on soil processes, plant biomass, litter accumulation and soil elevation changes in a coastal marsh". Journal of Ecology. 86 (6): 974–982. doi:10.1046/j.1365-2745.1998.00314.x.
45. Jordan, Jillian; Mouton, E. "Coastwide Nutria Control Program 2010-2011" (PDF). Nutria.com. Louisiana Department of Wildlife and Fisheries. (PDF) from the original on 25 April 2012. Retrieved 18 October 2011.
46. Lyon, W. J.; Milliet, J. B. (2000). "Microbial Flora Associated with Louisiana Processed Frozen and Fresh Nutria (Myocastor coypus) Carcasses". Journal of Food Science. 65 (6): 1041–1045. doi:10.1111/j.1365-2621.2000.tb09414.x.
47. National Wetlands Research Center (June 2000), Nutria, Eating Louisiana's Coast, United States Geological Survey
48. Carter, Jacoby, and Billy P. Leonard (2002). "A Review of the Literature on the Worldwide Distribution, Spread Of, and Efforts to Eradicate the Coypu (Myocastor coypus)." JSTOR. N.p., Web. 2 Nov. 2015.
49. Nutria, Eating Louisiana's Coast (PDF) (Report). U.S. Geological Survey/National Wetlands Research Center. June 2000. USGS FS-020-00. (PDF) from the original on 5 March 2016. Retrieved 28 March 2016.
50. Bernard, Shane K. (November 2015). "Vol. 43, No. 3". M'sieu Ned's Rat? Reconsidering the Origin of Nutria in Louisiana. Avery Island, Louisiana.: The E. A. McIlhenny Collection, Louisiana Historical Association. JSTOR 4233862. {{cite book}}: |work= ignored (help)
51. Scarborough, Janet; Mouton, Edmond (30 June 2007), Nutria Harvest Distribution 2006-2007 and a Survey of Nutria Herbivory Damage in Coastal Louisiana in 2007 (PDF), (PDF) from the original on 7 January 2009
52. "A Plague of Aliens" 2017-08-13 at the Wayback Machine Feb/Mar 2003 edition of National Wildlife magazine, published by the National Wildlife Federation, article by Laura Tangley; accessed online December 8, 2006.
53. Gosling, Morris (4 March 1989). "Extinction to Order". New Scientist. 121 (1564): 44–49.
54. . Sky. Archived from the original on April 25, 2012. Retrieved 14 May 2012.
55. Randall, Morgan (30 August 2019). "Nutria a la' Orange". from the original on 11 February 2022. Retrieved March 31, 2022.
56. Parola, Philippe (March 31, 2022). . Archived from the original on April 1, 2022. Retrieved May 8, 2022.
57. . Daily Comet. Archived from the original on 2016-08-03. Retrieved 2017-07-19.
58. . www.lawildlifefed.org. Archived from the original on 2016-07-29. Retrieved 2017-07-19.
59. Dodge, Victoria. "A rodent-like pest destroying the Louisiana coast finds new enemy in dog treat business". Lafayette Daily Advertiser. USA Today. from the original on December 24, 2019. Retrieved September 7, 2019.
60. Walker, Shaun (2016-11-18). "Hot rat is so hot right now: Moscow falls for the rodent burger". The Guardian. ISSN 0261-3077. from the original on 2017-07-04. Retrieved 2017-07-19.
61. "Rats! Rodent burger now the latest food craze in Moscow". The Straits Times. The Jakarta Post. 24 November 2016. from the original on 24 November 2016. Retrieved 24 November 2016.
62. "How do Wetlands Function and Why are they Valuable?". EPA. 2017. from the original on 17 July 2018. Retrieved 19 October 2011.
63. Schleifstein, Mark (2 June 2011). "Louisiana is losing a football field of wetlands an hour, new U.S. Geological Survey study says". The Times-Picayune. from the original on 4 September 2011. Retrieved 29 November 2011.
64. Ross, Bob (1 October 2007). . New Orleans Times-Picayune. Archived from the original on 11 October 2007. Retrieved 12 February 2018.
65. "Monitoring Plan: Project No. LA-02 Nutria Harvest and Wetland Restoration Demonstration Project" (PDF). 6 May 1998. (PDF) from the original on 20 October 2011. Retrieved 16 October 2011.
66. "Program Updates". Nutria.com. Louisiana Department of Wildlife and Fisheries. 2007. from the original on 30 August 2011. Retrieved 18 October 2011.
67. "Strongyloidiasis: Background, Pathophysiology, Etiology". 2 February 2019. from the original on 9 March 2011. Retrieved 22 March 2019 – via eMedicine. {{cite journal}}: Cite journal requires |journal= (help)
68. Bonilla, Hector F. MD; Blanchard, Diane H. MD; Sanders, Richard MD (June 2000). "Nutria Itch". Archives of Dermatology. Vol. 136, No. 6: JAMA Dermatology. 136 (6): 804–805. doi:10.1001/archderm.136.6.804-a. PMID 10871960. from the original on 2019-10-06. Retrieved 2019-10-06.{{cite journal}}: CS1 maint: location (link)
69. Animal and Plant Health Inspection Service, U.S. Department of Agriculture (April 1, 2022). "Nutria conflicts with people". from the original on May 22, 2022. Retrieved May 8, 2022.
70. Greenwood, Renetta (April 1, 2022). "Pacific Northwest Aquatic Invasive Species Profile, Nutria, Myocaster coypus" (PDF). (PDF) from the original on May 19, 2022. Retrieved May 8, 2022.
71. Howerth, E. W.; Reeves, A. J.; McElveen, M. R.; Austin, F. W. (July 1994). "Survey for Selected Diseases in Nutria (Myocastor coypus) from Louisiana". Journal of Wildlife Diseases. 30 (3): 450–453. doi:10.7589/0090-3558-30.3.450. ISSN 0090-3558. PMID 7933295. S2CID 43118277.
72. Lim, Se Ra; Lee, Do-Hun; Park, Seon Young; Lee, Seungki; Kim, Hyo Yeon; Lee, Moo-Seung; Lee, Jung Ro; Han, Jee Eun; Kim, Hye Kwon; Kim, Ji Hyung (2019-07-30). "Wild Nutria (Myocastor coypus) Is a Potential Reservoir of Carbapenem-Resistant and Zoonotic Aeromonas spp. in Korea". Microorganisms. 7 (8): 224. doi:10.3390/microorganisms7080224. ISSN 2076-2607. PMC 6723217. PMID 31366125.
73. Lavelle, Michael J.; Kay, Shannon L.; Pepin, Kim M.; Grear, Daniel A.; Campa, Henry; VerCauteren, Kurt C. (December 2016). "Evaluating wildlife-cattle contact rates to improve the understanding of dynamics of bovine tuberculosis transmission in Michigan, USA". Preventive Veterinary Medicine. 135: 28–36. doi:10.1016/j.prevetmed.2016.10.009. ISSN 0167-5877. PMID 27931926.
74. First-ever, CDC, USDA, DOI collaborative report lists top-priority zoonoses for U.S., Centers for Disease Control and Prevention (May 6, 2019). "*8 Zoonotic Diseases Shared Between Animals and People of Most Concern in the U.S." from the original on September 28, 2023. Retrieved May 8, 2022.{{cite web}}: CS1 maint: multiple names: authors list (link)
75. Nutria control Program, Louisiana Department of Wildlife and Fisheries (April 1, 2022). "Herbivory Damage and Harvest Maps". from the original on September 28, 2023. Retrieved May 8, 2022.
76. Israel, Brett (August 12, 2013). "swamp rats on the move as winters warm". Scientific American. from the original on May 7, 2022. Retrieved May 8, 2022.
77. "List of Invasive Alien Species of Union concern". Environment. Brussels: European Commission. from the original on 2017-07-29. Retrieved 2021-07-27.
78. "Regulation No. 1143/2014 of the European parliament and of the council of 22 October 2014 on the prevention and management of the introduction and spread of invasive alien species". Strasbourg: European Union. 2014-11-04. from the original on 2017-03-03. Retrieved 2021-07-27.
79. Kelly, Olivia (22 March 2019). "Invasive rodent spotted along Dublin's Royal Canal". The Irish Times. from the original on 28 September 2020. Retrieved 22 March 2019.
80. Conroy, MacDara (21 March 2019). "Appeal For Sightings Of Invasive Coypu On Royal Canal In Dublin". AFloat (magazine). Dublin: Baily Publications Ltd. from the original on 22 March 2019. Retrieved 22 March 2019.
81. Brophy, Daragh (22 March 2019). "Large invasive rodent species that can 'cause a lot of damage' spotted along Royal Canal". The Journal (Ireland). Dublin: Journal Media Ltd. from the original on 22 March 2019. Retrieved 22 March 2019.
82. "Coypu Species Alert". National Biodiversity Data Centre. Waterford, Ireland. 17 May 2017. from the original on 22 March 2019. Retrieved 22 March 2019.
83. Agriculture in Britain. B.I.S. 1961. p. 22. from the original on 2023-04-21. Retrieved 2023-03-21.
84. Baker, S. (2010). "control and eradication of invasive mammals in Great Britain". Revue Scientifique et Technique (International Office of Epizootics). 29 (2): 311–327. doi:10.20506/rst.29.2.1981. PMID 20919585.
85. "Invasive species of Japan". Ibaraki, Japan: National Institute for Environmental Studies; National Research and Development Agency. April 1, 2022. from the original on July 1, 2022. Retrieved May 8, 2022.
86. "Invasive Alien Species Act" (PDF). Tokyo: Government of Japan. 2004-06-02. Law No. 78 (June 2, 2004). (PDF) from the original on 2022-04-24. Retrieved 2022-05-08.
87. "Hazardous Substances and New Organisms Act 2003 - Schedule 2 Prohibited new organisms". New Zealand Government. from the original on 16 June 2012. Retrieved 26 January 2012.
88. Emery, Theo (July 5, 2012). "Killed by Thousands, Varmint Will Never Quit". The New York Times. from the original on July 5, 2012. Retrieved July 6, 2012.
89. "Decades-long Partnership Eradicates Destructive Nutria Rodents from Maryland". Hadley, MA: U.S. Fish and Wildlife Service. 2022-09-16. Press Release. from the original on 2022-09-16. Retrieved 2022-09-16.
90. Fenston, Jacob (2022-09-16). . DCist. Washington, D.C.: WAMU 88.5 Radio. Archived from the original on 2022-09-16. Retrieved 2022-09-16.
91. "California's Invaders: Nutria". Habitat Conservation Planning Branch. California Department of Fish and Wildlife. from the original on 21 July 2019. Retrieved 21 July 2019.
92. Fry, Hannah (February 16, 2019). "You think the rats at L.A. City Hall are bad? Officials have a $1.9-million plan to rid state marshlands of giant rodents". Los Angeles Times. from the original on 16 February 2019. Retrieved 16 February 2019.
93. Ferguson, Cat (July 16, 2019). "California pledges millions to battle enormous, destructive swamp rats". San Jose Mercury News. from the original on 17 July 2019. Retrieved 21 July 2019.
94. . California Outdoors. June 6, 2019. Archived from the original on March 6, 2021. Retrieved May 8, 2022.
95. "Louisiana Coastwide Nutria Control Program". Lafayette, LA: Louisiana Department of Wildlife and Fisheries. from the original on February 25, 2021. Retrieved January 15, 2021.
96. American Fur Breeder (37 ed.). 1964. p. 96. Rabbit and nutria meat are also fed on ranches. Both are lean and good sources of quality protein. Nutria, in particular, has been increasingly available in recent years. It is low in fat and leaner than either horse or rabbit meat
97. "Nutria in Louisiana" (PDF). New Iberia, LA: Louisiana Department of Wildlife & Fisheries. 2002. (PDF) from the original on 15 September 2011. Retrieved 3 November 2011.

Further reading

• Sandro Bertolino, Aurelio Perrone, and Laura Gola "Effectiveness of coypu control in small Italian wetland areas" Wildlife Society Bulletin Volume 33, Issue 2 (June 2005) pp. 714–72.
• Carter, Jacoby and Billy P. Leonard: "A Review of the Literature on the Worldwide Distribution, Spread of, and Efforts to Eradicate the Coypu (Myocastor coypus)" Wildlife Society Bulletin, Vol. 30, No. 1 (Spring, 2002), pp. 162–175.
• Carter, J., A.L. Foote, and L.A. Johnson-Randall. 1999. Modeling the effects of nutria (Myocastor coypus) on wetland loss. Wetlands 19(1):209-219
• Lauren E. Nolfo-Clements: Seasonal variations in habitat availability, habitat selection, and movement patterns of Myocastor coypus on a subtropical freshwater floating marsh. (Dissertation) Tulane University. New Orleans. 2006. ISBN 0-542-60916-9
• Sheffels, Trevor and Mark Systma. "Report on Nutria Management and Research in the Pacific Northwest" Center for Lakes and Reservoir Environmental Sciences and Resources, Portland State University. December 2007. Available on-line:

External links

 

Wikimedia Commons has media related to Myocastor coypus.

 

Look up nutria in Wiktionary, the free dictionary.

• The documentary Rodents of Unusual Size tells the story of the introduction of nutria to Louisiana and the creative efforts being used in the attempts to eradicate them.
• Saving the Bay: The History of the Chesapeake Bay Nutria Eradication Project 2022-09-20 at the Wayback Machine - USDA/Animal and Plant Health Inspection Service
• - Report on nutrias in the Pacific Northwest of North America.
• Species Profile - Nutria (Myocastor coypus), National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for nutria.