Myocastor coypus is native to South America. Its distribution ranges from middle Bolivia and southern Brazil to Tierra del Fuego. As a result of escapes and liberations from fur farms, feral populations now occur in Europe, Asia, and North America. Woods et al. (1992)
Biogeographic Regions: nearctic (Introduced ); palearctic (Introduced ); neotropical (Native )
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Unknown
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Native to South America (southern Brazil, Paraguay, Uruguay, Bolivia, Argentina, and Chile). Introduced in Louisiana in 1930s, transplanted in various parts of U.S. by weed control promoters. Most successful in southcentral U.S. U.S. range includes southeastern U.S., Oregon, Washington, Oklahoma, and Maryland. Introduced also in British Columbia, Europe, northern Asia, and eastern Africa.
Myocastor coypus looks like a large, robust rat. Its body is highly arched, and the head is large and almost triangular. The ears and eyes are small and are located in the upper part of the head. The incisors are broad, with orange-pigmented anterior surfaces. The legs are short. The hind feet are much longer than the forefeet, and contain five digits; the first four are connected by webbing, and the fifth is free. The forefeet have four long, flexible, unwebbed digits and a vestigial thumb. The tail is long and rounded. Females have four pairs of thoracic mammae that are situated well up on the sides of the body. The pelage consists of two kinds of hair, soft dense underfur, and long coarse guard hairs that vary from yellowish brown to reddish brown. The underfur is dark gray, and it is denser on the abdomen. The chin is covered by white hairs, and the tail is scantily haired.
Males are generally larger than females. The length of the head and body is 521 mm (472 - 575), and the length of tail is 375 mm (340 - 405).
Gosling (1977), Nowak (1991); Woods et al. (1992).
Range mass: 5.000 to 10.000 kg.
Range length: 472 to 575 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Length: 140 cm
Weight: 11400 grams
Catalog Number: USNM 96513
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Male; Adult
Preparation: Skin; Skull
Collector(s): W. Frakes
Year Collected: 1896
Locality: Los Palmares, near, N bank of Rio Salado, Santa Fe, Argentina, South America
- Type: Hollister, N. 1914 Mar 20. Proceedings of the Biological Society of Washington. 27: 57.
Nutrias inhabit marshes, lake edges, and sluggish streams, especially in areas with emergent or succulent vegetation along the banks. They are chiefly lowland animals, but may range up to 1,190 meters in the Andes. Although they generally prefer fresh water, the population of the Chonos Archipelago in Chile occurs in brackish and salt water. Greer (1966), Nowak (1991).
Range elevation: 1190 (high) m.
Habitat Regions: tropical ; freshwater
Terrestrial Biomes: savanna or grassland ; forest ; scrub forest
Aquatic Biomes: lakes and ponds; rivers and streams; brackish water
Other Habitat Features: riparian
Habitat and Ecology
Comments: Prefers freshwater marshes; also in brackish marshes. Nests in burrows, abandoned muskrat houses, or in dense vegetation.
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Nutria are herbivorous. The diet consists largely of aquatic vegetation: stems, leaves, roots, and even bark. They may use logs or other floating objects as feeding platforms. Woods et al. (1992).
Plant Foods: roots and tubers; wood, bark, or stems
Primary Diet: herbivore (Folivore )
Comments: Diet consists of a wide assortment of vegetation, particularly aquatic vegetation. Roots were most important in Maryland (Willner et al. 1979).
immersed, neck protruding perithecium of Podospora curvicolla is saprobic in/on dung or excretions of dung of Myocastor coypus
Other: minor host/prey
Animal / dung saprobe
perithecium of Schizothecium tetrasporum is saprobic in/on dung or excretions of dung of Myocastor coypus
Home range probably is less than 2.5 acres. Can become very abundant. May displace muskrat populations, though the two species may coexist where conditions are "good" (Jackson 1990). In Maryland, population density was estimated at 3-16 per ha; trapper harvest, and in one year, freezing, accounted for most mortality (Willner et al. 1979). Commonly preyed on by alligators. Lifespan generally is 2-3 years or less.
Life History and Behavior
Nutria probably communicate through tactile, chemical, and auditory channels. Their eyesight is limited.
Communication Channels: tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
Comments: Period of greatest activity is at night.
The potential longevity of Myocastor coypus is 6 years.
Status: wild: 6 (high) years.
Status: captivity: 6.0 years.
Status: captivity: 10.0 years.
Lifespan, longevity, and ageing
Myocastor coypus is polyestrus. The length of the estrus cycle is variable; intervals between cycles may range from 5 to 60 days. Nutrias are nonseasonal breeders. The gestation period is long, varying from 127 to 139 days. There is a post-partum estrus within 2 days of parturition. Mean litter size in general varies from three to six, although it may range from 1 to 13. Factors affecting reproductive potential of nutria are food type and availability, weather conditions, predators and disease.
Sexual maturity is attained when young are only 6 months old.
Gosling (1981), Gosling and Baker (1981), Woods et al. (1992).
Breeding interval: Nutrias may breed repeatedly throughout the year, the interval will depend on climate and nutritional status of the mother.
Breeding season: Breeding may occur throughout the year.
Range number of offspring: 3 to 12.
Average number of offspring: 5.75.
Range gestation period: 126 to 141 days.
Average weaning age: 54 days.
Average age at sexual or reproductive maturity (female): 6 months.
Average age at sexual or reproductive maturity (male): 6 months.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Average birth mass: 225 g.
Average number of offspring: 6.
Average age at sexual or reproductive maturity (male)
Sex: male: 152 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 152 days.
Females care exclusively for the young. Newborns are fully furred, and have their eyes open. They weigh approximately 225 grams each, and rapidly gain weight during the first 5 months. The lactation period extends for about 8 weeks.
Parental Investment: no parental involvement; precocial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
Breeds year-round. Gestation lasts 130 days. Produces several litters of 3-5 young per year; estimated annual productivity was 8 young per female in Maryland; oldest females were 3 years old (Willner et al. 1979). Sexually mature in 4-8 months, depending on environmental conditions.
Molecular Biology and Genetics
Statistics of barcoding coverage: Myocastor coypus
Public Records: 0
Specimens with Barcodes: 3
Species With Barcodes: 1
Mares et al. al. (1989) suggests that nutria are rapidly disappearing in many rivers and lakes of Argentina.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1996Lower Risk/least concern(Baillie and Groombridge 1996)
National NatureServe Conservation Status
Rounded National Status Rank: NNA - Not Applicable
Rounded National Status Rank: NNA - Not Applicable
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Management Requirements: See Evans (1970) for information on when, where, and how to control. Easily trapped.
Relevance to Humans and Ecosystems
In spite of been intensively trapped for its fur, nutria are considered pests in some places because their burrows damage dikes and irrigation facilities. Burrows sometimes penetrate or weaken the river banks. Myocastor coypus may raid rice and other cultivated crops, and they compete with native fur bearing animals. Nowak (1991), Woods et al. (1992).
A demand for nutria fur developed in the early 19th century and has continued to the present. For this reason, nutria have been introduced almost worldwide. For example, Argentina exported 20,000,000 pelts between the years 1972 and 1981, obtained both from wild and captivity animals; and in Louisiana (USA) nearly 1,000,000 pelts were harvested during the 1986 - 1987 trapping season. Nutria have also been hunted by people for meat. Mares et al. (1989), Woods et al. (1992).
Positive Impacts: food ; body parts are source of valuable material
Comments: Important furbearer in some areas, but low pelt prices have resulted in low harvests in recent years. Raising captives for fur not viable, costs more than return on fur (Jackson 1990). Regarded as pest in some areas due to damage to sugarcane, rice crops (Evans 1970), dikes, and levees; damages corn, wheat, oats, alfalfa, and other crops in Oregon. Large populations have caused extensive damage to marshes in Louisiana (Jackson 1990), Maryland (Shen 1994, Washington Post, 16 January), and elsewhere in the southeastern U.S.
The coypu (from the Mapudungun, koypu) or nutria (Myocastor coypus), is a large, herbivorous, semiaquatic rodent and the only member of the family Myocastoridae. Originally native to temperate South America, it has since been introduced to North America, Europe, Asia, and Africa, primarily by fur ranchers. Although it is still valued for its fur in some regions, its destructive feeding and burrowing behaviors make this invasive species a pest throughout most of its range.
There are two commonly-used names in the English language for Myocastor coypus. The name nutria (or local derivatives such as "nutria- or nutra- rat") is generally used in North America and Asia; however, in Spanish-speaking countries, the word nutria refers to the otter. To avoid this ambiguity, the name coypu (derived from the Mapudungun language) is used in Latin America and Europe. In France, the coypu is known as a ragondin. In Dutch it is known as beverrat (beaver rat). In Italy, instead, the popular name is, like in North America and Asia, nutria, but it is also called castorino (little beaver), by which its fur is known.
Coypus live in burrows alongside stretches of water. They feed on river plants, and waste close to 90% of the plant material while feeding on the stems.
The coypu was first described by Juan Ignacio Molina in 1782 as Mus coypus, a member of the mouse genus. The genus Myocastor, assigned in 1792 by Robert Kerr, is derived from the Greek mys and kastor, or "mouse-beaver". Geoffroy, independently of Kerr, named the species Myopotamus coypus, and it is occasionally referred to by this name.
Four subspecies are generally recognized:
- M. c. bonariensis: northern Argentina, Bolivia, Paraguay, Uruguay, southern Brazil
- 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 coypu's range, is believed to be the type of coypu most commonly introduced to other continents.
The coypu somewhat resembles a very large rat, or a beaver with a small tail. Adults are typically 5–9 kg (11–20 lb) in weight, and 40–60 cm (16–24 in) in body length, with a 30–45 cm (12–18 in) tail. They have a coarse, darkish brown outer fur with a soft under-fur. Two distinguishing marks are the presence of a white patch on the muzzle, and webbed hind feet. They can also be identified by their bright orange-yellow incisor teeth (unlike rats, which have brownish yellow incisors). The nipples of female coypu are high on her flanks. This allows their young to feed while the female is in the water.
Coypu can also be mistaken for another widely dispersed semi-aquatic rodent that occupies the same wetland habitats, the muskrat. The muskrat, however, is smaller, more tolerant of cold climates, and has a laterally flattened tail that it uses to assist in swimming, whereas the tail of a coypu is round. It can also be mistaken for a small beaver, as beavers and coypus have very similar anatomies; beavers' tails are flat and paddle-like, as opposed to the round rat-like tails of coypu.
Commercial and environmental issues
Local extinction in their native range due to overharvest led to the development of coypu 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 coypu often are released or escape as operations become unprofitable.
As demand for coypu fur declined, coypu have since become pests in many areas, destroying aquatic vegetation, irrigation systems, chewing through human-made items, such as tires and wooden house panelling in Louisiana, eroding river banks, and displacing native animals. Coypu were introduced to the Louisiana ecosystem in the 1930s when they escaped from fur farms that had imported them from South America. Nutria damage in Louisiana became so severe that in 2005, a bounty program was in effect to aid in controlling the animal. In the Chesapeake Bay region in Maryland, where they were introduced in the 1940s, coypu are believed to have destroyed 7,000 to 8,000 acres (2,800 to 3,200 ha) of marshland in the Blackwater National Wildlife Refuge. In response, by 2003, a multi-million dollar eradication program was underway.
Coypu meat is lean and low in cholesterol. While there have been many attempts to establish markets for coypu meat, all documented cases have generally been unsuccessful. Unscrupulous entrepreneurs have promoted coypu and coypu farms for their value as "meat", "fur", or "aquatic weed control". In recent years they have done so in countries such as the United States, China, Taiwan and Thailand. In every documented case the entrepreneurs sell coypu "breeding stock" at very high prices. Would-be coypu farmers find that the markets for their products disappear after the promoter has dropped out of the picture.
In the former Soviet republics of Central Asia, specifically 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.
In addition to direct environmental damage, coypu are the host for a nematode parasite (Strongyloides myopotami) that can infect the skin of humans causing dermatitis similar to strongyloidiasis. The condition is also called "nutria itch".
Nutria and the damage they cause, in particular the damage to the levees before Hurricane Katrina, were featured in a first season episode of the A&E Television series, Steven Seagal: Lawman. Some were shot by police officers and the dead animals were fed to alligators. Seagal, who is a practising Buddhist, says he is opposed to personally harming another creature without cause and did not actually shoot them. However, he said that he was happy that the food chain was being respected.
The distribution of coypu tends to expand and contract with successive cold or mild winters. During cold winters, coypu often suffer frostbite on their tails leading to infection or death. As a result, populations of coypu often contract and even become locally or regionally extinct as in the Scandinavian countries and states of the United States states such as Idaho, Montana and Nebraska and during the 1980s (Carter and Leonard 2002). During mild winters, their ranges tend to expand northward. For example in recent years range expansions have been noted in Washington State and Oregon (Sheffels and Sytsma 2007).
- 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: http://www.clr.pdx.edu/docs/CLR_nutria_report.pdf.
- ^ Lessa, E., Ojeda, R., Bidau, C. & Emmons, L. (2008). Myocastor coypus. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 6 January 2009.
- ^ Coypu. The American Heritage Dictionary of the English Language, Fourth Edition, 2006. Houghton Mifflin.
- ^ Muñoz Urrutia, Rafael, ed (2006) (in Spanish). Diccionario Mapuche: Mapudungun/Español, Español/Mapudungun (2nd ed.). Santiago, Chile. pp. 155. ISBN 956-8287-99-X.
- ^ LeBlanc, Dwight J. 1994. Prevention and Control of Wildlife Damage – Nutria. Animal and Plant Health Inspection Service.
- ^ a b Carter, Jacoby. Worldwide Distribution, Spread of, and Efforts to Eradicate the Nutria (Myocastor coypus) – South America. United States Geological Survey. January 29, 2007. Retrieved on September 4, 2007.
- ^ 6. Grace, James B.; Marx, B.D.; Taylor K.L. The effects of herbivory on neighbor interac-tions along a coastal marsh gradient. American Journal of Botany, Volume 84, Number 5 (May 1997), pp. 709-715.
- ^ a b C. A. Woods, L. Contreras, G. Willner-Chapman, H. P. Whidden. 1992. Mammalian Species: Myocastor coypus. American Society of Mammalogists, 398: 1-8.
- ^ ITIS Report. "ITIS Standard Report: Myocastor". http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=180401. Retrieved September 5, 2007.
- ^ Nutria Biology. Nutria.com. 2007. Retrieved on September 5, 2007.
- ^ ITIS Report. "ITIS Standard Report: Myopotamus". http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=203538. Retrieved December 19, 2007.
- ^ http://www.nwrc.usgs.gov/factshts/020-00.pdf
- ^ Nutria control program
- ^ "A Plague of Aliens" Feb/Mar 2003 edition of National Wildlife magazine, published by the National Wildlife Federation, article by Laura Tangley; accessed online December 8, 2006.
- ^ eMedicine: Strongyloidiasis
- ^ Bonilla et al. "Nutria Itch" in Archives of Dermatology. Vol. 136 No. 6, June 2000
Names and Taxonomy
Comments: Included in the Capromyidae or Echimyidae by some authors; placed in the Myocastoridae by Baker et al. (2003) and Woods and Kilpatrick (in Wilson and Reeder 2005).
Baker et al. (2003) applied the common name "Nutria or Coypu" whereas Woods and Kilpatrick (in Wilson and Reeder 2005) selected "Coypu" as the best choice because "Nutria" in Spanish means otter.