Myocastor coypus

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

Canada

Origin: Exotic

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Unknown

United States

Origin: Exotic

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

This species is native to South America, and has been introduced to North America, Europe, Africa, and Asia (not all these introduced locations are mapped here) (Bertolino 2005). It is patchily distributed throughout its historic range in association with mesic habitats and water bodies. Its distribution in the Patagonian steppe is likely the result of human introduction (Ojeda, Lessa, and Bidau pers. comm.).

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

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.

Length: 140 cm

Weight: 11400 grams

Habitat and Ecology

Systems

• Terrestrial

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

Wetlands: marsh

Other Habitat Features: riparian

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).

Animal / dung saprobe
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.

Nutria probably communicate through tactile, chemical, and auditory channels. Their eyesight is limited.

Communication Channels: tactile ; acoustic ; chemical

Perception Channels: visual ; acoustic

Comments: Period of greatest activity is at night.

The potential longevity of Myocastor coypus is 6 years.

Typical lifespan
Status: wild: 6 (high) years.

Average lifespan
Status: captivity: 6.0 years.

Average lifespan
Status: captivity: 10.0 years.

Maximum longevity: 8.5 years (captivity) Observations: Record longevity in captivity is 8.5 years (Richard Weigl 2005). It has been estimated that these animals may live over 10 years (Philip Altman and Dorothy Dittmer 1962), which is possible but unverified.

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); 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.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 3
Species With Barcodes: 1

Canada

Rounded National Status Rank: NNA - Not Applicable

United States

Rounded National Status Rank: NNA - Not Applicable

Year Assessed

Assessor/s

Reviewer/s

Justification

History

• 1996
  Lower Risk/least concern
  (Baillie and Groombridge 1996)

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

Rounded Global Status Rank: G5 - Secure

Population

Population Trend

Major Threats

Conservation Actions

Management Requirements: See Evans (1970) for information on when, where, and how to control. Easily trapped.

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.