The higher-level classification of nutria is controversial. Though nutrias are related to echimyids and capromyids, several morphological differences argue against uniting myocastorids with either of these taxa in the same family. Therefore, currently nutria are placed in their own family, Myocastoridae. Woods and Howland (1979), Woods et al. (1992).
Nutria probably communicate through tactile, chemical, and auditory channels. Their eyesight is limited.
Communication Channels: tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
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
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
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 )
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 )
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
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.
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
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)
