Complete Name : Myocastor coypus Molina, 1782
Taxonomy : Mammalia » Chordata » » » Myocastoridae » Myocastor coypus
Authors : Sandro Bertolino
Last Updated : November 31st, 2006

Coypu, nutria.

Large semi-aquatic rodent that lives along rivers, lakes, and marshes. The weight is often between 2-4 kg but adult males can reach 7-8 kg. Superficially it is rat-like, with short legs and a long cylindrical tail, the first four digits of the hind feet are webbed; the pelage is brown. It is herbivorous except for occasional feeding on mussels.

• Dispersal Mechanisms
  • Coypus are good swimmers and fast colonizers, able to rapidly occupy suitable vacant habitats using freshwater as a pathway.
• Reproduction
  • Coypus can breed throughout the year. The age of first parturition is 3-8 mo. Prenatal embryo losses (up to 50-60%) and abortion of litters could influence productivity. Mean litter size at birth is 4.5-5.4 (Italy, England). In good habitats females may have 2.7 litters/year with a mean of 15 young/year.
• Known Predators/Herbivores
  • Alligators, canids and large felids are the main predators in America and Russia. In Europe predation by foxes, dogs, and marsh harriers is probably more limited. Young are more vulnerable and taken more by predators than adults.
• Resistant Stages (seeds, spores etc.)
  • None.

• Native (EUNIS Code)
  • Aquatic habitats.
• Habitat Occupied in Invaded Range (EUNIS Code)
  • C1: Inland surface water habitats, D1: Mire, bog and fen habitats.
• Habitat Requirements
  • It can adapt to a wide variety of aquatic habitats, from freshwaters and lakes to drainage canals. They usually live in the lowlands, but can reach 1,200 m in the Andes. Cold winter reduces breeding success and influences population dynamics.

Often naturalized after escapes or releases from fur farms. In other cases animals were intentionally released into the wild with the aim of harvesting their furs. Spreading populations could invade other countries (e.g. in Spain coypus are entering from France).

• Native Range
  • The coypu is native to the Patagonian subregion of South America and occurs in the northern part of Argentina, Bolivia, Paraguay, Uruguay, southern Brazil, and Chile
• Known Introduced Range
  • Naturalized populations occur in North America, Europe, central and northern Asia, Japan, East Africa and the Middle East. In East Anglia (England) the species was eradicated after an 11-years removal campaign.
• Trend
  • Despite that in America and Europe there are many control programs to reduce spreading and population densities, distribution ranges and population densities are increasing in many countries.

known distribution area (in CGRS grid squares; in countries; along coast)

	eradicated
	extinct
	not present; eradicated
	native distribution range in CGRS grid squares
	native range
	assumed native range
	infrequent distribution
	key distribution area
	not established

• Ecosystem Impact
  • The impact on wetlands through feeding on aquatic vegetation could be severe. Selective feeding by coypu caused massive reduction in reedswamp areas, and eliminated plants of Rumex spp. and Nuphar lutea over large areas. It destroys nests and preys on eggs of several aquatic birds, including some endangered species.
• Health and Social Impact
  • It has been hypothesized that the species has a role in the epidemiology of leptospirosis, although its role is probably less important for the spread of the bacteria in the environment compared to rats.
• Economic Impact
  • The species is considered a pest for its feeding on crops, such as sugar beets and maize, and for its burrowing activity that disrupts riverbanks and dikes. In Italy during 1995-2000, despite control activities involving the removal of 220,688 coypus with a cost of 2,614,408 €, damage to the riverbanks exceeded 10 million € and impact on agriculture reached 935,138 €.

• Prevention
  • Where farming is still active, fences and security should be verified and improved. In some small areas, buried or partially buried fences have been used to avoid burrowing by animals to protect crops.
• Mechanical
  • Shooting is effective for population control when environmental conditions force the animals into the open, while cage trapping has also been used in the English eradication program.
• Chemical
  • In some countries like France and United States, baits with toxicants are used. North Americans use zinc phosphide on carrots or sweet potatoes.
• Biological
  • Unknown.

The following contributors have provided records in the DAISIE database for this species.

The following experts registered themselves as having knowledge about this species or its family.

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Carter J, Leonard BP (2002) A review of the literature on the worldwide distribution, spread of, and efforts to eradicate the coypu (Myocastor coypus). Wildl Soc Bull 30 (1):162-175

Gosling LM Baker SJ, Clarke CN (1988) An attempt to remove coypus (Myocastor coypus) from a wetland habitat in East Anglia. Journal of Applied Ecology 25:49-62

Woods CA, Contreras L, Willner-Chapman G, Whidden HP (1992) Myocastor coypus. Mammalian Species No. 398, The American Society of Mammalogists, pp 1-8

Bertolino S, Perrone A, Gola L (2005) Effectiveness of coypu control in small Italian wetland areas. Wildlife Society Bulletin 33 (2):714-720

Boorman LA, Fuller RM (1981) The changing status of reed swamp in the Norfolk broads. J. Appl Ecol 18: 241-269

Brown LN (1975) Ecological relationship and breeding biology of the nutria (Myocastor coypus) in the Tampa, Florida, area. Journal of Mammalogy 56:928–930

Carter J, Foote AL, Johnson-Randall LA (1999) Modelling the effects of coypu (Myocastor coypus) on wetland loss. Wetlands 19:209-219

Doncaster CP, Micol T (1989) Annual cycle of a coypu (Myocastor coypus) population: male and female strategies. Journal of Zoology 217:227–240

Doncaster CP, Micol T (1990) Response by coypus to catastrophic events of cold and flooding. Holoarctic Ecology 13:98–104

Foote AL, Johnson LA (1993) Plant stand development in Louisiana coastal wetlands: coypu grazing effects on plant biomass. In: Proceedings of the 13th Annual Conference of the Society of Wetland Scientists, New Orleans, Louisiana. Society of Wetland Scientists, Utica, Mississippi, USA, pp 265–271

Gosling LM (1989) Extinction to order. New Scientist 4 March 1989:44–51

Gosling LM (1981) Climatic determinants of spring littering by feral coypus Myocastor coypus. Journal of Zoology London 195:281-288

Gosling LM (1989) Extinction to order. New Scientist 4 March 1989:44-51

Gosling LM, Baker SJ (1987) Planning and monitoring an attempt to eradicate coypus from Britain. Symposium of the Zoological Society of London 58:99-113

Panzacchi M, Bertolino S, Cocchi R, Genovesi P (in press) Cost/benefit analysis of two opposite approaches to pest species management: permanent control of Myocastor coypus in Italy versus eradication in East Anglia (UK). Wildlife Biology

Reggiani G, Boitani L, D’Antoni S, De Stefano R (1993) Biology and control of the Coypu in the Mediterranean area. In: Spagnesi M, Randi E (eds) Atti VII Convegno dell’Associazione Alessandro Ghigi per la Biologia e la Conservazione dei Vertebrati. Suppl Ric Biol Selvaggina XXI:67-100

Reggiani G, Boitani L, De Stefano R (1995) Population dynamics and regulation in the coypu Myocastor coypus in central Italy. Ecography, 18:138-146

Shaffer GP, Charles ES, Gosselink JG, Rejmanek M (1992) Vegetation dynamics in the emerging Atchafalaya Delta, Louisiana, USA. Journal of Ecology 80:677-687

Willner GR, Chapman JA, Pursley D (1979) Reproduction, physiological responses, food habits and abundance of nutria on Maryland marshes. Wildl. Monogr. 65:1-43