Myocastor coypus - Nutria


Information Last Reviewed Spring 2007


The nutria (a semi-aquatic rodent native to temperate South America) was introduced into North America in the hopes of bolstering the fur industry, but the quality of the pelt proved to be poor. Feral populations are the result of numerous accidental and intentional introductions. Foraging nutria have significantly impacted many wetland plant communities, reducing biodiversity, and altering marsh habitats. Their burrowing activity has resulted in damage to a variety of manmade structures.



General Biology


Life Cycle

Habitat Characteristics






Web Sites







Phylum: Chordata

Class: Mammalia or Sarcopterygii

Order: Rodentia

Family: Echimyidae or Capromyidae*

Subfamily: Myocastoridae


* Although nutria exhibits traits of both the Echimyidae and Capromyidae families, distinguishing characteristics place it in its own subfamily (Myocastoridae).





General Biology


Adult Morphology

  • Body is arched and robust in appearance (Fig. 1), with a length of approximately 61 cm

  • Rounded tail, approximately 33-41 cm in length, is scaly and sparsely haired

  • Weight between 5.4 and 9.1 kg

  • Males slightly larger than females

  • Hind legs larger than forelegs

  • Forepaws with four-clawed toes and a fifth, non-functional toe

  • Hindpaws with five-clawed toes; four with webbing and a fifth, which is free

  • Dense, grey underfur overlaid by long, glossy, brown guard hairs

  • White chin and muzzle

  • Nostrils and small eyes and ears located high on head

  • Outer surface of protruding, large incisors is yellow-orange to orange-red in color

  • Female mammae located high on sides

  • Valves located in the nostrils and mouth seal out water












Distinguishing Characteristics







Life Cycle







Habitat Characteristics


Preferred Environment











Native Range

North American Distribution

Probable Means of Introduction






















Control Measures











Borgnia, M., Galante, M. L., and Cassini, M. H. 2000. Diet of the coypu (Nutria, Myocastor coypus) in agro-systems of Argentina Pampas. Journal of Wildlife Management 64(2):354-361.


Carter, J. and Leonard, B. P. 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.


Chabreck, R. H. 1962. Daily activity of nutria in Louisiana. Journal of Mammalogy 43(3):337-344.


Choate, J. R., Jones, J. K., Jr., and Jones, C. 1994. Handbook of Mammals of the South-Central United States. Louisiana State University Press. Baton Rouge, Louisiana. 304 pp.


Conniff, R. 1989. Keeping an immigrant in check. National Wildlife 27(1):43-44.


Doncaster, C. P. and Micol, T. 1989. Annual cycle of a coypu (Myocastor coypus) population: Male and female strategies. Journal of the Zoological Society of London 217:227-240.


Griffo, J.V., Jr. 1957. The status of the nutria in Florida. Quarterly Journal of the Florida Academy of Sciences 20(3):209-215.


Howerth, E. W., Reeves, A. J., McElveen, M. R., and Austin, W. 1994. Survey for selected diseases in nutria (Myocastor coypus) from Louisiana. Journal of Wildlife Diseases 30(3):450-453.


Nowak, R. M. 1991. Walker's Mammals of the World. The Johns Hopkins University Press. Baltimore, Maryland. 1629 pp.


Trillin, C. 1995. The nutria problem. Atlantic Monthly 275(2):30-32, 40-42.


Waldo, E. 1962. The Louisiana Nutria Story. Louisiana Wildlife and Fisheries Commission. New Orleans, Louisiana. 16 pp.


Whitaker, J. O., Jr. 1988. The Audubon Society Field Guide to North American Mammals. Alfred A. Knopf, Inc. New York, New York. 745 pp.


Willner, G. R., Chapman, J. A., and Pursley, D. 1979. Reproduction, physiological responses, food habits, and abundance of nutria on Maryland marshes. Wildlife Monograph 65:43.

Wolfe, J. L. 1981. Nutria: Our newest furbearer. Mississippi Outdoors 44(5):9.





Web Sites

Species summary for Myocastor coypus Kerr, 1792 myocastor/m._coypus$media.html

Myocastor coypus (Nutria, Coypu)

The Mammals of Texas Online Edition - Nutria (Myocastor coypus)


This report was prepared by Danielle M. Crosier and Daniel P. Molloy (New York State Museum).