Maryland Mammals

(Myocastor coypus)

Description & Range:

Nutria are large rodents that look like beavers with long, thin tails similar to muskrats. Nutria may weight up to 20 pounds and reach about 24 inches from tip of nose to tip of tail. Nutria have thick brown fur and orange front teeth. They are designed for aquatic life, with webbed feet and eyes, nostrils and ears located high on their heads to enable them to expose as little of their bodies as possible when breathing at the surface of the water.

Nutria are native to South America but have become established in 16 states in North America. Nutria were introduced to Blackwater National Wildlife Refuge in the 1940s, where they were farmed for fur. Currently, nutria can be found on the Eastern Shore of Maryland as well as in the Potomac and Patuxent rivers on the Western Shore.



Nutria can be found within wetlands such as fresh and brackish marshes, rivers, bayous, farm ponds, freshwater impoundments, drainage canals, swamps.


Nutria are herbivores, so they feed entirely on plants. Nutria eat wetland plants such as Three-square rush. Nutria can consume 25% of their body weight per day and tend to eat the roots of wetland vegetation, often causing erosion in wetlands. Occassionally, nutria will feed on agricultural crops.


Nutria breed year round and have a gestation period of 130 days. Males are able to reproduce at 4-9 months of age while females can reproduce at 3-9 months of age. Nutria can have 1-13 young per liter, and females can breed the day after they give birth.



Nutria spend much of their time in the water. They are colonial species which tend to live in groups consisting of a dominant male with 2-3 females and their offspring. These groups live in dens and are most active at night. If food is limited, then nutria will become active during the day to feed.

Bank erosion caused by Nutria photo by Tess McBride, USFWS


Nutria are an invasive species in Maryland due to their destructive feeding habits on marshes. As of 2016, all known nutria populations have been removed from over a quarter million acres of the Delmarva Peninsula, and the Chesapeake Bay Nutria Eradication Project is currently implementing efforts to verify total eradication.

Click here to learn more about furbearer management.