Overview
Nutria are a large, aquatic and invasive rodent that was native to South America and were imported to the US for their fur. They have been introduced to coastal wetlands of Maryland, Virginia and North Carolina and their populations are increasing and expanding. Nutria damage marshlands via their feeding and nesting behavior. These marshlands provide a number of critical ecosystem services such as filtering sediment and contaminants, reducing impacts of storms, and providing nursery grounds for a wide range of species. Nutria are negatively affecting the health of coastal ecosystems and the economies that depend on them, making their control of particular interest for wildlife managers.
Nutria closely resemble other wildlife species that are found in Virginia. Nutria have orange teeth, dense fur and round tails covered in short fur. Nutria closely resemble beaver, however, they are smaller and lack the flattened tail that is characteristic of beaver. Nutria are larger and darker colored than woodchucks (or groundhogs), lack long fur on their tails and are associated with aquatic habitats. Although muskrat are found in aquatic habitats, they are considerably smaller than nutria and have longer tails.
Management Options
Nutria cause damage through burrowing, foraging, and transmission of pathogens and parasites. Nutria don’t construct dens, they burrow. These burrows often cause water-retention or flood control levees to breech, weaken structural foundations, and erode banks. Nutria can eat up to 25% of their body weight in vegetation each day, but they waste and destroy up to 10 times as much while feeding, which can cause extensive damage to native plant communities, soil structure, and agricultural crops. The loss of plant cover and soil organic matter (roots, rhizomes, tubers) can result in severe erosion of soils, destroying marshlands and leaving behind open water and threatening populations of rare or endangered species that rely on critical wetland habitats.
Nutria also serve as hosts for tuberculosis and septicemia, which are threats to humans, livestock, and pets. They also carry tapeworms, a nematode that causes a rash known as “nutria itch”, and blood and liver flukes, which can contaminate swimming areas and drinking water supplies and negatively affect human health.
In order to limit the adverse impacts of nutria, control efforts are underway in Virginia. To help guide these efforts, wildlife managers are working to understand where nutria are present. To report a nutria sighting, please send an email with the date of the observation, location information, and picture (if possible) to ReportNutria@vt.edu.
Given the significant damage that has been caused by nutria in other regions where they have become established, the Center for Human Wildlife Conflict advocates the use of lethal control in conjunction with husbandry techniques to reduce their impacts and control their populations.
Lethal Control
Methods of directly controlling the nutria population include trapping (e.g., live trapping, leg-hold trapping), poisoning (zinc phosphide is the only chemical approved for nutria) and shooting. The most cost-effective control measure is trapping, which benefits the economy and lowers the population of nutria in the environment. For trapping to succeed however, pelt prices need to be at a profitable level for trappers. Zinc phosphide is a rodent poison that breaks down quickly in water and kills with one dose. Shooting is effective to remove small, relatively isolated populations of animals. All lethal methods to control the nutria population have potential to be controversial.
Husbandry Techniques
Husbandry control methods include using exclosures, individual tree sleeves or seedling protectors, aromatic plantings and rodent repellents (e.g., Ropel).
Legal Considerations
In Virginia, Nutria are considered a nuisance species. They can be taken throughout the year with no bag limits. However, care should be taken to reduce suffering and impacts on other species. Local regulations should also be consulted before engaging in control activities.
Additional Information
- USGS Non-indigenous Aquatic Species Database: provides a constantly updated database and map of locations where nutria have been found.