Nutria

Exotic Aquatics of the Gulf Coast:
Nutria (Myocastor coypus)

Nutria: Impacts on the Environment
The nutria is a nonindigenous (non-native or exotic) species that has become invasive. Although nutrias live in a burrow on land, they have webbed feet and spend much of their lives in the water. They are marsh dwellers.
At first, when nutria escaped to the wild from fur farms, they did not disrupt the existing ecosystem. However, as time passed and their numbers increased exponentially, nutria began to do serious damage to Louisiana’s wetlands.

Many hoped that the natural predators of nutria, such as the American alligator, would eat enough of the rodents to keep the population in check. This simply did not happen. The large populations of nutria continue to cause two types of damage in estuaries in coastal Louisiana: herbivory and burrowing damage.
Herbivory damage. In the late 1980s, increasing complaints from land managers regarding herbivory damage by nutria became routine in southeast Louisiana. A 1993 survey by the Louisiana Department of Wildlife and Fisheries of six parishes (counties) detected 91 damaged areas that covered more than 15,000 acres. "Eatouts," or areas where marsh grass was completely grazed, were easily recognized from the air. Some eatouts measured up to 500 acres in size. Another study, located in the newly forming Atchafalaya and Wax Lake deltas, used exclosures to document that grazing by nutria and waterfowl seriously slows the development of wetland vegetation in newly forming deltaic environments. Interestingly, duck herbivory created an approximately equal amount of damage as the nutria did to emergent vegetation. However, reduction of duck populations in the marshes of south Louisiana conflicts with the interests of wildlife managers interested in maintaining large duck populations for recreational hunting. In order to maximize growth of newly created marsh environments, control of the nutria population is considered essential.

Herbivory damage to emergent marsh grasses is not the only problem caused by nutria appetites. Concerted efforts to regenerate baldcypress forests have largely been unsuccessful due to nutria damage. Nutria herbivory of baldcypress seedlings has been documented since the early 1960s. Nutria find the tender roots of newly planted baldcypress seedlings particularly irresistible. One study by the Louisiana Soil Conservation Service and the Baruch Forest Science Institute of South Carolina found that nutria destroyed 86-100 percent of hand-planted cypress seedlings set out with various types of protective devices. This same study found that chickenwire fencing was most successful in protecting newly planted seedlings, but this protective measure is costly and time-consuming to install.

Nutria burrowing. Nutria burrowing is also causing significant damage in areas of infestation. Large underground tunnels built by nutria have weakened the sides of drainage canals, water impoundments and levees. Nutria overgrazing exacerbates cave-ins and erosion problems in these areas. It is estimated that since 1990 in Jefferson Parish, Louisiana, more than $8 million in damages to the parish canal system can be attributed to nutria damage. In Florida, nutria burrowing into the banks of golf course ponds has caused cave-ins. Also, large numbers of nutria sunning themselves on some of the golf course's tees, especially in the summer, have scared golfers who often mistake them for giant rats.

Nutria: An Introduction
Nutria: A Historical Nuisance
Nutria: Impacts on the Environments
Nutria: Prevention & Control Measures
Nutria: Online & Printed Resources

<< Back to Species List