How Maryland Got Rid of Nutria, and Why “Native” and “Invasive” Can Mislead

In 1943, nutria — large, semi-aquatic rodents from South America — were released into Dorchester County, Maryland. Over the following decades their feeding destroyed thousands of acres of wetlands. In 2022, after twenty years of work, the Chesapeake Bay Nutria Eradication Project announced that nutria were gone from the state.

A nutria. Image from the National Park Service Integrated Pest Management Program.

The story was one of the topics of the National Park Service Integrated Pest Management (IPM) Program's webinar series, which is open to anyone and covers pest management and invasive species.

Eradicating nutria

The project was run by a management team first made up of the U.S. Fish and Wildlife Service, the Maryland Department of Natural Resources, Tudor Farms, the U.S. Department of Agriculture and the University of Maryland — a partnership the webinar held up as a model.

When "native" can be invasive

A second session took on a problem of language. Land managers like to treat terms such as native and exotic, or invasive and non-invasive, as absolutes. But plants are plastic: their genes and environments shape how they behave, and all-or-nothing labels can mislead research and management.

The example was reed canary grass (Phalaris arundinacea), a native species that is nonetheless invasive. The proposal: judge each plant by its capacity to establish and spread and the threat it poses to natural or managed landscapes — not by labels that can steer resources away from controlling it. That would mean every kind of landholder, from federal, state, provincial, Tribal and local authorities to private landowners, rethinking how its managers decide whether to control a species, and regulators rewriting rules for native invasive species once assumed to be foreign.

Rethinking the program

The IPM Program also ran open-house webinars led by Jim Pieper and Jamie Howard on a major re-envisioning of the program, with a survey for feedback, aiming to build a program that works for everyone in the Park Service at every level, concessioners included.

Recordings of past sessions are on the IPM Program's YouTube playlist, and upcoming webinars are listed on the NPS Common Learning Portal.

Sources

Based on "November IPM Series: IPM Re-envisioning," National Park Service Integrated Pest Management Program; a work of the United States government in the public domain.