Proceedings of the Vertebrate Pest Conference

Nutria have been present in the Pacific Northwest for more than 70 years, and though their dramatic impacts on wetlands in the southeastern U.S. is well documented, the northwestern populations have been little studied. Using paired exclosure plots, nutria herbivory pressure on the native vegetation is shown to be considerable but dependent on species type and disturbance history. In coastal wetland habitats, nutria selectively feed on forbs compared to grasses, lowering their aboveground biomass. This study also shows opposing responses to nutria herbivory for disturbed and undisturbed plots, with nutria lowering total biomass in areas that have not experienced a biomass-clearing disturbance event and thus have diminished competition intensity.