About This Project

The muskrat, a charismatic semi-aquatic rodent, has experienced long-term declines across the United States dating back to the 1970s. The factors for this decline remain unclear. Our research will investigate health challenges in eastern US muskrat populations by determining the prevalence and distribution of pathogens and contaminants in these declining animals. The outcomes from our effort can provide context to observed declines and serve as a guide for management efforts of the species.

Ask the Scientists

What is the context of this research?

Muskrats have long been a ubiquitous and abundant rodent of wetland habitats throughout North America. However, that seems to be less the case as state fish and wildlife agency professionals have noted long-term declines in muskrat populations across their range. Those observations have since been proven through documentation of annual harvest trends, harvester reporting, and historical site surveys. All evidence points to a similar decline in the species occurring since the mid 20th century. The cause for such a decline to occur across a wide area is likely due to a combination of factors.

To begin to understand what underlying mechanisms may be responsible for muskrat declines, we have partnered with 13 state wildlife agencies across the eastern United States to investigate muskrat health through the lens of pathogen and contaminant exposure. It is our hope that our findings can shed light on factors affecting muskrat health and inform management to prevent further declines.

What is the significance of this project?

The importance of muskrats cannot be overstated. As ecosystem engineers, they consume wetland vegetation and construct structures known as huts, houses they reside in that are made of vegetative debris. These activities can create pockets of open habitat and add to the diversity in wetland landscapes. In addition to ecological importance, they remain significant to those who utilize them as a furbearer or for consumption. Such precipitous declines in an important species like the muskrat are concerning.

This project represents an effort to survey at a regional scale for pathogens and parasites known to negatively affect muskrat health, while simultaneously exploring the impact contaminants (PFAS, neonicotinoids, etc.) may have as health threats to muskrats. Comprehensive investigation of this nature is necessary to understand what factors are at play affecting the health of these contemporary muskrat populations.

What are the goals of the project?

The goal of our work is to characterize muskrat health across the eastern United States through pathogen, parasite, and contaminant exposure of trapper-harvested muskrats. This involves the detection of pathogens (Fransicella tularensis and Clostridium piliforme) and parasites (Toxoplasma gondii, Taenia taeniaeformis, and Versteria rafei). Several of which can cause disease in muskrats as well as people.

We then plan to test all animals for a suite of contaminants from forever chemicals like PFAS to insecticides like neonicotinoids. A subset of muskrats will also be screened for a variety of volatile organic compounds. The funds gathered for this project will be allocated directly to continued pathogen/parasite work and also kick off our preliminary PFAS exposure testing.

Our final goal is to pair exposure data with additional muskrat and habitat data to determine prevalence across muskrat populations spatially. Information that can guide state partners in future management.