Using Harvest Data to Assess Factors Influencing Regional Population Declines of Muskrats ( Ondatra zibethicus )

ABSTRACT

Although muskrats ( Ondatra zibethicus ) provide ecological, economic, and cultural values to wetlands, populations have experienced declines throughout North America. The cause(s) of declines remain unclear but may be linked to wetland loss, fragmentation, or degradation; weather; or diseases. We used harvest data from the Midwest, USA, as an index of abundance to investigate factors influencing population declines. Using linear mixed‐effects models, county‐level harvest of muskrats was positively associated with wetland connectivity and size, suggesting that population declines may be related to wetland loss. Site‐level harvest was positively influenced by wetland habitat conditions, though additional studies may be necessary to corroborate this pattern. Wetland‐restoration efforts directly benefiting muskrat habitat may also benefit other wetland‐obligate wildlife communities. Strategies for managers include increasing the value of data collected during annual fur‐harvester surveys (e.g., standardization) to more effectively monitor muskrat demographics and help reveal specific factors affecting population trends.