How do muskrats Ondatra zibethicus affect ecosystems? A review of evidence

Abstract

Abstract Muskrats Ondatra zibethicus are reported to have wide‐ranging effects on wetland habitats, sometimes earning them the labels ‘keystone species’ or ‘ecosystem engineers’. We conducted an extensive review of the scientific literature and evaluated evidence for muskrats as potential keystone species or ecosystem engineers, and more generally, their known impacts on wetland ecosystems. We identified 363 publications (peer‐reviewed articles, books, theses, and reports) regarding muskrats, 202 of which were in an ecological context. Only 6% (n = 13) of these explicitly considered muskrats as ecosystem engineers (n = 9) or keystone species (n = 4). Our review found that muskrat populations may have broad effects on both wetland flora and fauna. However, studies generally occurred over small spatiotemporal scales and used dissimilar methods and reporting, which limited our inference regarding muskrats’ influence on wetland ecosystems. Research explicitly identifying muskrats as ecosystem engineers or keystone species is limited, but published evidence suggests that muskrats may have an effect on plant species diversity and habitat heterogeneity, which in turn may influence other animal species. However, long‐term and experimental research is needed to uncover impacts that muskrats have on ecosystems.