Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Cross-scale interactions and non-native cattails influence the distributions of a wetland-obligate species.

Abstract

Context Landscape configuration and composition can influence the spatial distribution of species. Cross-scale interactions may exist when multiscale effects interplay to shape species' distribution patterns. Objectives We investigated how the spatial distribution of a semiaquatic mammal, muskrat (Ondatra zibethicus), is influenced by local-scale resource characteristics. We also assessed how fetch, the unobstructed distance wind can travel across water, influences fine-scale habitat use by muskrats. Methods We used 2 years of presence-absence surveys (2015-2016) at 71 wetland sites to evaluate the spatial distribution of muskrats in a lacustrine system in Minnesota, USA. We expected site occupancy and colonization to be positively associated with the amount of Typha x glauca (a rapidly establishing invasive hybrid cattail species) at sites, and negatively associated with fetch impact, water depths, and open water areas. Results As expected, sites with greater coverage of T. x glauca, shallower water depths, and less open water had greater initial occupancy probabilities. Muskrats were more likely to colonize fetch-impacted sites if there were also greater coverages of T. x glauca present. Conclusion The distribution and intensity of fetch, dictated by the watershed-scale configuration of upland landscapes, influenced site colonization by muskrats. Our results suggest that this landscape-scale effect is mediated by the amount of T. x glauca present at much finer scales. This cross-scale interaction may facilitate distribution expansions of wetland-obligate species into otherwise unsuitable habitats.