Small mammals represent an important component of the ecosystem, acting as seed dispersers, valuable prey species, and indicators of habitat change. They are also known to enhance soil structure and composition, influence vegetation diversity, affect invertebrate populations, and influence the abundance and distribution of predators that depend on them. Small mammals respond quickly to environmental changes and therefore are ideal for studying drivers of ecosystem dynamics and understanding the current and future impacts of climate change. Small mammal abundance can also be affected by predator–prey interactions. Therefore, careful monitoring of small mammal population dynamics and dispersal is valuable.

Research done in the Pauli Lab focuses on the impacts of changing winters on small mammal communities and how those changes affect the predator community. Specifically, small mammals in much of the northern hemisphere are subnivium–dependent species, meaning they rely on a thermally stable, under–snow refuge to survive the harsh winter. These species include southern red–backed voles, white–footed and deer mice, and northern short–tailed shrews. As winter conditions change, the small mammal community will likely change with it. Such changes can negatively impact the predator community that depends on small mammal prey in both winter and summer and can also alter forest composition as seed dispersal and herbivory patterns change. Research in Chequamegon–Nicolet National Forest (CNNF) and the Apostle Islands National Lakeshore (APIS) in northern Wisconsin focuses on how factors such as competition dynamics, snow conditions and resource abundance affect small mammal communities and population demography. In recent years, the region is experiencing high variability in winter conditions with later onset of snow and less stable subnivium conditions. These conditions affectsmall mammal survival and can lead to drastic fluctuations in populations and potential changes in community structure. We use live–trapping methods to assess small mammal population and community dynamics in both winter and summer. We combine our live trapping results with other data (such as vegetation structure, snow depth, temperature, and tree seed production) to draw conclusions about how habitat and environmental variables can impact population dynamics.

In addition, other work in the Pauli lab studies the interplay between bottom–up versus top–down forces on small mammals, evaluating shifting controls and the relative importance of habitat characteristics and predation on population dynamics of the dusky–footed woodrat. In the Sierra Nevada, California, the consumption of dusky–footed woodrats has emergent, population–level effects on spotted owls, a species that lies at the epicenter of forest management in an imperiled yet ecologically important ecosystem. By combining live trapping, VHF collaring, and behavioral studies of giving–up densities, our research employs an observational and experimental framework to provide important context on the consumptive and non–consumptive effects of spotted owl predation on woodrats, and how differences in local habitat conditions can mediate these interactions within a heterogeneous landscape.

Project Members: Sam Jolly, Corbin Kuntze

Funding and support for this work comes from the Wisconsin Department of Natural Resources, US Forest Service, Sierra Pacific Industries, Great Lakes Indian Fish and Wildlife Commission, and the National Park Service.