Winter ecology of prairie deer mice (Peromyscus maniculatus bairdii) in cultivated habitats: Implications for agricultural ecosystem services

Abstract Prairie deer mice ( Peromyscus maniculatus bairdii ) are permanent residents of row-crop fields in the Midwestern United Sates, and may provide ecosystem services by regulating weed seed and waste grain populations. Seed predation is especially critical in the months of highest seed availability following crop harvest, and is dictated by population density and individual patterns of diet choice. We used a combination of spatial mark-recapture demographic and stable isotope dietary analyses to investigate the ecology of prairie deer mice during this critical over-winter period within corn and soybean agro-ecosystems of west-central Indiana. Winter prairie deer mouse populations were robust in the row-crop habitats we sampled, with densities typically > 13 individuals/ha but variable among trapping grids and throughout winter. Apparent survival of individuals also varied throughout winter (57–79% monthly survival rate), and mean over-winter (December–April) survival of adults was 21%. Winter diets were dominated by waste grain, with corn and soybean contributing 55% and 77% of diet for mice sampled in corn and soybean fields, respectively. Weed seeds contributed less (2–27%) to winter diets. Based on our results and published field metabolic rates, we estimate that prairie deer mice consume 6.3 kg/ha of waste corn and 7.1 kg/ha of waste soybean seeds during the non-growing season. Collectively, our results suggest that prairie deer mice make meaningful contributions to reducing waste-grain populations during winter in post-harvest row-crop fields, during a time of year when most other seed predators are inactive.