Effects of resource distribution on overwinter foraging by mice in agricultural fields and the implications for maize volunteer control

Seed predation may be an important ecosystem service for controlling glyphosate-resistant crop volunteers, which are a growing management concern in conventional cropping systems that rely heavily on pesticide based management. In the Midwest USA, prairie deer mice (Peromyscus maniculatus) are important seed predators, removing unwanted weed seeds and waste grain from the soil surface all year round. In this study, we examined how the spatial distribution of experimental maize (Zea mays) seed patches influenced overwinter foraging, mouse populations and waste grain removal in conventional crop fields. We predicted that (1) individual mice will increase foraging on maize waste grain in fields with many small maize seed patches compared to fields with a few large maize seed patches (functional response) and (2) more mice will forage in fields with many small seed patches than in fields with a few large seed patches (numerical response). We found mouse functional responses were not influenced by the spatial distribution of maize seed patches nor did mice respond numerically to seed addition in general. Mice did, however, remove 59-66% (94-106 kg ha−1) of the maize seeds, providing a valuable ecosystem service. Our work shows that prairie deer mice are able to remove large amounts of waste grain from the soil surface over winter, supporting the hypothesis that overwinter seed predation by mice can drastically reduce volunteer maize densities in conventional crop fields. Future research should further examine what management practices (such as practicing no-till) increase mouse abundance and foraging efficacy, so that management strategies that maximize seed predation can be developed.