Patterns of rodent abundance on open-space grasslands in relation to suburban edges

Relatively little is known about the response of grassland rodent populations to urban and suburban edges. We live-trapped rodents for three summers on 65 3.1-ha grassland plots on open space of the city of Boulder, Colorado, and compared capture rates among species according to habitat type, percentage of the 40 ha surrounding each plot that was suburbanized, and proximity to a suburban edge. Deer mice ( Peromyscus maniculatus) and hispid pocket mice (Chaetodipus hispidus) were more abundant on interior than on edge plots in mixed grasslands, whereas prairie voles ( Microtus ochrogaster) were captured more often on interior than on edge plots in tallgrass/hayfields. House mouse (Mus musculus) abundance did not differ between edge and interior plots. Native rodents as a group were captured more often on interior than on edge plots in both habitat types. For each native species, plots with the highest capture rates were in landscapes <10% suburbanized. We conclude that proximity to suburban landscapes had a strongly negative effect on the abundance of native rodents in open-space grasslands.