Responses of a small mammal community to heterogeneity along forest-old-field edges

Despite the importance of edges effects in ecological systems, the causes a nd consequences of animal responses to habitat edges are largely unknown. W e used three years of live-trapping and measures of the plant community aro und trap stations to explore the responses of white-footed mice (Peromyscus leucopus), meadow voles (Microtus pennsylvanicus), and short-tailed shrews (Blarina brevicauda) to forest-field edges in upstate New York. We found t hat capture probabilities of voles were highest in grass- and forb-dominate d micro-habitats and in old-field zones distant from the forest edge. In co ntrast, capture probabilities of white-footed mice were highest in shrub-do minated microhabitats and in zones near the forest edge. Short-tailed shrew s did not show strong micro- or macrohabitat associations. The responses by voles, the competitive dominant in our system, to variation along forest-f ield edges were more consistent across years than were those of the competi tively inferior, white-footed mouse. Mice were less likely to use the old-f ield interiors when vole density was high than when it was low, suggesting competitive displacement of mice by voles. Finally, we found good agreement between the spatial activity patterns of mice and voles in old-fields and their impacts on patterns of survival of tree seeds and seedlings in concur rent studies. These results suggest that a dynamic interaction exists betwe en the plant and animal communities along forest edges.