Effects of Forest Fragmentation on Population Attributes of White-Footed Mice and Eastern Chipmunks

We examined differences between populations of white-footed mice ( Peromyscus leucopus ) and eastern chipmunks ( Tamias striatus ) in woodlot fragments and unfragmented forests and attempted to discriminate among potential causal mechanisms. White-footed mice showed increased population density and body mass in woodlots but otherwise no differences in population attributes between woodlots and forests. Eastern chipmunks showed decreased survival rates in woodlots but no other differences in population parameters between woodlots and forests. Mast production was variable among sites but showed no differences between woodlot and forest sites. Likewise, total biomass of mammalian granivores was similar between woodlot and forest sites, but woodlots contained an impoverished community of granivores. White-footed mice and eastern chipmunks may be affected differentially by forest fragmentation, presumably due to differences in their life-history stategies. Our results suggest that white-footed mice thrive in woodlot fragments due to increased mast availability resulting from decreased biomass of competing granivores. In contrast, eastern chipmunks may be influenced negatively by forest fragmentation, possibly because they are more susceptible to increased rates of predation occurring in woodlots than white-footed mice.