Abstract:
In the Eastern portion of the United States, geographically sympatric rodents Microtus
pennsylvanicus and Peromyscus spp. have been found to segregate themselves from one
another at the stand level. Thus, we characterize them as being locally allotopic. While the
existence of this allotopy is commonly recognized, its source is not as well understood. Many sympatric species compete for the same food resources, and this interspecific competition
motivates segregation from one another. However, it has been consistently documented that
M. pennsylvanicus and Peromyscus spp. consume markedly different foods, so it is highly
unlikely that they are in competition for these particular resources. Sympatric species have also
been found to separate themselves from one another across different microhabitat types. Thus, the goal of this study was to determine whether the allotopy present between M.
pennsylvanicus and Peromyscus spp. can be attributed to varying preferences for microhabitat.
This study was conducted on the Ball State University Cooper Farm property in Muncie, Indiana in Delaware County. From September of 2011 to March of 2012, Sherman live-trapping for M. pennsylvanicus and Peromyscus spp. was conducted in prairie and forest environments.
Microhabitat data were collected on soil volumetric water content, ground cover, vegetation density, vegetation height, and litter depth at successful trap sites and at an equivalent number of trap sites where target species were not found. The results of our study show that M. pennsylvanicus and Peromyscus spp. did not prefer different microhabitats. However, due to the overall homogeneity of our study site, we propose that we were unintentionally trapping
within a single microhabitat type. Since Peromyscus spp. were present in high numbers, and M. pennsylvanicus were virtually absent from our study site, we propose that M. pennsylvanicus
were indeed occupying differing microhabitats, possibly not within our study site. This is supported by our findings that M. pennsylvanicus did not show preference for particular microhabitat characteristics within our study side.
