Demography and Use of Space by a Small Mammal Community in Itasca State Park, Minnesota

Abstract

One of the most interesting and popular areas of study in the Great Plains is the investigation of small mammals and their associated ecological relationships. The objective of this study was to determine the species composition, home range, and sex ratio of selected small mammals inhabiting three habitat types: upland aspen (Populus spp.) forest, adjacent wet meadow, and the ecotonal area between them. This research was carried out at Itasca State Park, Minnesota from June through August of 1992. Longworth live traps and pitfalls were used in tandem in a 10 x 10 grid with 10 meter spacing. Home range was estimated using the computer program "Home Range."Population densities were calculated using the Schnabel index. Eleven species of small mammals representing 6 families, and 2 orders were captured during 2,384 trap nights. Home range estimates were lower than that reported in the literature. Possible explanations are discussed. Density estimates were similar to that reported in the literature. Distribution of small mammals was affected by many factors including, food, cover, moisture, vegetation, and predators. Clethrionomys gapperi was the most abundant species in the aspen forest. Microtus pennsylvanicus were most common in the wet meadow. Peromyscus maniculatus were captured most often in the aspen forest. Insectivores were well represented with 3 different species. Sorex cinereus were more abundant in the aspen forest, but trap mortality prevented any recaptures. Three Sorex arcticus were captured, in the aspen and wet meadow. Blarina brevicauda was most common in the aspen forest.