Range Changes of Mammals in the Great Lakes Region

Abstract

Range changes of mammals in the Great Lakes region (Minnesota, Michigan, Wisconsin, and those parts of Ontario, Ohio, Pennsylvania and New York bordering on the Great Lakes) are described, based on a review of the literature and recent data obtained by the author. Although the Great Lakes and their interconnecting rivers are a marked geographical barrier to the spread of mammals, many changes have taken place in the distribution and abundance of mammals since the last glacial period. These changes are influenced by human activities, climatic changes, and changes in biotic communities. Among these factors, the first one has been most influential. The elk (Cervus canadensis), the bison (Bison bison) and the wolverine (Gulo luscus) have become extinct since the arrival of white man. The cougar (Felis concolor) probably also disappeared, but may have reinvaded the region. Range restrictions have been recorded for the woodland caribou (Rangifer tarandus), Canada lynx (Lynx canadensis), bobcat (Lynx rufus), gray wolf (Canis lupus), black bear (Ursus americanus), marten (Martes americana), fisher (Martes pennanti), and snowshoe hare (Lepus americanus). The latter three species are reinvading formerly occupied ranges during recent years. Range extensions include the majority of species which have exhibited range changes. A distinct northward spread has been recorded for the moose (Alces americana), white-tailed deer (Odocoileus virginianus), opossum (Didelphis marsupialis), eastern cottontail (Sylvilagus floridanus), bobcat (Lynx rufus), raccoon (Procyon lotor), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), gray squirrel (Sciurus carolinensis), and fox squirrel (Sciurus niger). An eastward spread has been observed for the thirteen-lined ground squirrel (Citellus tridecemlineatus), Franklin ground squirrel (Citellus franklinii) and white-tailed jack rabbit (Lepus townsendii). The smoky shrew (Sorex fumeus) and the yellow-nosed vole (Microtus chrotorrhinus) have apparently displayed a westward spread.