Shifting Distributional Patterns of Mammals in Nebraska

New distributional records are presented for 20 species of mammals in Nebraska. The majority of these records appear to represent changes in geographic distribution rather than just better sampling in poorly known areas. One group of mammals, including the opossum, northern myotis, evening bat, red bat, woodchuck, white-footed mouse, and gray fox, is expanding westward, probably in response to increasing woodlands along river systems. Another group, including the meadow vole, masked shrew, and least weasel, is expanding southward, possibly in response to new prey species and changing microclimates. The eastern woodrat appears to be expanding northward in eastern Nebraska. The armadillo and hispid cotton rat also have been documented as expanding northward into Nebraska in previous studies. The mountain lion is expanding eastward into extreme western Nebraska and reclaiming some of its historical geographic range, whereas the northern grasshopper mouse also is expanding eastward, but in extreme eastern Nebraska. On the other hand, mammals requiring large tracts of undisturbed prairie appear to be contracting in geographic range in Nebraska