Geographic Variation
in Red-backed Mice (Genus Clethrionomys)
of the Southern Rocky Mountain Region

BY

E. LENDELL COCKRUM and KENNETH L. FITCH

University of Kansas Publications
Museum of Natural History

Volume 5, No. 22, pp. 281-292, 1 figure in text

November 15, 1952

UNIVERSITY OF KANSAS

LAWRENCE

1952

In the course of the preparation of a synopsis of the North American terrestrial microtines by one of us (Cockrum), and the completion of a Master's thesis on the geographical variation of the red-backed mice of Wyoming by the other (Fitch) we had occasion to study the red-backed mice of the southern Rocky Mountain region (see figure 1). Results of these studies are the recognition of two heretofore unnamed subspecies of the red-backed mouse in the southern Rocky Mountain region, and a clarification of the taxonomic status of two additional kinds.

1890. Evotomys galei Merriam, N. Amer. Fauna, 4:23, October 8.
1931. Clethrionomys gapperi galei, Hall, Univ. California Publ. Zool., 37:6, April 10.
1897. Evotomys gapperi galei, Bailey, Proc. Biol. Soc. Washington, 11:126, May 13.

Remarks.--C. g. galei, with the largest geographic range of any of the Rocky Mountain subspecies, is also the most variable. Three principal areas of geographic variation were found. These areas are: The mountains of north-central Colorado and southern Wyoming (this area includes the type locality); the Big Horn area probably northwest into Montana (no adult specimens from Montana or Alberta examined); and the Teton area which includes the mountains east and southeast of Yellowstone National Park. Specimens from these areas have noticeable differences in pelage, but no constant cranial differentiation could be detected. Specimens from the Medicine Bow Mountains of southern Wyoming have a more reddish dorsal stripe, and more buff and less gray on the sides than either of the northern geographic variants. The dorsal stripe continues farther anteriorly and is better defined through its