shorter tail than our various species of Field Mice, with one exception, 

 and that one is not likely to cause any confusion. 



Of this family the Field Mice have the greatest number of species in 



No. 11. Cantankerous Vole, Microtug mordax; about two-thirds life size. 



Colorado, namely five, and they are found almost everywhere except in 

 the driest prairie regions. When living in grassy places they make 

 numerous runways through the grass, along which they travel and which 

 are utilized by the other small mammals inhabiting such places, such as 

 deer mice and shrews. Their holes are not far from the runways, and in 

 the burrows are globular nests of grass and other plant fibers. In addition 

 to having holes these mice make nests on top of the ground of the same 

 materials as the underground nests, and they also make nests under pieces 

 of board or sheet iron which may be lying about. 



The names of our Field or Meadow Mice are as follows: The Saguache 

 Meadow Mouse, Microtus pennsylvanicus modestus; the Dwarf Meadow 

 Mouse, M. namis; the Cantankerous or Rocky Mountain Meadow Mouse, 

 M. mordax; the Pigmy Meadow Mouse, M. pauperrimus; and Hayden's 

 Meadow Mouse or Upland Mouse, M. ochrogaster haydeni. 



RED-BACKED MICE. 



The Red-backed Mice, genus Evotomys, are, as previously stated, dis- 

 tinguished from the other Colorado meadow mice by the reddish color of 

 the back. The genus is circumpolai in distribution, and ranges little, if 

 any, below the Canadian Zone. The species found in Colorado is the Colo- 

 lado Red-backed Mouse, Evotoinys gapperi galei. 



In Colorado 8,000 feet is about the lowest altitude to which this species 

 ranges. Whether it is to be found above timberline I cannot say as there 

 are no records bearing upon this point, but it is confined to the boreal 

 zones. It lives in the woods and is found about the fallen logs, making 

 its nests both under logs and in burrows. It does not hibernate and is not 

 known to lay up any stores of food for winter use. Its food is seeds of 



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