130 



ANIMAL LIFE IN THE YOSEMITE 



quapin eastward to Warren Fork of Leevining Creek and Walker Lake; present on 

 floor of Yosemite Valley in some numbers and taken once at El Portal. Lives chiefly 

 along banks of swift-flowing mountain streams and in marshes but also on dry hillsides 

 at some distance from water. Largely nocturnal. 



Besides the path-cutting meadow mice {calif ornims and montanus) 

 there is present in the Yosemite region a free-ranging species, the Can- 

 tankerous Meadow Mouse. It occurs in greatest numbers on the ground 

 beneath the bushes which line the banks of mountain streams, but strangely 

 enough is also found in some numbers on dry hillsides well away from 

 water. 



M.m. sierrae /\ M.m.sierrae 



Fig. 19. Cross-section of the Sierra Nevada through the Yosemite region showing 

 zonal and altitudinal ranges of Meadow Mice (genus MicroUos). 



The present species is a 'long-tailed' meadow mouse, but is so only by 

 comparison with others of its own tribe (figs. 16&, 20a.). The tail of niordax 

 is as a rule slightly over one-third the total length (one-half head and 

 body), whereas in the California and Yosemite voles the length of tail is 

 somewhat under the proportions given. In other features mordax closely 

 resembles other meadow mice with its blunt nose, black bead-like eyes, small 

 ear, and soft dense pelage. 



The range of the Cantankerous Meadow Mouse includes the whole of 

 the high Sierras. Nominally it embraces the Canadian and Hudsonian 

 zones, the 'boreal' portion of the region; but the species locally extends 

 Avell beloAV the limit of the lower of these zones. Thus on the floor of 

 Yosemite Valley, in the little swamp near the Happy Isles power house, 

 and again in an area near Rocky Point, some of these mice were found ; 

 and on one occasion (November 21, 1914) an individual was captured at 

 El Portal. It is an observed fact that along the course of a river or large 

 creek a tongue of the next higher zone will often extend down into the 

 zone below. This is due to the fact that the colder water and greater 

 evaporation keeps down the temperature in the neighborhood of the stream. 

 This, in the case of the Cantankerous Vole, would operate to permit the 

 animal to reside comfortably at lower levels as illustrated by its occur- 

 rence in Yosemite Valley. The occurrence at El Portal may, of course, 

 have been purely fortuitous, due to an individual having wandered or 



