WHITE-FOOTED MICE 



105 



obtained. Yet White-footed Mice are practically never seen by daylight, 

 for they are as strictly nocturnal as are bats. 



Except for the fact that it does most of its foraging on or close to the 

 ground there is scarcely any limitation to the range of this mouse. It 

 frequents the very edge of running water, thickets and grass clumps on 

 the banks of streams, the runs of meadow mice in damp grasslands, the 

 sides of dry gullies, mixed growths of brush plants on the hill slopes, old 

 buildings, logs and boulders in the forest, and heaps of slide rock on the 

 mountain sides. On one occasion some mice of this species were found 

 living in burrows on altogether open ground, a place where only kangaroo 

 rats were expected to occur. 



Fig. 10. Showing differences in ear between the four species of White-footed Mice 

 found in the Yosemite section, (a) Gambel (Common) White-footed Mouse; (6) Boyle 

 White-footed Mouse; (c) Parasitic White-footed Mouse; (d) Gilbert White-footed 

 Mouse. 



For nesting places and daytime retreats "White-footed Mice make use 

 of any available cover, such as is afforded by crevices or holes in rocks, 

 hollows in trees or in logs, or holes in the ground. Often they use burrows 

 made by other rodents, while in some cases it seems likely that they do a 

 certain amount of excavating themselves. 



Despite its great numbers this mouse does not leave any very obvious 

 indications of its presence. Its small black droppings are the only regular 

 and definite evidences to be found. Nothing distinctive pertaining to its 

 nest, or route of travel, or choice of food, is left as a clue, as is the case 



