76 YOSEMITE NATURE NOTES 



adults, but the upperparts are a bluish 

 gray. In "adolescence" the color resem- 

 bles that of adults, but is paler in tone. 

 These variations, due to differences in 

 age, often confuse the uninitiated into 

 believing that they represent different 

 species. 



Actually, three kinds of white-footed 

 mice are known from Yosemite, but 

 identification of a single individual would 

 be extremely difficult without technical 

 knowledge or the comparative material 

 available in a museum study collection, 

 having the specimen in hand. A possible 

 exception is the Gilbert white-footed 

 mouse. It is found only at the lower ele- 

 vations of the park and has comparative- 

 ly huge ears, three-fourths of an inch 

 long. Records are rare in the park for 

 iliis bubspecies. 



Rather than the well-known house 

 mouse, it is usually some form of this 

 group that enters the haunts of man in 

 Yosemite. Sometimes it is in search of 

 food that whitefoots come into the house. 

 However, many times they seem not to 

 bother the larder, but rather seek to find 

 shelter and to store food brought in from 

 the outside. 



In the autumn of a "good acorn year" 



in Yosemite Valley, residents may hear 

 these mice drop acorns while in the space 

 above the ceiling. The rolling nut re- 

 sounds, comparatively, as though it were 

 a billiard ball. These seem tiny creatures 

 to lug acorns so far above the ground 

 level, but they accomplish it, oftentimes 

 making the cache in a spot such as the 

 toe of a boot hanging upside down, 

 where it would appear impossible for 

 them to climb while carrying such a load. 

 In addition to acorns, their natural food 

 consists mainly of dried seeds, fruits, 

 nuts and insects. The chief period of 

 activity is at night. 



Nesting places near the caches in 

 buildings are not spurned. Overshoes, 

 hats, dresser drawers, upholstery (even in 

 cars) and, of course, the spaces between 

 walls or under rafters are among spots 

 chosen for a cozy home made of shred- 

 ded paper, cotton, kapok or similar ma- 

 terials, fluffed up by the teeth and nails. 

 Aside from these artificial situations, the 

 nest may be made in brush, hollow 

 stumps, under the ground, beneath rocks, 

 in fact almost any sheltered spot, depend- 

 ing on the habitat of the species. The 

 softest of materials available, such as 

 grass and milkweed silk, will be used. 





Photo by Inglei 



White-footed mouse. 



