MAMMALS OF YOSEMITE NATIONAL PARK 



57 



In certain instances, where the common 

 name applied by Grinnell and other west- 

 ern authors was preceded by a name 

 more widely known throughout the 



United States, I have favored the latter 

 in order to make the booklet more use- 

 ful to park visitors, who come from all 

 parts of the land. 



THE INSECT-EATERS — Moles and Shrews 



Shrews are the smallest mammals 

 found in the park, with only the Mer- 

 riam canyon bat as a possible rival (see 

 page 61). Four of the five species found 

 here are less than half the size of a house 

 mouse, have small feet and are some 

 shade of brown. The exception is the 

 mountain water shrew, which will be 

 dealt with later. All five have sharp, 

 pointed noses and tiny eyes. Again ex- 

 cepting the water shrew, they can be 

 identified as to species only by the expert 

 who has the specimen in hand. 



They are among the most voracious 

 of animals, requiring approximately the 

 equivalent of their own weight in food 

 each twenty-four hours! To obtain such 

 quantities of insects, carrion and other 

 flesh (they readily attack, kill and eat 

 mice larger than themselves), a great 

 deal of time must be spent in foraging. 

 They are among the most active of 

 mammals. Food seems to be located main- 

 ly by sense of smell. 



In Yosemite, shrews seem to prefer 

 moist situations and tend to keep under 

 cover, such as matted vegetation, logs 

 and rocks. The runs and burrows of 

 other mammals are often used as high- 

 ways in the relentless search for food. 



They have been found at all elevations 

 in the park and apparently are active 

 in winter as well as summer. I remember 

 an occasion, at Upper Lyell Base Camp, 

 one September morning when the thin 

 snow on the ground was marked with 

 tiny shrew trails widely ranging through- 

 out the area. 



The mountain water shrew is about 

 the size of a house mouse; dark, slaty 

 gray in color. It is apparently never found 



far fiom water. The narrow, scrub-wil- 

 low-lined streams of the higher eleva- 

 tions are a favorite haunt. 



This form is well suited to stream life. 

 The fur does not get soaked in the water, 

 but holds air within its surface, so that 

 when the animal swims under water, a 

 silvery envelope of air bubbles encloses it. 

 The hind toes are fringed with stiff hairs. 

 This fringe assists it in swimming, by 

 serving much like webbing, and enables 

 it to skitter right across the surface, lit- 

 erally walking on the water. It is said 

 that the mountain water shrew can also 

 walk on the bottom of a stream or pool. 



The Yosemite mole is well suited for 

 life underground The pointed nose, ta- 

 pered head, short neck, cylindrical body 

 and lack of protruding ears contribute to 

 smooth passage through loose soil or open 

 tunnel. The short, sturdy front legs with 



ntc*. 



#, ^ 



Pluilo by Author 



Mole run. Note cracks in the earth. 



