48 



AMMAL LI Ft: IS Till: YOSKMITK 



observation, ami usually trapping:, to clenionstrate tlu'ir presence. Shrews 

 and moles have many features of structure and behavior in common and 

 are classed together in an order known as Insectivora, a term which 

 indicates their principal food. The two groups are quite distinct, however; 

 the shrews exhibit none of the peculiar specializations for digging possessed 

 by moles, being in general much like small mice. 



' ;!iii!i!;!i::!i:i !i»'^ 



Fifj. 6. Cross-section of the Sierra Nevada through the Yoseniite region showing 

 general zonal ami altitudinal distribution of the shrews (genera Surex and Xeosorex). 



The shrews live and do most of their foraging above ground, yet they 

 keep beneath cover of varj-ing kinds such as is atforded by matted vege- 

 tation and prostrate logs. Sometimes when foraging they invade the 

 runways and even the burrows of other mammals — meadow mice, for 

 instance — but none of our local species of shrews are known to make runs 

 of their own or to put up mounds as do moles. Most kinds of shrews 

 regularlj^ patrol the sides of streams where often there are little beaten 

 paths close under the overhanging banks. The Dusky Shrew, and to a less 

 degree, the Adorned Shrew, are to be found away from water, sometimes 

 a hundred yards or more, on hill slopes covered with trees and rocks. But 

 none is known to inhabit the dry foothill chaparral, or the sagebrush tracts. 



The nose of a shrew (pi. 20) is long and slender and eciuipped with 

 numerous sensory hairs or vibrissae. The snout witii its tHpiipment is in 

 almost constant motion when the animal is active. The eyes, while dis- 

 cernible, are small and do not seem to be of much use to the animal. The 

 external ear also is small though the sense of hearing of shrews is said 

 to be acute. The body of the shrew is cylindrical as in the mole, but the 

 forefeet are normal in appearance like the iiind feet. The tail, thougli 

 varying somewhat according to the species, usually occupies slightly less 

 thfui half the total length; it is thinly haired and has a constriction or 

 narrowing at the extreme base where it joins with the body. This latter 

 feature is not possessed by any of the mice. The teeth of shrews are sharply 

 pointed and serve well in holding and killing insects or tearing the flesh 

 of other .sorts of prey. 



