SHBEWS 51 



or semi-aquatic animals; it does not soak up water, but holds air within 

 its surface. An animal swimming beneath the water presents a shining 

 silvery appearance because of this 'envelope' of air. 



This is the species which fishermen, patrolling the banks of Sierran 

 trout streams, often see swimming in the water. The fact that this shrew 

 is active during the daytime is thus attested. 



The breeding season of this shrew occupies the summer months. In 

 1915, suckling females were captured at Merced Grove on June 11, in 

 Indian Caiion on June 20, and at Porcupine Flat on June 26 (this latter 

 individual contained 6 small embryos). A female containing 7 embryos 

 nearly large enough to be born was taken on June 23, 1915, in East Fork 

 of Indian Canon. Since none of the individuals collected in the fall months 

 was sufficiently small to be classed on superficial inspection as young-of- 

 the-year, the adult size must be attained rapidly. 



At Mono Lake Post Office two specimens of Navigator Shrew were 

 collected, on June 30 and July 2, 1916. These were taken in grass along 

 a stream through a poplar grove, while in the sagebrush not over 100 feet 

 away, specimens of the Great Basin Pocket Mouse were captured. The 

 capture of this species of shrew at such a low station on the east side of 

 the central Sierras was unusual and also furnished a striking example of 

 how species of animals with totally different habitat preferences may occur 

 in close proximity because of the juxtaposition of their respective niches. 



Little California Bat 

 Myotis californicus californicus (Audubon and Bachman) 



Field characters. — Size small, much smaller than House Mouse (slightly larger than 

 Merriam Bat, about % size of Large Brown Bat). (See pi. 21ft) Total length about 

 3 inches (75-80 mm.), tail about 1^^ inches (30-39 mm.), hind foot l^ inch (6-7 mm.), 

 spread of wings about 8i/^ inches (220 mm.). Coloration dark brown above, slightly 

 paler on under surface; flight membranes, ears, lips, and muzzle brownish black. Flies 

 with rapid fluttering of wings and marked indirection of course. 



Occurrence. — Common in Upper Sonoran and Transition zones on west slope of Sierra 

 Nevada. Recorded from Pleasant Valley eastward to Yosemite Valley. Extreme alti- 

 tudes, 600 and 4500 feet. Forages about foliage of oaks and other trees, and around 

 larger brush plants ; keeps usually less than 25 feet from the ground. Not colonial. 



The Little California Bat is probably the most common of the bats in 

 the Yosemite region. It is relatively abundant on the floor of Yosemite 

 Valley and so is likely to come to the attention of summer visitors there 

 who go walking beneath the oaJks and pines at twilight. This species does 

 its foraging close about the foliage of the trees and larger shrubs, and 

 ordinarily it stays within a few feet of the ground. It is seemingly 

 oblivious to human presence, so that its actions may be watched at close 

 range. 



