50 ANIMAL LIFE IN THE YOSEMITE 



two or three may have been resident in the meadow ; the others may have 

 wandered in from adjacent territory. 



The bodies of shrews have a distinctive odor, similar to that possessed 

 by moles. This odor is currently presumed to be disagreeable to the flesh- 

 eating birds and larger mammals, and so is of value to the shrews in saving 

 them from attack. Examination of the stomach contents of hawks and 

 owls elsewhere has shown that but few ' insectivores ' are taken by predatory 

 birds. As an exception, however, a Sparrow Hawk collected by us in 

 Yosemite Valley on October 25, 1915, had the remains of a shrew in its 

 stomach along with parts of a meadow mouse and some insects. Perhaps 

 each individual carnivore has to make one trial in order to learn that a 

 shrew is an undesirable article of food. 



We learned nothing with regard to the breeding places of shrews. As 

 to season of birth and the numbers of young in a litter, only the following 

 records can be offered: (1) Sierra Nevada Shrew, Mono Lake Post Office, 

 May 21, 1916: 6 embryos. (2) Yosemite Shrew, Chinquapin, June 13, 

 1915: 4 small embryos. (3) Dusky Shrew, Mount Hoffmann, June 27, 

 1915 : 6 large embryos ; Porcupine Flat, June 29, 1915 : 4 large embryos ; 

 Tuolumne Meadows, July 7, 1915 : 5 large embryos ; Merced Lake, August 

 24, 1915 : 2 embryos. 



Navigator Shrew. Neosorex palustris navigator (Baird) 



Field characters. — Size about that of House Mouse; total length 6 to 6% inches 

 (150-165 mm.), tail about 3 inches (75 mm.) long. Snout pointed; fore and hind feet 

 of about same size and structure; ear inconspicuous. Pelage short, fine in texture; 

 hind toes fringed with short close-set hairs (pi. 20fl). Coloration black or hoary black 

 above, often with a distinct sheen; whitish on under surface. 



Occurrence. — Common in Canadian Zone and parts of Hudsonian Zone, on both 

 slopes of Sierra Nevada. Eecorded from Merced Grove Big Trees (5500 feet altitude) 

 and Chinquapin, eastward to Mono Lake Post Office and Walker Lake. Highest station, 

 10,350 feet altitude at Vogelsang Lake. Lives in and near swift-flowing streams. 

 Solitary. 



The Navigator Shrew is larger than any of the other shrews in the 

 Yosemite section and is more strictly an inhabitant of aquatic situations. 

 We did not find even one of the animals that was more than four feet from 

 running or standing water, and most of our specimens were taken imme- 

 diately at the water's edge. 



In structure the Navigator ShreAv exhibits marked adaptations for 

 existence in and near streams. The feet are large (pi. 20a) ; the toes of 

 the hind foot are obliquely placed and margined with close-set fringes of 

 hairs which serve like webbing to increase the surface of the foot. Further- 

 more, the pelage is of a rather distinctive type, like that found in aquatic 



