122 ANIMAL LIFE IX THE YOSEMITE 



This species is less of a builder than its foothill cousin. Nowhere did 

 we find the large accumulations of material that the Streator Wood Rat 

 gathers. In a few places bushy-tails had accumulated twigs, sticks, old 

 bones, and similar material in crevices among the rocks, much after the 

 manner of tiie Streator Wood Rat in the boulder taluses of Yosemite Valley. 

 But many of the localities inhabited by the bushy-tail were entirely devoid 

 of building material of any sort. Since there are, in such places, many 

 crevices within the rocks in which the animals may take shelter, they have, 

 perhaps, no need to build elaborately. In those cases w^here we saw no 

 external evidences of a nest, there may have been inhabited shelters deep 

 down among the rocks where human beings and the larger carnivores could 

 never penetrate. 



The young of the Bushy-tailed Wood Rat are produced during the mid- 

 summer season. One female, taken in Lyell Caiion on July 17, 1915, 

 contained 3 embryos. The females have only four teats, which suggests 

 that the litters are small. Several females captured between July 9 and 21, 

 1915, gave evidence of having recently suckled young. By the last week 

 of August young were being trapped in considerable numbers and were 

 then from one-fourth to one-half the weight of the parents. Their juvenal 

 pelage is very soft and short and lacks the prominent sandy brown overcast 

 seen on adult animals. At this age the tail is only beginning to show the 

 lengthened hairing at the sides and end. 



Yosemite Meadow Mouse. Microtus montanus yosemite Grinnell 



Field characters. — Body size about three times that of House Mouse; tail short 

 (fig. 16a), less than % head and body; pelage long and lax; ear nearly buried in fur. 

 (See fig. 20b.) Head and body 4% to 5% inches (112-138 mm.), tail 1% to 2^^ 

 inches (35-54 mm.), hind foot about % inch (20-22 mm.), ear from crown % to % inch 

 (10-17 mm.); weight 1% to 2% ounces (38.0-74.8 grams). Coloration dark brown 

 above, sometimes with a reddish tinge on back; under surface dark gray. Workings: 

 Pathways or runways 1 to 1^/^ inches wide, cut along surface of turf and connecting 

 \vith small round holes in earth, which are always open. 



Occurrence. — Common resident chiefly in Canadian and Hudsonian zones on both 

 slopes of Sierra Nevada. Rroorded from Gentrys (on Big Oak Flat Road) and from 

 Mono Mea<low (south of Glacier Point) eastward across the mountains to Mono Lake 

 Post Office and to near Williams Butte; present in numbers on floor of Yosemite Valley. 

 Lives in meadows and grasslands, usually at no groat distance from water. Active to 

 some extent during daytime, but otherwise nocturnal. 



The level or slo])ing grasslands of the Yosemite region are inhabited by 

 many of the small furry-coated animals known popularly as field mice and 

 to students of natural history as meadow mice or voles. Two distinct 

 groups are represented, a long-tailed, free-ranging type, the Cantankerous 

 Meadow Mouse, and several short-tailed species, the Tule, Mariposa, and 



