120 ANIMAL LIFE IX THE YOSEMITE 



at Pleasant Valley contained one embryo, and another obtained June 1, 

 3 miles east of Coulterville, contained 2 small embryos. By late autumn 

 (November), young born during the current year weigh about 5 ounces 

 (150 grams), which is about three-fifths the weight of adults. 



Gray Bushy-tailed Wood Rat. Neotoma cinerea cinerea (Ord) 



Field characters. — Size larger than Streator Wood Eat or House Eat; tail shorter 

 than head and body, with long hairs on sides forming a flat brush (figs. 12c, 15) ; pelage 

 thick and soft. Head and body 7 to 9% inches (180-237 mm.), tail 4% to 7% inches 

 (120-188 mm.), hind foot 1% to 1% inches (40-46 mm.), ear from crown 1 to IVs 

 inches (26-34 mm.); weight 9i/^ to IGV^ ounces (271-459 grams). Coloration above 

 sandy brown, tail somewhat darker; feet, and under surface of body and tail, pure white. 

 Workings: Sparse accumulations of sticks and other debris in crevices among rocks. 

 Droppings : Black, cylindrical, about % by % inch. 



Occvrrence. — Eesident in boreal parts of Sierra Nevada. Eecorded from near Gentrys 

 (5900 feet) and Little Yosemite Valley eastward to Williams Butte. Life zone, upper 

 Canadian and whole of Hudsonian. Lives in rock slides and in and about logs. Noc- 

 turnal ; partially colonial. 



The Gray Bushy-tailed Wood Rat is an inhabitant of the higher and 

 more easterly portions of the Yosemite section and so comes only to the 

 attention of those visitors who spend some time in the back country. When 

 human beings do become aware of the presence of this rodent it is because 

 the animal literally forces itself upon their attention. Campers tell many 

 tales, some humorous, some semi-tragic, of the activities of the big 'pack- 

 rat' or 'trade rat' among their belongings. 



The range of this species is separated from that of the foothill-inhabiting 

 Streator Wood Rat by a hiatus usually several miles in width and a gap 

 of at least 1500 feet in altitude. The nearest approach of one to the other, 

 according to our records, is that of streatori on the floor of the Yosemite 

 Valley to cinerea on the slopes close above Gentrys. The main range of 

 the bushy-tail involves the belt of country characterized by the alpine 

 hemlock, namely the Hudsonian Zone. A few of these rats live at or above 

 timber line, as on Mount Lyell (up to an altitude of 13,090 feet) ; and on 

 the east slope of the Sierras, as at Walker Lake and on AVilliams Butte, 

 they occur at much lower altitudes and in lower zones. 



In the Yosemite region the Bushy-tailed W^ood Rat is an inhabitant of 

 rock slides. A very few were captured away from rocks, but only enough 

 to emphasize the mass preference of the species for heaps of talus. There 

 are rock slides in the Transition and Canadian zones on the west slope 

 which to our eyes seem indistinguishable from those at higher levels, but 

 the bushy-tails do not inhabit them. Immediate competition with the other 

 near-related species is lacking, for the Streator Wood Rat is not found to 

 any large extent in the Transition Zone rocks and is entirely absent from 

 the Canadian. 



