186 



NORTH AMERICAN FAUNA 



[No. 55 



Distribution and habitat. This form ranges widely over south- 

 ern British Columbia, western Montana, and northern Idaho, and 

 extends into northeastern Oregon in the Blue Mountain section (fig. 

 36). While found mainly in the Transition Zone in this area, iti 

 seems to have no zone limits but ranges from the lowest valleys 

 to timber; line on the mountains. These mice are more partial to 

 a forest and brush country but adapt themselves to almost any 

 habitat. 



General habits. In habits they show no well-marked differences 

 from Gambel's mouse, occupying as does that form the open 

 timbered area and brushy country, including the sagebrush from 

 which their name is taken. In the early settlement of the Blue 

 Mountains they were often troublesome in camps and new buildings 

 in the timber, and even in 1916, in a forest ranger's cabin near 

 Sheep Creek on the Wenaha Forest they kept running over the 

 writer all night and making a great racket in the cabin. The grub 

 box was) lined with tin and the pantry well screened, however, so 

 they could do no serious mischief. 



In food and breeding habits they are practically identical with 

 garribelii, and their economic status is essentially the same. 



PEROMYSCUS CRINITUS CRINITUS (MERRIAM) 

 IDAHO CANYON MOUSE 



Hesperomys crinitus Merriam, North Amer. Fauna No. 5, p. 53, 1891. 



Type. Collected at Shoshone Falls, Snake River Canyon, Idaho, by Merriam 



and Bailey, in 1890. 



General character's. A rather small, slender, silky-furred mouse with long, 



hairy tail, medium large, very thin, and nearly naked ears, mostly naked 



soles, and only four mam- 

 mae. Upper parts of adults 

 dull dark buffy gray with a 

 touch of rich buff along sides ; 

 top of tail dark brown or 

 blackish ; feet, lower parts, 

 and lower half of tail white 

 or whitish. Immature, ashy 

 or slaty gray over upper 

 parts. 



Measurements. Average of 

 typical adults: Total length, 

 176 mm; tail, 95; foot, 20; 

 ear (dry), 16. 



Distribution and habi- 

 tat. These beautiful lit- 

 tle mice are found in the 

 Great Basin area of Ne- 

 vada, Utah, Idaho, and 

 Oregon wherever deep canyons and lava-rock cliffs and rimrocks 

 afford their favorite habitat in arid Upper Sonoran Zone (fig. 37). 

 In Oregon they are found in the Snake, Malheur, and Deschutes 

 River Valleys wherever there are suitable cliffs. 



General habits. Bock, cliff, and canyon dwellers, these silky little 

 mice must be expert climbers among and over the rocks. Their 

 long, well-haired, and almost bushy tails undoubtedly serve to 

 steady and balance them on lofty walls, or to guide and steer them 



FIGURE 37. Range of the silky cliff mouse, Peromys- 

 cus crinitus crinitus, in Oregon. 



