The pine forest habitat includes many diurnal species, such as the red squirrel, yellow-pine chipmunk, and Columbian ground squirrel. The white-tailed deer occurs here and, for most of the year, the mule deer. Snowshoe rabbits are usually present. Near rocks the bushy-tailed wood rat is common. Mice are scarce, probably because of the open nature of the surface of the ground. A night's trapping usually yields only a few _Peromyscus maniculatus_. The mammalian fauna of the marshes and streamside thickets is similar. Shrews including _Sorex vagrans_ and _Sorex obscurus_ are uncommon. Meadow mice, including _Microtus pennsylvanicus_, _Microtus longicaudus_, and more rarely _Microtus montanus_, are taken. THE ARID GRASSLANDS SUBDIVISION OF THE TRANSITION LIFE-ZONE This subdivision is so much utilized by man where it occupies any considerable areas, and is of such a transitional nature elsewhere, that it is important for only a few native wild mammals. The sagebrush vole (_Lagurus curtatus_) seems to be confined to the arid grasslands. The white-tailed jack rabbit is now found principally in the arid grasslands, but its confinement there has resulted probably from competition with the black-tailed jack rabbit. The montane meadow mouse (_Microtus montanus_) is the only common, representative species. Many species from the Upper Sonoran Life-zone extend into the arid grasslands where conditions are suitable. These include _Reithrodontomys megalotis_, _Perognathus parvus_, _Citellus washingtoni_ and _Marmota flaviventris_. A few species more typical of the Arid timbered subdivision of the Transition Life-zone stray onto the arid grasslands. _Citellus columbianus_ and _Microtus longicaudus_ may be included here. THE UPPER SONORAN LIFE-ZONE The sagebrush desert in Washington is relatively uniform in nature. Several different habitats may be distinguished, such as sandy areas, open sage, dense sage, stony ground, and talus. Qualitatively, however, the mammalian fauna of these areas is surprisingly similar. Quantitatively, there are great differences. For example, the grasshopper mouse is rare in the open sage areas with hard, claylike soil but common on drifted sand. The harvest mouse is common in dense sage but rare in open sage or in open, sandy areas. Mammals are abundant on the sagebrush desert and typical species include: the black-tailed jack rabbit, Nuttall cottontail, Ord kangaroo rat, Great Basin pocket mouse, Townsend ground squirrel, Washington ground squirrel.