1936] 



MAMMALS OF OREGON 



207 



The mice are abroad throughout the year and seem to be about 

 equally active day and night. 



Breeding habits. There is little on record of their breeding habits. 

 The mammae are in 4 pairs, and the young, as in other species with 

 this arrangement, probably number 4 to 8. One old female taken at 

 Albany on October 2 contained 5 small embryos. 



Food habits. In food as in other habits they resemble M. mon- 

 tofrws, cutting and eating the tender parts of grass and tule stems 

 and roots, or drawing down the seed-laden tops for food. In the 

 grainfields they cut the stems in sections as the heads are drawn 

 down and eaten with sometimes considerable damage to the crop. 

 They are especially fond of clovers and alfalfa and are always eager 

 for rolled oats or grain with which the collector baits his traps. 



Economic status. There have been few complaints of damage 

 by these mice, but they have great possibilities for crop destruction. 

 On Government Island, in the Columbia River near Portland, in 

 1911, Jewett reported them as "simply swarming in the alfalfa 

 fields." The farmers had done nothing to check them but were 

 becoming alarmed and asked for instructions for poisoning them. 

 On one farm they had already killed about 80 young fruit trees. 



Such outbreaks, however, are insignificant in comparison with the 

 unnoticed but steady drain on farm products by even the normal 

 numbers of such mice over a wide extent of rich agricultural land 

 like that of western Oregon valleys. 



MICROTUS CALIFORNICUS CALIFORNICUS (PEALB) 

 CALIFORNIA MEADOW MOUSE 



Arvicola calif ornica Peale, U. S. Explor. Exped., v. 8, Mammalogy, p. 46, 1848. 



Type. -Collected at San Francisco Bay, Calif., by Titian R. Peale, on the 

 United States Exploring Expedition, 1838 to 1842. 



General characters. Large ; 

 ears conspicuous above fur; 

 hip glands in adult males well 

 concealed under fur; pelage 

 relatively coarse and harsh; 

 skull wide and angular with 

 incisive foramina widest pos- 

 teriorly, incisors abruptly de- 

 curved. Upper parts dull 

 buffy brown or clay color, 

 slightly lined with dark hairs ; 

 belly buffy gray or soiled 

 whitish ; feet gray ; tail bi- 

 color, brown above, buffy 

 below. 



Measurements. Typical 

 adults : Total length, 171 mm ; 

 tail, 49 ; foot, 21 ; ear (dry ) ,15. 



7>9*o/W7>4s/4V>M //7 Ttsihi FIGURE 45. Range of California meadow mouse, 

 L>^Str^OUl^On ana naOl- Microtus californicus oaUfomicus, in Oregon. 



tat. From a wide range 



in California these mice extend into Oregon in the Rogue River and 

 Umpqua Valleys, reaching their northernmost points of known dis- 

 tribution at Roseburg and Drain (fig. 45). They are found mainly 

 in the dry upland meadows and grassy slopes of the open valleys, 

 and belong primarily to Upper Sonoran Zone. 



