1936] 



MAMMALS OF OREGON 



191 





as shown by embryos, usually number 4 to 6. There are records of 

 embryos in specimens taken in almost every month of the year, and it 

 seems probable that several litters may be produced in a year by 

 each female. 



Food habits. Like many other rodents, they live on partly green 

 vegetation, grass, and other plants, and the seeds of grass and other 

 grains. Their little stomachs often show mainly green food and 

 again mainly the white starchy dough of seeds. 



Economic status. A small quantity of grass, other forage plants, 

 and seeds are consumed by these little animals, which added to that 

 taken by numerous other rodents causes a serious loss each year to 

 the farmers. 



CLETHRIONOMYS CALIFORNICUS CALIFORNICUS (MEEBIAM) 

 CALIFORNIA RED-BACKED MOUSE 



Evotomys californicus Merriam, North Amer. Fauna No. 4, p. 26, 1890. 



Type. Collected at Eureka, Calif., by T. S. Palmer, in 1890. 



General characters. The 



compact form, short legs, 

 small tail, and long fur that 

 partly conceals the ears, gives 

 the red-backs much the ap- 

 pearance of meadow mice, to 

 which they are related as a 

 subfamily. This is one of the 

 large, dark-colored, long- 

 tailed forms in which the red 

 of the back is much obscured 

 or sometimes wholly con- 

 cealed by black. Color of 

 adults, deep chestnut over the 

 back, much obscured by dusky 

 hairs ; sides dark buffy gray ; 

 belly buffy or ochraceous over 

 dark underfur; toes white or 

 whitish; tail indistinctly bi- 

 color, dusky above, whitish 

 below. Young much darker, 

 sometimes almost black. 



Measurements. Average of typical adults: Total length, 165 mm; tail, 53; 

 foot, 20.5; ear (dry), 10. 



Distribution and habitat. The coastal area of western Oregon 

 and northwestern California, mainly in heavy forests of humid 

 Transition Zone (fig. 40). 



General habits This is a scarce or rarely collected species, repre- 

 sented in Oregon by specimens from only four localities Astoria, 

 Yaquina Bay, Wells, and Oregon City. The animals live mainly on 

 the ground, and are generally caught under old logs in the woods. 



They feed largely on green vegetation, grass, seeds, and various 

 small plants. They are eager for rolled oats or any kind of grain 

 used for trap bait. 



Little is known of their breeding or other habits. 



FIGURE 40. Range of the four forms of red-backed 

 mice in Oregon: 1, Glethrionomys calif ornicus caili- 

 fornicus ; 2, G. c. obscurus; 3, G. c. mazama*; 4, 

 G. gapperi saiuratus. Type localities circled. 



