1936] MAMMALS OF OREGON 193 



mountain forests of pine, spruce, fir, and hemlock. They are in part 

 diurnal, and seem to get into the traps about as much in daytime 

 as at night. Preble saw one running in the spruce woods near Anna 

 Creek in the early afternoon. In this, as in many other habits, they 

 resemble the common meadow mice, except that they rarely make 

 runways. 



They feed mainly on green vegetation and seeds, the contents of 

 the stomachs usually being dominated by green pulp of grass and 

 other plants. They are always eager for rolled oats, which are gen- 

 erally used for trap bait. 



There seems to be only one record of breeding for this subspecies, 

 a female taken near the Three Sisters, July 19, containing 4 well- 

 developed embryos; but the females have 4 pairs of mammae 2 

 inguinal and 2 pectoral and like other forms of the genus the young 

 probably vary from 4 to 8 in a litter. 



Their abundance and scarcity probably depend on the extent to 

 which they furnish food for the smaller carnivores and birds of prey. 



CLETHRIONOMYS GAPPERI SATURATUS (RHOADS) 

 BRITISH COLUMBIA RED-BACKED MOUSE 



Evotomys gappcri saturatus Rhoads, Acad. Nat. Sci. Phila. Proc., p. 284, 1894. 



Type. Collected at Nelson, British Columbia, by Samuel N. Rhoads, in 1892. 



General characters. Size about the same as mazama, but of the shorter tailed, 

 brighter colored yapperl group. Whole back of adults bright chestnut, with 

 scarce a trace of black-tipped hairs ; sides buffy gray, belly washed with 

 whitish or very pale buffy ; feet and lower surface of tail whitish or light gray. 

 Young duller and darker colored. 



Measurements. Average of several typical adults : Total length 149 mm ; 

 tail, 45; foot, 18.2; ear (dry), 12. 



Distribution and habitat. From a wide range over British Colum- 

 bia, Washington, and northern Idaho, this form of the eastern group 

 of red-backed mice comes into northeastern Oregon in the Blue 

 Mountain section, filling the Canadian Zone and coming down cold 

 slopes and gulches into what seems to be Transition (fig. 40). 



General habits. They are forest dwellers, but in Oregon are found 

 mainly in the open pine and spruce forests of the Rocky Mountain 

 type, living around the trees and logs and under cover of low vegeta- 

 tion in the driest parts of the forest as well as along streams and the 

 edges of meadows. They are to a great extent diurnal, and where 

 abundant are often seen in the daytime, running over the ground or 

 on logs, and occasionally up the trunks of trees. They have larger 

 eyes and ears, and are much more active and keen, than the meadow 

 mice and less restricted to cover and runways. In fact they rarely 

 make noticeable runways but burrow under the mellow surface of 

 the woods earth and leaves, and in part live in hollow logs and trees 

 or under loose bark of logs. 



Occasionally they are as abundant as meadow mice and are the 

 most abundant animal of their habitat. At Sled Springs, 25 miles 

 north of Enterprise, in April and May 1919, Cantwell reported them 

 taken every day in 75 percent of his traps, and in several of the 

 traps 1 every day for a period of 10 days. More often, however, 

 they are rather scarce and very irregular in distribution, seeming to 

 find existence possible only where there is especially favorable cover. 



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