PHENACOMYS 



Forest Tree Mouse. — Phenacomys silvicola A. B. Howell. 

 Resembling longicaudus in characters of long tail and toes, 

 but nose sooty and color warm brown. Upperparts cinna- 

 mon-brown, with some black-tipped hairs; sides slightly 

 paler; tail blackish; underparts whitish. Total length, 7.7 

 inches; tail vertebras, 3.5 inches; hind foot, .84 inch. 

 "Known only from the type locality, [Tillamook, Oregon] 

 and from Corvallis, Oreg.; undoubtedly confined to the 

 forested area of the humid coast belt." (Howell) 



The members of the genus Phenacomys are rare in collections 

 and comparatively little is known of their life-histories. The 

 group is confined to North America, and although it has 

 rather a wide geographic distribution and has been eagerly 

 sought by collectors, only a few specimens have been taken 

 in the thirty-seven years that Phenacomys has been known. 



These Mice frequent various habitats and have different 

 habits accordingly. Some forms, such as the intermedins 

 group, live in open, grassy parks in the forest, or in patches of 

 heather or moss; albipes haunts borders of small streams in 

 humid forests ; while longicaudus and silvicola are arboreal and 

 have well-made nests in coniferous trees. The terrestrial 

 forms sometimes make well-defined runways, when the cover 

 is dense, similar to those of Meadow Mice. 



The nests of longicaudus are large affairs made of the 

 needles and twigs of the fir (Douglas and Grand Firs), four to 

 ten inches deep and a foot or more in diameter. The average 

 height from the ground is about thirty feet and there is evi- 

 dence to indicate that perhaps it is mostly the females which 

 have an arboreal existence and that the males may be almost 

 entirely terrestrial in habit. Also there is reason to believe 

 that the Tree Mouse is rather more plentiful in its chosen 

 habitat than its scarcity in collections would indicate. 



The terrestrial forms of Phenacomys are very easily con- 

 fused with the small species of Meadow Mice. There are no 

 good field characters to afford a quick and certain identifica- 

 tion of these mammals and about the only safe way to proceed 

 is to suspect all small, short-tailed Aloles which are caught in 

 territory known to be inhabited by the genus. Specimens of 

 this rare genus are very desirable for museum collections, and 

 any large museum will be glad to identify these specimens for 

 the sake of adding to our knowledge of the group. 



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