182 NOETH AMERICAN FAUNA [No. 55 



essentially the same characters. Open timber and brush land are its 

 main habitat. 



General habits. These mice adapt themselves to all sorts of cover 

 and conditions, from meadows, grassland, sagebrush, chaparral, open 

 coniferous and deciduous forests, to rocks, cliffs, and earth banks 

 wherever they obtain safe homes and a food supply. Generally they 

 are the most abundant mammal found within their range, causing 

 much annoyance to collectors by filling traps set for other more desir- 

 able specimens. Even out in the sagebrush country they are often 

 numerous where there is growth enough to hide them from owls. 

 Many live in burrows in the ground, usually those of pocket gophers 

 or other rodents, borrowed for the occasion, but rarely dug for 

 themselves. 



Breeding habits. The females have normally 3' pairs of mammae 

 2 inguinal and 1 pair of pectoral on 4 widely separated mammary 

 glands. The young are usually 4 to 6 in number, but in rare instances 

 as many as 8 or 9. They are born at all times of the year, but mostly 

 during the spring and summer months, and in some cases probably 

 several litters are produced during the year. The rate of reproduc- 

 tion depends in these as in other mammals on the nature and abun- 

 dance of their food supply. 



Food habits. Seeds constitute their principal food, including 

 almost every available kind, from acorns and hazelnuts down to the 

 smallest seeds of grass and many other tiny plants. Berries and 

 berry seeds are often eaten, also a little green foliage, and many 

 insects and probably insect eggs. Almost every kind of food is 

 acceptable to them, and in camp stores they sometimes do slight 

 mischief. 



Economic statute. Although exceedingly quick at running and 

 dodging and skillful at climbing and hiding, still these little mice 

 are an important article of diet for bobcats, foxes, coyotes, skunks, 

 badgers, marten, mink, and weasels. Next to the meadow mice they 

 probably feed more owls than any other mammal of their area, and 

 their abundance and scarcity have a direct relation to the numbers of 

 their enemies. While their destruction of insects may be of benefit 

 to vegetation in general and to some cultivated crops, their con- 

 sumption of seeds must in some cases, and especially in semiarid 

 areas, serve as a serious check to the reseeding of the vegetation, and 

 even to reforestation by many of the trees that scatter edible seeds. 

 The potential damage by a great number of these mice could be 

 heavy, but their hosts of enemies generally keep a fair balance of 

 abundance and prevent serious losses. 



The mice are easily poisoned or trapped, but it is generally better 

 economy to protect such of their enemies as are otherwise harmless 

 and leave the mice to natural control. 



PEROMYSCUS MANICULATUS RUBIDUS OSGOOD 

 RUDDY DEER MOUSE; WESTERN WOODS MOUSE; WHITE-FOOTED MOUSE 



Peromyscus oreas ruUdus Osgood, Biol. Soc. Wash. Proc. 14 : 193, 1901. 

 Peromyscus perimekurus Elliot, Field Columb. Mus. Pub. 74, Zool. Ser. 3 : 156, 

 1903. Type from Gold Beach, Oreg. 



Type. Collected at Mendocino City, Calif., by J. Alden Loring in 1897. 

 General characters. Large for the maniculatus group, tail about as long or 

 longer than head and body, slender, not crested ; ears medium, nearly naked ; 



