1936] 



MAMMALS OF OREGON 



181 





Economic status. So far as known the habits of these mice are 

 mainly beneficial to man in the agricultural field, not only in destroy- 

 ing insects, but in keeping down the abundance of other rodents. 

 Undoubtedly some of the insects eaten are of predatory and beneficial 

 species, but the check on abundance would be greatest in the numer- 

 ous and usually most destructive species, such as grasshoppers, 

 crickets, cockroaches, beetles, and beetle larvae. Some of the most 

 abundant predatory species, such as ants and myriapods, are re- 

 jected by them, and others do not commonly come within their reach. 

 The number of adult mice they are able to capture is probably not 

 great, but their fondness for young mice would indicate that these 

 might furnish a considerable item of their summer diet. 



The possibility of using them in gardens, greenhouses, cellars, or 

 other restricted areas to control insect pests has been considered but 

 not demonstrated. 



Their destruction of ground-dwelling and burrowing insects 

 locally may be almost equal to that of the birds on insect life above- 

 ground. 



PEROMYSCUS MANICULATUS GAMBELII (BAIRD) 



GAMBEL'S DEER MOUSE; WHITE-FOOTED MOUSE; MEKO-KA of the Klamath 



(C. H. M.) 



Hesperomys gambelil Baird, Mamm. North Amer., p. 464, 1857. 



Type. Collected at Monterey, Calif., by W. P. Trowbridge about 1854. 



General characters. Size medium (pi. 32, B) ; tail less than half of total 

 length; ears smaller than in rubidus, colors paler. In summer, adults, upper 

 parts light cinnamon brown ; 

 top of tail the same; feet, 

 lower parts, and lower half of 

 tail white or whitish. Im- 

 mature, slaty gray above, 

 whitish below. Colors bright- 

 est in winter. 



Measurements. Average 

 of a series of typical adults: 

 Total length, 159 mm; tail, 

 72; foot, 20; ear (dry), 15. 



Distribution and habi- 

 tat. This is a widely 

 distributed form, ranging 

 from Baja California to 

 central Washington and 

 covering most of Oregon 

 east of the Cascades, as 

 well as the less heavily 

 timbered part of the Cascade Range, and the upper Rogue River Val- 

 ley from Grants Pass to Ashland and across to the Klamath country 

 (fig. 35). Its place is taken in the southeastern corner of the State 

 by P. m. sonoriensis, and in the northeastern corner by P. m. arte- 

 misiae. It belongs to the more open, semiarid area lying back from 

 the humid coast region and reaching to the edges of the more arid 

 interior. As it is mainly a color variety of its group, humidity, 

 light, and shade determine its range, rather than altitude and life- 

 zone factors. Specimens taken from sea level to timber line have 



FlGDRE 35 '~ Ran ?em f 



maniculatu8 



