650 THE MONTHLY BULLETIN. 



Rodent Control, of the Davis, Williams, Willows and Orland districts. 

 The reason for this is twofold: The Douglas Squirrels never did have 

 a secure foothold in the Sacramento Valley, such as the Beechey Squir- 

 rels have in the San Joaquin Valley; and the former, according to 

 current impression, takes the poisoned grain more readily. 



On the other hand, with the clearing of forest lands in the coast dis- 

 trict, through lumbering and homesteading, the squirrels are thought 

 to have extended their confines locally. At any rate, they have become 

 numerous where formerly absent altogether or present in such small 

 numbers as to have been overlooked by the average person. 



In certain sequestered valleys among the northern coast ranges we 

 have been assured of a loss to grain crops, where no effort at poisoning 

 the squirrels had been made, of from 5 to 25 per cent. In such cases 

 the squirrel population from the wild land immediately adjacent seemed 

 to have moved in en masse, as harvest time approached, to take advan- 

 tage of the special food supply thus made available. Nevertheless, the 

 Douglas Ground Squirrel, by reason of its relatively sparse population 

 over most of its range, and the ease with which it can be reduced in 

 numbers with reasonable effort, does not rank as of so much economic 

 importance as some other species. We would place it fourth among 

 our ground squirrels, giving precedence to the California, Oregon 

 and Fisher. 



ROCK SQUIRREL. 

 Citellus variegatus grammurus (Say). 



other names. — Plateau Ground Squirrel ; Rocky Mountain Ground Squirrel ; 

 Citellus grammurus. 



Field characters. — As for the Beechey Ground Squirrel, differing in longer tail and 

 grayer general coloration ; fore parts of body continuously grayish white, without 

 specially set-off shoulder patches. Length of body alone about 10^ inches, with tail 

 about 8 inches more. 



Description. — Summer pelage: Head dull buckthorn brown, grizzled on cheeks and 

 sides of snout ; eyelids dull white ; whiskers black ; backs of ears dull buffy brown, 

 insides of ears pinkish buff. Forward half of upper surface of body light gray, with 

 decided dusky mottling in transverse trend ; hinder half of upper surface, of a tawny- 

 olive tone, lighter on sides, and with similar transverse mottling. Whole lower surface 

 of body and upper surfaces of feet, pale pinkish buff, nearly white in some specimens ; 

 belly with grayish bases of hairs showing through. Tail considerably bushier than in 

 beecheyi, as well as being longer; length of hairs up to 50 mm. (2 inches) ; tips 

 of hairs more extensively white, thus nearly as in douglasii; dark and light intervals 

 on individual hairs same as in heecheyi, that is, three dark and four light, the latter 

 including the tipping. 



Color variations. — Wear and exposure to intense sunshine evidently accounts for 

 the yellowing of the pelage of one specimen at hand ; also the tail of the animal shows 

 a curious crinkling of the hairs as if scorched. An adult of date June 2 has the 

 forward half of the body in fresh new (summer) pelage ; this is relatively harsh in 

 texture, without underfur. Young less than half grown are colored almost exactly as 

 described above for adults, but the pelage on the under surface is very scanty, so 

 that the bare skin shows through extensively. No winter specimens are at hand from 

 within the state of California. 



Measurements. — Only two adult specimens are available from California. These 

 are from the Providence Mountains, eastern San Bernardino County, and show meas- 



58 



