636 



THE MONTHLY BULLETIN. 



of squirrels, with results already given. These, summarized, show that 

 one ounce of dry grain or seeds, or four ounces of green vegetation, is 

 consumed each day by an average California Ground Squirrel. If we 

 take fifty pounds of green stuff as representing the amount of forage 

 consumed daily by one steer on open range, then 200 squirrels would 

 appropriate the forage which would keep one steer. Twenty squirrels 

 would eat as much as one sheep, and this last estimate would be most 

 significant, because sheep graze closer and hence the competition here 

 would be sharpest. 



Expressing this relationship in another way, taking the average popu- 

 lation of ground squirrels on open range as one per acre or 640 per square 

 mile, the squirrels on each square mile appropriate the forage of three 

 steers or 32 sheep. If the entire range of the California Ground 

 Squirrel be taken into account and be supposed to consist purely of 

 grazing lands (and so of minimum land value) grazed to their fullest 

 capacity, then the squirrels of this species take the place of 160,000 

 cattle or 1,600,000 sheep. Of course, it is not likely that the squirrels 

 come into actual close competition with livestock in ordinary years ; but 

 in extra dry years, such as that of 1917-18, when all the living things 

 which depend on vegetation for support are hard pressed to maintain 

 existence, then the squirrels cannot help but crowd the cattle interests 

 of the country, which are of such vital human importance. 



FISHER GROUND SQUIRREL. 

 Citellus beecheyi fisheri (Merriam). 

 plate v. 



Other names. — Fisher Spermophile ; Digger Squirrel, part; Spermophilus beecheyi, 

 part; Spermophilus beecheyi fisheri; Spermophilus grammurus fisheri; Citellus 

 variegatus fisheri; Citellus grammurus fisheri; Otospermophilus beecheyi fisheri; 

 Spermophilus grammurus beecheyi, part. 



Field characters. — As for the Beechey Ground Squirrel, differing in paler tone of 

 general coloration, and in more extensive and purer white shoulder patches. Length 

 of body alone about 9| inches, with tail about 6 inches more. 



Description. — In all pelages: Closely like beecheyi, except for pallid tones of 

 color predominantly light cinnamon-drab, and extension of light areas. The shoulder 

 patches in typical fisheri are much clearer white and tend to meet on the fore back 

 between the shoulders; in some specimens the mid-dorsal grayish brown stripe is 

 almost obliterated by these white invasions. The back of the ear is usually grizzled 

 buffy in fisheri instead of chiefly black, and its hinder margin and base are silvery 

 white. The lower surface of the body and the upper surfaces of the feet are usually 

 much whiter, less buffy, than in beecheyi. 



Color variations. — The range of individual and seasonal variation in fisheri seems 

 to be about the same as in beecheyi. 



The extreme of the characters of fisheri are developed in the Inyo region, and grad- 

 ual intergradation or blending takes place towards beecheyi chiefly through southern 

 Tulare and Kern Counties. The dotted line on the map (fig. 17) separating the ranges 

 of fisheri and beecheyi represents no place of abrupt demarcation but only somewhere 

 near the middle of the belt of intergradation. Many individuals from the vicinity 

 of this hypothetical line are so nearly betwixt typical beecheyi and typical fisheri 

 that they can only arbitrarily be placed under one name or the other. This has been 

 done with such intermediate examples in the lists of specimens examined. 



44 



