262 ECONOMIC MAMMALOGY 



.the remainder to their underground storehouses." At a single stack 

 three hundred were trapped and many more poisoned; two hundred 

 were seen about one barley stack and later at the same place one hun- 

 dred and fifty-eight were ''in sight at one time." A few hours after 

 poison was set out one hundred and fifteen dead squirrels were 

 picked up on a six-acre field. The flesh of the young squirrels is good 

 and they were sold in the San Francisco markets until it was discovered 

 that they were one of the disseminators of bubonic plague during the 

 epidemic there. 21 



The Columbian ground squirrel (Citellus columbianus) is said to be 

 the most important host of the spotted fever tick. It prefers green 

 vegetation to ripe seeds and grains more than most ground squirrels 

 do, including alfalfa, clover, timothy, garden vegetables, etc. One 

 farmer for six years could not get a crop because of these squirrels, 

 but after he cleaned them out he got 35 bushels of wheat per acre. One 

 company lost 45,000 young trees in one year through their depre- 

 dations. Their burrows injure irrigation systems. 22 Two tracts of 

 land were fenced to retain these squirrels and two check tracts fenced 

 to exclude them. The check tracts yielded 41 pounds of wheat to each 

 500 square feet, the infested tracts only 4 pounds. The destruction of 

 wheat was 50 1/3 pounds for each squirrel, worth then $1.76, and 

 there were 25 squirrels to the acre. 23 



Each Oregon ground squirrel (C. or eg onus) is said to consume 

 30 grams of forage daily, and in some localities there are 70,000 of 

 them to the square mile, consuming 2 tons of green forage a square 

 mile daily, which would support 90 head of cattle. 24 A Franklin ground 

 squirrel (Citellus franklini) killed and ate a portion of a young rabbit 

 and another was seen chasing a striped ground squirrel. 25 Of 35 

 stomachs of the chestnut-tailed ground squirrel (Callospermophilus 

 lateralis castanurus), "all but ten contained remains of insects (grass- 

 hoppers, beetles, flies and larvae). Most of them contained also seeds 



21 Merriam, The California ground squirrel, U. S. Biol. Surv. Circular No. 76, 

 1910. Rucker, Plague among ground squirrels in Contra Costa County, California, 

 Reprint No. 38 from U. S. Public Health Reports, xxiv, No. 35, 1909. Dixon, Con- 

 trol of the California ground squirrel, Univ. California Agric. Exper. Sta. Circular 

 No. 181, 1917. 



22 Birdseye, Some common mammals of western Montana in relation to agricul- 

 ture and spotted fever, Farmers' Bull., No. 484, p. 10, 1912. 



23 Shaw, The cost of a squirrel and squirrel control, Washington Agric. Exper. 

 Sta. Bull. No. 118, pp. 1-19, 1920; Journ. Mammalogy, I, 192, 1920. 



24 Grinnell and others, California ground squirrels, California Comm. Horticulture 

 Bull, vn, 595-807 1919; Journ. Mammalogy, i, 97-99, 1919. 



25 Johnson, An observation on the carnivorous propensities of the gray gopher, 

 Journ. Mammalogy, in, 187, 1922. 



