•120 



was 

 ]>r;iii 



ferl i 



A. 



Yearbook of th, Department of Agriculture, 1020. 



being reduced from 10 to 50 per cent or more by the 

 ie doga and ground squirrels, which occupied the most 

 eand favorably situated valleys and bench lands, denud- 

 ing them of grass and render- 

 ing (hem useless for pasturage 

 purposes, it became evident that 

 eradication of these animals was 

 the most practical way of provid- 

 ing additional forage to maintain 

 and increase flocks and herds. 



Fortunately, positive evidence 

 that the carrying capacity of pas- 

 ture ranges could be greatly in- 

 creased by this means was at 

 hand. Large areas of Govern- 

 ment lands, cleared of rodents bv 

 Biological Survey field parties, 

 had shown quick recovery of for- 

 age grasses and a marked increase 

 in the number of cattle and sheep 

 that could be carried on them. 

 Smaller demonstration plots, 

 which had been established under 

 similar conditions to illustrate the 

 difference in productivity between 

 infested and cleared areas, showed 

 grass knee high on the land where 

 rodents had been destroyed and 

 reinvasion prevented, as con- 

 trasted with grass cropped close 

 to the ground on land imme- 

 diately adjoining, where the ro- 

 dents had been left in their usual 

 numbers. 



Typical Grass Specimens from 

 Experimental Plots. 



A, The best samples found in the inclosure 

 where the prairie-dog population was nor- 

 mal. B, Sample of normal p'"duction in 

 adjacent plot, where prairie do^s had been 

 eradicated and reinfestation prevented. 



"7 



