THE GROUND SQUIRRELS OF CALIFORNIA. 787 



The work during the 1918 season has been outside the forests on 

 public and Indian lands adjacent to farming land. The acreage treated 

 up to October 1 is as follows: 



Indian Lands. Acres 



In Mendocino County 36,495 



In Modoc County __ 640 



In Tulare County 3,100 



In Lake County 485 



40,720 



Public Lands. Acres 



In Mendocino County 5,860 



In Shasta County 1,160 



In Modoc County 20,955 



In Lassen County 26,685 



In Tulare County 8,600 



In Kern County 12,299 



In Merced County 18,490 



In Santa Barbara County : — 5,875 



99,924 



Acreage, as shown by reports not yet complete, treated in co-operation 

 with the Rodent Control Division of the State Commission of Horti- 

 culture, in which the Bureau of Biological Survey furnished the poison 



and the state provided the labor: 



Acres 



In San Luis Obispo County 13,600 



In Glenn County 8,000 



In Tehama County 5,619 



27,219 



Total acreage treated to destroy ground squirrels and pocket gophers 



in California 1 . 827,715 



The first operations on the forests were on those areas known to be 

 heavily infested, the open meadows and glades. It was found, however, 

 that the areas were soon reinfested because of the migratory habits of 

 the squirrels. They moved readily into new territory where feed was 

 found to be better than that in which they happened to be. To prevent 

 reinfestation due to this natural habit of the animals, it has been 

 necessary to treat both the open and timbered areas of the forests, even 

 though the infestation might be very light in the latter. A few breeding 

 animals left soon reinfest a vicinity, as they are very prolific. It is 

 quite necessary to kill the last squirrel. 



The infestation of the forests averaged about five burrows to the 

 acre. The poisoning crews consist of two to four men who work on 

 horseback wherever possible. They have bags of poison hanging from 

 the saddle horn and ride abreast about 25 yards apart, treating all 

 the land that is infested as they go. The thick brushy belt is not 

 infested with squirrels except along the edges. In brushy country one 

 man averages about 100 acres per day. 



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