704 THE MONTHLY BULLETIN. 



SUMMARY OF POINTS OF SPECIAL IMPORTANCE FROM 

 THE STANDPOINT OF GROUND SQUIRREL CONTROL. 



From the foregoing account of the natural history of the ground 

 squirrels of California the following facts and inferences stand out as 

 seemingly of special importance in connection with the determination 

 and application of methods of ground squirrel control. 



1. Of the eighteen kinds of ground squirrels occurring within the 

 limits of the state, there appear to be only four meriting any particular 

 consideration from an economic standpoint. These four are the Cali- 

 fornia (or Beechey), the Oregon, the Fisher and the Douglas ground 

 squirrels, here named in the estimated order of importance (see fig. 30). 

 All the other fourteen kinds are, for the present at least, negligible, in 

 most of the cases because they inhabit areas not cultivated by man. 



2. The Oregon Ground Squirrel is less than half the size of a ''dig- 

 ger" squirrel, but it is ordinarily present in much greater numbers 

 per given area within its range (most of Siskiyou, Modoc and Lassen 

 counties) than is any one of the "digger" squirrels in its range. The 

 Oregon inhabits open grass lands and hence comes into sharp competition 

 with cattle interests. 



3. The Oregon Ground Squirrel is more of a grass eater than a seed 

 or grain eater, and the most successful method of poisoning should 

 involve the selection of an appropriate bait accordingly. It does not 

 store up food to the extent that the "digger" squirrels do. The Oregon 

 Ground Squirrel, more than any of the "digger" category, is subject 

 to a sharply defined period of hibernation, and this involves all the 

 individuals, of whatever age. 



4. The California Ground Squirrel is our species of greatest aggregate 

 numbers and is the one which is most widely distributed over the 

 cultivated parts of the state. Its close relatives, the Fisher and Douglas 

 ground squirrels, are known along with the California as "digger" 

 squirrels ; regarding most of the following considerations the three may 

 be classed together. 



5. Because of relatively large size the individuals of the "digger" 

 category are able to inflict serious loss. Adults average 1| to 1^ pounds 

 in weight, and are easily able to consume -^ ounce of dry grain or 2 

 ounces of green forage at a meal. 



6. On open range and pasture lands these squirrels feed largely on 

 alfilaria and bur clover, two of the most valuable forage plants in the 

 state. The squirrels are then serious competitors for subsistence against 

 the flocks and herds upon which man depends for his own support. 

 On cultivated ground these squirrels feed upon or destroy in other 

 ways grain and fruit crops to a very large extent where present even 

 in numbers not above those reached on wild land. The tendency seems 

 to be to increase to extraordinary numbers on cultivated lands unless 

 effectively cheeked by man. This is due both to improvements of food 

 conditions from the standpoint of the squirrel, and to removal of its 

 natural enemies by man either purposefully or thoughtlessly. 



112 , 



