BUREAU OF BIOLOGICAL SURVEY. 339 



ings. Funds contributed by State and count}- appropriations and 

 those expended by landowners in this cooperative undertaking during 

 the year amounted to $799,974. Poisoned gi'ain amounting to 1,008 

 tons was prepared and distributed under the direction and supervi- 

 sion of bureau reprosenratives and 7."')-J:.803 pounds of carbon bisul- 

 phide were used in fumigating burrows to complete the eradication 

 of these rodents. Approximately 105,000 farmers and stockmen 

 took active part in clearing their lands. Taking into consideration 

 the low prices prevailing on farm and range jjroducts during the 

 year, it is estimated that a saving of $6,000,000 was effected. The 

 estimated annual saving of crops and range grasses since this work 

 Avas instituted on a large scale in 1916 totals $60,000,000. As the 

 lands are progressively and permanently cleared of these pests the 

 savings effected by the annual campaigns become cumulative, per- 

 manent additions to the productiveness of the lands. 



Field operations against prairie dogs and ground S(}uirrels are 

 l)eing conducted with a view to the complete eradication of these 

 rodents in a systematic manner over great units of land through such 

 initial and follow-up measures as may be required. From 75 to 95 

 per cent of the animals are usually destroyed by the first poison treat- 

 ment, and eradication is completed by later applications of poisoned 

 grain and carbon bisulphide or other fumigating agents. Many coun- 

 ties throughout tlie West. ])reviously heavily infested, have been 

 thus cleared to a point wliere only an occasional animal can be found, 

 Avhile some counties report complete eradication of prairie dogs this 

 year. The following extracts from a letter from a prominent stock- 

 man in Arizona indicate benefits accruing from this work: 



On .Tune 25, 1922, the la.st pruirie do.ir was exterminated from the counte.s 

 of Cochise and Graham. This was the result of three years of unite<l effort on 

 the i)art of over 800 stockmen and fiu'niers cooperating with two experts of the 

 Biological Survey. An areii 120 miles long an<l from 10 to 20 miles wide was 

 actually cleared of this pest. 



Three years ago when I visited this district. I rode through miles and miles 

 of prairie-dog infestation, and bare denuded lands lay on every side. To-day, 

 after these pests have been exterminated, the grass is Ivnee-lilgli, fat stoclc and 

 fertile farms are to he seen on every hand, and a prosperous conmumity is in 

 the malving where heretofore at least 5,000,000 prairie dogs had their way and 

 held in checlv the development of that fertile valley. 



It is estimated that the increased forage now made possible will support at 

 least 50,000 head of sheep, and farmers are now growing alfalfa and grain on 

 ground whidi was formerly so heavily infested- with prairie dogs tliat it was 

 quite impossil)le to rai.se anything. 



As the county eradication campai'gns reach a point where the few 

 remaining rodents are no longer regarded as a menace there is often 

 a tendency for landowners to slacken in the work. Definite effort is 

 made by the bureau to have the w-ork continued to complete extermi- 

 nation in order to insure against the rodents again reinfesting the 

 lands. A number of counties which failed to push the follow-up* 

 work suffered considerable reinfestation and have now taken up the 

 work in earnest with a view to being permanently rid of. these de- 

 structive animals. The progress of the cooperative campaigns is 

 seriously impeded, owing to insufficient Federal funds to clear Fed- 

 eral lands bordering private holdings. In many places this deters 

 local activity, which would respond promptly but for the lack of 

 mone}^ to enable the bureau to do its part. 



