How TO Combat Rabbits, etc. 331 



Valley near Hereford, and westward toward »^he Huachuca Mountains; 

 and in the upper part of the San Simon Valley. The grass on much of 

 these 250 sections in the county has been destroyed, and is rapidly being 

 destroyed on the balance of this area. 



Assuming 250 sections of land in Cochise County infested by these 

 animals, a conservative estimate of the value of this area before the 

 prairie dogs reduced it may be made from the number of cattle it would 

 support. Twenty-five acres of average range in Sulphur Spring Valley 

 will support one yearling for one year. Two hundred and fifty sections, 

 160,000 acres, will therefore support 6,400 yearlings which at a value 

 of $25 each would be worth $160,000. This is a conservative estimate 

 of the annual damage doen by these pssts in one county. 



The means by which to prevent this enormous loss is to exterminate 

 the prairie dogs by poisoning them. This work should be planned, un- 

 dertaken and carried out on a community, state-wide basis, although 

 individuals can profitably keep them killed off their own land. The 

 State Legislature (Session laws of Arizona, 1917, Chapter 48) has pro- 

 vided that, upon petition of 100 residents of any county a tax of one- 

 half mill may be assessed, and the resulting fund used to purchase 

 and prepare poisons and distribute them to landholders for use against 

 rodent pests. This law should be strengthened by compelling every land- 

 owner to kill the "dogs" on his holdings. This should apply, also, to 

 state and school lands. The National Government, through the Biologi- 

 cal Survey, will co-operate by killing the "dogs" on Forest Reserves and the 

 public domain, as it is now doing in the northern part of the State. 

 Advisory assistance may also be rendered to communities and individuals. 



According to the U. S. Biological Survey there are seven species of 

 prairie dogs. There are two distinct species in Arizona, — the small 

 species in the northern part of the State and the large species, which is 

 found in the Sulphur Spring Valley. According to Mr. D. A. Gilchrist 

 of the U. S. Biological Survey, who has charge of predatory animal ex- 

 termination work in Arizona, and who has had experience in poisoning 

 these pests in both sections of the State, the small northern spxies hiber- 

 nates during winter. This species, therefore, must be poisoned in spring 

 and summer, when the grass is good, and hence it is more difficult to kill 

 with poisoned bait than the southern species which is active the entire year 

 and can be killed easily by putting out poisoned bait in winter, spring or 

 late fall. However, in Cochise County, best results have been secured by 

 poisoning during the dry months of March, April and May. 



Mr. Gilchrist and the writer tested milo, feterita, wheat and rolled 

 barley for poisoned bait for prairie dogs in the Sulphur Spring Valley. 



