14 BULLETIN 1227, U. S. DEPARTMENT OF AGRICULTURE 



rodents destroy 83 per cent of the blue-grama crop, the most impor- 

 tant forage grass of the region. These experiments were made under 

 conditions where the vegetation is at present maintaining itself; in 

 many areas the prairie, dogs destroy 100 per cent of the forage and 

 have to move out themselves. Such extreme destruction favors the 

 growth of unpalatable weeds, makes range recovery difficult, and 

 opens the way for soil deterioration through erosion. The prairie 

 dog has not been shown to have a single beneficial food habit. 



Prairie dogs and cattle come into direct, and, in times of drought, 

 deadly, competition. The evidence from these experiments indicates 

 that these rodents do not eat anything that cattle do not and that 

 the two eat the grasses in the same order of preference; sand 

 dropseed (Sporobolus cvyptandrus) is preferred to western wheat 

 grass (Agropyron smithii) and, when present with these, blue grama 

 (Bouteloua- gracilis) appears to be third in order of preference. The 

 wheat grass apparently endures grazing by both prairie dogs and 

 stock better than the dropseed. 



The impressive total of forage that may be destroyed by prairie 

 dogs clearly indicates the constant losses suffered almost unconsciously 

 by stockmen who utilize the open range in places where the rodents 

 have not been eliminated. The possible destruction of 80 per cent 

 of the forage, or even of a far smaller proportion, is serious enough 

 at any time, but in periods of drought it is likely to> be calamitous, 

 especially if in normal years the range is stocked to> capacity. In 

 some overgrazed areas the total eradication of prairie dogs, as well- 

 as the reduction of the number of cattle per unit area, apparently 

 will be necessar} 7 if the forage grasses are to continue in profitable 

 quantity. 



The original equilibrium between prairie dogs and grass has been 

 upset by man in his grazing of cattle and other livestock and in his 

 extermination of coyotes and other predatory animals. As an offset 

 the Biological Survey and its cooperators have undertaken system- 

 atic campaigns for the destruction of injurious rodents. Extension 

 of such campaigns is necessary if the prairie dog is to be eliminated 

 as a strong factor in the destruction of forage upon vast areas of 

 good stock ranges and in reducing profits of the livestock industry 

 there. 



